Method and apparatus for configuring multi-connectivity based on location in satellite networks

Abstract

The disclosure relates to a 5G or 6G communication system for supporting higher data transmission rates or higher stability than a 4G communication system such as LTE. A method and apparatus for adding a secondary node for multi-connection in a satellite network (or non-terrestrial network (NTN)) are disclosed.

Description

Technical Field

[0001] This disclosure relates to a method and apparatus for adding secondary nodes for multiple connections in a satellite network (or non-terrestrial network (NTN)). Background Technology

[0002] Given the successive generations of wireless communication development, technologies have been developed primarily for services aimed at humans, such as voice calls, multimedia services, and data services. Following the commercialization of 5G (5th generation) communication systems, the number of connected devices is expected to grow exponentially. These devices will increasingly connect to communication networks. Examples of connected things can include vehicles, robots, drones, home appliances, displays, smart sensors connected to various infrastructures, construction machinery, and factory equipment. Mobile devices are expected to evolve in various form factors, such as augmented reality glasses, virtual reality headsets, and holographic devices. Efforts are underway to develop improved 6G communication systems to provide a wide range of services by connecting hundreds of billions of devices and things in the 6G (6th generation) era. For these reasons, 6G communication systems are referred to as "beyond 5G" systems.

[0003] The 6G communication system, which is expected to be commercialized around 2030, will have peak data rates in the terabit (1,000 gigabits) range and wireless latency of less than 100 μsec, and will therefore be 50 times faster than 5G communication systems with 1 / 10 of their wireless latency.

[0004] To achieve such high data rates and ultra-low latency, 6G communication systems have been considered for implementation in the terahertz band (e.g., the 95 GHz to 3 THz band). It is anticipated that technologies to ensure signal transmission distance (i.e., coverage) will become more critical due to the more severe path loss and atmospheric absorption in the terahertz band compared to the millimeter-wave band introduced in 5G. As key technologies for ensuring coverage, it is necessary to develop radio frequency (RF) components, antennas, new waveforms with better coverage than orthogonal frequency division multiplexing (OFDM), beamforming and massive MIMO, full-dimensional MIMO (FD-MIMO), array antennas, and multi-antenna transmission technologies such as massive MIMO. Furthermore, new technologies for improving the coverage of terahertz band signals have been discussed, such as metamaterial-based lenses and antennas, orbital angular momentum (OAM), and reconfigurable smart surfaces (RIS).

[0005] Furthermore, to improve spectrum efficiency and overall network performance, the following technologies have been developed for 6G communication systems: full-duplex technology to enable uplink and downlink transmissions to simultaneously utilize the same frequency resources at the same time; network technologies to utilize satellites, high-altitude platform stations (HAPS), etc., in an integrated manner; improved network architectures to support mobile base stations and achieve network operation optimization and automation; dynamic spectrum sharing technology based on spectrum usage prediction via conflict avoidance; the use of artificial intelligence (AI) in wireless communication to improve overall network operation by utilizing AI from the 6G development design phase and internalizing end-to-end AI support functions; and next-generation distributed computing technologies to overcome the limits of UE computing capabilities through achievable ultra-high-performance communication and computing resources on the network, such as mobile edge computing (MEC), cloud, etc. Additionally, efforts continue to be made to enhance connectivity between devices, optimize networks, promote the software-defined networking of network entities, and improve the openness of wireless communication by designing new protocols for use in 6G communication networks, developing mechanisms for achieving hardware-based secure environments and secure data usage, and developing technologies for maintaining privacy.

[0006] The research and development of hyper-connected 6G communication systems, including human-to-machine (P2M) and machine-to-machine (M2M) communication, is expected to enable future hyper-connected experiences. Specifically, 6G communication systems are anticipated to provide services such as truly immersive extended reality (XR), high-fidelity mobile holograms, and digital replicas. Furthermore, 6G communication systems will enable services such as enhanced security and reliability in remote surgery, industrial automation, and emergency response, allowing for the application of technology across various sectors, including industry, healthcare, automotive, and home appliances.

[0007] In next-generation mobile communication systems, non-terrestrial networks (NTNs) are being considered, which combine mobile and satellite communications to extend communication coverage globally. NTNs are technologies that use satellites as relays to create communicable areas in regions where base stations cannot be installed for mobile communication due to physical or economic reasons.

[0008] It is predicted that the maximum number of currently operational or operational satellites for NTN can be increased to approximately 7,500, and therefore, the number of candidate satellites that each UE can connect to can increase from approximately 1 or 2 or approximately 10 to approximately 100. This creates an environment suitable for improving communication performance when user equipment (UE) uses multiple satellites. However, communication methods need to take this into account because satellites move at their own speeds according to different altitudes and orbits. Summary of the Invention

[0009] Technical issues

[0010] Therefore, one aspect of this disclosure is to provide a method and apparatus for improving the performance of direct communication with a UE when using a satellite system in a 6G mobile communication system.

[0011] More specifically, the purpose of this disclosure is to propose a method for configuring multiple connections for a UE using multiple satellites, taking into account the mobility of satellites.

[0012] Solution to the problem

[0013] A method performed by a terminal in a communication system according to an example of the present disclosure may include: receiving a measurement configuration message from a base station, the measurement configuration message including configuration information relating to a measurement report for at least one non-terrestrial network (NTN) cell, the configuration information including information relating to events in the measurement report; performing a measurement on at least one NTN cell based on the measurement configuration message; identifying, based on the measurement, an NTN cell among the at least one NTN cell that meets the triggering conditions of an event; and sending a measurement report message to the base station, the measurement report message including measurement results of the identified NTN cell, wherein the event-related information includes threshold information associated with the duration for which the at least one NTN cell can serve the terminal.

[0014] A method performed by a base station in a communication system according to an example of the present disclosure may include: sending a measurement configuration message to a terminal, the measurement configuration message including configuration information relating to a measurement report for at least one non-terrestrial network (NTN) cell; and receiving a measurement report message from the terminal based on the measurement configuration message, the measurement report message including measurement results of at least one NTN cell, wherein the configuration information includes information relating to events in the measurement report, and wherein the event-related information includes threshold information associated with the duration for which the at least one NTN cell is able to serve the terminal.

[0015] A terminal in a communication system according to an example of the present disclosure may include a transceiver and a controller configured to: control the transceiver to receive a measurement configuration message from a base station, the measurement configuration message including configuration information relating to a measurement report for at least one non-terrestrial network (NTN) cell, the configuration information including information relating to events in the measurement report; perform a measurement on at least one NTN cell based on the measurement configuration message; identify, based on the measurement, an NTN cell in the at least one NTN cell that meets the triggering conditions of an event; and control the transceiver to send a measurement report message to the base station, the measurement report message including measurement results of the identified NTN cell, wherein the event-related information includes threshold information associated with the duration for which the at least one NTN cell can serve the terminal.

[0016] A base station in a communication system according to an example of the present disclosure may include: a transceiver and a controller configured to: control the transceiver to send a measurement configuration message to a terminal, the measurement configuration message including configuration information relating to a measurement report for at least one non-terrestrial network (NTN) cell; and control the transceiver to receive a measurement report message from the terminal based on the measurement configuration message, the measurement report message including measurement results of at least one NTN cell, wherein the configuration information includes information relating to events in the measurement report, and wherein the event-related information includes threshold information associated with the duration for which the at least one NTN cell is able to serve the terminal.

[0017] Beneficial effects

[0018] According to this disclosure, by taking into account the mobility of satellites when reporting the measurements required for a multi-connectivity configuration, the measurement reporting process can be performed efficiently.

[0019] Furthermore, according to embodiments of this disclosure, the UE can reduce power consumption and resource consumption by performing appropriate measurements and measurement reports, and can prevent the ping-pong effect caused by satellite mobility in the connection configuration.

[0020] Furthermore, according to embodiments of this disclosure, when reporting additional information for multi-connection configuration, the overhead of measurement reporting is reduced, taking into account the limited wireless resources of NTN. Attached Figure Description

[0021] Figure 1 The structure of an LTE system according to an embodiment of the present disclosure is shown.

[0022] Figure 2 The wireless protocol structure of an LTE system according to an embodiment of the present disclosure is shown.

[0023] Figure 3 The structure of a next-generation mobile communication system according to an embodiment of the present disclosure is shown; Figure 4 A wireless protocol structure for a next-generation mobile communication system according to an embodiment of the present disclosure is shown.

[0024] Figure 5a This is a diagram illustrating an example of configuring a similar ground-stationary cell in an NTN according to this disclosure.

[0025] Figure 5b This is a diagram illustrating an example of configuring a mobile cell in an NTN according to this disclosure.

[0026] Figure 6a This is a graph illustrating the throughput performance in the case of direct communication between an NTN satellite and a handheld UE according to this disclosure.

[0027] Figure 6b This is a graph illustrating the line-of-sight (LOS) / non-LOS (NLOS) performance in the case of direct communication between an NTN satellite and a handheld UE according to this disclosure.

[0028] Figure 7 This is a diagram illustrating a comparison of signal strength in an NTN based on the location of the UE within the cell, according to an example of this disclosure.

[0029] Figure 8 This is a flowchart illustrating the measurement reporting operation of a UE according to an example of this disclosure.

[0030] Figure 9 This is a diagram illustrating a first example of an event in a measurement report according to an example of this disclosure.

[0031] Figure 10 This is a diagram illustrating a second example of an event in a measurement report according to an example of this disclosure.

[0032] Figure 11 This is a diagram illustrating a third example of an event in a measurement report according to an example of this disclosure.

[0033] Figure 12 This is a diagram illustrating a fourth example of an event in a measurement report according to an example of this disclosure.

