Method and apparatus for controlling transmission and reception operations in non-terrestrial network

Abstract

A method and apparatus for controlling transmission and reception operations in a non-terrestrial network are disclosed. The method comprises the steps of: transmitting a first message including an RA preamble to a non-terrestrial node in a random access procedure; performing a downlink monitoring operation in an RA response window that starts after a first offset from the time of transmission of the first message; and receiving a second message that is a response to the first message from the non-terrestrial node by means of the downlink monitoring operation. The first offset is set considering the minimum transmission delay between the non-terrestrial node and terminals located in a cell formed by the non-terrestrial node, and the RA response window is set considering the difference between the minimum transmission delay and the maximum transmission delay between the non-terrestrial node and the terminals. Accordingly, the performance of the non-terrestrial network can be improved.

Description

Technology Field

[0001] The present invention relates to communication technology in non-terrestrial networks, and more specifically, to technology for controlling the transmission and reception operations of a terminal. Background Technology

[0002] To handle the rapidly increasing volume of wireless data, communication networks (e.g., new radio (NR) communication networks) that use frequency bands higher than the frequency bands of LTE (long term evolution) (or LTE-A) (e.g., frequency bands below 6 GHz) (e.g., frequency bands below 6 GHz) are being considered. NR communication networks can support frequency bands above 6 GHz as well as frequency bands below 6 GHz, and can support a wider variety of communication services and scenarios compared to LTE communication networks. For example, usage scenarios for NR communication networks may include eMBB (enhanced Mobile BroadBand), URLLC (Ultra Reliable Low Latency Communication), mMTC (massive Machine Type Communication), etc.

[0003] NR communication networks can provide communication services to terminals located on the ground (terrestrial). Recently, there has been an increasing demand for communication services for aircraft, drones, unmanned aerial vehicles (UAVs), UAN base stations (UBS), and satellites located not only on the ground but also in non-terrestrial areas; to meet this demand, technologies for non-terrestrial networks (NTNs) are being discussed. Non-terrestrial networks can be implemented based on NR technology. For example, in a non-terrestrial network, communication between a satellite and a communication node located on the ground (e.g., user equipment (UE)) or a communication node located in a non-terrestrial area (e.g., an aircraft, UAV, or drone) can be performed based on NR technology. In a non-terrestrial network, the satellite can perform the function of a base station in the NR communication network. Here, in terms of communication range, a non-terrestrial network may refer to a long-distance communication network.

[0004] Meanwhile, in non-terrestrial networks, terminals can perform communication using the 6GHz to 90GHz band. In other words, high-speed data transmission can be performed in non-terrestrial networks by utilizing a wide bandwidth. Since the round trip delay (RTD) between the satellite and the terminal in non-terrestrial networks is long, transmission and reception methods and control methods based on wireless protocols that take this into account are required. The problem to be solved

[0005] The objective of the present invention to solve the above-mentioned problems is to provide a transmission and reception method and a control method that take into account transmission delay in a non-terrestrial network. means of solving the problem

[0006] An embodiment of a method for operating a terminal in a non-terrestrial network to achieve the above objective comprises the steps of: transmitting a first message including a random access (RA) preamble to a non-terrestrial node in a random access procedure; performing a first downlink monitoring operation in an RA response window that starts after a first offset from the time of transmission of the first message; and receiving a second message from the non-terrestrial node as a response to the first message by means of the first downlink monitoring operation, wherein the first offset may be set considering the minimum transmission delay between the non-terrestrial node and terminals located in a cell formed by the non-terrestrial node. The method for operating the terminal comprises, after the step of receiving the second message, the steps of: transmitting a third message to the non-terrestrial node using uplink resources allocated by the non-terrestrial node; starting a first timer; and performing a second downlink monitoring operation for a fourth message transmitted from the non-terrestrial node as a response to the third message until the first timer expires. The method may further include a step of determining whether the random access procedure is successful based on the result of the second downlink monitoring operation for the fourth message. The step of starting the first timer includes starting the first timer after a second offset from the time of transmission of the third message, and the second offset may be set considering the minimum transmission delay. The first offset may be set to have a size greater than or equal to twice the minimum transmission delay. The RA response window may be set considering the difference between the minimum transmission delay and the maximum transmission delay between the non-ground node and the terminals.Another embodiment of a method for operating a terminal in a non-terrestrial network to achieve the above objective comprises the steps of: transmitting a first message to a non-terrestrial node containing first information for a first procedure for performing communication between a non-terrestrial node and the terminal; starting a first timer after a first offset from the time of transmission of the first message; and checking whether a second message transmitted from the non-terrestrial node as a response to the first message is received during the operation of the first timer, wherein the first offset is set considering the minimum transmission delay between the non-terrestrial node and terminals located in a cell formed by the non-terrestrial node, and whether a third message corresponding to the first message is transmitted may be determined based on whether the second message is received during the operation of the first timer. The first procedure is a scheduling request (SR) procedure, and the method for operating the terminal, if the second message is not received during the operation of the first timer, transmits the third message containing the second information after the first timer has expired. The method further includes the step of transmitting to a non-ground node, wherein the first information and the second information may each include the same scheduling request identifier. The first procedure is a buffer status report (BSR) procedure, and the method of operation of the terminal further includes the step of transmitting the third message containing the second information to the non-ground node after the first timer has expired, if the second message is not received during the operation of the first timer, and the first information and the second information may each be the same BSR information.The first procedure is a contention-based random access procedure for beam failure recovery (BFR), and the method of operation of the terminal may further include the step of transmitting the third message to the non-ground node that triggers the first procedure again after the first timer expires if the second message is not received during the operation of the first timer. The first procedure is a contention-based random access procedure for BFR, and the first message is a message that includes a random access (RA) preamble and triggers the first procedure, and the method of operation of the terminal may further include the step of transmitting the third message to the non-ground node that triggers a contention-based random access procedure after the second timer, which started simultaneously with the first timer, expires if the second message is not received during the operation of the first timer, and the size of the second timer may be set considering the minimum transmission delay. Effects of the invention

