Method and device for performing communication by terminal in wireless communication system

Abstract

Disclosed are a method and a device for triggering a measurement report by a first user equipment (UE) in a wireless communication system according to various embodiments. Disclosed are a method and a device therefor, the method comprising the steps of: forming a direct link for direct connection to a base station; forming at least one indirect link connecting at least one UE and the base station via a first UE; on the basis that the signal strength of the direct link is less than a specific threshold, transmitting, to the at least one UE, a message requesting to transmit a response message related to signal quality regarding the base station; and determining whether to trigger a measurement report on the basis of whether the response message is received.

Description

Method for a terminal to perform communication in a wireless communication system and device therefor

[0001] A method for a terminal to trigger a measurement report in a wireless communication system and a device therefor are provided.

[0002] Wireless communication systems are multiple access systems that support communication with multiple users by sharing available system resources (e.g., bandwidth, transmission power, etc.). Examples of multiple access systems include code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and multi-carrier frequency division multiple access (MC-FDMA).

[0003] Sidelink (SL) refers to a communication method that establishes a direct link between user equipment (UE), allowing voice or data to be exchanged directly between terminals without going through a base station (BS). SL is being considered as a solution to address the burden on base stations due to rapidly increasing data traffic.

[0004] V2X (vehicle-to-everything) refers to a communication technology that exchanges information with other vehicles, pedestrians, and infrastructure-based objects through wired / wireless communication. V2X can be divided into four types: V2V (vehicle-to-vehicle), V2I (vehicle-to-infrastructure), V2N (vehicle-to-network), and V2P (vehicle-to-pedestrian). V2X communication can be provided through the PC5 interface and / or Uu interface.

[0005] Meanwhile, as more and more communication devices demand greater communication capacity, the need for improved mobile broadband communication compared to existing radio access technology (RAT) is emerging. Accordingly, communication systems that consider services or terminals sensitive to reliability and latency are being discussed. Next-generation wireless access technologies that consider improved mobile broadband communication, massive machine type communication (MTC), and ultra-reliable and low latency communication (URLLC) can be called new radio access technology (RAT) or new radio (NR). NR can also support vehicle-to-everything (V2X) communication.

[0006] Figure 1 is a diagram for comparing and explaining V2X communication based on RAT before NR and V2X communication based on NR.

[0007] In relation to V2X communication, in RATs prior to NR, methods for providing safety services based on V2X messages such as Basic Safety Message (BSM), Cooperative Awareness Message (CAM), and Decentralized Environmental Notification Message (DENM) were mainly discussed. V2X messages may include location information, dynamic information, attribute information, etc. For example, a terminal may transmit a CAM of a periodic message type and / or a DENM of an event triggered message type to another terminal.

[0008] For example, a CAM may include basic vehicle information such as dynamic vehicle status information, such as direction and speed, static vehicle data, such as dimensions, external lighting conditions, and route history. For example, a terminal may broadcast a CAM, and the latency of the CAM may be less than 100 ms. For example, in the event of an emergency, such as a vehicle breakdown or accident, a terminal may generate a DENM and transmit it to other terminals. For example, all vehicles within the transmission range of the terminal may receive the CAM and / or DENM. In this case, the DENM may have a higher priority than the CAM.

[0009] Since then, various V2X scenarios have been proposed in NR in relation to V2X communications. For example, various V2X scenarios may include vehicle platooning, advanced driving, extended sensors, and remote driving.

[0010] For example, based on vehicle platooning, vehicles can dynamically form groups and move together. For example, to perform platoon operations based on vehicle platooning, vehicles in the group can receive periodic data from the lead vehicle. For example, vehicles in the group can use this periodic data to narrow or widen the gap between vehicles.

[0011] For example, based on improved driving, vehicles can become semi-autonomous or fully automated. For example, each vehicle can adjust its trajectories or maneuvers based on data acquired from local sensors of nearby vehicles and / or nearby logical entities. Furthermore, for example, each vehicle can share driving intentions with nearby vehicles.

[0012] For example, based on extended sensors, raw data, processed data, or live video data acquired through local sensors can be exchanged between vehicles, logical entities, pedestrian terminals, and / or V2X application servers. Thus, for example, a vehicle can perceive its environment better than it can perceive using its own sensors.

[0013] For example, based on remote driving, a remote driver or V2X application can operate or control the remote vehicle for people who cannot drive or for remote vehicles located in hazardous environments. For example, in cases where the route is predictable, such as public transportation, cloud computing-based driving can be utilized to operate or control the remote vehicle. Additionally, access to a cloud-based back-end service platform, for example, can be considered for remote driving.

[0014] Meanwhile, a method to specify service requirements for various V2X scenarios, such as vehicle platooning, enhanced driving, expanded sensors, and remote driving, is being discussed in NR-based V2X communication.

[0015] The technical problem to be solved by the present invention is to provide a method for performing communication more accurately and efficiently.

[0016] The technical challenges are not limited to the technical challenges mentioned above, and other technical challenges not mentioned will be clearly understood by those skilled in the art to which the present invention pertains from the description below.

[0017] In a wireless communication system according to one aspect, a method for triggering a measurement report by a first UE may include: forming a direct link directly connected to a base station; forming at least one indirect link connecting the at least one UE and the base station via a first UE (User Equipment); transmitting a message requesting transmission of a response message related to signal quality for the base station to the at least one UE based on whether a signal strength of the direct link is below a specific threshold; and determining whether to trigger a measurement report based on whether the response message is received.

[0018] Alternatively, the response message is characterized in that it is received from a UE having a signal quality measured for the base station that is above a specific threshold among the at least one UE.

[0019] Alternatively, based on the reception of the response message, the measurement report is not triggered.

[0020] Alternatively, the measurement report is characterized in that it is triggered based on the response message not being received.

[0021] Alternatively, the response message is characterized in that it includes information about the signal strength measured for the base station, the amount of change in the signal strength, and the capability of the UE.

[0022] Alternatively, the direct link is characterized in that it is formed based on a virtual C-RNTI (Cell Radio Network Temporary Identifier) ​​preset for the first UE and the cluster group including the at least one UE.

[0023] Alternatively, the method further comprises the step of transmitting a request message requesting the specific UE to form a direct connection with the base station based on the response message being received from a specific UE among the at least one UE.

[0024] Alternatively, the method further comprises a step of forming an indirect link connected to the base station through the specific UE based on transmission of the request message.

[0025] Alternatively, the measurement report is characterized in that it includes information about the signal strength measured for at least one neighboring cell.

[0026] Alternatively, the message is characterized in that the first UE is a leader UAV (Unmanned Aerial Vehicle) UE of a first constellation group consisting of at least one UE and the first UE is located above a specific height.

[0027] According to another aspect, a non-transitory computer-readable storage medium having recorded thereon instructions for performing the method for triggering the measurement report described above may be provided.

[0028] According to another aspect, a first UE may be provided that performs a method for triggering the measurement report described above.

[0029] According to another aspect, a processing device may be provided for controlling a first UE to perform a method for triggering the measurement report described above.

[0030] According to another aspect, a method for a second UE to perform communication in a wireless communication system may include: forming an indirect link connected to a base station through a first UE (User Equipment); receiving a request message requesting transmission of a response message related to signal quality for the base station from the first UE; transmitting the response message to the first UE based on the measured signal quality for the base station satisfying a specific condition; and performing a procedure for forming a direct link with the base station.

[0031] According to another aspect, a second UE may be provided that performs the method of performing the communication described above.

[0032] According to one embodiment, communication can be performed more accurately and efficiently in a wireless communication system.

[0033] The effects that can be obtained in various embodiments are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art to which the present invention pertains from the description below.

[0034] The drawings attached to this specification are intended to provide an understanding of the present invention, illustrate various embodiments of the present invention, and together with the description of the specification serve to explain the principles of the present invention.

[0035] Figure 1 is a diagram for comparing and explaining V2X communication based on RAT before NR and V2X communication based on NR.

[0036] Figure 2 shows the structure of the LTE system.

[0037] Figure 3 shows the structure of the NR system.

[0038] Figure 4 shows the structure of a radio frame of NR.

[0039] Figure 5 shows the slot structure of an NR frame.

[0040] FIG. 6 illustrates a communication structure that can be provided in a 6G system according to one embodiment of the present disclosure.

[0041] FIG. 7 illustrates an electromagnetic spectrum according to one embodiment of the present disclosure.

[0042] Figure 8 shows a radio protocol architecture for SL communication.

[0043] Figure 9 shows a terminal performing V2X or SL communication.

[0044] Figure 10 shows resource units for V2X or SL communication.

[0045] FIG. 11 illustrates an example of a BWP according to one embodiment of the present disclosure.

[0046] FIG. 12 illustrates a procedure for a terminal to perform V2X or SL communication according to a resource allocation mode, according to one embodiment of the present disclosure.

[0047] Figure 13 is a diagram for explaining the control plane procedure of L2 U2N relay (UE-to-Network Relay).

[0048] Figures 14 to 18 are drawings for explaining the U2X system.

[0049] Figure 19 is a diagram for explaining the occurrence of interference in a public communication environment.

[0050] FIG. 20 is a diagram for explaining how a leader of a cluster of UAV UEs performs a handover operation.

[0051] Figure 21 is a diagram for explaining a method for triggering a measurement report by a first UE.

[0052] Figure 22 is a diagram for explaining how a second UE performs communication.

[0053] Figure 23 illustrates a communication system applied to the present invention.

[0054] Figure 24 illustrates a wireless device applicable to the present invention.

[0055] Figure 25 illustrates another example of a wireless device applicable to the present invention. The wireless device may be implemented in various forms depending on the use case / service.

[0056] Figure 26 illustrates a vehicle or autonomous vehicle to which the present invention is applied.

[0057] A wireless communication system is a multiple access system that supports communication with multiple users by sharing available system resources (e.g., bandwidth, transmission power, etc.). Examples of multiple access systems include code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and multi-carrier frequency division multiple access (MC-FDMA).

[0058] Sidelink refers to a communication method that establishes a direct link between user equipment (UE), allowing voice or data to be exchanged directly between terminals without going through a base station (BS). Sidelink is being considered as a solution to address the burden on base stations due to rapidly increasing data traffic.

[0059] V2X (vehicle-to-everything) refers to a communication technology that exchanges information with other vehicles, pedestrians, and infrastructure-based objects through wired / wireless communication. V2X can be divided into four types: V2V (vehicle-to-vehicle), V2I (vehicle-to-infrastructure), V2N (vehicle-to-network), and V2P (vehicle-to-pedestrian). V2X communication can be provided through the PC5 interface and / or Uu interface.

[0060] Meanwhile, as more and more communication devices demand greater communication capacity, the need for improved mobile broadband communication compared to existing radio access technology (RAT) is emerging. Accordingly, communication systems that consider services or terminals sensitive to reliability and latency are being discussed. Next-generation wireless access technologies that consider improved mobile broadband communication, massive MTC, and URLLC (Ultra-Reliable and Low Latency Communication) can be called new radio access technology (RAT) or new radio (NR). NR can also support V2X (vehicle-to-everything) communication.

[0061] The following technologies can be used in various wireless communication systems, such as CDMA (code division multiple access), FDMA (frequency division multiple access), TDMA (time division multiple access), OFDMA (orthogonal frequency division multiple access), and SC-FDMA (single carrier frequency division multiple access). CDMA can be implemented with wireless technologies such as UTRA (universal terrestrial radio access) or CDMA2000. TDMA can be implemented with wireless technologies such as GSM (global system for mobile communications) / GPRS (general packet radio service) / EDGE (enhanced data rates for GSM evolution). OFDMA can be implemented with wireless technologies such as IEEE (Institute of Electrical and Electronics Engineers) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, and E-UTRA (evolved UTRA). IEEE 802.16m is an evolution of IEEE 802.16e, providing backward compatibility with systems based on IEEE 802.16e. UTRA is part of UMTS (universal mobile telecommunications system). 3GPP (3rd generation partnership project) LTE (long term evolution) is a part of E-UMTS (evolved UMTS) that uses E-UTRA (evolved-UMTS terrestrial radio access), employing OFDMA in the downlink and SC-FDMA in the uplink.LTE-A (advanced) is an evolution of 3GPP LTE.

[0062] 5G NR, the successor to LTE-A, is a new clean-slate mobile communications system featuring high performance, low latency, and high availability. 5G NR can utilize all available spectrum resources, from low-frequency bands below 1 GHz, mid-frequency bands between 1 GHz and 10 GHz, and high-frequency (millimeter wave) bands above 24 GHz.

[0063] For clarity, the description will focus on LTE-A or 5G NR, but the technical ideas of the embodiment(s) are not limited thereto.

[0064] Figure 2 illustrates the architecture of an applicable LTE system. This may be referred to as an Evolved-UMTS Terrestrial Radio Access Network (E-UTRAN) or a Long Term Evolution (LTE) / LTE-A system.