[0034] Figure 13 This is a flowchart illustrating the measurement configuration operation of a gNB according to an example of this disclosure.

[0035] Figure 14 This is a flowchart illustrating a process for configuring multiple connections according to an example of this disclosure.

[0036] Figure 15a This is a diagram illustrating a method for configuring UE location information as GPS coordinates according to an example of this disclosure.

[0037] Figure 15b This is a diagram illustrating a method for configuring UE location information as GPS coordinates according to an example of this disclosure.

[0038] Figure 15c This is a diagram illustrating a method for configuring UE location information as a grid-based index according to an example of this disclosure.

[0039] Figure 16 This is a diagram that comparatively illustrates a method for transmitting UE location information according to an example of this disclosure.

[0040] Figure 17 This is a flowchart illustrating an example of a process for configuring multiple connections based on UE location information, according to an example of this disclosure.

[0041] Figure 18 This is a diagram illustrating an example of a measurement configuration message according to this disclosure.

[0042] Figure 19 This is a diagram illustrating an example of a measurement report message according to this disclosure.

[0043] Figure 20 This is a block diagram illustrating the structure of a UE according to an embodiment of the present disclosure.

[0044] Figure 21 This is a block diagram illustrating the structure of a base station according to an embodiment of the present disclosure. Detailed Implementation

[0045] The operating principle of the invention will be described in detail below with reference to the accompanying drawings. In the following description of the invention, detailed descriptions of known functions or configurations that have been determined to be relevant may unnecessarily obscure the essence of the invention, and such detailed descriptions will be omitted. Furthermore, the terms described below are defined in consideration of their function in the invention, and these terms may vary according to the intention or convention of the user or operator. Therefore, these definitions should be based on the entire contents of this specification.

[0046] In the following description of the invention, detailed descriptions of known functions or configurations will be omitted if they are determined to unnecessarily obscure the essence of the invention. Embodiments of the invention will be described below with reference to the accompanying drawings.

[0047] The terms used in the following description to identify connected nodes, to refer to messages, to refer to interfaces between connected nodes, and to refer to various identification information are examples provided for ease of explanation. Therefore, the present invention is not limited to the terms described below, and other terms referring to objects with equivalent technical meanings may be used.

[0048] For ease of explanation, this invention uses terms and names defined in the 1gPP LTE (First Generation Partner Program Long Term Evolution) standard. However, this disclosure is not limited to the above terms and names and can be applied equally to systems conforming to other standards. In this invention, for ease of explanation, eNB and gNB can be used interchangeably. That is, a base station described as eNB can represent a gNB.

[0049] Figure 1 The structure of an LTE system according to an embodiment of the present disclosure is shown.

[0050] refer to Figure 1As shown in the figure, the radio access network of the LTE system includes next-generation base stations (Evolved Node B (hereinafter referred to as ENB), Node B or base station) 1-05, 1-10, 1-15 and 1-20, Mobility Management Entity (MME) 1-25 and Serving Gateway (S-GW) 1-30. User equipment (hereinafter referred to as UE or terminal) 1-35 accesses the external network through ENB 1-05 to 1-20 and S-GW 1-30.

[0051] exist Figure 1 In LTE, ENBs 1-05 to 1-20 correspond to conventional Node Bs in the Universal Mobile Telecommunications System (UMTS). The ENB connects to UE 1-35 via a radio channel and plays a more complex role than a conventional Node B. In LTE systems, because all user services, including real-time services such as Voice over IP (VoIP) via the Internet Protocol, are served through a shared channel, a device is needed to collect state information such as the UE's buffer state, available transmit power state, and channel state, and ENBs 1-05 to 1-20 act as this device. Generally, one ENB controls multiple cells. For example, to achieve a transmission rate of 100 Mbps, the LTE system uses Orthogonal Frequency Division Multiplexing (hereinafter referred to as OFDM) as a radio access technology with a bandwidth of, for example, 20 MHz. Furthermore, the LTE system employs an Adaptive Modulation and Coding (hereinafter referred to as AMC) scheme to determine the modulation scheme and channel coding rate based on the UE's channel state.

[0052] S-GW 1-30 is a device that provides data bearers and generates or removes data bearers under the control of MME 1-25.

[0053] The MME is a device responsible for various control functions and mobility management functions of the UE, and it is connected to multiple base stations.

[0054] Figure 2 The wireless protocol structure of an LTE system according to an embodiment of the present disclosure is shown.

[0055] refer to Figure 2 The LTE system's radio protocols on both the UE and ENB sides include Packet Data Convergence Protocol (PDCP) 2-05 or 2-40, Radio Link Control (RLC) 2-10 or 2-35, and Media Access Control (MAC) 2-15 or 2-30. PDCP 2-05 or 2-40 is responsible for operations such as IP header compression / reconstruction. The main functions of PDCP are summarized below.

[0056] - Header compression and decompression: Robust header compression: ROHC only

[0057] - Transmission of user data

[0058] - During the PDCP reconstruction process for RLC AM, upper-layer PDUs are delivered sequentially.

[0059] - For split bearers in the DC (RLC AM only): PDCP PDU routing for transmission and PDCP PDU reordering for reception.

[0060] - For RLC AM, repeatedly detect the lower-layer SDU during PDCP reconstruction.

[0061] - For RLC AM, PDCP SDUs are retransmitted during handover, and for separate bearers in the DC, PDCP PDUs are retransmitted during PDCP data recovery.

[0062] - Encryption and decryption

[0063] - Timer-based SDU dropping in the uplink

[0064] The Radio Link Control (hereinafter referred to as RLC) 2-10 or 2-35 reconfigures PDCP Protocol Data Units (PDUs) to appropriate sizes to perform ARQ operations, etc. The main functions of the RLC are summarized below.

[0065] - Transmission of upper-layer PDUs

[0066] - Error correction via ARQ (AM data transmission only)

[0067] - Cascading, segmentation, and reassembly of RLC SDUs (UM and AM data transfer only)

[0068] - Resegmentation of RLC data PDUs (AM data transmission only)

[0069] - Reordering of RLC data PDUs (for UM and AM data transfers only)

[0070] - Duplicate detection (only for UM and AM data transmissions)

[0071] - Protocol error detection (AM data transmission only)

[0072] - RLC SDU discard (only for UM and AM data transfers)

[0073] - RLC Reconstruction

[0074] MAC 2-15 or 2-30 connects to multiple RLC layer devices configured in a single UE and performs operations to multiplex RLC PDUs into MAC PDUs and to demultiplex RLC PDUs from MAC PDUs. The main functions of the MAC are summarized below.

[0075] - Mapping between logical channels and transport channels

[0076] - Multiplexing MAC SDUs belonging to one or different logical channels into a transport block (TB) delivered to the physical layer on the transport channel / Demultiplexing MAC SDUs belonging to one or different logical channels from a transport block (TB) delivered from the physical layer on the transport channel.

[0077] - Scheduling Information Report

[0078] - Error correction via HARQ

[0079] Priority handling between logical channels of a UE

[0080] - Prioritization among UEs is achieved through dynamic scheduling.

[0081] - MBMS service identification

[0082] - Transmission format

[0083] - Fill

[0084] Physical layer 2-20 or 2-25 performs the following operations: channel coding and modulation of upper layer data to obtain OFDM symbols and deliver them via a wireless channel; or demodulation, channel decoding, and delivery of OFDM symbols received via a wireless channel to the upper layer.

[0085] Figure 3 The structure of a next-generation mobile communication system according to an embodiment of the present disclosure is shown.

[0086] refer to Figure 3 As shown in the figure, the radio access network of the next-generation mobile communication system (hereinafter referred to as NR or 5G) includes a next-generation base station (New Radio Node B, hereinafter referred to as NR gNB or NR base station) 3-10 and a New Radio Core Network (NRCN) 3-05. User terminals (New Radio User Equipment, hereinafter referred to as NR UE or NR terminal) 3-15 access the external network via NR gNB 3-10 and NR CN 3-05.

[0087] exist Figure 3In this context, NR gNB 3-10 corresponds to the Evolved Node B (eNB) of a conventional LTE system. The NR gNB connects to the NR UE 3-15 via a radio channel and offers superior service compared to a conventional Node B. In next-generation mobile communication systems, because all user services, including real-time services such as Voice over IP (VoIP) via the Internet Protocol, are served through shared channels, a device is needed to collect state information (such as the UE's buffer state, available transmit power state, and channel state) and perform scheduling accordingly; the NR gNB 3-10 acts as this device. Generally, one NR gNB controls multiple cells. To achieve ultra-high-speed data transmission beyond current LTE, next-generation mobile communication systems can provide bandwidths wider than the current maximum bandwidth, employing Orthogonal Frequency Division Multiplexing (hereinafter referred to as OFDM) as the radio access technology, and further integrating beamforming technology. Furthermore, next-generation mobile communication systems employ adaptive modulation and coding (hereinafter referred to as AMC) schemes to determine the modulation scheme and channel coding rate based on the UE's channel state.

[0088] The NR CN 3-05 performs functions such as mobility support, bearer configuration, and QoS configuration. The NR CN is responsible for various control functions and mobility management functions of the UE and connects to multiple base stations. Furthermore, the next-generation mobile communication system can interoperate with conventional LTE systems, and the NR CN connects to the MME 3-25 via a network interface. The MME connects to the eNB 3-30, which acts as a conventional base station.

[0089] Figure 4 A wireless protocol structure for a next-generation mobile communication system according to an embodiment of the present disclosure is shown.

[0090] refer to Figure 4 The next-generation wireless communication system's wireless protocols include NR Service Data Adaptation Protocol (SDAP) 4-01 or 4-45, NR Packet Data Convergence Protocol (PDCP) 4-05 or 4-40, NR Radio Link Control (RLC) 4-10 or 4-35, and NR Media Access Control (MAC) 4-15 or 4-30 on both the UE and NR gNB sides.