[0007] According to the present invention, a timer, an offset, and / or a window may be set considering the transmission delay between a non-terrestrial node (e.g., a satellite) and a terminal in a non-terrestrial network. For example, a timer, an offset, and / or a window may be used considering the transmission delay (e.g., minimum transmission delay, maximum transmission delay, and the difference between transmission delays) in each of the random access procedure, the SR (scheduling request) information transmission procedure, the BSR (buffer status report) information transmission procedure, and the BFR (beam failure recovery) procedure. Accordingly, transmission and reception operations in a non-terrestrial network can be performed efficiently, and the performance of the non-terrestrial network can be improved. Brief explanation of the drawing

[0008] FIG. 1 is a conceptual diagram illustrating a first embodiment of a communication network. FIG. 2 is a block diagram illustrating a first embodiment of a communication node constituting a communication network. FIG. 3 is a conceptual diagram illustrating a first embodiment of the operating state of a terminal in a communication network. FIG. 4 is a conceptual diagram illustrating a first embodiment of a non-ground network. FIG. 5 is a conceptual diagram illustrating a second embodiment of a non-ground network. FIG. 6 is a conceptual diagram illustrating a third embodiment of a non-ground network. FIG. 7 is a timing diagram illustrating a first embodiment of a random access procedure in a non-terrestrial network. FIG. 8 is a timing diagram illustrating a first embodiment of a transmission procedure of SR information considering Ldelay_min in a non-terrestrial network. FIG. 9 is a timing diagram illustrating a first embodiment of a beam recovery procedure considering Ldelay_min in a non-ground network. Specific details for implementing the invention

[0009] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the invention to specific embodiments, and it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0010] Terms such as "first," "second," etc., may be used to describe various components, but said components should not be limited by said terms. These terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the first component. The term "and / or" includes a combination of a plurality of related described items or any of a plurality of related described items.

[0011] When it is stated that one component is "connected" or "connected" to another component, it should be understood that while it may be directly connected or connected to that other component, there may also be other components in between. On the other hand, when it is stated that one component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between.

[0012] The terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, terms such as "comprising" or "having" are intended to specify the presence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0013] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0014] Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the attached drawings. In order to facilitate an overall understanding of the present invention, the same reference numerals are used for identical components in the drawings, and redundant descriptions of identical components are omitted.

[0015] A communication network to which embodiments according to the present invention are applied will be described. The communication network may be a non-terrestrial network (NTN), a 4G communication network (e.g., an LTE (long-term evolution) communication network), a 5G communication network (e.g., a NR (new radio) communication network), etc. 4G communication networks and 5G communication networks may be classified as terrestrial networks.

[0016] Non-terrestrial networks may operate based on LTE technology and / or NR technology. Non-terrestrial networks may support communication in frequency bands above 6 GHz as well as in frequency bands below 6 GHz. 4G communication networks may support communication in frequency bands below 6 GHz. 5G communication networks may support communication in frequency bands above 6 GHz as well as in frequency bands below 6 GHz. The communication networks to which the embodiments according to the present invention are applied are not limited to those described below, and the embodiments according to the present invention may be applied to various communication networks. Here, the term "communication network" may be used interchangeably with "communication system."

[0017] FIG. 1 is a conceptual diagram illustrating a first embodiment of a communication network.

[0018] Referring to FIG. 1, a communication network (100) may include a plurality of communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, 130-6). The plurality of communication nodes may support 4G communication (e.g., LTE (long term evolution), LTE-A (advanced)), 5G communication (e.g., NR (new radio)), etc., as defined in 3GPP (3rd generation partnership project) standards. 4G communication may be performed in a frequency band of 6 GHz or lower, and 5G communication may be performed not only in a frequency band of 6 GHz or lower but also in a frequency band of 6 GHz or higher.