[0065] Referring to FIG. 2, the E-UTRAN includes a base station (20; BS) that provides a control plane and a user plane to a terminal (10). The terminal (10) may be fixed or mobile, and may be referred to by other terms such as a mobile station (MS), a user terminal (UT), a subscriber station (SS), a mobile terminal (MT), a wireless device, etc. The base station (20) refers to a fixed station that communicates with the terminal (10), and may be referred to by other terms such as an evolved-NodeB (eNB), a base transceiver system (BTS), an access point, etc.

[0066] Base stations (20) can be connected to each other via the X2 interface. The base station (20) is connected to an EPC (Evolved Packet Core, 30) via the S1 interface, more specifically, to an MME (Mobility Management Entity) via the S1-MME, and to an S-GW (Serving Gateway) via the S1-U.

[0067] The EPC (30) consists of an MME, an S-GW, and a P-GW (Packet Data Network-Gateway). The MME holds information about terminal access and capabilities, and this information is primarily used for terminal mobility management. The S-GW is a gateway with the E-UTRAN as its endpoint, and the P-GW is a gateway with the PDN as its endpoint.

[0068] The layers of the radio interface protocol between the terminal and the network can be divided into L1 (Layer 1), L2 (Layer 2), and L3 (Layer 3) based on the three lower layers of the Open System Interconnection (OSI) standard model, which is widely known in communication systems. Among these, the physical layer belonging to Layer 1 provides an information transfer service using a physical channel, and the RRC (Radio Resource Control) layer located in Layer 3 controls radio resources between the terminal and the network. To this end, the RRC layer exchanges RRC messages between the terminal and the base station.

[0069] Figure 3 shows the structure of the NR system.

[0070] Referring to FIG. 3, the NG-RAN may include a gNB and / or an eNB that provides user plane and control plane protocol termination to the UE. FIG. 7 illustrates a case where only a gNB is included. The gNB and eNB are connected to each other via an Xn interface. The gNB and eNB are connected to the 5th generation core network (5G Core Network: 5GC) via the NG interface. More specifically, the gNB is connected to the access and mobility management function (AMF) via the NG-C interface, and the gNB is connected to the user plane function (UPF) via the NG-U interface.

[0071] Figure 4 shows the structure of a radio frame of NR.

[0072] Referring to FIG. 4, radio frames can be used for uplink and downlink transmission in NR. A radio frame has a length of 10 ms and can be defined as two 5 ms half-frames (Half-Frames, HF). A half-frame can include five 1 ms sub-frames (Subframes, SF). A sub-frame can be divided into one or more slots, and the number of slots within a sub-frame can be determined by the Subcarrier Spacing (SCS). Each slot can include 12 or 14 OFDM (A) symbols depending on the cyclic prefix (CP).

[0073] When normal CP is used, each slot can contain 14 symbols. When extended CP is used, each slot can contain 12 symbols. Here, the symbols can include OFDM symbols (or CP-OFDM symbols), SC-FDMA (Single Carrier - FDMA) symbols (or DFT-s-OFDM (Discrete Fourier Transform-spread-OFDM) symbols).

[0074] Table 1 below shows the number of symbols per slot ((N)) depending on the SCS setting (u) when normal CP is used. slot symb ), number of slots per frame ((N frame,u slot ) and the number of slots per subframe ((N subframe,u slot ) is an example.

[0075] SCS (15*2 u )N slot symb N frame,u slot N subframe,u slot 15KHz (u=0)1410130KHz (u=1)1420260KHz (u=2)14404120KHz (u=3)14808240KHz (u=4)1416016

[0076] Table 2 illustrates the number of symbols per slot, the number of slots per frame, and the number of slots per subframe according to SCS when extended CP is used.

[0077] SCS (15*2 u )N slot symb N frame,u slot N subframe,u slot 60KHz (u=2)12404

[0078] In an NR system, OFDM(A) numerology (e.g., SCS, CP length, etc.) may be set differently between multiple cells that are merged into a single terminal. Accordingly, the (absolute time) interval of a time resource (e.g., subframe, slot, or TTI) (conveniently referred to as TU (Time Unit)) consisting of the same number of symbols may be set differently between the merged cells.

[0079] In NR, multiple numerologies, or SCSs, can be supported to support various 5G services. For example, a 15 kHz SCS can support wide areas in traditional cellular bands, while a 30 kHz / 60 kHz SCS can support dense urban areas, lower latency, and wider carrier bandwidth. A 60 kHz or higher SCS can support bandwidths greater than 24.25 GHz to overcome phase noise.

[0080] The NR frequency band can be defined by two types of frequency ranges. The two types of frequency ranges can be FR1 and FR2. The numerical values ​​of the frequency ranges can be changed, and for example, the two types of frequency ranges can be as shown in Table 3 below. Among the frequency ranges used in the NR system, FR1 can mean the "sub 6 GHz range", and FR2 can mean the "above 6 GHz range" and can be called millimeter wave (mmW).

[0081] Frequency Range designationCorresponding frequency rangeSubcarrier Spacing (SCS)FR1450MHz - 6000MHz15, 30, 60kHzFR224250MHz - 52600MHz60, 120, 240kHz

[0082] As described above, the numerical value of the frequency range of the NR system can be changed. For example, FR1 may include a band from 410 MHz to 7125 MHz, as shown in Table 4 below. That is, FR1 may include a frequency band above 6 GHz (or 5850, 5900, 5925 MHz, etc.). For example, the frequency band above 6 GHz (or 5850, 5900, 5925 MHz, etc.) included within FR1 may include an unlicensed band. The unlicensed band may be used for various purposes, such as for vehicular communications (e.g., autonomous driving).

[0083] Frequency Range designationCorresponding frequency rangeSubcarrier Spacing (SCS)FR1410MHz - 7125MHz15, 30, 60kHzFR224250MHz - 52600MHz60, 120, 240kHz

[0084] Figure 5 shows the slot structure of an NR frame.

[0085] Referring to Figure 5, a slot includes multiple symbols in the time domain. For example, in the case of a normal CP, one slot may include 14 symbols, but in the case of an extended CP, one slot may include 12 symbols. Alternatively, in the case of a normal CP, one slot may include 7 symbols, but in the case of an extended CP, one slot may include 6 symbols.

[0086] A carrier includes multiple subcarriers in the frequency domain. An RB (Resource Block) can be defined as multiple (e.g., 12) consecutive subcarriers in the frequency domain. A BWP (Bandwidth Part) can be defined as multiple consecutive (P)RBs ((Physical) Resource Blocks) in the frequency domain, and can correspond to one numerology (e.g., SCS, CP length, etc.). A carrier can include up to N (e.g., 5) BWPs. Data communication can be performed through activated BWPs. Each element can be referred to as a Resource Element (RE) in the resource grid, and one complex symbol can be mapped to it.

[0087] Meanwhile, the wireless interface between terminals or between terminals and a network may be composed of an L1 layer, an L2 layer, and an L3 layer. In various embodiments of the present disclosure, the L1 layer may refer to a physical layer. Furthermore, for example, the L2 layer may refer to at least one of a MAC layer, an RLC layer, a PDCP layer, and an SDAP layer. Furthermore, for example, the L3 layer may refer to an RRC layer.

[0088] FIG. 6 illustrates a communication structure that can be provided in a 6G system according to an embodiment of the present disclosure. The embodiment of FIG. 6 can be combined with various embodiments of the present disclosure.

[0089] New network characteristics in 6G may include:

[0090] - Satellite integrated network

[0091] - Connected Intelligence: Unlike previous generations of wireless communication systems, 6G is revolutionary, upgrading the wireless evolution from "connected objects" to "connected intelligence." AI can be applied at every stage of the communication process (or at every signal processing step, as described below).

[0092] - Seamless integration of wireless information and energy transfer

[0093] - Ubiquitous super 3D connectivity: Access to networks and core network functions of drones and very low Earth orbit satellites will create super 3D connectivity in 6G ubiquitous.

[0094] Some general requirements for the new network characteristics of 6G, such as the above, may be as follows:

[0095] - small cell networks

[0096] - Ultra-dense heterogeneous network

[0097] - High-capacity backhaul

[0098] - Radar technology integrated with mobile technology: High-precision localization (or location-based services) through communications is a key feature of 6G wireless communication systems. Therefore, radar systems will be integrated with 6G networks.

[0099] - Softwarization and virtualization

[0100] Below, the core implementation technologies of the 6G system are described.

[0101] - Artificial Intelligence: Incorporating AI into communications can streamline and improve real-time data transmission. AI can use numerous analytics to determine how complex target tasks should be performed. This means AI can increase efficiency and reduce processing delays. Time-consuming tasks such as handovers, network selection, and resource scheduling can be performed instantly using AI. AI can also play a crucial role in machine-to-machine (M2M), machine-to-human, and human-to-machine communications. Furthermore, AI can facilitate rapid communication in brain-computer interfaces (BCIs). AI-based communication systems can be supported by metamaterials, intelligent structures, intelligent networks, intelligent devices, intelligent cognitive radios, self-sustaining wireless networks, and machine learning.

[0102] - THz communication (terahertz communication): Data rates can be increased by increasing the bandwidth. This can be achieved by using sub-THz communication with wide bandwidths and applying advanced massive MIMO technology. THz waves, also known as sub-millimeter waves, typically refer to the frequency range between 0.1 THz and 10 THz, with corresponding wavelengths ranging from 0.03 mm to 3 mm. The 100 GHz to 300 GHz band (sub-THz band) is considered a key part of the THz spectrum for cellular communications. Adding the sub-THz band to the mmWave band will increase the capacity of 6G cellular communications. Among the defined THz bands, 300 GHz to 3 THz lies in the far infrared (IR) frequency band. While part of the optical band, the 300 GHz to 3 THz band lies at the boundary of the optical band, immediately following the RF band. Therefore, this 300 GHz to 3 THz band exhibits similarities to RF.

[0103] Figure 7 illustrates the electromagnetic spectrum according to one embodiment of the present disclosure. The embodiment of Figure 7 can be combined with various embodiments of the present disclosure. Key characteristics of THz communications include (i) a widely available bandwidth to support very high data rates, and (ii) high path loss at high frequencies (highly directional antennas are essential). The narrow beamwidth generated by the highly directional antenna reduces interference. The small wavelength of THz signals allows for a much larger number of antenna elements to be integrated into devices and base stations operating in this band. This enables the use of advanced adaptive array techniques to overcome range limitations.

[0104] - Large-scale MIMO technology

[0105] - Hologram beamforming (HBF)

[0106] - Optical wireless technology

[0107] - Free-space optical transmission backhaul network (FSO backhaul network)

[0108] - Quantum communication

[0109] - Cell-free communication

[0110] - Integration of wireless information and power transmission

[0111] - Integration of wireless communication and sensing

[0112] - Integrated access and backhaul network

[0113] - Big data analysis

[0114] - Reconfigurable intelligent surface

[0115] - metaverse

[0116] - Block chain

[0117] Unmanned aerial vehicles (UAVs): UAVs, or drones, will be a key element in 6G wireless communications. In most cases, high-speed data wireless connectivity can be provided using UAV technology. Base stations (BSs) can be installed on UAVs to provide cellular connectivity. UAVs may offer specific capabilities not found in fixed BS infrastructure, such as easy deployment, robust line-of-sight links, and controlled mobility. During emergencies such as natural disasters, deploying terrestrial communications infrastructure is not economically feasible and sometimes cannot provide services in volatile environments. UAVs can easily handle these situations. UAVs will become a new paradigm in wireless communications. This technology facilitates three fundamental requirements for wireless networks: enhanced mobile broadband (eMBB), URLLC, and mMTC. UAVs can also support various purposes, such as enhancing network connectivity, fire detection, disaster emergency services, security and surveillance, pollution monitoring, parking monitoring, and accident monitoring. Therefore, UAV technology is recognized as one of the most important technologies for 6G communications.

[0118] - Autonomous driving (self-driving): V2X (vehicle to everything), a key element in building autonomous driving infrastructure, can be a technology that allows cars to communicate and share with various elements on the road for autonomous driving, such as vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) wireless communication. Fast transmission speeds and low-latency technologies are essential to maximize autonomous driving performance and ensure high safety. Furthermore, in the future, autonomous driving will go beyond simply providing warnings or guidance messages to drivers and may require active intervention in vehicle operation and direct control of the vehicle in dangerous situations. To this end, the amount of information that needs to be transmitted and received may become enormous, so 6G is expected to maximize autonomous driving with faster transmission speeds and lower latency than 5G.

[0119] Figure 8 illustrates a radio protocol architecture for SL communication. Specifically, Figure 8 (a) illustrates the user plane protocol stack of NR, and Figure 8 (b) illustrates the control plane protocol stack of NR.

[0120] Below, the SL synchronization signal (Sidelink Synchronization Signal, SLSS) and synchronization information are described.