[0091] The main functions of NR SDAP 4-01 or 4-45 may include some of the following functions.

[0092] - Transmission of user plane data

[0093] - Mapping between QoS flows and DRB for both UL and DL

[0094] - Mark QoS flow IDs in both DL and UL groups

[0095] - Mapping of reflective QoS flows to DRB for UL SDAP PDUs

[0096] Regarding SDAP layer devices, RRC messages can be used to configure whether the UE uses the SDAP layer device header, or whether to use the SDAP layer device functionality for each PDCP layer device, each bearer, or each logical channel. If the SDAP header is configured, a 1-bit Non-Access Stratum (NAS) QoS reflection configuration indicator (NAS reflective QoS) and an 1-bit AS QoS reflection configuration indicator (AS reflective QoS) can be specified in the SDAP header, allowing the UE to update or reconfigure the mapping information for uplink and downlink QoS flows and data bearers. The SDAP header can include QoS flow ID information indicating QoS. QoS information can be used for data processing priority, scheduling information, etc., to smoothly support service.

[0097] The main functions of NR PDCP 4-05 or 4-40 may include some of the following functions.

[0098] - Header compression and decompression: ROHC only

[0099] - Transmission of user data

[0100] - Sequential delivery of upper-layer PDUs

[0101] - Out-of-order delivery of upper-layer PDUs

[0102] - PDCP PDU reordering for reception

[0103] - Duplicate detection of lower-level SDUs

[0104] - Retransmission of PDCP SDU

[0105] - Encryption and decryption

[0106] - Timer-based SDU dropping in the uplink

[0107] In the above functions, the reordering of the NR PDCP device refers to the function of reordering the PDCP PDUs received from the lower layer based on the PDCP sequence number (SN), and may include the function of transmitting data to the upper layer in the reordered order, the function of transmitting data directly without considering the order, the function of rearranging the order to record lost PDCP PDUs, the function of reporting the status of lost PDCP PDUs to the transmitting side, or the function of requesting the retransmission of lost PDCP PDUs.

[0108] The main functions of NR RLC 4-10 or 4-35 may include some of the following functions.

[0109] - Transmission of upper-layer PDUs

[0110] - Sequential delivery of upper-layer PDUs

[0111] - Out-of-order delivery of upper-layer PDUs

[0112] - ARQ function (error correction via ARQ)

[0113] - Cascading, segmentation, and reassembly of RLC SDUs

[0114] - Resegmentation of RLC data PDUs

[0115] - Reordering of RLC data PDUs

[0116] - Duplicate Detection

[0117] - Protocol error detection

[0118] - RLC SDU discard

[0119] - RLC Reconstruction

[0120] In the above functions, the sequential delivery of the NR RLC device refers to the function of transmitting RLC SDUs received from the lower layer to the upper layer in sequence. It may include the function of reassembling and transmitting the reassembled RLC SDUs if an original RLC SDU is divided into several RLC SDUs and then these RLC SDUs are received. It may include the function of rearranging the received RLC PDUs by referring to the RLC sequence number (SN) or PDCP sequence number (SN). It may include the function of rearranging the order to record lost RLC PDUs. It may include the function of reporting the status of lost RLC PDUs to the transmitting side. It may include the function of requesting the retransmission of lost RLC PDUs. It may include the function of transmitting only the RLC SDUs before the lost RLC SDU in sequence to the upper layer if there are lost RLC SDUs. It may include the function of transmitting all RLC SDUs received before the timer started in sequence to the upper layer if a predetermined timer has expired, even if there are lost RLC SDUs. It may also include the function of transmitting all RLC SDUs received so far in sequence to the upper layer if a predetermined timer has expired, even if there are lost RLC SDUs. Furthermore, RLC PDUs can be processed in the order they are received (regardless of the sequence number order, but according to the order of arrival) and subsequently delivered out of order to the PDCP device (out-of-order delivery). In the case of fragmentation, segments stored in a buffer or segments to be received later can be received, then reconstructed into a complete RLC PDU, processed, and delivered to the PDCP device. The NR RLC layer may not include cascading functionality, and this functionality can be implemented in the NR MAC layer or replaced by multiplexing functionality of the NR MAC layer.

[0121] In the above functions, out-of-order delivery of the NR RLC device refers to the function of directly delivering RLC SDUs received from the lower layer to the upper layer regardless of the order, and may include the function of reassembling and delivering RLC SDUs that have been divided into multiple RLC SDUs from one RLC SDU, and may include the function of storing the RLC SN or PDC PSN of the received RLC PDUs, sorting the sequence and recording the lost RLC PDUs.

[0122] NR MAC 4-15 or 4-30 can be connected to multiple NR RLC layer devices configured in a single UE, and the main functions of NR MAC can include some of the following functions.

[0123] - Mapping between logical channels and transport channels

[0124] - MAC SDU multiplexing / demultiplexing

[0125] - Scheduling Information Report

[0126] - Error correction via HARQ

[0127] Priority handling between logical channels of a UE

[0128] - Prioritization among UEs is achieved through dynamic scheduling.

[0129] - MBMS service identification

[0130] - Transmission format selection

[0131] - Fill

[0132] The NR PHY layer 4-20 or 4-25 can perform the following operations: channel coding and modulation of upper-layer data to obtain OFDM symbols and deliver them via a wireless channel; or demodulate and channel decode OFDM symbols received via a wireless channel and deliver them to the upper layer.

[0133] The non-terrestrial network (NTN) applied in this disclosure refers to a system that utilizes unmanned aerial vehicle (UAS) systems, including high-altitude platform stations (HAPS) and artificial satellites, as relays or base stations for terrestrial base stations. NTN is a technology applied to situations where satellites are used as relays to establish communicable areas in areas where base stations cannot be installed for mobile communications due to physical or economic reasons. Depending on the satellite's altitude, satellites that can be used in NTN can include geostationary orbit (GEO), medium Earth orbit (MEO), and low Earth orbit (LEO). For example, when using LEO satellites in NTN, the correlation between satellite altitude and latency can ensure relatively low latency.

[0134] Meanwhile, in NR (New Radio) NTN, the methods of operating satellite cells are classified as: 1) fixed earth cells, 2) quasi-fixed earth cells, and 3) moving earth cells.

[0135] First, a fixed Earth cell is a method of configuring a stationary satellite cell within a predetermined area, with its orbital period matching the Earth's rotation period. Fixed Earth cells can be implemented using GEO satellites.

[0136] Quasi-Earth-fixed cells and Earth-moving cells are methods for configuring satellite cells in satellites with orbital periods different from the Earth's rotation period, and can be implemented using satellites such as MEO / LEO. Quasi-Earth-fixed cells can be implemented by rotating the satellite beam antenna (beam steering) to configure a cell within a fixed area over a period of time, while Earth-moving cells can be implemented by rotating around the Earth while maintaining a constant angle of the beam illuminating the Earth's surface through the satellite beam antenna used to configure the cell. Unlike GEO satellites with Earth-fixed cells (which do not move relative to the Earth's surface and can configure a predetermined area within 24 hours), LEO and MEO satellites move relative to the Earth's surface, and therefore a single satellite cannot continuously configure a cell within a predetermined area.

[0137] Figure 5a This is a diagram illustrating an example of configuring a ground-stationary cell in an NTN according to the present disclosure, and Figure 5b This is a diagram illustrating an example of configuring a land mobile cell in an NTN according to the present disclosure.

[0138] More specifically, see reference Figure 5a Satellite (NTN carrier) S1 can move from time point t1 to time point t2 as shown in the diagram. Depending on the direction of movement of satellite S1, a satellite coverage area 501a can be formed at time point t1, and a satellite coverage area 502a can be formed at time point t2. In this case, the service area (satellite coverage area) formed by the corresponding satellite S1 is the largest area on the Earth's surface where a UE can receive communication services via the satellite, and can be defined as, for example, any area where the elevation angle (the angle between the Earth's surface (horizontal line) and the line-of-sight distance relative to a satellite located at a predetermined altitude above the horizontal line) has a minimum value. At this point, the minimum elevation angle can be configured as the minimum angular value at which the satellite can provide services to a UE located on the Earth's surface with a predetermined quality or higher, and it can be expected that the communication quality within the service area will be optimal when the elevation angle has a maximum value.

[0139] At the same time, such as Figure 5a As shown, satellite S1 can configure cell 500 in a fixed area within a predetermined time by rotating its satellite beam antenna (beam steering). A UE located within the service area of ​​the configured satellite cell can receive service from satellite S1 via cell 500 from time point t1 to time point t2. Subsequently, when the UE is located at an angle equal to or greater than the maximum antenna rotation angle of S1 due to the movement of satellite S1, the UE can be served by another satellite in the surrounding area. According to this scheme, in the case of quasi-earth fixed cells, after a predetermined time has elapsed, the next quasi-earth fixed cell will sequentially serve the area corresponding to that point.

[0140] refer to Figure 5b In a mobile Earth cell, because satellite S2 continuously maintains the angle of its beam illuminating the Earth's surface while rotating around the Earth, the service area is formed on the Earth's surface at time point t1, as shown by reference numeral 501b, but moves relative to the Earth's surface at time point t2, as shown by reference numeral 502b. As described above, in the case of a mobile Earth cell, because the beam antenna of the satellite configuring the cell moves while maintaining the angle of its beam illuminating the Earth's surface, the specific beam area moves from 51 to 52 over time.