[0019] For example, for 4G communication and 5G communication, multiple communication nodes can support communication protocols based on CDMA (code division multiple access), WCDMA (wideband CDMA), TDMA (time division multiple access), FDMA (frequency division multiple access), OFDM (orthogonal frequency division multiplexing), Filtered OFDM, CP (cyclic prefix)-OFDM, DFT-s-OFDM (discrete Fourier transform-spread-OFDM), OFDMA (orthogonal frequency division multiple access), SC (single carrier)-FDMA, NOMA (Non-orthogonal Multiple Access), GFDM (generalized frequency division multiplexing), FBMC (filter bank multi-carrier) based communication protocol, UFMC (universal filtered multi-carrier) based communication protocol, SDMA (Space Division Multiple Access) based communication protocol, etc.

[0020] Additionally, the communication network (100) may further include a core network. If the communication network (100) supports 4G communication, the core network may include an S-GW (serving-gateway), a P-GW (PDN (packet data network)-gateway), an MME (mobility management entity), etc. If the communication network (100) supports 5G communication, the core network may include a UPF (user plane function), an SMF (session management function), an AMF (access and mobility management function), etc.

[0021] Meanwhile, each of the plurality of communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, 130-6) constituting the communication network (100) may have the following structure.

[0022] FIG. 2 is a block diagram illustrating a first embodiment of a communication node constituting a communication network.

[0023] Referring to FIG. 2, the communication node (200) may include at least one processor (210), a memory (220), and a transceiver (230) that is connected to a network to perform communication. Additionally, the communication node (200) may further include an input interface device (240), an output interface device (250), a storage device (260), etc. Each component included in the communication node (200) may be connected by a bus (270) to communicate with one another.

[0024] However, each component included in the communication node (200) may be connected via individual interfaces or individual buses centered around the processor (210), rather than via a common bus (270). For example, the processor (210) may be connected via a dedicated interface to at least one of a memory (220), a transmission / reception device (230), an input interface device (240), an output interface device (250), and a storage device (260).

[0025] The processor (210) can execute a program command stored in at least one of the memory (220) and the storage device (260). The processor (210) may mean a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which methods according to embodiments of the present invention are performed. Each of the memory (220) and the storage device (260) may be composed of at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory (220) may be composed of at least one of read-only memory (ROM) and random access memory (RAM).

[0026] Referring again to FIG. 1, a communication network (100) may include a plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) and a plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6). A communication network (100) including base stations (110-1, 110-2, 110-3, 120-1, 120-2) and terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) may be referred to as an "access network". Each of the first base station (110-1), the second base station (110-2), and the third base station (110-3) can form a macro cell. Each of the fourth base station (120-1) and the fifth base station (120-2) can form a small cell. The fourth base station (120-1), the third terminal (130-3), and the fourth terminal (130-4) may be located within the cell coverage of the first base station (110-1). The second terminal (130-2), the fourth terminal (130-4), and the fifth terminal (130-5) may be located within the cell coverage of the second base station (110-2). The fifth base station (120-2), the fourth terminal (130-4), the fifth terminal (130-5), and the sixth terminal (130-6) may be located within the cell coverage of the third base station (110-3). The first terminal (130-1) may be located within the cell coverage of the fourth base station (120-1). The sixth terminal (130-6) may be located within the cell coverage of the fifth base station (120-2).

[0027] Here, each of the multiple base stations (110-1, 110-2, 110-3, 120-1, 120-2) may be referred to as Node B, evolved Node B, base transceiver station (BTS), radio base station, radio transceiver, access point, access node, road side unit (RSU), radio remote head (RRH), transmission point (TP), transmission and reception point (TRP), eNB, gNB, etc.

[0028] Each of the multiple terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) may be referred to as a UE (user equipment), terminal, access terminal, mobile terminal, station, subscriber station, mobile station, portable subscriber station, node, device, IoT (Internet of Thing) device, mounted module / device / terminal or on board device / terminal, etc.

[0029] Meanwhile, each of the multiple base stations (110-1, 110-2, 110-3, 120-1, 120-2) may operate in different frequency bands or in the same frequency band. Each of the multiple base stations (110-1, 110-2, 110-3, 120-1, 120-2) may be connected to each other via an ideal backhaul link or a non-ideal backhaul link, and may exchange information with each other via an ideal backhaul link or a non-ideal backhaul link. Each of the multiple base stations (110-1, 110-2, 110-3, 120-1, 120-2) may be connected to a core network via an ideal backhaul link or a non-ideal backhaul link. Each of the multiple base stations (110-1, 110-2, 110-3, 120-1, 120-2) can transmit a signal received from the core network to the corresponding terminal (130-1, 130-2, 130-3, 130-4, 130-5, 130-6), and can transmit a signal received from the corresponding terminal (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) to the core network.