[0121] SLSS is an SL-specific sequence and may include a Primary Sidelink Synchronization Signal (PSSS) and a Secondary Sidelink Synchronization Signal (SSSS). The PSSS may be referred to as a Sidelink Primary Synchronization Signal (S-PSS), and the SSSS may be referred to as a Sidelink Secondary Synchronization Signal (S-SSS). For example, length-127 M-sequences may be used for the S-PSS, and length-127 Gold sequences may be used for the S-SSS. For example, a terminal may detect an initial signal and acquire synchronization using the S-PSS. For example, a terminal may acquire detailed synchronization and detect a synchronization signal ID using the S-PSS and the S-SSS.

[0122] PSBCH (Physical Sidelink Broadcast Channel) may be a (broadcast) channel that transmits basic (system) information that a terminal must know first before transmitting or receiving an SL signal. For example, the basic information may be information related to SLSS, duplex mode (DM), TDD UL / DL (Time Division Duplex Uplink / Downlink) configuration, resource pool-related information, type of application related to SLSS, subframe offset, broadcast information, etc. For example, in NR V2X, for evaluating PSBCH performance, the payload size of PSBCH may be 56 bits, including a 24-bit CRC.

[0123] S-PSS, S-SSS and PSBCH may be included in a block format supporting periodic transmission (e.g., SL SS (Synchronization Signal) / PSBCH block, hereinafter referred to as S-SSB (Sidelink-Synchronization Signal Block)). The S-SSB may have the same numerology (i.e., SCS and CP length) as the PSCCH (Physical Sidelink Control Channel) / PSSCH (Physical Sidelink Shared Channel) in the carrier, and the transmission bandwidth may be within a (pre-)configured SL BWP (Sidelink BWP). For example, the bandwidth of the S-SSB may be 11 RBs (Resource Blocks). For example, the PSBCH may span 11 RBs. And, the frequency location of the S-SSB may be (pre-)configured. Therefore, the terminal does not need to perform hypothesis detection in the frequency to discover the S-SSB in the carrier.

[0124] Meanwhile, in the NR SL system, multiple numerologies having different SCS and / or CP lengths may be supported. In this case, as the SCS increases, the length of the time resource for a transmitting terminal to transmit an S-SSB may become shorter. Accordingly, the coverage of the S-SSB may decrease. Therefore, in order to ensure the coverage of the S-SSB, the transmitting terminal may transmit one or more S-SSBs to a receiving terminal within one S-SSB transmission period according to the SCS. For example, the number of S-SSBs that the transmitting terminal transmits to the receiving terminal within one S-SSB transmission period may be pre-configured or configured for the transmitting terminal. For example, the S-SSB transmission period may be 160 ms. For example, an S-SSB transmission period of 160 ms may be supported for all SCSs.

[0125] For example, when the SCS is 15 kHz at FR1, the transmitting terminal can transmit one or two S-SSBs to the receiving terminal within one S-SSB transmission period. For example, when the SCS is 30 kHz at FR1, the transmitting terminal can transmit one or two S-SSBs to the receiving terminal within one S-SSB transmission period. For example, when the SCS is 60 kHz at FR1, the transmitting terminal can transmit one, two, or four S-SSBs to the receiving terminal within one S-SSB transmission period.

[0126] For example, when the SCS is 60 kHz at FR2, the transmitting terminal can transmit 1, 2, 4, 8, 16, or 32 S-SSBs to the receiving terminal within one S-SSB transmission period. For example, when the SCS is 120 kHz at FR2, the transmitting terminal can transmit 1, 2, 4, 8, 16, 32, or 64 S-SSBs to the receiving terminal within one S-SSB transmission period.

[0127] Meanwhile, when the SCS is 60 kHz, two types of CP may be supported. In addition, the structure of the S-SSB transmitted by the transmitting terminal to the receiving terminal may be different depending on the CP type. For example, the CP type may be Normal CP (NCP) or Extended CP (ECP). Specifically, for example, when the CP type is NCP, the number of symbols to which the PSBCH is mapped within the S-SSB transmitted by the transmitting terminal may be 9 or 8. On the other hand, for example, when the CP type is ECP, the number of symbols to which the PSBCH is mapped within the S-SSB transmitted by the transmitting terminal may be 7 or 6. For example, the PSBCH may be mapped to the first symbol within the S-SSB transmitted by the transmitting terminal. For example, the receiving terminal receiving the S-SSB may perform an Automatic Gain Control (AGC) operation in the first symbol section of the S-SSB.

[0128] Figure 9 shows a terminal performing V2X or SL communication.

[0129] Referring to FIG. 9, the term "terminal" in V2X or SL communication may primarily refer to a user's terminal. However, if a network device such as a base station transmits and receives signals according to a communication method between terminals, the base station may also be considered a type of terminal. For example, terminal 1 may be a first device (100), and terminal 2 may be a second device (200).

[0130] For example, terminal 1 can select a resource unit corresponding to a specific resource within a resource pool, which represents a set of resources. Then, terminal 1 can transmit an SL signal using the resource unit. For example, terminal 2, which is a receiving terminal, can be configured with a resource pool in which terminal 1 can transmit a signal, and can detect a signal from terminal 1 within the resource pool.

[0131] Here, if terminal 1 is within the connection range of the base station, the base station can inform terminal 1 of the resource pool. On the other hand, if terminal 1 is outside the connection range of the base station, another terminal can inform terminal 1 of the resource pool, or terminal 1 can use a pre-configured resource pool.

[0132] In general, a resource pool can be composed of multiple resource units, and each terminal can select one or multiple resource units to use for its SL signal transmission.

[0133] Figure 10 shows resource units for V2X or SL communication.

[0134] Referring to Figure 10, the entire frequency resources of the resource pool can be divided into NF units, and the entire time resources of the resource pool can be divided into NT units. Therefore, a total of NF * NT resource units can be defined within the resource pool. Figure 13 illustrates an example where the resource pool repeats with a cycle of NT subframes.

[0135] As shown in Figure 10, a single resource unit (e.g., Unit #0) may appear periodically and repeatedly. Alternatively, to achieve diversity effects in the time or frequency dimensions, the index of the physical resource unit to which a single logical resource unit is mapped may change in a predetermined pattern over time. In this resource unit structure, a resource pool may refer to a set of resource units that a terminal wishing to transmit an SL signal can use for transmission.

[0136] Resource pools can be subdivided into several categories. For example, based on the content of the SL signal transmitted from each resource pool, resource pools can be categorized as follows:

[0137] (1) Scheduling Assignment (SA) may be a signal that includes information such as the location of resources used by a transmitting terminal for transmission of an SL data channel, MCS (Modulation and Coding Scheme) or MIMO (Multiple Input Multiple Output) transmission method required for demodulation of other data channels, and TA (Timing Advance). SA may also be transmitted multiplexed with SL data on the same resource unit, in which case the SA resource pool may mean a resource pool in which SA is multiplexed with SL data and transmitted. SA may also be called an SL control channel.

[0138] (2) The SL data channel (Physical Sidelink Shared Channel, PSSCH) may be a resource pool used by a transmitting terminal to transmit user data. If SA is multiplexed and transmitted together with SL data on the same resource unit, only the SL data channel excluding SA information may be transmitted from the resource pool for the SL data channel. In other words, the REs (Resource Elements) that were used to transmit SA information on individual resource units within the SA resource pool may still be used to transmit SL data in the resource pool of the SL data channel. For example, the transmitting terminal may transmit the PSSCH by mapping it to consecutive PRBs.

[0139] (3) A discovery channel may be a resource pool for transmitting terminals to transmit information such as their IDs. Through this, transmitting terminals can enable neighboring terminals to discover them.

[0140] Even if the content of the SL signal described above is the same, different resource pools may be used depending on the transmission and reception properties of the SL signal. For example, even if it is the same SL data channel or discovery message, it may be again divided into different resource pools depending on the transmission timing determination method of the SL signal (for example, whether it is transmitted at the time of reception of a synchronization reference signal or whether it is transmitted by applying a certain timing advance at the time of reception), the resource allocation method (for example, whether the base station designates transmission resources for individual signals to individual transmitting terminals or whether individual transmitting terminals independently select individual signal transmission resources within the resource pool), the signal format (for example, the number of symbols each SL signal occupies in one subframe or the number of subframes used for transmission of one SL signal), the signal strength from the base station, the transmission power strength of the SL terminal, etc.

[0141] FIG. 11 illustrates an example of a BWP according to an embodiment of the present disclosure. The embodiment of FIG. 11 can be combined with various embodiments of the present disclosure. In the embodiment of FIG. 11, it is assumed that there are three BWPs.

[0142] Referring to Figure 11, a common resource block (CRB) may be a carrier resource block numbered from one end of a carrier band to the other. Furthermore, a PRB may be a numbered resource block within each BWP. Point A may indicate a common reference point for the resource block grid.

[0143] The BWP can be set by Point A, an offset from Point A (NstartBWP), and a bandwidth (NsizeBWP). For example, Point A can be an outer reference point of a PRB of a carrier where subcarrier 0 of all numerologies (e.g., all numerologies supported by the network on that carrier) are aligned. For example, the offset can be the PRB spacing between the lowest subcarrier in a given numerology and Point A. For example, the bandwidth can be the number of PRBs in a given numerology.

[0144] SLSS (Sidelink Synchronization Signal) is a SL (sidelink) specific sequence and may include PSSS (Primary Sidelink Synchronization Signal) and SSSS (Secondary Sidelink Synchronization Signal). The PSSS may be referred to as S-PSS (Sidelink Primary Synchronization Signal) and the SSSS may be referred to as S-SSS (Sidelink Secondary Synchronization Signal). For example, length-127 M-sequences may be used for S-PSS and length-127 Gold sequences may be used for S-SSS. For example, a terminal may detect an initial signal (signal detection) and obtain synchronization using S-PSS. For example, the terminal can obtain detailed synchronization using S-PSS and S-SSS and detect a synchronization signal ID.

[0145] PSBCH (Physical Sidelink Broadcast Channel) may be a (broadcast) channel that transmits basic (system) information that a terminal must know first before transmitting or receiving an SL signal. For example, the basic information may be information related to SLSS, duplex mode (DM), TDD UL / DL (Time Division Duplex Uplink / Downlink) configuration, resource pool-related information, type of application related to SLSS, subframe offset, broadcast information, etc. For example, in order to evaluate PSBCH performance, in NR V2X, the payload size of PSBCH may be 56 bits, including a 24-bit CRC (Cyclic Redundancy Check).

[0146] S-PSS, S-SSS and PSBCH may be included in a block format supporting periodic transmission (e.g., SL SS (Synchronization Signal) / PSBCH block, hereinafter referred to as S-SSB (Sidelink-Synchronization Signal Block)). The S-SSB may have the same numerology (i.e., SCS and CP length) as the PSCCH (Physical Sidelink Control Channel) / PSSCH (Physical Sidelink Shared Channel) in the carrier, and the transmission bandwidth may be within a (pre-)configured SL BWP (Sidelink BWP). For example, the bandwidth of the S-SSB may be 11 RBs (Resource Blocks). For example, the PSBCH may span 11 RBs. And, the frequency location of the S-SSB may be (pre-)configured. Therefore, the terminal does not need to perform hypothesis detection in the frequency to discover the S-SSB in the carrier.

[0147] FIG. 12 illustrates a procedure for a terminal to perform V2X or SL communication according to a resource allocation mode, according to one embodiment of the present disclosure. The embodiment of FIG. 12 may be combined with various embodiments of the present disclosure.

[0148] Referring to (a) of FIG. 12, in resource allocation mode 1, the base station may schedule SL resources to be used by the terminal for SL transmission. For example, in step S1200, the base station may transmit information related to SL resources and / or information related to UL resources to the first terminal. For example, the UL resources may include PUCCH resources and / or PUSCH resources. For example, the UL resources may be resources for reporting SL HARQ feedback to the base station.

[0149] For example, a first terminal may receive information related to a dynamic grant (DG) resource and / or information related to a configured grant (CG) resource from a base station. For example, a CG resource may include a CG type 1 resource or a CG type 2 resource. In this specification, a DG resource may be a resource that a base station configures / allocates to the first terminal via downlink control information (DCI). In this specification, a CG resource may be a (periodic) resource that a base station configures / allocates to the first terminal via DCI and / or an RRC message. For example, in the case of a CG type 1 resource, the base station may transmit an RRC message including information related to the CG resource to the first terminal. For example, in the case of a CG type 2 resource, the base station may transmit an RRC message including information related to the CG resource to the first terminal, and the base station may transmit a DCI related to activation or release of the CG resource to the first terminal.