[0141] As described above, with satellites constantly moving, the satellite configuration for a UE located at the cell edge changes every maximum of 256 seconds in a quasi-fixed Earth cell and every maximum of 22 seconds in a moving Earth cell. In other words, a UE in a Radio Resource Control (RRC) connected state relative to a specific satellite needs to perform a handover to another satellite at predetermined intervals in order to receive appropriate services from the satellite, and a UE in an RRC idle / inactive state should perform cell selection and reselection operations.

[0142] Furthermore, since the time a UE can connect to a corresponding satellite varies depending on whether the UE is located at the edge or center of the cell configured by the satellite, selecting a suitable satellite to serve the UE requires considering not only the satellite's mobility but also its orbit and the UE's location. This will be discussed later. Figure 7 This will be described. In the following text, for ease of description, satellites operating in the NTN will be described interchangeably with terms such as NTN cell, satellite cell, NTN satellite, and satellite.

[0143] At the same time, in the case of direct communication between the satellite and the UE, the characteristics of NTN also need to be considered.

[0144] Figure 6a This is a graph illustrating the throughput performance in the case of direct communication between an NTN satellite and a handheld UE according to this disclosure, and Figure 6b This is a graph illustrating the line-of-sight (LOS) / non-LOS (NLOS) performance in the case of direct communication between an NTN satellite and a handheld UE according to this disclosure.

[0145] In LEO-based communication scenarios, when considering direct communication between the NTN satellite and the UE, its throughput reaches 5% of the total throughput of a Very Small Aperture Terminal (VSAT), such as... Figure 6aAs shown, the overall throughput performance differs significantly between VSAT and handheld UE due to their significantly different antenna gain performance and different available frequency bands. The reduced throughput performance of handheld UEs is due to the decrease in signal-to-interference-plus-noise ratio (SINR) caused by inter-cell and inter-satellite interference, as well as the use of frequency division to address interference issues. Furthermore, handheld UEs may have a 3 dB polarization loss because it is difficult to distinguish between left-hand circular circular polarization (LHCP) and right-hand circular circular polarization (RHCP) using circular polarization, and significant performance degradation occurs when the satellite's orientation is not aligned with the handheld UE's orientation, leading to a decrease in throughput performance.

[0146] When considering direct communication between NTN satellites and the UE, it can also be identified that the difference in communication performance increases depending on whether the communication connection is line-of-sight (LOS) or non-line-of-sight (NLOS), such as... Figure 6b As shown. For example, in the NLOS case, due to an increase of approximately 25 dB in shadow fading and cluster loss, the throughput corresponding to UE performance is reduced to 1 / 10 or less compared to the LOS case. Based on data modeled for the probability of NLOS occurrence, the indication of LOS probability is only about 40% in dense urban scenes (e.g., at an elevation angle of 30°).

[0147] like Figure 6a and Figure 6b As mentioned above, when considering the characteristics of NTN itself, it is known that direct communication between satellites and UEs has poor connectivity. Furthermore, when satellites at different altitudes are used for direct communication with the UE, GEOs farther from the ground can have long round-trip times (RTTs), and LEOs may experience communication performance degradation due to high mobility, such as changing from LOS to NLOS. To address this issue, this disclosure proposes a multi-connection establishment method for UEs to connect to multiple satellites.

[0148] When a UE is configured with multiple connections implemented by multiple satellites, the gNB needs information to determine whether the satellite to be added to the connection is suitable for serving the corresponding UE. For this purpose, for example, the UE can send a measurement report as a signal strength value measured relative to other surrounding satellite cells to the gNB currently serving the UE (e.g., an NTN satellite). In this case, the signal strength based on the UE's location within the satellite-configured cell should be considered.

[0149] Figure 7 This is a diagram illustrating a comparison of signal strength in an NTN based on the location of the UE within the cell, according to an embodiment of the present disclosure.

[0150] like Figure 7As shown in section (a), in the case of a terrestrial network, the difference in signal received strength (e.g., reference received signal power RSRP) varies significantly depending on whether the UE is located at the cell edge or the cell center.

[0151] In comparison, reference Figure 7 In part (b), the difference in signal strength is relatively small in non-terrestrial networks. For example, the difference in signal strength between a UE located at the cell center and a UE located at the cell edge is approximately 1 dB for GEO and 9.8 dB for 600 km LEO. This means that, particularly at the cell edge where beam overlaps between two satellites, the difference in signal strength is not significant compared to the cell center.

[0152] In other words, when measurement reports are generated by applying measurement events (e.g., A1 events, B1 events, etc.) based on existing signal strength, the serving gNB may have difficulty distinguishing which satellite is more suitable to support the corresponding UE. For example, even if the cell edge has sufficient signal strength, and the duration of service to the UE by the corresponding satellite moving away from the UE is not adequately guaranteed, the gNB may configure the UE to connect to the satellite based on signal strength, potentially leading to frequent ping-pong effects between cells. Furthermore, without distinguishing between satellites moving towards the UE and satellites moving away from the UE, the UE may perform unnecessary or excessively frequent measurement event triggering / reporting operations, which can become a burden in NTNs with limited radio resources. Therefore, this disclosure proposes a method to support location-based multiple connectivity to prevent the decrease in robustness caused by inter-cell ping-pong effects when multiple connectivity is performed by satellites.

[0153] More specifically, in this disclosure, when measurement events-based measurement reports are applied in a satellite multi-connectivity configuration, location-based triggering conditions that take into account NTN characteristics are added to existing signal strength-based measurement report triggering conditions (e.g., A1 event, B1 event) to trigger the measurement report only when appropriate. As mentioned above, since the duration for which an NTN cell can serve a UE varies depending on the UE's location, the mobility of the NTN cell, and the location of the NTN cell (orbit, altitude, etc.), this disclosure proposes a method that, in addition to the measurement report triggering conditions, reflects various parameters that can indicate the possible duration of UE service on the satellite, in order to support location-based multi-connectivity configurations.

[0154] In the following text, for descriptive purposes, a method for adding a secondary node (SN) based on a dual connectivity (DC) scenario will be described by way of example. In this case, the gNB currently serving the UE will operate as the primary node (MN) of the DC, and although it is assumed that the satellite of the NTN is the MN, those skilled in the art will obviously not rule out the possibility that a terrestrial base station will operate as the MN of the DC.

[0155] Figure 8 This is a flowchart illustrating the measurement reporting operation of a UE according to an embodiment of the present disclosure.

[0156] refer to Figure 8 According to the examples in this disclosure, the UE can receive a measurement configuration message from the gNB in ​​S810, which includes configuration information for measurement reports of at least one NTN cell.

[0157] According to the examples of this disclosure, measurement messages can be sent to the UE via RRC signaling, and when the report type is set to event-triggered, the configuration information of the measurement report can include information related to the events in the measurement report. Here, the information related to the events in the measurement report is, for example, information about the conditions for determining the triggering of the events in the measurement report, and can include an identifier (ID) for identifying each event, as well as threshold information, time information, etc., for determining the triggering conditions of the event. Furthermore, the threshold information can include, for example, a threshold for signal strength values, and specifically, in the examples according to this disclosure, the threshold information can include threshold information related to the duration for which at least one NTN cell around the UE can serve the UE. More specific examples of threshold information will be referenced below. Figures 9 to 12 Describe it.

[0158] In S820, the UE that receives the measurement configuration message can perform measurements on at least one NTN cell based on the measurement configuration message.

[0159] Information about at least one NTN cell to be measured can be provided via a measurement configuration message (e.g., measobject). Furthermore, the UE according to embodiments of this disclosure can obtain the information required for measurement through system information periodically broadcast by the gNB. For example, the system information may include at least one of the following: cell identification information capable of identifying an NTN satellite that can be used as a measurement target, information about the orbit of the corresponding satellite, or information about the altitude of the corresponding satellite.

[0160] Subsequently, in S830, the UE can identify, based on the measurement results, at least one NTN cell that meets the triggering conditions of the measurement event.

[0161] In other words, according to embodiments of this disclosure, the UE can identify an NTN cell that corresponds to a measurement result value that satisfies the triggering conditions of a measurement event based on the measurement results of at least one NTN cell.

[0162] In addition, in S840, the UE can send a measurement report message to the gNB that includes the measurement results of the identified NTN cell.

[0163] By configuring threshold information for determining the duration for which a satellite can serve the UE as an event trigger condition for measurement reporting based on the UE and satellite locations, the UE can perform measurement reporting only when necessary if a satellite is additionally connected (e.g., an SN is added). This has the following effects: reducing frequent or unnecessary measurement reporting and selecting satellites suitable for serving the UE.

[0164] The following describes in detail the event configuration for measurement reports to support measurement reports based on satellite mobility and UE location. In this disclosure, the N1 event is defined as threshold information added to the SN based on the measurement report event. The N1 event is an additional condition considered separately from triggering conditions such as existing A1 and B1 events added for the SN, and can be defined as an event value relating to the duration for which the satellite can serve the UE. Calculating values ​​related to the duration for which the satellite can serve the UE requires multiple pieces of information, such as the satellite's orbit or velocity and the UE's location. However, calculating the possible service connection time or distance based on this information can place a heavy burden on the UE's computing power. Therefore, in this disclosure, reference will be made to… Figures 9 to 12 This paper describes a method that allows the application of a more simplified calculation scheme using some information about satellite orbit and satellite velocity.

[0165] Figure 9 This is a diagram illustrating a first example of an event in a measurement report according to an embodiment of this disclosure.

[0166] refer to Figure 9 According to embodiments of this disclosure, threshold information related to the triggering conditions of a measurement reporting event can indicate a threshold for the service duration of an NTN cell. time The service duration here can be defined, for example, as an estimate (t'-service) of the time during which the elevation angle of the UE's NTN cell meets the minimum elevation angle or a greater angle. For instance, when the time t1 is when the NTN cell approaches the UE and the elevation angle begins to be greater than the minimum elevation angle, and the time t2 is when the corresponding NTN cell begins to move away from the UE and the elevation angle begins to be less than the minimum elevation angle, t'-service can be defined as t2-t1. In other words, based on t'-service, the duration for which the corresponding NTN cell can serve the UE can be identified.