[0030] In addition, each of the multiple base stations (110-1, 110-2, 110-3, 120-1, 120-2) can support MIMO transmission (e.g., SU (single user)-MIMO, MU (multi user)-MIMO, massive MIMO, etc.), CoMP (coordinated multipoint) transmission, CA (carrier aggregation) transmission, transmission in an unlicensed band, device-to-device communication (D2D) (or ProSe (proximity services)), etc. Here, each of the plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) can perform an operation corresponding to the base station (110-1, 110-2, 110-3, 120-1, 120-2) and an operation supported by the base station (110-1, 110-2, 110-3, 120-1, 120-2). For example, the second base station (110-2) can transmit a signal to the fourth terminal (130-4) based on the SU-MIMO method, and the fourth terminal (130-4) can receive a signal from the second base station (110-2) based on the SU-MIMO method. Alternatively, the second base station (110-2) can transmit a signal to the fourth terminal (130-4) and the fifth terminal (130-5) based on the MU-MIMO method, and each of the fourth terminal (130-4) and the fifth terminal (130-5) can receive a signal from the second base station (110-2) by the MU-MIMO method.

[0031] Each of the first base station (110-1), the second base station (110-2), and the third base station (110-3) can transmit a signal to the fourth terminal (130-4) based on the CoMP method, and the fourth terminal (130-4) can receive a signal from the first base station (110-1), the second base station (110-2), and the third base station (110-3) by the CoMP method. Each of the multiple base stations (110-1, 110-2, 110-3, 120-1, 120-2) can transmit and receive signals based on the CA method with terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) within its cell coverage area. Each of the first base station (110-1), the second base station (110-2), and the third base station (110-3) can control D2D between the fourth terminal (130-4) and the fifth terminal (130-5), and each of the fourth terminal (130-4) and the fifth terminal (130-5) can perform D2D by controlling each of the second base station (110-2) and the third base station (110-3).

[0032] Next, transmission and reception methods and control methods in a communication network will be described. Even when a method performed by a first communication node among the communication nodes (e.g., transmission or reception of a signal) is described, the corresponding second communication node may perform a method corresponding to the method performed by the first communication node (e.g., reception or transmission of a signal). That is, when the operation of a terminal is described, the corresponding base station may perform an operation corresponding to the operation of the terminal. Conversely, when the operation of a base station is described, the corresponding terminal may perform an operation corresponding to the operation of the base station.

[0033] In the embodiments below, UPF (or S-GW) may refer to an end communication node of a core network that exchanges packets (e.g., control information, data) with a base station, and AMF (or MME) may refer to a communication node of a core network that performs control functions at the radio access section (or interface) of a terminal. Here, S-GW, MME, AMF, and UPF may each be referred to by different terms depending on the function of the communication protocol according to the RAT (radio access technology) (e.g., function of the core network).

[0034] In a communication network that supports dual connectivity, a connection can be established between a terminal and multiple base stations. Multiple base stations can provide services to the terminal. Multiple base stations that support dual connectivity (e.g., multiple base stations connected to the terminal) can be classified into a master base station and a secondary base station. In the embodiments below, dual connectivity may refer to single-radio dual connectivity (SR-DC) by multiple base stations supporting the same RAT or multi-radio dual connectivity (MR-DC) by multiple base stations supporting different RATs.

[0035] A master base station may be referred to as a "master node." A master node may be a node that proactively performs RRC functions to support dual linkage capabilities. A master node may provide control plane connectivity with the core network. A master node may be composed of multiple cells. The multiple cells included in a master node may be referred to as an MCG (master cell group). An MCG bearer may refer to a bearer established through the logical channel configuration between the RLC layer and the MAC layer of a cell belonging to the MCG.

[0036] A secondary base station may be referred to as a "secondary node." A secondary node may not provide control plane connectivity with the core network. A secondary node may provide services to terminals using additional radio resources. A secondary node may be composed of multiple cells. Multiple cells included in a secondary node may be referred to as a secondary cell group (SCG). A split bearer may use logical channel configurations between the RLC layer and the MAC layer of cells belonging to an MCG, and logical channel configurations between the RLC layer and the MAC layer of cells belonging to an SCG. A split bearer may be classified as a secondary node (SN) terminated bearer and a master node (MN) terminated bearer depending on the form of the node performing the PDCP function. If the PDCP function for a split bearer is performed at a master node, the split bearer may be an MN terminated bearer. If the PDCP function for a split bearer is performed at a secondary node, the split bearer may be an SN end bearer.

[0037] FIG. 3 is a conceptual diagram illustrating a first embodiment of the operating state of a terminal in a communication network.