[0150] In step S1510, the first terminal may transmit a PSCCH (e.g., Sidelink Control Information (SCI) or 1st-stage SCI) to the second terminal based on the resource scheduling. In step S1220, the first terminal may transmit a PSSCH (e.g., 2nd-stage SCI, MAC PDU, data, etc.) related to the PSCCH to the second terminal. In step S1230, the first terminal may receive a PSFCH related to the PSCCH / PSSCH from the second terminal. For example, HARQ feedback information (e.g., NACK information or ACK information) may be received from the second terminal via the PSFCH. In step S1240, the first terminal may transmit / report HARQ feedback information to the base station via a PUCCH or a PUSCH. For example, the HARQ feedback information reported to the base station may be information generated by the first terminal based on the HARQ feedback information received from the second terminal. For example, the HARQ feedback information reported to the base station may be information generated by the first terminal based on a rule set in advance. For example, the DCI may be DCI for scheduling SL.

[0151] Referring to (b) of FIG. 12, in resource allocation mode 2, a terminal can determine an SL transmission resource within the SL resources set by the base station / network or within the preset SL resources. For example, the set SL resources or the preset SL resources may be a resource pool. For example, the terminal can autonomously select or schedule resources for SL transmission. For example, the terminal can perform SL communication by selecting a resource within the set resource pool. For example, the terminal can select a resource within a selection window by performing sensing and resource (re)selection procedures. For example, the sensing can be performed on a subchannel basis. For example, in step S1210, a first terminal that has selected a resource within the resource pool can transmit a PSCCH (e.g., Sidelink Control Information (SCI) or 1st-stage SCI) to a second terminal using the resource. In step S1220, the first terminal may transmit a PSSCH (e.g., 2nd-stage SCI, MAC PDU, data, etc.) related to the PSCCH to the second terminal. In step S1230, the first terminal may receive a PSFCH related to the PSCCH / PSSCH from the second terminal.

[0152] Referring to (a) or (b) of FIG. 12, for example, a first terminal may transmit an SCI to a second terminal on a PSCCH. Or, for example, the first terminal may transmit two consecutive SCIs (e.g., 2-stage SCIs) to the second terminal on the PSCCH and / or the PSSCH. In this case, the second terminal may decode the two consecutive SCIs (e.g., 2-stage SCIs) to receive the PSSCH from the first terminal. In this specification, an SCI transmitted on a PSCCH may be referred to as a 1st SCI, a 1st SCI, a 1st-stage SCI, or a 1st-stage SCI format, and an SCI transmitted on a PSSCH may be referred to as a 2nd SCI, a 2nd SCI, a 2nd-stage SCI, or a 2nd-stage SCI format.

[0153] Referring to (a) or (b) of FIG. 12, in step S1530, the first terminal may receive a PSFCH. For example, the first terminal and the second terminal may determine PSFCH resources, and the second terminal may use the PSFCH resources to transmit HARQ feedback to the first terminal.

[0154] Referring to (a) of FIG. 12, in step S1540, the first terminal may transmit SL HARQ feedback to the base station via PUCCH and / or PUSCH.

[0155] Figure 13 is a diagram for explaining the control plane procedure of L2 U2N relay (UE-to-Network Relay).

[0156] The PC5-RRC aspect PC5 unicast link establishment procedure of Rel-16 NR V2X can be reused to establish a secure unicast link for L2 U2N relay (layer 2 UE-to-Network relaying) between the remote UE and the relay UE before the remote UE establishes a Uu RRC connection with the network via the relay UE.

[0157] For both in-coverage and out-of-coverage scenarios, when a remote UE initiates the first RRC message to establish a connection with a gNB, the PC5 L2 configuration for transmissions between the remote UE and the U2N relay UE can be based on the RLC / MAC configuration defined in the standard. The establishment of Uu SRB1 / SRB2 and DRB of the remote UE follows the legacy Uu configuration procedure for the L2 U2N relay.

[0158] A given scenario (TS 38.300) describes the control plane procedures of an L2 U2N relay as follows:

[0159] In step S1300, the remote UE and the relay UE can perform a discovery procedure and establish a PC5-RRC connection in step S1301 based on the existing Rel-16 procedure.

[0160] In step S1302, the remote UE can transmit the first RRC message (i.e., RRCSetupRequest) to establish a connection with the gNB via the relay UE using the default L2 configuration of PC5. The gNB responds to the remote UE with an RRCSetup message (S1303). The RRCSetup delivery to the remote UE uses the default configuration of PC5. If the relay UE is not initiated in RRC_CONNECTED, it must perform its own connection establishment upon receiving the message for the default L2 configuration of PC5.

[0161] In step S1304, the gNB and the relay UE perform a relay channel setup procedure via Uu. Depending on the configuration of the gNB, the relay / remote UE establishes an RLC channel for relaying SRB1 to the remote UE via PC5. This step prepares the relay channel for SRB1.

[0162] In step S1305, a remote UE SRB1 message (e.g., an RRCSetupComplete message) is transmitted to the gNB via the relay UE using the SRB1 relay channel over PC5. The remote UE is then RRC connected over Uu.

[0163] In steps S1306 and S1307, the remote UE and the gNB establish security according to legacy procedures, and the security message is transmitted through the Relay UE.

[0164] In steps S1308 and S1309, the gNB transmits RRCReconfiguration to the remote UE via the relay UE to set up the relay SRB2 / DRB. The remote UE responds by transmitting RRCReconfigurationComplete to the gNB via the relay UE.

[0165] In step S1310, the gNB establishes an additional RLC channel between the gNB and the relay UE for traffic relay. Depending on the configuration of the gNB, the relay / remote UE establishes an additional RLC channel between the remote UE and the relay UE for traffic relay.

[0166] In the above scenario, in addition to the connection setup procedure, for L2 UE-to-Network relay:

[0167] - RRC reconfiguration and RRC disconnection procedures can reuse legacy RRC procedures with message content / configuration design left in the WI phase.

[0168] - The RRC connection re-establishment and RRC connection resumption procedures can be reused as a baseline by considering the connection establishment procedure of the L2 U2N relay above to handle relay-specific parts along with the message content / structure design. The message content / structure can be defined later.

[0169] Unmanned Aerial Vehicle (UAV)-to-everything (U2X)

[0170] Figures 14 to 18 are drawings for explaining the U2X system.

[0171] The key points of the proposed U2X solution in the given scenario (TR 23.700-58) are as follows:

[0172] - U2X can support BRID and Direct DAA by leveraging the V2X mechanism defined in TS 23.287. In this case, both LTE PC5 and NR PC5 defined in TS 23.285 are supported, and RAT selection can be performed based on U2XP.

[0173] - Communication mode: BRID (Broadcasting UAV identification) can use Broadcast communication mode. DAA can use Broadcast communication mode to advertise UAV information. Broadcast via PC5 or unicast via PC5 can be used between two or more UAVs for DAA de-collision. Unicast via Uu via U2X AS may not be supported in the above-mentioned U2X solution. Groupcast mode for NR-based PC5 may not be supported in the above-mentioned U2X solution. When NR PC5 is selected, connectionless groupcast communication can be used for DAA. Meanwhile, application layer managed groupcast may not be considered in this release due to lack of clear requirements.

[0174] - U2X can be supported by a U2X Application Server that interfaces with the operator network via NEF, as in the case of a V2X Application Server.

[0175] Meanwhile, the above given scenario / solution needs to allow for multiple deployment scenarios where a dedicated service set can be defined and the U2X AS and USS providing the UAV are the same or different entities.

[0176] - A U2X policy (U2XP) can be defined to provide configuration parameters to a UE for U2X communication via a PC5 reference point or a Uu reference point. The configuration parameters can be preset in the ME (Mobile Equipment), set in the UICC (universal IC card), pre-set in the ME and set in the UICC, provided / updated by a U2X application server via a policy control function (PCF) and / or a V1 reference point, or provided / updated to the UE by the PCF. Here, the UE needs to consider the U2X policies in the following order of priority: those provided / updated by the PCF, those provided / updated by the U2X application server via the V1 reference point, those configured in the UICC, and those pre-configured in the ME. A de-conflicting policy can be a policy indicating a communication mode for de-conflicting (unicast or broadcast), a communication frequency for de-conflicting, etc.

[0177] - As with V2X, the Tx profile or NR Tx profile can be determined based on the U2XP mapping of the U2X service type.

[0178] - Both UAVs with UICC and UAVs without UICC (i.e. not subscribed to an MNO) can be supported. Here, UAVs without UICC can perform U2X communication only if they are approved as “Not provided in E-UTRA” and “Not provided in NR.”

[0179] - U2X communication parameters of the U2X application server or PCF can be transmitted via the UAV-C UE.

[0180] - In addition to the existing parameters for V2X, PC5 RAT-specific radio parameters (e.g., LTE PC5, NR PC5) may be configured, including geographic area, altitude restrictions, and validity timers. Such additional information / parameters may be required to policy-specifically control PC5 usage based on the specific location of the UAV.

[0181] - The definition of DAA / UAV service types may go beyond the scope of the given scenarios described above.

[0182] - For UAVs with UICC to use PC5-based communications for BRID and DAA, successful UUAA authentication / authorization as defined in TS 23.256 and authorization via U2XP are required. However, the FAA does not require specific authorization for the use of PC5 for BRID or DAA. For UAVs without UICC, the use of PC5-based communications for BRID and DAA can only be authorized via U2XP. Meanwhile, U2X services can be identified by one of the following values ​​specifically defined for aviation applications: ITS Application Identifier (ITS-AID), Provider Service Identifier (PSID), or Application Identifier (AID).

[0183] - As in TS 23.287, security for broadcast U2X communications over the PC5 reference point can be supported in U2X application layer schemes developed in other SDOs.

[0184] Referring to FIG. 14, a non-roaming 5G system architecture for U2X communication via PC5 can be configured as illustrated in FIG. 14. Here, the non-roaming 5G system architecture for U2X communication via PC5 can be applied with the reference point of TS 23.287, and the following differences can be present.

[0185] - U2X1: As a reference point between the UE and the UAV-C and the U2X application of the U2X application server, this reference point may be outside the scope of the above-mentioned scenario.

[0186] - U2X5: As a reference point between U2X applications within the UE, this reference point may / may not be specified in the release of a given scenario.

[0187] - N1: In addition to the relevant functions defined in TS 23.501 for N1, it can also be used to transfer U2X policies and parameters (including service authorization) from AMF to UE for U2X services, and PC5 functions for U2X capabilities and U2X information of UE to AMF.

[0188] - N2: In addition to the relevant functions defined in TS 23.501 for N2, it can also be used to convey U2X policies and parameters (including service authorization) from AMF to NG-RAN for U2X services.

[0189] - The above-described solution can support UAV UEs utilizing Uu connections and UAV UEs that do not utilize Uu connections (i.e., UAV UEs that are either Uu capable or Uu non-capable). UAVs that do not utilize Uu capabilities can use U2X for BRID and DAA and can be configured via U2X1 for transmissions outside the scope of 3GPP. On the other hand, UAV UEs that do not utilize Uu capabilities can be part of the 3GPP ecosystem as they use U2X1 for configuration by U2X application servers and implement PC5 connections as specified by 3GPP.

[0190] A roaming 5G system architecture for U2X communication over PC5 can be configured as illustrated in FIGS. 15 and 16. Specifically, FIG. 15 illustrates a roaming 5G system architecture for U2X communication over PC5 in a local breakout scenario, and FIG. 16 illustrates a roaming 5G system architecture for U2X communication over PC5 in a home routing scenario.

[0191] A 5G system architecture between Public Land Mobile Networks (PLMNs) for U2X communication over PC5 reference points could be as follows.

[0192] - For U2X communication between PLMNs via PC5 reference point, PC5 parameters need to be set in a consistent manner between UEs within a specific area.

[0193] - The architecture for Inter-PLMN PC5 may be similar to that defined in the non-roaming 5G system architecture for U2X communication over PC5 described with reference to FIG. 14.

[0194] AF-based service parameter provisioning for U2X communication can be defined as follows.

[0195] - As defined in TS 23.287, a 5G system may provide NEF services to enable communication between a PLMN's NF and a U2X application server. Specifically, a high level view of AF-based service parameter provisioning for U2X communication may be illustrated in FIG. 17. Service parameters may also be pre-configured in the UAV using methods outside the scope of 3GPP (e.g., when not utilizing Uu functionality).

[0196] In a U2X scenario, the following may be considered:

[0197] - Usage / Usage of U2X for BRID: The message content for BRID can be defined according to regional regulations for BRID (e.g. message sets of ASTM F3411.19 or ASD-STAN prEN 4709-002 P1) and optionally according to regional means in compliance documents.

[0198] - Usage / Usage of U2X for DAA: Message content for DAA is defined by local regulations for DAA and may go beyond the scope of the given scenarios described above.

[0199] The procedures and mechanisms of TS 23.287 can be applied to U2X scenarios. Specifically, the procedure for broadcasting via PC5 for DAA collision resolution can be performed as shown in Fig. 18. Meanwhile, the procedure for broadcasting via PC5 for DAA collision resolution can be assumed that the UAV is provisioned with a U2X policy that includes a DAA collision resolution policy (e.g., unicast or broadcast communication for collision resolution, communication frequency).