[0167] Based on this, when the t'-service calculated by the UE is greater than or equal to the service duration threshold (Thresh) time When the UE is in the form of a measurement report, according to the example of this disclosure, it can determine that the event triggering conditions for the measurement report have been met, and can send the measurement report of the NTN cell to the gNB.

[0168] - Triggering condition: t'-service ≥ Thresh time

[0169] Figure 10 This is a diagram illustrating a second example of an event in a measurement report according to an embodiment of this disclosure.

[0170] refer to Figure 10 According to embodiments of this disclosure, threshold information related to the triggering conditions of a measurement reporting event can indicate the degree of elevation angle change in an NTN cell. threshold () (and the minimum elevation angle related to the degree of elevation angle change).

[0171] The degree of elevation angle change is related to the direction in which the NTN cell moves relative to the UE. For example, when the NTN cell moves in a direction closer to the UE, the degree of elevation angle change is derived as a value equal to or greater than 0. Furthermore, when the NTN cell moves away from the UE, the degree of elevation angle change is derived to a value less than 0. Therefore, when the NTN cell moves in a direction away from the UE ( Since the UE can be served for a relatively short period of time, or the UE will soon leave the service area where the UE can be served, the measurement report can be configured to trigger only at a specific elevation angle or higher (i.e., when service can be provided for a sufficiently long time). However, in an embodiment, the UE can be configured to trigger only when the elevation angle change is derived to a value greater than or equal to 0. A measurement report is triggered when ( ).

[0172] Meanwhile, when the satellite orbit of the NTN cell passes vertically above the UE and moves away from the UE, the absolute value of the change in the elevation angle of the NTN cell can change within a predetermined time period. For example, when the satellite orbit of the NTN cell passes vertically above the UE, the absolute value of the change in the elevation angle of the NTN cell can be greater than or equal to a threshold (…). Conversely, when the satellite orbit of the NTN cell moves away from the UE, the absolute value of the change in the elevation angle of the NTN cell within a predetermined time period can be less than a threshold ( ).

[0173] In this case, the minimum elevation angle that serves as the trigger condition for a measurement reporting event can be applied differently depending on the magnitude of the absolute value of the elevation angle change in the NTN cell.

[0174] More specifically, such as Figure 10 As shown, when NTN cell 10a passes vertically above the UE, the elevation angle of NTN cell 10a will undergo a significant change, starting from a minimum value and reaching a relatively large elevation angle value (e.g., a maximum of 90°). In other words, in the case of NTN cell 10a, by moving vertically above the UE, the service duration for the UE can be relatively long. Therefore, when it is determined that the elevation angle corresponding to NTN cell 10a is greater than the minimum elevation angle value... At that time, the UE can determine the event that has triggered a measurement report.

[0175] In contrast, when the track of NTN cell 10b is relatively far from the UE, even if the track is as close to the UE as possible, the maximum elevation angle relative to the UE is implemented as a relatively small value, and therefore the elevation angle change is relatively small compared to the case of NTN cell 10a. In this case, if the elevation angle of the corresponding NTN cell 10b is determined to be greater than the minimum elevation angle value... Then the UE can determine that an event has triggered a measurement report. However, since NTN cell 10b has a shorter UE service duration than NTN cell 10a and cannot provide service at a larger elevation angle, the minimum elevation angle can be set to a value greater than that of NTN cell 10a.

[0176] - Triggering conditions

[0177] if

[0178] if and

[0179] if and

[0180] Figure 11 This is a diagram illustrating a third example of an event in a measurement report according to an embodiment of this disclosure.

[0181] refer to Figure 11 According to embodiments of this disclosure, threshold information related to the triggering conditions of a measurement report event can indicate a threshold of the distance the NTN cell has moved within a pre-configured service area. ).

[0182] As above Figure 5aAs shown, the pre-configured service area can refer to the maximum area on the Earth's surface where a UE can receive communication services through an NTN cell, and can be determined based on the UE's location on the Earth's surface, the altitude of the NTN cell, and the minimum elevation angle based on the positional relationship between the NTN cell and the UE. In this case, when the pre-configured service area is defined on the Earth's surface where the UE is located, the pre-configured service area can be defined as a circle with a predetermined cell radius centered on the point where the UE is located.

[0183] For example, when assuming that the NTN cell moves almost parallel to the Earth's surface where the UE is located, and when implementing the movement path of the NTN cell along its movement on the Earth's surface, the distance the NTN cell has moved within the pre-configured service area can be calculated using the points corresponding to the curve of the movement path entering the service area defined as a circle based on the UE. For example, such as Figure 11 As shown, the distance that an NTN cell has moved within the pre-configured service area can be calculated as the straight-line distance between the moving path of the NTN cell and the point tangent to the circle based on the UE.

[0184] Based on the straight-line distance calculated as described above, the UE according to the example of this disclosure can identify the duration for which the NTN cell can serve the UE, and can determine a specific proportion when the straight-line distance is equal to or greater than the cell diameter ( When ), the measurement report event is triggered.

[0185] In this example, a simplified method using two points where the NTN cell enters the UE-based circle has been used to calculate the distance the NTN cell moves within the UE-based circle, but it is also possible to use a calculation method with more points.

[0186] -Triggering conditions:

[0187] Figure 12 This is a diagram illustrating a fourth example of an event in a measurement report according to an embodiment of this disclosure.

[0188] refer to Figure 12 According to embodiments of this disclosure, threshold information related to the triggering conditions of a measurement report event can indicate a threshold value for the angle at which the NTN cell moves toward the UE to enter the pre-configured service area. ).

[0189] like Figure 11 As shown, the pre-configured service area can be determined based on the minimum elevation angle of the UE's position on the Earth's surface, the altitude of the NTN cell, and the positional relationship between the NTN cell and the UE, and as... Figure 12 As shown, it can be defined as a circle with a predetermined cell radius centered at the point where the UE is located.

[0190] As in Figure 11 In this context, when assuming the NTN cell moves almost parallel to the Earth's surface where the UE is located, and when implementing the movement path of the NTN cell along its movement path on the Earth's surface, a point 12 can be defined as the NTN cell moving towards the UE entering the pre-configured service area. The angle formed by the tangent 12a at the corresponding point 12 and the directions 12b and 12c of the NTN cell's movement from point 12 can be defined as the entry angle. .

[0191] In this case, based on The value is used to identify the duration for which the corresponding NTN cell can serve the UE, based on the example UE of this disclosure. For example, based on... The value can be used to determine when the satellite passes vertically above the UE (e.g., Whether longer service duration for the UE is guaranteed, or alternatively, whether it can be determined when the satellite passes tangentially to the UE-based circle (e.g., Is the service duration for the UE very short? Therefore, when The value is equal to or greater than the configured threshold. When this happens, the UE can determine the triggering conditions for the measurement report event.

[0192] -Triggering conditions:

[0193] exist Figures 9 to 12 The document illustrates four examples of event (N1 event) information from various measurement reports for predicting the duration for which an NTN cell can serve a UE based on location-based SN addition. The four examples can be configured individually, but a gNB according to embodiments of this disclosure can be configured to trigger a measurement report when at least one of the four examples is satisfied.

[0194] Figure 13 This is a flowchart illustrating the measurement configuration operation of a gNB according to an embodiment of the present disclosure.

[0195] In the diagram, descriptions that are repeated above are omitted or briefly explained.

[0196] In S1310, the gNB according to an embodiment of the present disclosure can send a measurement configuration message to the UE, which includes configuration information of a measurement report of at least one NTN cell.

[0197] In this case, the measurement configuration message can be referenced as described above. Figure 8The aforementioned RRC message is sent and may include information related to the event in the measurement report. This information related to the event in the measurement report may include information about the above-mentioned events. Figures 9 to 12 Information of at least one of the N1 event values ​​described herein. When the gNB, according to the example of this disclosure, determines the configuration of multiple connections based on communication service support, congestion conditions, load conditions, etc., for the serving UE, the gNB may select an N1 event value applicable to that condition and configure that N1 event value for the UE.

[0198] In S1320, based on the measurement configuration message, the UE can receive a measurement report message from the UE that includes measurement results about the NTN cell.

[0199] The measurement report message may include information about the signal strength measurements of the UE used in the NTN cell. Additionally, as described later, depending on how the gNB configures the measurement configuration message, the measurement report message may include location information related to the UE.

[0200] Based on the UE's measurement report message, the gNB, according to the example of this disclosure, can determine whether to add the corresponding NTN cell to the UE and configure multiple connections.

[0201] The relevant process will refer to Figure 14 Describe it.

[0202] Figure 14 This is a flowchart illustrating a process for configuring multiple connections according to an embodiment of the present disclosure.

[0203] refer to Figure 14 In the example according to this disclosure, UE 1401 is connected to gNB 1402 in RRC connection state. In order to measure the surrounding NTN cells and configure the measurement report in UE 1401, gNB 1402 can send a measurement configuration message to UE 1401 in S1410.

[0204] Based on the locational relationship between UE 1401 and the NTN cell as described above, the measurement configuration message here may include a predetermined event value, i.e., information about the N1 event, to trigger a measurement report from the NTN cell sufficient to serve the UE. The information about the N1 event may include details referenced above. Figures 9 to 12 At least one threshold is described. Furthermore, although not shown in the figure, in the measurement configuration added for a general SN, the configuration of event values ​​(A1 event, B1 event, etc.) related to signal strength can also be included in the measurement configuration message.