[0038] Referring to FIG. 3, the operating state of the terminal can be classified into an RRC connected state, an RRC inactive state, and an RRC idle state. When the terminal operates in an RRC connected state or an RRC inactive state, the RAN (radio access network) (e.g., a control function block of the RAN) and the base station can store / manage the RRC connection setup information and / or context information (e.g., RRC context information, AS (access stratum) context information) of the terminal. Additionally, the terminal operating in an RRC connected state or an RRC inactive state can store the RRC connection setup information and / or context information.

[0039] "When the operating state of the terminal transitions from an RRC connected state to an RRC idle state" or "when the operating state of the terminal transitions from an RRC inactive state to an RRC idle state," context information may be deleted from the RAN and the base station. Context information (e.g., RRC context information) may include an identifier assigned to the terminal, PDU session information, encryption key (security key), capability information, etc.

[0040] A terminal operating in an RRC idle state may perform a cell selection or cell reselection operation to camp at an optimal base station (e.g., optimal cell) by performing a downlink signal monitoring operation (e.g., measurement operation) during on-duration or active time according to a DRX (discontinuous reception) cycle configured for low-power consumption operation. To camp at a new base station (e.g., new cell), the terminal may obtain system information from the base station. Additionally, if system information required by the terminal exists, the terminal may request the transmission of the system information. The terminal may perform a paging message reception operation during on-duration or active time according to a paging occasion.

[0041] A terminal operating in an RRC connection state can establish a base station (e.g., a serving cell) and a radio bearer (e.g., a DRB (data radio bearer), a SRB (signaling radio bearer)), and can store / manage context information required in the RRC connection state (e.g., RRC context information). A terminal operating in an RRC connection state can perform PDCCH monitoring operations using context information and connection setup information. The terminal can receive downlink data from the base station through radio resources indicated by the DCI obtained through the PDCCH monitoring operation. Additionally, the terminal can transmit uplink data to the base station using the radio resources indicated by the DCI obtained through the PDCCH monitoring operation.

[0042] Mobility functions for a terminal operating in an RRC connected state may be supported through a handover procedure when the base station changes. For the handover procedure, the terminal may perform measurement operations on the base station and / or adjacent base stations (e.g., adjacent cells) based on measurement and / or reporting parameters set by the base station, and may report the measurement results to the base station. In the embodiments below, the measurement operation may include an operation to report measurement results. Additionally, the terminal operating in an RRC connected state may perform DRX operations based on DRX parameters set by the base station. For example, the terminal operating in an RRC connected state may perform PDCCH monitoring operations during on-duration or active time according to the DRX cycle.

[0043] A terminal operating in an RRC inactive state can store / manage context information required for the RRC inactive state. A terminal operating in an RRC inactive state or an RRC idle state can perform DRX operations based on DRX parameters set by the last base station (e.g., serving cell). For example, a terminal operating in an RRC inactive state can perform monitoring or measurement operations of downlink signals during the on-duration or active time according to the DRX cycle, and can perform cell selection or cell reselection operations based on the results of the monitoring or measurement operations to camp at the optimal base station (e.g., optimal cell). The terminal can acquire system information to camp at a new base station (e.g., new cell) and, if necessary, request the transmission of system information (e.g., system information required by the terminal). A terminal operating in an RRC inactive state or an RRC idle state can perform receiving operations of paging messages during the on-duration or active time according to paging occupancy.

[0044] Communication procedures between a base station and a terminal can be performed based on a beamforming method. Signals transmitted from the terminal may be used to provide mobility functions between base stations or to select an optimal beam within a base station. A connection may be established between the terminal and one or more base stations (e.g., one or more cells), and one or more base stations may provide services to the terminal. The connection established between the terminal and one or more base stations may be maintained. For example, one or more base stations may store / manage context information (e.g., AS context information). Alternatively, the terminal may be located within the service area of ​​a base station without establishing a connection with the base station.

[0045] When beamforming is used in the high-frequency band, the communication system may support "a beam-level mobility function that changes the configured beam of a terminal," "a mobility function that changes the configured beam between base stations (e.g., cells)," and "a resource management function that changes the configuration of a wireless link."

[0046] To perform mobility support functions and radio resource management functions, the base station may transmit a synchronization signal (e.g., SS / PBCH (synchronization signal / physical broadcast channel) block) and / or a reference signal. To support multiple numerologies, a frame format supporting symbols of different lengths may be configured. In this case, the terminal may perform monitoring operations of the synchronization signal and / or reference signal in a frame according to the initial numerology, default numerology, or default symbol length. The initial numerology and default numerology may each be applied to a frame format applied to a radio resource where the UE-common search space is configured, a frame format applied to a radio resource where CORESET (control resource set) #0 of the NR communication system is configured, and / or a frame format applied to a radio resource where a synchronization symbol burst capable of identifying a cell in the NR communication system is transmitted.