[0200] Specifically, the procedure for broadcasting through PC5 for DAA collision resolution according to FIG. 18 can be performed as follows.

[0201] 1. UAV1 may receive a broadcast message from UAV2 that may include an application layer DAA payload (e.g., CAA level UAV ID, USS address of UAV2, speed, heading, position, etc.).

[0202] - Note 1: A USS address (Unmanned aerial system Traffic Management (UTM) Service Supplier address) is not required if UAV-to-UAV conflicts are resolved locally, but may be required if USS coordination of the UAVs involved in the conflict is required.

[0203] 2. UAV1 can transmit the DAA payload to the upper layer. The application layer can detect collisions by comparing the broadcast message received from UAV2 with its own trajectory and position. If UAV1's application layer detects a collision, it can initiate collision avoidance / resolution procedures with UAV2.

[0204] 3. Optionally, UAV1 can notify its USS (UTM Service Supplier) about the detected collision, including the ID of peer UAV 2.

[0205] 4. UAV1 can select a communication mode (broadcast or unicast) for DAA deconfliction based on input received from the application layer and DAA policy. If the broadcast deconfliction method is selected, the following messages can be exchanged between UAVs.

[0206] 5. UAV1 broadcasts a message (e.g., PC5-S message) (e.g., de-collision request message), which is part of the U2X functionality and may include DAA functionality indicating whether the UAV can participate in communication for protocol, DAA de-collision policy (broadcast-based, de-collision message frequency), collision detection warning, ID of other UAVs detected in collision with its CAA level UAV ID, and certain parameters (e.g., de-collision information) (e.g., trajectory correction information to avoid collision). (UAV1 broadcasts a message (eg PC5-S message), eg deconfliction request message and may include DAA capability, which is part of U2X capability and indicates whether the UAV is able to engage in communication for deconflicting protocol, DAA deconflicting policy (broadcast based, deconflicting message frequency), collision detection alert, its CAA-level UAV IDs and the one(s) from other detected conflicting UAV(s), and deconflicting specific parameters (eg trajectory correction information to avoid collision))

[0207] 6. UAV2 may broadcast a message (e.g., a PC5-S message) to provide the agreed-upon DAA deconfliction policy, updated trajectories, and other information (e.g., a message deconfliction status response, a conflict resolution warning, and the CAA-level UAV ID of the participating UAV from the receiving UAV). Subsequent broadcast messages may be exchanged between UAVs at an agreed-upon message frequency until a traffic conflict resolution (e.g., mutual position / trajectory monitoring) is reached.

[0208] The impact on services, entities and interfaces related to the above-described U2X may be as shown in Tables 5 and 6 below.

[0209] 1. UE: In addition to the capabilities defined in the given scenario (TS 23.501), the UE may support the following capabilities:- Report U2X capabilities (including DAA capabilities) and PC5 capabilities to the 5GC via the N1 reference point.- Indicate U2X policy provisioning requests in the UE policy container for UE-triggered U2X policy provisioning.- Receive U2X parameters from the 5GC via the N1 reference point.- U2X communication procedures via the PC5 reference point.- Configuration of parameters for U2X communication. The parameters may be pre-configured in the UE or may be provisioned or updated by signalling from the PCF in the HPLMN via the N1 reference point or from the U2X application server via the U2X1 reference point, if applicable. 2. AMF: In addition to the functions defined in the given scenario (TS 23.501), the AMF may:- Obtain subscription information related to U2X from the UDM and store it as part of the UE context data.- Select a PCF that supports U2X policy / parameter provisioning and report PC5 capabilities for U2X to the selected PCF.- Obtain PC5 QoS information related to U2X from the PCF and store it as part of the UE context data.- Provide an indication to the NG-RAN about the UE authorization status for U2X communications over the PC5 reference point.- Provide PC5 QoS parameters related to U2X communications to the NG-RAN.- PCF: In addition to the functions defined in the given scenario (TS 23.501), the PCF may include the functions described in the given scenario (TS 23.287) to provide the UE and the AMF with the parameters required to enable U2X communications.- UDM: Subscription management for U2X communications over the PC5 reference point. UE subscription data types can be extended. 3. U2X Application Server: Specific scenarios (TS 23.287) may implement a subset of the V2X AS capabilities specified in: - Includes AF capabilities and may support at least the following capabilities: - For U2X service parameter provisioning, the U2X AS may provide parameters for U2X communication via PC5 and Uu reference points to the 5GC and UAV UE (perhaps via UAVC). - UDR: In addition to the capabilities defined in the given scenario (TS 23.501), the UDR may store U2X service parameters. - NRF: In addition to the capabilities defined in the given scenario (TS 23.501), the NRF may perform PCF lookup taking into account the U2X capabilities. - NEF: In case of a U2X AS, the NEF may support U2X service parameters.

[0210] U2X Subscription data NR U2X Service Authorization Indicates whether the UE is authorized to use NR sidelink for U2X services as a UAV UE, UAV-C UE, or Authority UE. LTE U2X Service Authorization Indicates whether the UE is authorized to use LTE sidelink for U2X services as a UAV UE, UAV-C UE, or Authority UE. NR UE-PC5-AMBRU AMBR of the NR sidelink (i.e., PC5) communications of the UE for 2X services. LTE UE-PC5-AMBRU AMBR of the LTE sidelink (i.e., PC5) communications of the UE for 2X services

[0211] Additionally, recent discussions regarding measurement reporting in relation to the above-described scenarios include:

[0212] - Using LTE principles as a baseline, similar events H1 (aerial UE height becomes higher than threshold) and H2 (aerial UE height becomes lower than threshold) are introduced. FFS: Further discussion on whether additional NR enhancement is needed. Research on scaling of RRM parameters (e.g., which parameters and what is the purpose / benefit of scaling and how).

[0213] -- FFS: How to limit excessive measurement and measurement reporting.

[0214] -- FFS: FFS: Study of vertical movement and related mobility of UAV UEs when user consent is required for location reporting in CONNECTED.

[0215] - Rel-18 NR can support height, position, and velocity reporting from UAV UEs. Further discussion is needed regarding accuracy and reporting mechanisms, as well as whether further improvements are needed.

[0216] - Similar to LTE, flight path planning reporting has been introduced. A list of waypoints (3D position information) and timestamps are adopted as the basic content of flight path reporting. Whether timestamps are mandatory or optional in NR is FFS. Whether further improvements are needed is FFS.

[0217] - A feature similar to LTE (numberofTriggeringCells) has been introduced. FFS: Whether numberoftriggerbeams is required for NR or whether there are other improvements. FFS: How to avoid sending measurement reports primarily due to reportOnLeave.

[0218] - A waypoint is a planned location for a UE along a flight path and is described via the existing parameter type LocationCoordinates defined in a given scenario (TS 37.355).

[0219] - The timestamp provides the UTC time associated with the expected time of arrival at the waypoint as a baseline. FFS: Discussion of granularity.

[0220] - There are no requirements for the spatial distribution of path points.

[0221] - The UE may indicate whether flight plan information is available within the RRCReconfigurationComplete, RRCReestablishmentComplete, RRCResumeComplete, or RRCSetupComplete messages. Flight path reporting may be used as a basis for the UE information request / response procedure.

[0222] - The UE can indicate to the network that a new flight path is available for use by the UE (whether it is initial or update). The normal request / response procedure for flight path reporting can then be reused.

[0223] - The UAI message can also be used to indicate to the UE that a flight path is available.

[0224] - FFS: whether and what triggering conditions are specified for flight update. FFS The maximum number of waypoints within flight path plan is left FFS.

[0225] - When event H1 or H2 is triggered, the content of the measurement report can be configured by the network (i.e. it can contain UAV UE height, location information and / or RSRP / RSRQ measurement results). FFS whether UAV UE's height is mandatorily reported and which parameter / IE is used for height reporting.

[0226] - Joint use of height-dependent conditions and RSRP / RSRQ / SINR-based conditions for triggering measurement reports in NR Rel-18 UAVs may be supported. Combinations of existing events may be used.

[0227] - Height-dependent parameter scaling is not supported as part of Rel-18 NR.

[0228] - The Number of triggering cells mechanism is extended and does not apply to inter-RAT scenarios (i.e. event B1 and B2 triggering).

[0229] - The applicability of the number of triggering cells mechanism is not limited to FR1. That is, the number of triggering cells mechanism can be applied to FR1 and FR2 (depending on the network configuration).

[0230] - The UE shall not ignore or bypass the Number of triggering cells mechanism, once configured.

[0231] - Do not introduce the use of a "numberOfTriggeringBeams" mechanism.

[0232] - Do not introduce an alternative mechanism to the Number of triggering cells mechanism.

[0233] - Do not introduce an additional mechanism based on the number of changed cells.

[0234] - For the purpose of interference control (i.e. for number of trigger cells), do not introduce a prohibit timer mechanism.

[0235] - Report on leave is not triggered by a cell that was not previously included in the measurement report for the number of triggering cells.

[0236] - It can support setting multiple settings based on height, aiming at improving measurement and measurement reporting. The UE can apply corresponding settings based on the UE height. The proposed solution should aim to avoid RAN4 impact. FFS: How this would be configured (i.e. different MO configurations or different parameters) FFS Exact parameters and details.

[0237] - At the parameter / field level, more than one configuration can be supported depending on the height (i.e. different fields / values ​​within the same MO). Here, different values ​​(or value ranges) of a parameter / field can be applied to different heights or height ranges.

[0238] -- For MO configuration parameters: at least the following will have the ability to be configured with height-dependent more-than-one configurations / values, each for a specific height region: SSB-ToMeasure. Details on how to specify is FFS. FFS on UE behavior on L1 and L3 measurement.

[0239] - For MR configuration parameters: at least the following will have the ability to be configured with height-dependent more-than-one configurations / values, each for a specific height region: Event A4 threshold and numberoftriggeringcells. Details on how to specify is FFS (i.e. maybe it can be achieved by combination of events).

[0240] - If two or more settings are provided based on height, the UE may apply the new value when moving to a new height (or height range), similar to the case of RRC reconfiguration. Codes, field descriptions, etc. may be required, as in legacy specifications.

[0241] - If a height-specific value is not explicitly configured for a certain height, whether to keep using the value that was used or consider the parameter as released (i.e. parameter / value not applicable at this height) should be looked into case by case, and can be clarified by need code, field description, or procedural text as needed.

[0242] Figure 19 is a diagram for explaining the occurrence of interference in a public communication environment.

[0243] Referring to Fig. 19, the RSRP (Reference Signals Received Power) measured for the same cell (cell ID(=0)) may be distributed differently depending on the height. This is because in an airborne communication environment, compared to a terrestrial communication environment, LoS (Line of Sight) is secured, and thus the influence of cell-to-cell interference may be greater.

[0244] Specifically, referring to FIG. 19, the RSRP distribution of cell ID = 0 at various heights is illustrated. Referring to FIG. 19 (a), the RSRP distribution associated with a ground UE at a height of 0 m is illustrated. The RSRP distribution degrades smoothly as the distance increases from the cell antenna. Referring to FIG. 19 (b), the RSRP distribution at a height of 100 m is illustrated. Here, the RSRP distribution may form several rings, and the reason for the occurrence of the rings is the variation in cell quality between nulls and side lobes. The variation pattern (in time) may vary depending on the position, height, speed, and heading, orientation of the UE (or drone). Referring to FIG. 19 (c), the case of a height of 300 m may form the largest number of rings with the largest gap. Such fluctuations can lead to handover failures, as the airborne UE may be supported by the BS's sidelobes and attempt handovers back and forth based on measurements. Meanwhile, in Figure 19, the darker the color, the weaker the cell signal strength, and the black ring area may indicate an area where signal strength below a certain threshold for connection to the cell is detected.

[0245] In other words, it can be seen that the distribution of RSRP more clearly shows a ring shape at a height of 300 m in Fig. 19 (c). For example, referring to Fig. 19 (c), it can be assumed that a UAV or UE moves in the direction of the arrow at an altitude of 300 m. In this case, the UAV may experience frequent handovers (HOs). For example, after connecting to cell=0 in a non-black area, it may HO to another cell in a black area, and then connect to cell=0 again in a non-black area, and so on, a phenomenon may occur in which the same cell is repeatedly connected and disconnected over time (the added arrow (the UAV's moving direction) can be viewed as a time axis).

[0246] Below, we detail how to minimize frequent HO operations performed by swarming UAV ( / UAM / AAM / normal) UEs.

[0247] Handover operation of swarm UAV UEs

[0248] FIG. 20 is a diagram for explaining how a leader of a cluster of UAV UEs performs a handover operation.