[0205] In S1420, UE 1401 can perform measurements on at least one NTN cell located around the UE based on a measurement configuration message. gNB 1402 can periodically broadcast information about each NTN cell via system information (e.g., SIB 19), such as data (ephemeris data) including NTN cell identification information or orbital information, and UE 1401 can perform measurement operations using the information included in the system information. Furthermore, UE 1401 can determine whether an N1 event has been triggered based on the measurement result value.

[0206] In S1430, when it is determined that an N1 event has been triggered, UE 1401 can send information about the NTN cell with the measurement result value of the triggered N1 event to gNB 1402 via a measurement report message.

[0207] In S1440, gNB 1402 can determine whether to add a connection to NTN cell 1403 to UE 1401 based on a measurement report message from UE 1401. In this case, when a measurement report message containing information about multiple NTN cells is received, gNB 1402 can select, for example, the NTN cell with the best signal strength value among the multiple NTN cells as the cell to be added to UE 1401.

[0208] In S1450, gNB 1402 can send an SN add request message containing information about UE 1401 to the selected NTN cell 1403, and when the request is approved, NTN cell 1403 can send an SN add confirmation (ACK) message containing the predetermined information necessary for UE 1401 to access the corresponding NTN cell 1403 to gNB 1402 in S1460.

[0209] In S1470, gNB 1402 can send information about sending an SN-added confirmation message to UE 1401 via an RRC message (e.g., RRC connection reconfiguration), and UE 1401 can send its response (e.g., RRC connection reconfiguration complete) to gNB 1402 in S1480.

[0210] Although not shown in the figure, when a UE performs random access to an NTN cell, the DC between the gNB and the target NTN cell is configured for the corresponding UE.

[0211] According to the embodiments described above, frequent and inefficient measurement events that may occur in the NTN can be triggered only when necessary, preventing the ping-pong effect caused by satellite mobility during connection support. Furthermore, the UE can trigger measurement reports only when necessary, thereby reducing power consumption caused by unnecessary measurement reports and resource consumption. In addition, through information-based SN addition, suitable satellites for serving the UE can be selected from an ever-increasing number of satellite candidates.

[0212] like Figure 13 As mentioned, when a measurement report for SN addition is sent, the UE can transmit additional information so that the gNB can perform appropriate SN addition. In this case, this disclosure proposes to include UE location information as additional information sent by the UE. When the gNB additionally receives the UE's location information, the gNB can accurately calculate the time when each UE can actually receive service along with the satellite orbit, thereby achieving the effect of selecting a more suitable NTN cell for SN addition. Based on this, this disclosure proposes a method to reduce overhead when considering that NTNs with limited radio resources transmit location information through the UE's uplink. The following describes the case where the UE additionally includes its location information when sending a measurement report message, but this process can be performed independently of the measurement reporting process. For example, the gNB can request the UE's location information from the UE when needed and can accordingly trigger the UE's location information reporting process.

[0213] This disclosure presents two methods for sending location information while reducing overhead.

[0214] First, a method for transmitting the location information of the UE using Global Positioning System (GPS) coordinates. Figure 15a and Figure 15b This is a diagram illustrating a method for configuring the location information of a UE using GPS coordinates according to an embodiment of the present disclosure.

[0215] In the case of GPS coordinates, the resolution and accuracy of location information vary depending on the number of decimal places in the GPS coordinates. Previously, GPS coordinates could be transmitted, for example, via RRC's commonLocationInformation, but the format had certain limitations. Furthermore, since GPS information is transmitted along with associated location information, a large number of bits must be allocated, making existing GPS coordinate transmission methods unsuitable for NTNs with limited radio resources. Therefore, this disclosure proposes a method for transmitting location information using GPS coordinates while allowing flexible configuration of the GPS coordinate information size. For example, the gNB can specify and allocate the number of bits for the GPS coordinates to the UE. For instance, the gNB can configure the number of decimal places in the GPS coordinate information that the gNB wants to receive for the UE via an RRC message, and the UE can transmit the location information to the gNB using the configured number of bits.

[0216] Because the UE's location is restricted to a predetermined cell range, the gNB can infer the UE's location sufficiently without transmitting all GPS coordinate information. For example, since 10 digits of GPS coordinates distinguish approximately 1000 km, the plus or minus sign (±) representing latitude / longitude can be omitted, and the 100 digits of longitude can also be omitted, such as... Figure 15a As shown (latitude: -90° to 90°, longitude: -180° to 180°). Additionally, as... Figure 15b As shown, information about the markers can be transmitted only near the equator and the prime meridian (i.e., longitudes of 0° and 180°). For example, based on a cell radius of 200 km, transmitting the markers within latitude / longitude ±0 to 10° and longitude ±170 to 180° is sufficient. Therefore, according to this disclosure, the gNB can roughly determine the location of the UE based on GPS coordinate information indicated by a relatively small number of bits.

[0217] Secondly, based on the premise of obtaining a grid by expanding the cells of MN into squares, there exists a way to transmit information about the index where the UE is located. The method of information. Figure 15c This is a diagram illustrating a method for configuring UE location information as a grid-based index according to an example of this disclosure.

[0218] refer to Figure 15c System information (e.g., SIB 19) sent by the gNB to the UE can include information about the center point and radius of the corresponding gNB cell. In addition to this information, when the gNB provides the grid spacing width value via RRC messages, the UE can deduce the index of the grid to which the UE belongs. For example, the cell center point can be represented as index = 0, and the range of the index can be represented as {-maxIndexSize ... 0 ... maxIndexSize-1}.

[0219] In this case, one method for calculating the UE index is as follows.

[0220] - UE location

[0221] - Community Center and cell radius

[0222] - Index spacing Column index spacing

[0223] - Row Index Column index

[0224] (1) Maximum row index size Maximum column index size

[0225] (2) If ,but , and if ,but

[0226] (3) If ,but , and if ,but

[0227] (4) Otherwise, and

[0228] According to the example, the UE can calculate maxIndexSize by (1) and the index by (4). If the UE determines that it is outside the cell range, the UE can determine the index of the location closest to the UE by (2) and (3).

[0229] Figure 16 This is a diagram that comparatively illustrates a method for transmitting UE location information according to an example of this disclosure.

[0230] for Figure 15a , Figure 15b and Figure 15c The number of bits required for the two methods of sending location information described in the document, if based on... Figure 16 By omitting the GPS coordinate markers and 100 digits at the same resolution, approximately 1 to 3 digits can be reduced, and if a grid method is used, 1 / 2 to 1 / 3 of the digits can be reduced.

[0231] The limitation of transmitting GPS coordinates is that the resolution of the location is limited by the number of decimal places in the GPS coordinates. The advantage of transmitting grid indexes is that the resolution can be adjusted by controlling the grid interval width, and therefore there are no limitations compared to GPS coordinates. For example, to achieve a resolution of 50 m, only the grid interval width needs to be set to 50 m without changing the number of decimal places in the grid indexing method. However, in the GPS coordinates method, a 4-digit decimal number needs to be set in a 10 m result.

[0232] Figure 17 This is a flowchart illustrating a process for configuring multiple connections based on UE location information, according to an example of this disclosure. In the following text, details will be omitted or briefly described. Figure 14 The operations and features described in the document are repeated.

[0233] refer to Figure 17 According to the example of this disclosure, UE 1701 accesses gNB 1702 in RRC connected state. In S1710, gNB 1702 can send a measurement configuration message to UE 1701 to measure surrounding NTN cells and configure measurement reports.

[0234] Based on the locational relationship between UE 1701 and the NTN cell as described above, the measurement configuration message here may include a predetermined event value, i.e., information about the N1 event, to trigger a measurement report from the NTN cell sufficient to serve the UE. The information about the N1 event may include details referenced above. Figures 9 to 12 At least one threshold mentioned above.

[0235] In S1720, UE 1701 can perform measurements on at least one NTN cell located in the surrounding environment based on the measurement configuration message.

[0236] UE 1701 can perform measurements based on information about NTN candidate cells and measurement triggering events included in the measurement configuration message, and can also use information obtained through system information (e.g., SIB 19). Furthermore, the measurement configuration message according to embodiments of this disclosure may include information instructing UE 1701 to report the UE's location information along with the measurement report. For example, it may additionally include information for configuring whether to report the UE's location information based on GPS coordinates or a grid index within the cell range of the corresponding gNB 1702.

[0237] In S1730, when it is determined that an N1 event has been triggered based on the measurement result value, UE 1701 can send information about the NTN cell with the triggered N1 event to gNB 1702 via a measurement report message. In this case, based on the configuration of gNB 1702, UE 1701 can report the UE's location information and the measurement result value to gNB 1702 together based on GPS coordinates or grid index.

[0238] In S1740, gNB 1702 can determine to add the connection of NTN cell 1703 to UE 1701 based on the measurement report message from UE 1701.

[0239] In this scenario, gNB 1702 can select the NTN cell for which additional connectivity is to be provided for UE 1701 by using measurement results and the location information of UE 1701. For example, when receiving a measurement report message from UE 1701 that includes information about multiple NTN cells, gNB 1702 can select the most suitable NTN cell for serving UE 1701 by considering the UE's location among the multiple NTN cells.

[0240] In S1750, gNB 1702 can send an SN add request message containing information about UE 1703 to the selected NTN cell 1703, and when the request from gNB 1702 is approved, NTN cell 1701 can send an SN add confirmation (ACK) message containing the predetermined information necessary for UE 1701 to access the corresponding NTN cell 1703 to gNB 1702 in S1760.

[0241] In S1770, gNB 1702 can send the information of sending the SN addition confirmation message to UE 1701 through the RRC connection reconfiguration message, and in S1780, in response, UE 1701 can send the RRC connection reconfiguration complete message to gNB 1702.