[0047] The frame format may refer to information regarding configuration parameters (e.g., values ​​of configuration parameters, offset, index, identifier, range, period, interval, duration) for subcarrier spacing, control channels (e.g., CORESET), symbols, slots, and / or reference signals in a radio frame (or subframe). The base station may inform the terminal of the frame format using system information and / or control messages (e.g., dedicated control messages).

[0048] A terminal connected to a base station may transmit a reference signal (e.g., an uplink-only reference signal) to the base station using resources configured by the base station. For example, the uplink-only reference signal may include a sounding reference signal (SRS). Additionally, the terminal connected to the base station may receive a reference signal (e.g., a downlink-only reference signal) from the base station using resources configured by the base station. The downlink-only reference signal may be a channel state information-reference signal (CSI-RS), a phase tracking-reference signal (PT-RS), a demodulation-reference signal (DM-RS), etc. Each of the base station and the terminal may perform beam management operations through monitoring of the configured beam or active beam based on the reference signal.

[0049] For example, a base station may transmit synchronization signals and / or reference signals so that a terminal located within the communication service area can discover it and perform downlink synchronization maintenance, beam setting, or link monitoring operations. A terminal connected to a base station (e.g., a serving base station) may receive physical layer radio resource configuration information from the base station for connection establishment and radio resource management. The physical layer radio resource configuration information may be configuration parameters included in RRC control messages in LTE communication systems and / or NR communication systems. For example, the radio resource configuration information PhysicalConfigDedicated, PhysicalCellGroupConfig , PDCCH - Config (Common), PDSCH-Config(Common), PDCCH - ConfigSIB1 , ConfigCommon , PUCCH - Config (Common), PUSCH-Config(Common), BWP - DownlinkCommon , BWP - UplinkCommon , ControlResourceSet, RACH - ConfigCommon , RACH - ConfigDedicated , RadioResourceConfigCommon, RadioResourceConfigDedicated, ServingCellConfig , ServingCellConfigCommon It may include the back.

[0050] Wireless resource configuration information may include parameter values ​​such as the configuration period (or allocation period) of a signal (or wireless resource) according to the frame format of the base station (or transmission frequency), time resource allocation information for transmission, frequency resource allocation information for transmission, and transmission timing (or allocation timing). To support multiple numerals, the frame format of the base station (or transmission frequency) may refer to a frame format having different symbol lengths according to multiple subcarrier intervals within a single wireless frame. For example, within a single wireless frame (e.g., a frame having a length of 10 ms), the number of symbols constituting each of the mini-slot, slot, and subframe may differ.

[0051] ● Base station transmission frequency and frame format setting information

[0052] ■ Transmission frequency configuration information: All transmission carriers of the base station (e.g., cell-level transmission frequencies), bandwidth part (BWP), transmission reference time or time difference information between the base station's transmission frequencies (e.g., transmission period or offset parameter indicating the transmission reference time (or time difference) of the synchronization signal), etc.

[0053] ■ Frame Format Configuration Information: Configuration parameters for mini-slots, slots, and subframes having different symbol lengths depending on the subcarrier spacing

[0054] ● Configuration information for downlink reference signals (e.g., CSI-RS, common RS, etc.)

[0055] ■ Common RS configuration information refers to configuration parameters such as the transmission period, transmission location, code sequence, and masking sequence (or scrambling sequence) of the reference signal commonly applied within the base station (or beam) coverage.

[0056] ● Uplink control signal setting information

[0057] ■ SRS, reference signal for uplink beam sweeping (or beam monitoring), radio resources (or preamble) for uplink grant-free, etc.

[0058] ● Configuration information of the downlink control channel (e.g., PDCCH (physical downlink control channel))

[0059] ■ Reference signals for PDCCH demodulation, common beam reference signals (e.g., reference signals receivable by all terminals within beam coverage), reference signals for beam sweeping (or beam monitoring), reference signals for channel estimation, etc.

[0060] ● Configuration information of the uplink control channel (e.g., PUCCH (physical uplink control channel))

[0061] ● Configuration information for the scheduling request signal

[0062] ● Configuration information of the resource for transmitting feedback (e.g., ACK (acknowledgement) or NACK (negative ACK)) in the HARQ (hybrid automatic repeat request) procedure

[0063] ● Number of antenna ports, information on the antenna array, beam configuration and / or beam index mapping information for beamforming application

[0064] ● Configuration information for downlink signals and / or uplink signals (or uplink access channel resources) for beam sweeping (or beam monitoring)

[0065] ● Configuration information such as beam setting operation, beam recovery operation, beam reconfiguration operation, wireless link re-establishment operation, beam change operation within the same base station, received beam signal triggering handover procedure to another base station, and control timers for the aforementioned operations

[0066] In a wireless frame format that supports different symbol lengths to support multiple numerals, the setting period (or allocation period), time resource allocation information, frequency resource allocation information, transmission time, and / or allocation time of the parameters constituting the information described above may be information set according to the corresponding symbol length (or subcarrier interval).