[0249] In the current UAV environment, frequent HO (or detach / attach) to the same cell may occur due to the reasons described in FIG. 19. This process may trigger frequent measurement reporting for the UE or UAV UE. To address this issue, a method for reducing the number of HOs is described in detail below, assuming that UAV UEs operating in a cluster behave as a single UE. Meanwhile, the UAV UE may be a UE included or mounted on a UAV, or a UE located within the UAV. For convenience of explanation, it is defined as a UE below.

[0250] Specifically, referring to FIG. 20, by changing the leader UE of a cluster (or cluster group, group) including UEs, the entire cluster can be treated as a single UE. In FIG. 20, small circles represent individual UEs, and the solid lines (or elliptical solid lines) surrounding them represent a cluster. Individual UEs within a cluster are performing cluster driving. A leader UE (black circle) can be selected / configured within the cluster performing cluster driving.

[0251] The leader UE is connected or accessed by the gNB and can perform a relay role (e.g., (mobile)IAB or SL relay) between the gNB and other member UEs. Other member UEs within the cluster can transmit / receive data from / to the gNB through the leader UE. The cell information to which the member UE belongs can be processed as inheriting / subordinating to the cell information to which the leader UE belongs. That is, when the leader UE is accessing cell A, other member UEs within the corresponding cluster can also be regarded as UEs belonging to or accessing the same cell A. At this time, when the leader UE is fixed when moving from FIG. 20 (a) to FIG. 20 (c), the leader UE can perform a connection to cell A in FIG. 20 (a), perform a handover (HO) to connect to cell B in FIG. 20 (b), and perform a handover (HO) again to connect to cell C in FIG. 20 (c). That is, frequent HO can be performed on the above cluster.

[0252] In such clustering operations, a method may be considered to reduce frequent HOs by treating the entire cluster as a single virtual UE. For example, in FIG. 20 (a) (i.e., the first time interval (time-1)), a leader UE may access cell A, and the UEs within the entire cluster may be treated as belonging to cell A. Referring to FIG. 20 (b), in the second time interval (time-2), another UE (a member UE that can continuously receive signals from cell A with a quality higher than a threshold) may become the leader UE. In this case, the cluster UAV may still maintain connection to cell A. Referring to FIG. 20 (c), in the third time interval (time-3), no UE within the cluster may maintain a signal quality higher than a certain threshold with cell A. In this case, another UE within the cluster is determined to be the leader UE, and the leader UE may perform HO to another cell. Such an action can effectively reduce the number of HOs when the size of the cluster is larger than the range in which the signal value above the threshold (RSRP) is measured for one specific cell (e.g., the line area indicated as Cell A, Cell B, and Cell C in FIG. 20).

[0253] In order to treat the entire cluster as a single virtual UE, the leader ( / individual) UE can maintain connection with the gNB by using a virtual C-RNTI value commonly used in the cluster when performing a connection with the gNB. That is, when a specific UE within the cluster is determined / configured as a leader UE, the leader UE can connect to the gNB by using the virtual C-RNTI value, and the gNB can treat the cluster to which the leader UE belongs as a single UE.

[0254] Specifically, according to the existing method, if the current signal strength with respect to the gNB( / cell) measured by the leader UE is below a certain threshold (e.g., measurement reporting is triggered in the existing method), the leader UE reports the measurement to the gNB (to request HO to be performed). In the proposed method, the leader UE may trigger an operation to search for a new leader UE within the cluster (or group) without triggering measurement reporting even if the current signal strength with respect to the gNB( / cell) is below a certain threshold. To this end, the leader UE may transmit a request message requesting or requesting other member UEs within the cluster (or other candidate leader UEs within the cluster) to transmit / respond with a response signal when the signal strength with respect to the gNB( / cell) with which the current connection is formed is above a certain threshold. In this case, the responding member UE can report (to the leader UE) the signal strength, signal strength change (or change in the average signal strength), its location, moving speed, direction, remaining power, capability and / or load, etc., with respect to the gNB (e.g., the gNB / Cell to which the current leader UE is connected), which it has measured. The leader UE can select one UE from at least one UE that has responded, and force / recommend / request that one UE become the new leader UE. If the leader UE requests other member UEs to respond when the signal strength with the currently connected gNB( / cell) is above a certain threshold, but does not receive a response / response signal from any UE in the cluster, the leader UE can trigger a measurement report and report measurement information including the measured signal strength of the neighboring cell to the gNB. Alternatively, in this case, a specific UE (initial leader UE, a UE located at the very front in the traveling direction, a UE with a specific function) can become the leader UE again, and trigger a measurement report for HO.In the above operation, the UEs that can become leaders may be limited to specific UEs. That is, several candidate leader UEs may be predetermined within the cluster.

[0255] A new leader UE that has changed through the above-described method (e.g., a UE that has transmitted or responded to a response signal to a previous leader UE) can connect to the gNB using a virtual C-RNTI representing the cluster or group. In this case, the gNB may not be aware that the leader UE has changed within the corresponding cluster or group. In addition, the previous leader UE no longer directly communicates with the gNB without being released to the gNB (or without performing an RRC release procedure with the gNB), and can transmit and receive data through the new leader UE (i.e., relay communication through the new leader UE). The gNB can determine whether to perform HO only based on what the leader UE reports.

[0256] When using mmWave, UEs included in the entire cluster can be considered as a single UE and transmit and receive signals. In this case, there may be an advantage of facilitating transmission / reception even when the beam width of mmWave is widened or transmitted broadly. For example, when a gNB transmits data / message by widening the transmission beam width, and the data / message is received by an individual UE, the quality of the data / message received by the individual UE may deteriorate. However, if all received messages are integrated, the quality of the data / message may be improved. For example, a leader UE may collect (or, may collect to a neighboring UE that can process) the messages / data received by the individual UEs, integrate them, and then the leader UE ( / UE that processed the integrated information) may transmit the integrated message / data to the individual UEs, thereby improving the quality of the message / data. This operation may be more suitable for a specific cast type (broadcast / unicast / groupcast). For example, this operation may be suitable for a broadcast or groupcast method.

[0257] Meanwhile, it is natural that in the above-described proposed method, the relay UE (or leader UE) can be extended to include a gNB, IAB-node, etc.

[0258] In this way, the proposed method can prevent frequent handovers due to the distribution characteristics of RSRP above a certain height. Alternatively, the proposed method can maximize the stability of communication links for UEs located above a certain height by preventing frequent handovers. Furthermore, the proposed method can maintain communication with a group or cluster without a separate direct link release procedure even when the leader UE changes by forming a direct link based on a virtual C-RNTI for the group or cluster.

[0259] Figure 21 is a diagram for explaining a method for triggering a measurement report by a first UE.

[0260] As described above, the first UE may be a relay UE that has a direct link formed directly with a base station or gNB, and an indirect link formed to connect at least one UE and the base station. The at least one UE may be a remote UE that is connected to the base station through an indirect link with the first UE. In addition, the first UE and the at least one UE may be an Unmanned Aerial Vehicle (UAV) that may be positioned above a certain height, or a UE included in the UAV. Alternatively, as described with reference to FIG. 20, the first UE and the at least one UE may be UEs that form a cluster or group at a certain height and drive in a cluster.

[0261] Referring to FIG. 21, a first UE can form a direct link directly connected to a base station (S211). For example, the first UE can form a direct link to the base station by performing RRC configuration with the base station through a RACH procedure or the like. If the first UE is configured as a leader UE in a group or cluster comprised of multiple UEs, the first UE can form a direct link with the base station based on a virtual C-RNTI (Cell Radio Network Temporary Identifier) ​​configured for the group or cluster. In this case, the base station can treat the cluster or group as a single UE and perform communication with the cluster or group.

[0262] Next, the first UE may form at least one indirect link (or at least one relay link) to connect the at least one UE and the base station (S213). Even if the at least one UE can form a direct link with the base station, the at least one UE may communicate with the base station through an indirect link connected to the base station through the first UE in order to perform low-power communication. Alternatively, as described above, the at least one UE may be a UE that forms a cluster or group together with the first UE, and may be a member UE of the cluster or group.

[0263] Next, the first UE may transmit a message requesting transmission of a response message related to the signal quality of the base station to the at least one UE when the signal strength of the direct link is below a specific threshold (S215). For example, the first UE may trigger a measurement report related to the handover procedure when the signal strength or signal quality of the direct link is below a specific threshold; however, the measurement report may not be triggered immediately when the first UE forms a cluster or group with the at least one UE and is located at a specific altitude or higher (e.g., 100 m, 200 m, or 300 m). For example, even if the signal strength or signal quality of the direct link is below a specific threshold, the first UE may not immediately trigger the measurement report, but may transmit a message (or request message) requesting transmission of a response message to the at least one UE included in its cluster or group based on the signal quality of the base station and whether a specific condition is satisfied. For example, the first UE may transmit the request message to the at least one UE, and receive the response message only from a specific UE among the at least one UE whose signal quality with the base station is at a specific threshold. Here, the specific condition may be satisfied when the signal quality with the base station is at least the specific threshold or a separately set first specific threshold (which may be included in the message or preset as a threshold value higher than the specific threshold).

[0264] Next, the first UE may determine whether to trigger a measurement report based on whether the response message is received (S217). For example, if the first UE receives the response message from a specific UE that satisfies the specific condition among the at least one UE, the first UE may not trigger the measurement report. In this case, the first UE may request the specific UE to perform the role of a leader UE of the cluster or group and to form a direct link with the base station. At this time, the specific UE may form the direct link and an indirect link connecting the UEs within the group or cluster and the base station, and the first UE may also be connected to the base station through the specific UE.

[0265] Alternatively, if the first UE does not receive the response message from the at least one UE (or if the response message is not received within a preset threshold time), the first UE may trigger the measurement report and report measurement information about the signal strength (or signal quality) measured for the direct link and / or the signal strength (or signal quality) measured for a neighboring cell to the base station. In this case, the base station may perform a handover procedure targeting the neighboring cell based on the report of the measurement information to the first UE.

[0266] Alternatively, as described above, the response message may include information about the signal strength for the base station, the amount of change in the signal strength (or the amount of change in the average value of the signal strength), the location, moving speed, direction, remaining power, capability, and / or load of the UE.

[0267] Figure 22 is a diagram for explaining how a second UE performs communication.

[0268] As described above, the second UE may be connected to the base station via the first UE, which has a direct link directly connected to the base station or gNB. For example, the second UE may be a remote UE connected to the base station via an indirect link with the first UE, and the first UE may be a relay UE. In addition, the first UE and the at least one UE may be a UAV UE or a UE mounted on the UAV, which may be located at a certain height or higher. Alternatively, as described with reference to FIG. 20, the first UE and the second UE may be UEs included in a cluster or group consisting of multiple UEs at a certain height or higher.

[0269] Referring to FIG. 22, the second UE may form an indirect link connected to the base station through the first UE (S221). As described with reference to FIG. 13, the second UE may form an indirect link with the first UE discovered through a discovery procedure or the like, and may transmit and receive data with the base station through the indirect link. Since the second UE may consume significantly high power to maintain a direct link with the base station when located at a high altitude, even if it can form a direct link with the base station, it may transmit and receive data using the indirect link connected to the base station through the first UE in order to perform low-power communication.

[0270] Next, the second UE may receive a request message from the first UE requesting transmission of a response message related to signal quality to the base station (S223). For example, the second UE may form a cluster or group with the first UE and be located above a certain altitude (e.g., 100 m, 200 m, or 300 m). In this case, if the signal strength or signal quality of the direct link from the first UE is below a certain threshold, the second UE may receive the request message from the first UE. As described above, the request message may be a message transmitted in connection with determining whether to trigger a measurement report of the first UE.

[0271] Next, the second UE may transmit a response message in response to the request message if the signal quality measured for the base station satisfies a specific condition (S225). Here, the specific condition may be satisfied if the signal quality of the base station is higher than the specific threshold or a separately set first specific threshold (which may be included in the message or preset as a threshold value higher than the specific threshold). For example, the second UE may determine whether to transmit the response message in response to the request message based on whether the signal quality measured for the base station satisfies the specific condition. The second UE may transmit the response message if the signal quality satisfies the specific condition, and may not transmit the response message if the signal quality does not satisfy the specific condition.

[0272] For example, the second UE may measure the signal quality (e.g., signal quality associated with a direct link) for the base station upon receiving the request message. The second UE may transmit a response message in response to the request message if the signal quality is above a certain threshold. Alternatively, the second UE may not transmit a response message in response to the request message if the signal quality is below a certain threshold.

[0273] Alternatively, the response message may include information about the signal strength for the base station, the amount of change in the signal strength (or the amount of change in the average value of the signal strength), the location, moving speed, direction, remaining power, capability and / or load of the UE.

[0274] Next, the second UE to which the second UE has transmitted the response message can form a direct link directly connected to the base station (S227). Specifically, when the second UE has transmitted the response message, the second UE can receive a message from the first UE requesting the performance of the role of the leader UE of the cluster or group and the formation of a direct link with the base station. In this case, the second UE can perform a procedure for establishing a direct link with the base station, and, as the leader UE of the group or cluster, can form an indirect link connecting the base station and UEs within the group or cluster through relay communication. At this time, the second UE can form the direct link using a virtual C-RNTI for the group or cluster, like the first UE. Meanwhile, at this time, the first UE may not separately perform a procedure for releasing the direct link with the base station as described above.