[0242] Subsequently, when the UE successfully completes random access to the NTN cell, a DC is configured between the gNB and the NTN cell.

[0243] According to this disclosure, the UE can provide the gNB with information about the high-precision UE location with a minimal information size without causing excessive resource consumption or overhead, and the gNB can select the most suitable cell as the NTN cell that can serve the UE and support multiple connections based on the UE location, thereby providing the desired effect.

[0244] Figure 18 This is a diagram illustrating an example of a measurement configuration message according to an example of this disclosure, and Figure 19 This is a diagram illustrating an example of a measurement report message according to this disclosure.

[0245] According to publicly available examples, when the corresponding measurement report is configured as "event-triggered," the measurement configuration message sent by the gNB to the UE can include information about the corresponding event as an information field, such as... Figure 18 As shown above, the measurement configuration message may include information about the N1 event proposed in this disclosure, in addition to information about existing signal strength-related events, or optionally include information about the N1 event proposed in this disclosure together with existing signal strength-related events.

[0246] Information about N1 events, in addition to the event ID and trigger time, can also include threshold values ​​for various parameters as measurement types. These threshold values ​​indicate the duration for which the NTN cell can serve the UE. For example, Figure 9 The service duration threshold (approx-Tservice) of NTN cells mentioned in the document, and Figure 10 The threshold (deltaElevationAngle) related to the degree of elevation angle change of NTN cells described in the text. Figure 11 The threshold for the UE service distance (distanceUEcell) of the NTN cell described in the document, and Figure 12 The threshold of the penetration angle of the UE serving area of ​​the NTN cell described herein can be included as a measurement type.

[0247] Furthermore, when the gNB according to an embodiment of this disclosure is additionally configured to report the location information of the UE, the gNB can indicate that the reported UE location information is one of GPS coordinates or grid indexes through the configuration of the report type.

[0248] In addition, in response to the gNB's measurement configuration, the UE can include various information about the measurement report message, such as Figure 19 As shown. The measurement report message may include information indicating the following as UE location information: the NTN cell associated with the corresponding measurement result; the measurement result information of the corresponding NTN cell; and, when location information is configured for reporting, GPS coordinates or grid indexes based on the configuration type.

[0249] Figure 20 The structure of a UE according to an embodiment of the present disclosure is shown.

[0250] refer to Figure 20According to embodiments of the present disclosure, the UE may include a radio frequency (RF) processor 20-10, a baseband processor 20-20, a storage device 20-30, and a controller 20-40.

[0251] RF processor 20-10 can perform functions for transmitting / receiving signals via a wireless channel, such as signal band conversion and amplification. That is, RF processor 20-10 can up-convert baseband signals provided by baseband processor 20-20 into RF band signals, which can be transmitted via an antenna, and can down-convert RF band signals received via the antenna back into baseband signals. For example, RF processor 20-10 may include transmit filters, receive filters, amplifiers, mixers, oscillators, digital-to-analog converters (DACs), analog-to-digital converters (ADCs), etc. Although only one antenna is shown in the figures, the UE may include multiple antennas. Additionally, RF processor 20-10 may include multiple RF links. Furthermore, RF processor 20-10 can perform beamforming. For beamforming, RF processor 20-10 can adjust the phase and amplitude of signals transmitted / received through multiple antennas or antenna elements respectively. Additionally, the RF processor can perform MIMO and can receive multiple layers when performing MIMO operation.

[0252] Baseband processors 20-20 can perform baseband signal-to-bit string conversion functions according to the system's physical layer specifications. For example, during data transmission, baseband processors 20-20 can encode and modulate the transmitted bit string to generate complex symbols. Additionally, during data reception, baseband processors 20-20 can demodulate and decode the baseband signal provided from RF processors 10-10 to recover the received bit string. For example, when following an Orthogonal Frequency Division Multiplexing (OFDM) scheme, during data transmission, baseband processors 20-20 can encode and modulate the transmitted bit string to generate complex symbols, map these complex symbols to subcarriers, and configure OFDM symbols using inverse Fast Fourier Transform (IFFT) operations and cyclic prefix (CP) insertion. Furthermore, during data reception, baseband processors 20-20 can separate the baseband signal provided from RF processors 20-10 at the OFDM symbol level, recover the signal mapped to the subcarriers using Fast Fourier Transform (FFT) operations, and recover the received bit string through demodulation and decoding.

[0253] The baseband processor 20-20 and the RF processor 20-10 can transmit and receive signals, as described above. Therefore, the baseband processor 20-20 and the RF processor 20-10 can be referred to as a transmitter, receiver, transceiver, or communication unit. Furthermore, at least one of the baseband processor 20-20 and the RF processor 20-10 may include multiple communication modules to support various wireless access technologies. Additionally, at least one of the baseband processor 20-20 and the RF processor 20-10 may include different communication modules to process signals in different frequency bands. For example, different wireless access technologies may include wireless LAN (e.g., IEEE 802.11), cellular networks (e.g., LTE), etc. Furthermore, different frequency bands may include ultra-high frequency (SHF) bands (e.g., 2NRHz) and millimeter wave (mmWave) bands (e.g., 60 GHz).

[0254] Storage devices 20-30 can store basic programs, application programs, and data, such as configuration information, for the operation of the UE. Specifically, storage devices 20-30 can store information about nodes configured to perform wireless communication using wireless access technology. Furthermore, storage devices 20-30 can provide the stored data upon request from controller 20-40.

[0255] Controllers 20-40 control the overall operation of the UE. For example, controllers 20-40 can transmit / receive signals via baseband processors 20-20 and RF processors 20-10. Additionally, controllers 20-40 record data in and read data from storage devices 20-30. For this purpose, controllers 20-40 may include at least one processor. For example, controllers 20-40 may include a communication processor (CP) configured to perform communication control and an application processor (AP) configured to control upper layers (such as applications).

[0256] Figure 21 This is a block diagram illustrating the structure of a base station according to an embodiment of the present disclosure.

[0257] Here, the base station according to the embodiments of this disclosure may refer to the base station, first node, second node, primary node, secondary node, or NTN cell described in the embodiments of this disclosure. For example, the first node may refer to the node that first establishes a connection with the UE, and the second node may refer to the node that last establishes a connection with the UE or last adds a connection to the UE.

[0258] refer to Figure 21 The base station may include an RF processor 21-10, a baseband processor 21-20, a backhaul communication unit 21-30, a storage device 21-40, and a controller 21-50.

[0259] RF processor 21-10 can perform functions for transmitting / receiving signals via a wireless channel, such as signal band conversion and amplification. That is, RF processor 21-10 can up-convert baseband signals provided by baseband processor 21-20 into RF band signals, which can be transmitted via an antenna, and can down-convert RF band signals received via the antenna back into baseband signals. For example, RF processor 21-10 may include transmit filters, receive filters, amplifiers, mixers, oscillators, DACs, and ADCs. Although only one antenna is shown in the figures, the base station may include multiple antennas. Additionally, RF processor 21-10 may include multiple RF links. Furthermore, RF processor 21-10 can perform beamforming. For beamforming, RF processor 21-10 can adjust the phase and amplitude of signals transmitted / received through multiple antennas or antenna elements respectively. RF processor 21-10 can transmit one or more layers to perform down-MIMO operation.

[0260] Baseband processors 21-20 can perform baseband signal-to-bit string conversion functions according to the physical layer specifications of the radio access technology. For example, during data transmission, baseband processors 21-20 can encode and modulate the transmitted bit string to generate complex symbols. Additionally, during data reception, baseband processors 21-20 can demodulate and decode the baseband signal provided from RF processors 11-10 to recover the received bit string. For example, when following an OFDM scheme, during data transmission, baseband processors 21-20 can encode and modulate the transmitted bit string to generate complex symbols, map these complex symbols to subcarriers, and configure OFDM symbols via IFFT operations and CP insertion. Furthermore, during data reception, baseband processors 21-20 can separate the baseband signal provided from RF processors 21-10 at the OFDM symbol level, recover the signal mapped to the subcarrier via FFT operations, and recover the received bit string via demodulation and decoding. Baseband processors 21-20 and RF processors 21-10 can transmit and receive signals as described above. Therefore, the baseband processor 21-20 and the RF processor 21-10 can be referred to as transmitters, receivers, transceivers, or communication units.

[0261] Backhaul communication units 21-30 provide an interface for communicating with other nodes in the network. That is, backhaul communication units 21-30 convert bit strings sent from the main base station to other nodes (e.g., auxiliary base stations, core network, etc.) into physical signals, and convert physical signals received from other nodes into bit strings.

[0262] Storage devices 21-40 can store basic programs, applications, and data, such as configuration information, for the operation of the main base station. Specifically, storage devices 21-40 can store information about bearers assigned to connected UEs, measurement results reported by connected UEs, etc. Additionally, storage devices 21-40 can store information used as criteria for determining whether to provide multiple connections to a UE or suspend it. Furthermore, storage devices 21-40 can provide the stored data upon request from controller 21-50.

[0263] Controller 21-50 controls the overall operation of the main base station. For example, controller 21-50 transmits / receives signals via baseband processor 21-20 and RF processor 21-10 or via backhaul communication unit 21-30. Additionally, controller 21-50 records data in storage device 21-40 and reads data from storage device 21-40. For this purpose, controller 21-50 may include at least one processor.

[0264] In the specific embodiments of the present invention described above, the components included in the present invention are represented as singular or plural, depending on the presented specific embodiments. However, for ease of explanation, singular or plural representations are chosen to suit the presented situation, and the present invention is not limited to singular or plural components; even if components are expressed in plural form, they may also consist of singular forms, and even if components are expressed in singular form, they may also consist of plural forms.