[0067] In the embodiments below, "Resource-Config information" may be a control message containing one or more parameters among the wireless resource configuration information of the physical layer. Additionally, "Resource-Config information" may refer to the attributes and / or configuration values ​​(or ranges) of an information element (or parameter) transmitted by the control message. The information element (or parameter) transmitted by the control message may be wireless resource configuration information that is commonly applied across the entire coverage of the base station (or beam) or wireless resource configuration information that is exclusively allocated to a specific terminal (or specific terminal group).

[0068] The configuration information included in "Resource-Config Information" may be transmitted via a single control message or different control messages depending on the attributes of the configuration information. Beam index information may not clearly distinguish between the index of the transmitting beam and the index of the receiving beam. For example, beam index information may be expressed using a reference signal mapped to or associated with the corresponding beam index, or an index (or identifier) ​​of the transmission configuration indicator (TCI) status for beam management.

[0069] Accordingly, a terminal operating in an RRC connection state can receive communication services through a beam (e.g., beam pair) configured between the terminal and a base station (e.g., serving cell). The terminal can perform search or monitoring operations on the radio channel using a synchronization signal (e.g., SS / PBCH block) and / or reference signal (e.g., CSI-RS) transmitted from the base station (e.g., serving cell). Here, "communication services being provided through a beam (e.g., configured beam)" may mean "packets being transmitted and received through an active beam among one or more configured beams." In an NR communication system, "a beam being activated" may mean "a configured TCI state being activated."

[0070] The terminal may operate in an RRC idle state or an RRC inactive state. In this case, the terminal may perform a search operation (e.g., a monitoring operation) on the downlink channel using parameter(s) obtained from system information or common Resource-Config information. Additionally, the terminal operating in an RRC idle state or an RRC inactive state may attempt to establish a connection using an uplink channel (e.g., a random access channel or a physical layer uplink control channel, etc.). Alternatively, the terminal may transmit control information using the uplink channel.

[0071] The terminal can detect or identify a problem with the wireless link by performing a radio link monitoring (RLM) operation. Here, "detection of a wireless link problem" may mean "an abnormality in the establishment or maintenance of physical layer synchronization for the wireless link." For example, "detection of a wireless link problem" may mean "detection that physical layer synchronization between the base station and the terminal is mismatched for a preset period of time." If a wireless link problem is detected, the terminal can perform a wireless link recovery operation. If the wireless link is not recovered, the terminal can declare a radio link failure (RLF) and perform a wireless link re-establishment procedure.

[0072] Procedures for detecting physical layer problems of a wireless link, recovery of the wireless link, failure detection (or, declaration) of the wireless link, and re-establishment of the wireless link according to RLM operations may be performed by functions of layer 1 (e.g., physical layer), layer 2 (e.g., MAC layer, RLC layer, PDCP layer, etc.), and / or layer 3 (e.g., RRC layer) of the wireless protocol constituting the wireless link.

[0073] The physical layer of a terminal can monitor the wireless link by receiving downlink synchronization signals (e.g., primary synchronization signal (PSS), secondary synchronization signal (SSS), SS / PBCH block) and / or a reference signal. In this case, the reference signal may be a base station common reference signal, a beam common reference signal, or a terminal (or terminal group) specific reference signal (e.g., a dedicated reference signal assigned to a terminal (or terminal group)). Here, the common reference signal may be used for channel estimation operations of all terminals located within the coverage (or service area) of the corresponding base station or beam. The dedicated reference signal may be used for channel estimation operations of a specific terminal or a specific terminal group within the coverage of the base station or beam.

[0074] Accordingly, if a base station or a beam (e.g., a configuration beam between a base station and a terminal) is changed, a dedicated reference signal for beam management may be changed. A beam may be changed based on the configuration parameter(s) between the base station and the terminal. A procedure for changing the configuration beam may be required. "Changing a beam in an NR communication system" may mean "changing the index (or identifier) ​​of a TCI state to a different index of a TCI state," "setting a new TCI state," or "changing the TCI state to an active state." The base station may transmit system information containing configuration information of a common reference signal to the terminal. The terminal may obtain the common reference signal based on the system information. In a handover procedure, a reconfiguration procedure, or a connection reconfiguration procedure, the base station may transmit a dedicated control message containing configuration information of a common reference signal to the terminal.

[0075] Information for distinguishing base stations (e.g., cells) may be transmitted to a terminal according to the configuration conditions of the base station's wireless protocol. Information for distinguishing base stations may be transmitted to the terminal using an RRC layer control message, a MAC layer control message, or a physical layer control channel, depending on the layer(s) included in the base station. In the embodiments, the RRC layer control message may be referred to as "RRC control message" or "RRC message," the MAC layer control message may be referred to as "MAC control message" or "MAC message," and the physical layer control channel may be referred to as "PHY control channel," "PHY control message," or "PHY message."