[0275] In this way, the proposed method can prevent frequent handovers due to the distribution characteristics of RSRP above a certain height. Alternatively, the proposed method can maximize the stability of communication links for UEs located above a certain height by preventing frequent handovers. Furthermore, the proposed method can maintain communication with a group or cluster without a separate direct link release procedure even when the leader UE changes by forming a direct link based on a virtual C-RNTI for the group or cluster.

[0276] Examples of communication systems to which the invention applies

[0277] Although not limited thereto, the various descriptions, functions, procedures, proposals, methods and / or operational flowcharts of the present invention disclosed in this document may be applied to various fields requiring wireless communication / connection (e.g., 5G) between devices.

[0278] Hereinafter, more specific examples will be provided with reference to the drawings. In the drawings / descriptions below, the same drawing reference numerals may represent identical or corresponding hardware blocks, software blocks, or functional blocks, unless otherwise described.

[0279] Figure 23 illustrates a communication system applied to the present invention.

[0280] Referring to FIG. 23, a communication system (1) applied to the present invention includes a wireless device, a base station, and a network. Here, the wireless device refers to a device that performs communication using a wireless access technology (e.g., 5G NR (New RAT), LTE (Long Term Evolution)) and may be referred to as a communication / wireless / 5G device. Although not limited thereto, the wireless device may include a robot (100a), a vehicle (100b-1, 100b-2), an XR (eXtended Reality) device (100c), a hand-held device (100d), a home appliance (100e), an IoT (Internet of Things) device (100f), and an AI device / server (400). For example, the vehicle may include a vehicle equipped with a wireless communication function, an autonomous vehicle, a vehicle capable of performing vehicle-to-vehicle communication, etc. Here, the vehicle may include an Unmanned Aerial Vehicle (UAV) (e.g., a drone). XR devices include AR (Augmented Reality) / VR (Virtual Reality) / MR (Mixed Reality) devices, and can be implemented in the form of HMD (Head-Mounted Device), HUD (Head-Up Display) installed in a vehicle, television, smartphone, computer, wearable device, home appliance, digital signage, vehicle, robot, etc. Mobile devices can include smartphone, smart pad, wearable device (e.g., smart watch, smart glass), computer (e.g., laptop, etc.), etc. Home appliances can include TV, refrigerator, washing machine, etc. IoT devices can include sensors, smart meters, etc. For example, base stations and networks can also be implemented as wireless devices, and a specific wireless device (200a) can act as a base station / network node to other wireless devices.

[0281] Wireless devices (100a to 100f) can be connected to a network (300) via a base station (200). Artificial Intelligence (AI) technology can be applied to the wireless devices (100a to 100f), and the wireless devices (100a to 100f) can be connected to an AI server (400) via the network (300). The network (300) can be configured using a 3G network, a 4G (e.g., LTE) network, a 5G (e.g., NR) network, etc. The wireless devices (100a to 100f) can communicate with each other via the base station (200) / network (300), but can also communicate directly (e.g., sidelink communication) without going through the base station / network. For example, vehicles (100b-1, 100b-2) can communicate directly (e.g., V2V (Vehicle to Vehicle) / V2X (Vehicle to Everything) communication). In addition, IoT devices (e.g., sensors) can communicate directly with other IoT devices (e.g., sensors) or other wireless devices (100a to 100f).

[0282] Wireless communication / connection (150a, 150b, 150c) can be established between wireless devices (100a~100f) / base stations (200), and base stations (200) / base stations (200). Here, wireless communication / connection can be achieved through various wireless access technologies (e.g., 5G NR) such as uplink / downlink communication (150a), sidelink communication (150b) (or, D2D communication), and communication between base stations (150c) (e.g., relay, IAB (Integrated Access Backhaul). Through wireless communication / connection (150a, 150b, 150c), wireless devices and base stations / wireless devices, and base stations and base stations can transmit / receive wireless signals to each other. For example, wireless communication / connection (150a, 150b, 150c) can transmit / receive signals through various physical channels. To this end, at least some of various configuration information setting processes for transmitting / receiving wireless signals, various signal processing processes (e.g., channel encoding / decoding, modulation / demodulation, resource mapping / demapping, etc.), and resource allocation processes can be performed based on various proposals of the present invention.

[0283] Examples of wireless devices to which the present invention is applied

[0284] Figure 24 illustrates a wireless device applicable to the present invention.

[0285] Referring to FIG. 24, the first wireless device (100) and the second wireless device (200) can transmit and receive wireless signals through various wireless access technologies (e.g., LTE, NR). Here, {the first wireless device (100), the second wireless device (200)} can correspond to {the wireless device (100x), the base station (200)} and / or {the wireless device (100x), the wireless device (100x)} of FIG. 23.

[0286] A first wireless device (100) includes one or more processors (102) and one or more memories (104), and may further include one or more transceivers (106) and / or one or more antennas (108). The processor (102) controls the memories (104) and / or the transceivers (106), and may be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in this document. For example, the processor (102) may process information in the memory (104) to generate first information / signal, and then transmit a wireless signal including the first information / signal via the transceiver (106). In addition, the processor (102) may receive a wireless signal including second information / signal via the transceiver (106), and then store information obtained from signal processing of the second information / signal in the memory (104). The memory (104) may be connected to the processor (102) and may store various information related to the operation of the processor (102). For example, the memory (104) may perform some or all of the processes controlled by the processor (102), or may store software code including commands for performing the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in this document. Here, the processor (102) and the memory (104) may be part of a communication modem / circuit / chipset designed to implement wireless communication technology (e.g., LTE, NR). The transceiver (106) may be connected to the processor (102) and may transmit and / or receive wireless signals via one or more antennas (108). The transceiver (106) may include a transmitter and / or a receiver. The transceiver (106) may be used interchangeably with an RF (Radio Frequency) unit. In the present invention, a wireless device may also mean a communication modem / circuit / chipset.

[0287] Specifically, the first wireless device or first UE (100) may include a processor (102) and a memory (104) connected to a transceiver (106). The memory (104) may include at least one program capable of performing operations related to the embodiments described in FIGS. 19 to 22.

[0288] The processor (102) controls the transceiver (106) to form a direct link directly connected to a base station, and to form at least one indirect link for connecting at least one UE (User Equipment) and the base station, and transmits a message requesting transmission of a response message related to signal quality for the base station to the at least one UE based on whether the signal strength of the direct link is below a specific threshold, and determines whether to trigger a measurement report based on whether the response message is received.

[0289] Alternatively, a processing device may be configured, including a processor (102) and a memory (104) for controlling a first UE that triggers a measurement report. In this case, at least one processor; and at least one memory connected to the at least one processor and storing instructions, wherein the instructions, based on being executed by the at least one processor, cause the first UE to: form a direct link directly connected to a base station, form at least one indirect link for connecting at least one UE (User Equipment) and the base station, transmit a message requesting transmission of a response message related to signal quality for the base station to the at least one UE based on whether a signal strength of the direct link is below a specific threshold, and determine whether to trigger a measurement report based on whether the response message is received.

[0290] The second wireless device (200) includes one or more processors (202), one or more memories (204), and may further include one or more transceivers (206) and / or one or more antennas (208). The processor (202) controls the memories (204) and / or the transceivers (206), and may be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in this document. For example, the processor (202) may process information in the memory (204) to generate third information / signals, and then transmit a wireless signal including the third information / signals via the transceivers (206). Furthermore, the processor (202) may receive a wireless signal including fourth information / signals via the transceivers (206), and then store information obtained from signal processing of the fourth information / signals in the memory (204). The memory (204) may be connected to the processor (202) and may store various information related to the operation of the processor (202). For example, the memory (204) may perform some or all of the processes controlled by the processor (202), or may store software code including commands for performing the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in this document. Here, the processor (202) and the memory (204) may be part of a communication modem / circuit / chip designed to implement wireless communication technology (e.g., LTE, NR). The transceiver (206) may be connected to the processor (202) and may transmit and / or receive wireless signals via one or more antennas (208). The transceiver (206) may include a transmitter and / or a receiver. The transceiver (206) may be used interchangeably with an RF unit. In the present invention, a wireless device may also mean a communication modem / circuit / chip.

[0291] Specifically, the second wireless device or base station (200) may include a processor (202) and a memory (204) connected to a transceiver or RF transceiver (206). The memory (204) may include at least one program capable of performing operations related to the embodiments described in FIGS. 19 to 22.

[0292] The processor (202) controls the transceiver (206) to form an indirect link connected to a base station through a first UE (User Equipment), receive a request message requesting transmission of a response message related to signal quality for the base station from the first UE, transmit the response message to the first UE based on the measured signal quality for the base station satisfying a specific condition, and perform a procedure for forming a direct link with the base station.

[0293] Hereinafter, the hardware elements of the wireless device (100, 200) will be described in more detail. Although not limited thereto, one or more protocol layers may be implemented by one or more processors (102, 202). For example, one or more processors (102, 202) may implement one or more layers (e.g., functional layers such as PHY, MAC, RLC, PDCP, RRC, SDAP). One or more processors (102, 202) may generate one or more Protocol Data Units (PDUs) and / or one or more Service Data Units (SDUs) according to the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in this document. One or more processors (102, 202) may generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in this document. One or more processors (102, 202) can generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data or information according to the functions, procedures, proposals and / or methods disclosed herein, and provide the signals to one or more transceivers (106, 206). One or more processors (102, 202) can receive signals (e.g., baseband signals) from one or more transceivers (106, 206) and obtain PDUs, SDUs, messages, control information, data or information according to the descriptions, functions, procedures, proposals, methods and / or operational flowcharts disclosed herein.

[0294] One or more processors (102, 202) may be referred to as a controller, a microcontroller, a microprocessor, or a microcomputer. One or more processors (102, 202) may be implemented by hardware, firmware, software, or a combination thereof. For example, one or more Application Specific Integrated Circuits (ASICs), one or more Digital Signal Processors (DSPs), one or more Digital Signal Processing Devices (DSPDs), one or more Programmable Logic Devices (PLDs), or one or more Field Programmable Gate Arrays (FPGAs) may be included in one or more processors (102, 202). The descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in this document may be implemented using firmware or software, and the firmware or software may be implemented to include modules, procedures, functions, etc. The descriptions, functions, procedures, suggestions, methods and / or operation flowcharts disclosed in this document may be implemented using firmware or software configured to perform one or more processors (102, 202) or stored in one or more memories (104, 204) and executed by one or more processors (102, 202). The descriptions, functions, procedures, suggestions, methods and / or operation flowcharts disclosed in this document may be implemented using firmware or software in the form of codes, instructions and / or sets of instructions.

[0295] One or more memories (104, 204) may be coupled to one or more processors (102, 202) and may store various forms of data, signals, messages, information, programs, codes, instructions, and / or commands. The one or more memories (104, 204) may be configured as ROM, RAM, EPROM, flash memory, hard drives, registers, cache memory, computer-readable storage media, and / or combinations thereof. The one or more memories (104, 204) may be located internally and / or externally to the one or more processors (102, 202). Additionally, the one or more memories (104, 204) may be coupled to the one or more processors (102, 202) via various technologies, such as wired or wireless connections.

[0296] One or more transceivers (106, 206) can transmit user data, control information, wireless signals / channels, etc., as mentioned in the methods and / or flowcharts of this document, to one or more other devices. One or more transceivers (106, 206) can receive user data, control information, wireless signals / channels, etc., as mentioned in the descriptions, functions, procedures, proposals, methods and / or flowcharts of this document, from one or more other devices. For example, one or more transceivers (106, 206) can be connected to one or more processors (102, 202) and can transmit and receive wireless signals. For example, one or more processors (102, 202) can control one or more transceivers (106, 206) to transmit user data, control information, or wireless signals to one or more other devices. Additionally, one or more processors (102, 202) may control one or more transceivers (106, 206) to receive user data, control information, or wireless signals from one or more other devices. Additionally, one or more transceivers (106, 206) may be coupled to one or more antennas (108, 208), and one or more transceivers (106, 206) may be configured to transmit and receive user data, control information, wireless signals / channels, or the like, as referred to in the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed herein, via one or more antennas (108, 208). In this document, one or more antennas may be multiple physical antennas or multiple logical antennas (e.g., antenna ports). One or more transceivers (106, 206) can convert received user data, control information, wireless signals / channels, etc. from RF band signals to baseband signals in order to process the received user data, control information, wireless signals / channels, etc. using one or more processors (102, 202).One or more transceivers (106, 206) may convert user data, control information, wireless signals / channels, etc. processed by one or more processors (102, 202) from baseband signals to RF band signals. For this purpose, one or more transceivers (106, 206) may include an (analog) oscillator and / or filter.