[0265] Furthermore, although specific embodiments have been described in the detailed description of the invention, it should be understood that various modifications can be made within the scope of the invention. Therefore, the scope of the invention should not be limited to the described embodiments, but should be defined by the claims set forth below and their equivalents.

Claims

1. A method performed by a terminal in a communication system, the method comprising: Receive a measurement configuration message from the base station, the measurement configuration message including configuration information related to a measurement report for at least one non-terrestrial network (NTN) cell, the configuration information including information related to events in the measurement report; Based on the measurement configuration message, measurements are performed on the at least one NTN cell; Based on the measurement, an NTN cell that meets the triggering conditions of the event is identified among the at least one NTN cell; as well as A measurement report message is sent to the base station, the measurement report message including the measurement results of the identified NTN cell. The information related to the event includes threshold information associated with the duration for which the at least one NTN cell can serve the terminal.

2. The method as described in claim 1, in, The threshold information includes a threshold for the service duration of the NTN cell. The duration for which the NTN cell can serve the terminal is determined based on the time interval between a first time point when the elevation angle of the NTN cell for the terminal begins to increase from its minimum value and a second time point when the elevation angle begins to decrease from its minimum value. Specifically, if the time interval is greater than or equal to the threshold, the triggering condition is determined to be met.

3. The method as described in claim 1, wherein, The threshold information includes: a threshold for the degree of elevation angle change of the NTN cell, and a minimum elevation angle associated with the degree of elevation angle change, wherein the minimum elevation angle includes a first minimum elevation angle and a second minimum elevation angle greater than the first minimum elevation angle. Specifically, when the elevation angle of the NTN cell increases, the duration for which the NTN cell can serve the terminal is identified based on a comparison between the elevation angle and the minimum elevation angle. Wherein, if the elevation angle change of the NTN cell is greater than or equal to the threshold within a predetermined time period, the triggering condition is determined to be met based on the fact that the elevation angle of the NTN cell is greater than the first minimum elevation angle. Wherein, if the elevation angle change of the NTN cell is less than the threshold within the predetermined time, the triggering condition is determined to be met based on the fact that the elevation angle of the NTN cell is greater than the second minimum elevation angle.

4. The method as described in claim 1, in, The threshold information includes: a threshold value for the distance the NTN cell moves within the pre-configured service area, or a threshold value for the angle at which the NTN cell moves toward the terminal as it enters the pre-configured service area. The pre-configured service area is determined based on the altitude of the NTN cell and the location of the terminal. Wherein, when the threshold information includes a threshold for the distance the NTN cell moves within the pre-configured service area, the duration for which the NTN cell can serve the terminal is identified based on the straight-line distance between the point on a predetermined plane where the NTN cell's movement path contacts the pre-configured service area. Wherein, when the threshold information includes a threshold for the angle at which the NTN cell enters the pre-configured service area toward the terminal, the duration for which the NTN cell can serve the terminal is identified based on the angle between the tangent line on the predetermined plane at the point where the NTN cell enters the pre-configured service area and the direction in which the NTN cell moves from the point; and Specifically, if the straight-line distance or the angle is greater than a threshold, the triggering condition is determined to be met.

5. A method performed by a base station in a communication system, the method comprising: Send a measurement configuration message to the terminal, the measurement configuration message including configuration information related to measurement reports for at least one non-terrestrial network NTN cell; as well as Based on the measurement configuration message, a measurement report message is received from the terminal, the measurement report message including the measurement results of the NTN cell in the at least one NTN cell. The configuration information includes information related to the events in the measurement report, and The information related to the event includes threshold information associated with the duration for which the at least one NTN cell can serve the terminal.

6. The method as described in claim 5, in, The threshold information includes a threshold for the service duration of the NTN cell, and Wherein, the time interval between the first time point when the elevation angle of the NTN cell based on the terminal increases from the minimum value and the second time point when the elevation angle decreases from the minimum value is greater than or equal to the threshold, the measurement report message is received from the terminal.

7. The method as described in claim 5, in, The threshold information includes: a threshold for the degree of elevation angle change of the NTN cell, and a minimum elevation angle associated with the degree of elevation angle change, wherein the minimum elevation angle includes a first minimum elevation angle and a second minimum elevation angle greater than the first minimum elevation angle, and Specifically, the measurement report message is received from the terminal based on the fact that the increase in the elevation angle of the NTN cell is greater than or equal to the threshold within a predetermined time and the elevation angle of the NTN cell is greater than the first minimum elevation angle; or the measurement report message is received from the terminal based on the fact that the increase in the elevation angle of the NTN cell is less than the threshold within the predetermined time and the elevation angle of the NTN cell is greater than the second minimum elevation angle.

8. The method as described in claim 5, in, The threshold information includes: a threshold value for the distance the NTN cell moves within the pre-configured service area, or a threshold value for the angle at which the NTN cell moves toward the terminal as it enters the pre-configured service area. The pre-configured service area is determined based on the altitude of the NTN cell and the location of the terminal. The measurement report message is received from the terminal when the straight-line distance between the point on the predetermined plane where the movement path of the NTN cell contacts the pre-configured service area is greater than a threshold, or when the angle between the tangent on the predetermined plane at the point where the NTN cell enters the pre-configured service area and the direction in which the NTN cell moves from the point is greater than a threshold.

9. A terminal in a communication system, the terminal comprising: transceiver; as well as The controller is configured as follows: The transceiver is controlled to receive a measurement configuration message from the base station. The measurement configuration message includes configuration information related to a measurement report for at least one non-terrestrial network (NTN) cell, and the configuration information includes information related to events in the measurement report. Based on the measurement configuration message, measurements are performed on the at least one NTN cell. Based on the measurement, an NTN cell satisfying the triggering conditions of the event is identified among the at least one NTN cell, and The transceiver is controlled to send a measurement report message to the base station. The measurement report message includes the measurement results of the identified NTN cell. The information related to the event includes threshold information associated with the duration for which the at least one NTN cell can serve the terminal.

10. The terminal as described in claim 9, in, The threshold information includes a threshold for the service duration of the NTN cell, and The controller is configured to identify the duration for which the NTN cell can serve the terminal based on the time interval between a first time point when the elevation angle of the NTN cell of the terminal increases from its minimum value and a second time point when the elevation angle decreases from its minimum value, and to determine that the triggering condition is met if the time interval is greater than or equal to the threshold.

11. The terminal as described in claim 9, in, The threshold information includes: a threshold for the degree of elevation angle change of the NTN cell, and a minimum elevation angle associated with the degree of elevation angle change, wherein the minimum elevation angle includes a first minimum elevation angle and a second minimum elevation angle greater than the first minimum elevation angle, and The controller is configured to: when the elevation angle of the NTN cell increases, identify the duration for which the NTN cell can serve the terminal based on a comparison between the elevation angle and the minimum elevation angle; if the degree of change in the elevation angle of the NTN cell is greater than or equal to the threshold within a predetermined time, determine that the trigger condition is met based on the elevation angle of the NTN cell being greater than the first minimum elevation angle; and if the degree of change in the elevation angle of the NTN cell is less than the threshold within the predetermined time, determine that the trigger condition is met based on the elevation angle of the NTN cell being greater than the second minimum elevation angle.

12. The terminal as described in claim 9, in, The threshold information includes: a threshold value for the distance the NTN cell moves within the pre-configured service area, or a threshold value for the angle at which the NTN cell moves toward the terminal as it enters the pre-configured service area. The pre-configured service area is determined based on the altitude of the NTN cell and the location of the terminal. The controller is configured to: when the threshold information includes a threshold for the distance the NTN cell moves within the pre-configured service area, identify the duration for which the NTN cell can serve the terminal based on the straight-line distance between the point on the predetermined plane where the NTN cell's movement path contacts the pre-configured service area; and when the threshold information includes a threshold for the angle at which the NTN cell enters the pre-configured service area toward the terminal, identify the duration for which the NTN cell can serve the terminal based on the angle between the tangent on the predetermined plane at the point where the NTN cell enters the pre-configured service area and the direction in which the NTN cell moves from that point.

13. A base station in a communication system, the base station comprising: transceiver; as well as The controller is configured as follows: The transceiver is controlled to send a measurement configuration message to the terminal. The measurement configuration message includes configuration information related to measurement reports for at least one non-terrestrial network (NTN) cell, and... The transceiver is controlled to receive a measurement report message from the terminal based on the measurement configuration message. The measurement report message includes the measurement results of the NTN cell in the at least one NTN cell. The configuration information includes information related to the events in the measurement report, and The information related to the event includes threshold information associated with the duration for which the at least one NTN cell can serve the terminal.

14. The base station as described in claim 13, in, The threshold information includes a threshold for the service duration of the NTN cell, and Wherein, the time interval between the first time point when the elevation angle of the NTN cell based on the terminal increases from the minimum value and the second time point when the elevation angle decreases from the minimum value is greater than or equal to the threshold, the measurement report message is received from the terminal.

15. The base station as described in claim 13, in, The threshold information includes: a threshold for the degree of elevation angle change of the NTN cell, and a minimum elevation angle associated with the degree of elevation angle change, wherein the minimum elevation angle includes a first minimum elevation angle and a second minimum elevation angle greater than the first minimum elevation angle, and Specifically, the measurement report message is received from the terminal based on the fact that the increase in the elevation angle of the NTN cell is greater than or equal to the threshold within a predetermined time and the elevation angle of the NTN cell is greater than the first minimum elevation angle; or the measurement report message is received from the terminal based on the fact that the increase in the elevation angle of the NTN cell is less than the threshold within the predetermined time and the elevation angle of the NTN cell is greater than the second minimum elevation angle.

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