[0297] Examples of wireless devices to which the present invention is applied

[0298] Figure 25 illustrates another example of a wireless device applicable to the present invention. The wireless device may be implemented in various forms depending on the use case / service (see Figure 23).

[0299] Referring to FIG. 25, the wireless device (100, 200) corresponds to the wireless device (100, 200) of FIG. 24 and may be composed of various elements, components, units / units, and / or modules. For example, the wireless device (100, 200) may include a communication unit (110), a control unit (120), a memory unit (130), and additional elements (140). The communication unit may include a communication circuit (112) and a transceiver(s) (114). For example, the communication circuit (112) may include one or more processors (102, 202) and / or one or more memories (104, 204) of FIG. 25. For example, the transceiver(s) (114) may include one or more transceivers (106, 206) and / or one or more antennas (108, 208) of FIG. 24. The control unit (120) is electrically connected to the communication unit (110), the memory unit (130), and the additional elements (140) and controls the overall operation of the wireless device. For example, the control unit (120) may control the electrical / mechanical operation of the wireless device based on the program / code / command / information stored in the memory unit (130). In addition, the control unit (120) may transmit information stored in the memory unit (130) to an external device (e.g., another communication device) via a wireless / wired interface through the communication unit (110), or store information received from an external device (e.g., another communication device) via a wireless / wired interface in the memory unit (130).

[0300] The additional element (140) may be configured in various ways depending on the type of the wireless device. For example, the additional element (140) may include at least one of a power unit / battery, an input / output unit (I / O unit), a driving unit, and a computing unit. Although not limited thereto, the wireless device may be implemented in the form of a robot (Fig. 23, 100a), a vehicle (Fig. 23, 100b-1, 100b-2), an XR device (Fig. 23, 100c), a portable device (Fig. 23, 100d), a home appliance (Fig. 23, 100e), an IoT device (Fig. 23, 100f), a digital broadcasting terminal, a hologram device, a public safety device, an MTC device, a medical device, a fintech device (or a financial device), a security device, a climate / environmental device, an AI server / device (Fig. 23, 400), a base station (Fig. 23, 200), a network node, etc. Wireless devices may be mobile or stationary depending on the use / service.

[0301] In FIG. 25, various elements, components, units / parts, and / or modules within the wireless device (100, 200) may be entirely interconnected via a wired interface, or at least some may be wirelessly connected via a communication unit (110). For example, within the wireless device (100, 200), the control unit (120) and the communication unit (110) may be wired, and the control unit (120) and a first unit (e.g., 130, 140) may be wirelessly connected via the communication unit (110). In addition, each element, component, unit / part, and / or module within the wireless device (100, 200) may further include one or more elements. For example, the control unit (120) may be composed of a set of one or more processors. For example, the control unit (120) may be composed of a set of a communication control processor, an application processor, an electronic control unit (ECU), a graphics processing processor, a memory control processor, etc. As another example, the memory unit (130) may be composed of RAM (Random Access Memory), DRAM (Dynamic RAM), ROM (Read Only Memory), flash memory, volatile memory, non-volatile memory, and / or a combination thereof.

[0302] Examples of vehicles or autonomous vehicles to which the present invention is applied

[0303] Figure 26 illustrates a vehicle or autonomous vehicle applicable to the present invention. The vehicle or autonomous vehicle may be implemented as a mobile robot, a car, a train, a manned or unmanned aerial vehicle (AV), a ship, or the like.

[0304] Referring to FIG. 26, a vehicle or autonomous vehicle (100) may include an antenna unit (108), a communication unit (110), a control unit (120), a driving unit (140a), a power supply unit (140b), a sensor unit (140c), and an autonomous driving unit (140d). The antenna unit (108) may be configured as a part of the communication unit (110). Blocks 110 / 130 / 140a to 140d correspond to blocks 110 / 130 / 140 of FIG. 25, respectively.

[0305] The communication unit (110) can transmit and receive signals (e.g., data, control signals, etc.) with external devices such as other vehicles, base stations (e.g., base stations, road side units, etc.), and servers. The control unit (120) can control elements of the vehicle or autonomous vehicle (100) to perform various operations. The control unit (120) can include an ECU (Electronic Control Unit). The drive unit (140a) can drive the vehicle or autonomous vehicle (100) on the ground. The drive unit (140a) can include an engine, a motor, a power train, wheels, brakes, a steering device, etc. The power supply unit (140b) supplies power to the vehicle or autonomous vehicle (100) and can include a wired / wireless charging circuit, a battery, etc. The sensor unit (140c) can obtain vehicle status, surrounding environment information, user information, etc. The sensor unit (140c) may include an IMU (inertial measurement unit) sensor, a collision sensor, a wheel sensor, a speed sensor, an incline sensor, a weight detection sensor, a heading sensor, a position module, a vehicle forward / backward sensor, a battery sensor, a fuel sensor, a tire sensor, a steering sensor, a temperature sensor, a humidity sensor, an ultrasonic sensor, an illuminance sensor, a pedal position sensor, etc. The autonomous driving unit (140d) may implement a technology for maintaining a driving lane, a technology for automatically controlling speed such as adaptive cruise control, a technology for automatically driving along a set path, a technology for automatically setting a path and driving when a destination is set, etc.

[0306] For example, the communication unit (110) can receive map data, traffic information data, etc. from an external server. The autonomous driving unit (140d) can generate an autonomous driving route and driving plan based on the acquired data. The control unit (120) can control the drive unit (140a) so that the vehicle or autonomous vehicle (100) moves along the autonomous driving route according to the driving plan (e.g., speed / direction control). During autonomous driving, the communication unit (110) can irregularly / periodically acquire the latest traffic information data from an external server and can acquire surrounding traffic information data from surrounding vehicles. In addition, during autonomous driving, the sensor unit (140c) can acquire vehicle status and surrounding environment information. The autonomous driving unit (140d) can update the autonomous driving route and driving plan based on newly acquired data / information. The communication unit (110) can transmit information regarding the vehicle location, autonomous driving route, driving plan, etc. to the external server. External servers can predict traffic information data in advance using AI technology or other technologies based on information collected from vehicles or autonomous vehicles, and provide the predicted traffic information data to the vehicles or autonomous vehicles.

[0307] Here, the wireless communication technology implemented in the wireless device (XXX, YYY) of the present specification may include not only LTE, NR, and 6G, but also Narrowband Internet of Things for low-power communication. At this time, for example, NB-IoT technology may be an example of LPWAN (Low Power Wide Area Network) technology, and may be implemented with standards such as LTE Cat NB1 and / or LTE Cat NB2, and is not limited to the above-described names. Additionally or alternatively, the wireless communication technology implemented in the wireless device (XXX, YYY) of the present specification may perform communication based on LTE-M technology. At this time, for example, LTE-M technology may be an example of LPWAN technology, and may be called by various names such as eMTC (enhanced Machine Type Communication). For example, LTE-M technology can be implemented by at least one of various standards such as 1) LTE CAT 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-BL (non-Bandwidth Limited), 5) LTE-MTC, 6) LTE Machine Type Communication, and / or 7) LTE M, and is not limited to the above-described names. Additionally or alternatively, the wireless communication technology implemented in the wireless device (XXX, YYY) of the present specification can include at least one of ZigBee, Bluetooth, and Low Power Wide Area Network (LPWAN) considering low-power communication, and is not limited to the above-described names. For example, ZigBee technology can create PAN (personal area networks) related to small / low-power digital communication based on various standards such as IEEE 802.15.4, and can be called by various names.

[0308] The embodiments described above are combinations of components and features of the present invention in a predetermined form. Each component or feature should be considered optional unless explicitly stated otherwise. Each component or feature may be implemented without being combined with other components or features. Furthermore, it is also possible to form an embodiment of the present invention by combining some components and / or features. The order of operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment. It is self-evident that claims that do not have an explicit citation relationship in the patent claims may be combined to form an embodiment or may be incorporated as a new claim through a post-application amendment.

[0309] In this document, embodiments of the present invention have been described primarily focusing on the signal transmission and reception relationship between a terminal and a base station. This transmission and reception relationship is equally / similarly extended to signal transmission and reception between a terminal and a relay or a base station and a relay. Certain operations described as being performed by a base station in this document may, in some cases, be performed by its upper node. That is, it is obvious that various operations performed for communication with a terminal in a network composed of multiple network nodes including a base station may be performed by the base station or other network nodes other than the base station. The base station may be replaced by terms such as fixed station, Node B, eNode B (eNB), and access point. In addition, the terminal may be replaced by terms such as UE (User Equipment), MS (Mobile Station), MSS (Mobile Subscriber Station).

[0310] Embodiments of the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In the case of hardware implementation, an embodiment of the present invention may be implemented by one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, etc.

[0311] When implemented via firmware or software, an embodiment of the present invention may be implemented in the form of modules, procedures, functions, etc. that perform the functions or operations described above. The software code may be stored in a memory unit and executed by a processor. The memory unit may be located within or outside the processor and may exchange data with the processor via various known means.

[0312] It will be apparent to those skilled in the art that the present invention can be embodied in other specific forms without departing from the scope of the invention. Therefore, the above detailed description should not be construed as limiting in any respect, but rather as illustrative. The scope of the present invention should be determined by a reasonable interpretation of the appended claims, and all modifications within the scope of equivalents of the present invention are intended to be included within the scope of the present invention.

[0313] The embodiments of the present invention as described above can be applied to various mobile communication systems.

Claims

1. A step of forming a direct link directly connected to a base station; A step of forming at least one indirect link connecting at least one UE and the base station through a first UE (User Equipment); A step of transmitting a message requesting transmission of a response message related to signal quality to the base station to the at least one UE based on the signal strength of the direct link being below a specific threshold; and A method comprising the step of determining whether to trigger a measurement report based on whether the above response message has been received.

2. In paragraph 1, A method, characterized in that the response message is received from a UE having a signal quality measured for the base station that is above a specific threshold among the at least one UE.

3. In paragraph 1, A method, characterized in that the measurement report is not triggered based on receipt of the response message.

4. In paragraph 1, A method, characterized in that the measurement report is triggered based on the above response message not being received.

5. In paragraph 1, A method, characterized in that the response message includes information about the signal strength measured for the base station, the amount of change in the signal strength, and the capability of the UE.

6. In paragraph 1, A method, characterized in that the direct link is formed based on a virtual C-RNTI (Cell Radio Network Temporary Identifier) preset for the first UE and the cluster group including at least one UE.

7. In paragraph 1, A method, characterized in that it further comprises the step of transmitting a request message requesting the specific UE to form a direct connection with the base station based on the reception of the response message from a specific UE among the at least one UE.

8. In paragraph 7, A method, characterized in that it further comprises a step of forming an indirect link connected to the base station through the specific UE based on transmission of the request message.

9. In paragraph 1, A method, characterized in that the above measurement report includes information about a signal strength measured for at least one neighboring cell.

10. In paragraph 1, A method, characterized in that the message is transmitted based on the first UE being a leader UAV (Unmanned Aerial Vehicle) UE of a first constellation group consisting of at least one UE and the first UE being located above a specific height.

11. A computer-readable recording medium having recorded thereon a program for performing the method described in Article 1. 12.RF(Radio Frequency) Transmitter / Receiver; and comprising a processor connected to the RF transceiver; The processor controls the RF transceiver to form a direct link directly connected to a base station, and forms at least one indirect link for connecting at least one UE (User Equipment) and the base station, and transmits a message requesting transmission of a response message related to signal quality for the base station to the at least one UE based on whether a signal strength of the direct link is below a specific threshold, and determines whether to trigger a measurement report based on whether the response message is received.

13. In a processing device controlling the first UE (User Equipment), at least one processor; and At least one memory coupled to said at least one processor and storing instructions, said instructions causing said first UE to: A processing device that forms a direct link directly connected to a base station, and forms at least one indirect link for connecting at least one UE (User Equipment) and the base station, and transmits a message requesting transmission of a response message related to signal quality for the base station to the at least one UE based on whether a signal strength of the direct link is below a specific threshold, and determines whether to trigger a measurement report based on whether the response message is received.

14. A step of forming an indirect link connected to a base station through a first UE (User Equipment); A step of receiving a request message requesting transmission of a response message related to signal quality to the base station from the first UE; A step of transmitting a response message to the first UE based on the measured signal quality for the base station satisfying a specific condition; and A method comprising the step of performing a procedure for forming a direct link with the base station. 15.RF(Radio Frequency) Transmitter / Receiver; and comprising a processor connected to the RF transceiver; The processor controls the RF transceiver to form an indirect link connected to a base station through a first UE (User Equipment), receives a request message requesting transmission of a response message related to signal quality for the base station from the first UE, transmits the response message to the first UE based on the measured signal quality for the base station satisfying a specific condition, and performs a procedure for forming a direct link with the base station.

Images