[0076] Here, information for distinguishing base stations may include one or more of a base station identifier, reference signal information, reference symbol information, configured beam information, and configured TCI status information. The reference signal information (or reference symbol information) may include configuration information of a reference signal assigned per base station (e.g., radio resource, sequence, index) and / or configuration information of a dedicated reference signal assigned to a terminal (e.g., radio resource, sequence, index).

[0077] Here, the radio resource information of the reference signal may include time domain resource information (e.g., frame index, subframe index, slot index, symbol index) and frequency domain resource information (e.g., a parameter indicating the relative or absolute position of a subcarrier). The parameter indicating the radio resource of the reference signal may be a RE (resource element) index, a resource set index, an RB (resource block) index, a subcarrier index, or a symbol index. The RB index may be a PRB (physical resource block) index or a CRB (common resource block) index.

[0078] In the embodiments below, the reference signal information may include transmission period information of the reference signal, sequence information (e.g., code sequence), masking information (e.g., scrambling information), radio resource information, and / or index information. The reference signal identifier may refer to a parameter (e.g., resource ID, resource set ID) used to distinguish each of the plurality of reference signal information. The reference signal information may refer to configuration information of the reference signal.

[0079] The configured beam information may include one or more of the following: a configured beam index (or identifier), a configured TCI status index (or identifier), configuration information for each beam (e.g., transmit power, beam width, vertical angle, horizontal angle), transmit and / or receive timing information for each beam (e.g., subframe index, slot index, mini-slot index, symbol index, offset), reference signal information corresponding to each beam, and a reference signal identifier. In the embodiments, the base station may be a base station installed in the air. For example, the base station may be installed on an unmanned aerial vehicle (e.g., a drone), a manned aircraft, or a satellite.

[0080] The terminal can receive configuration information of a base station (e.g., identification information of a base station) from a base station through one or more of RRC messages, MAC messages, and PHY messages, and can identify a base station to perform beam monitoring operations, wireless access operations, and / or transmission and reception operations of control (or, data) packets based on the configuration information.

[0081] When multiple beams are configured, communication between the base station and the terminal can be performed using multiple beams. In this case, the number of downlink beams may be the same as the number of uplink beams. Alternatively, the number of downlink beams may be different from the number of uplink beams. For example, the number of downlink beams may be two or more, and the number of uplink beams may be one.

[0082] The base station may obtain the results of a beam measurement operation or a beam monitoring operation from the terminal, and may change the attributes of the beam or the attributes of the TCI state based on the results of the beam measurement operation or the beam monitoring operation. Beams may be classified into primary beams, secondary beams, reserve (or candidate) beams, active beams, and inactive beams according to their attributes. TCI states may be classified into primary TCI state, secondary TCI state, reserve (or candidate) TCI state, serving TCI state, configured TCI state, active TCI state, and inactive TCI state according to their attributes. TCI states may be assumed to be active TCI state and serving TCI state. Reserve (or candidate) TCI state may be assumed to be inactive TCI state or configured TCI state.

[0083] The procedure for changing beam (or TCI state) attributes may be controlled by the RRC layer and / or the MAC layer. If the procedure for changing beam (or TCI state) attributes is controlled by the MAC layer, the MAC layer may notify the upper layer of information regarding the change in beam (or TCI state) attributes. Information regarding the change in beam (or TCI state) attributes may be transmitted to the terminal via MAC messages and / or a physical layer control channel (e.g., PDCCH). Information regarding the change in beam (or TCI state) attributes may be included in downlink control information (DCI) or uplink control information (UCI). Information regarding the change in beam (or TCI state) attributes may be represented by a separate indicator or field.

[0084] The terminal may request a change in the attributes of the TCI state based on the results of a beam measurement operation or a beam monitoring operation. The terminal may transmit control information (or feedback information) requesting a change in the attributes of the TCI state to the base station using one or more of PHY messages, MAC messages, and RRC messages. The control information (or feedback information, control message, control channel) requesting a change in the attributes of the TCI state may be configured using one or more of the aforementioned configuration beam information.

[0085] A change in beam (or TCI state) attributes may mean a "change from an active beam to an inactive beam." The procedure for changing beam (or TCI state) attributes may be controlled by the RRC layer and / or MAC layer. The procedure for changing beam (or TCI state) attributes may be performed through partial cooperation between the RRC layer and the MAC layer.

[0086] When multiple beams are allocated, one or more of the multiple beams may be configured as beam(s) that transmit a physical layer control channel. For example, a primary beam and / or a secondary beam may be used for transmitting and receiving a physical layer control channel (e.g., a PHY message). Here, the physical layer control channel may be a PDCCH or a PUCCH. The physical layer control channel may be used for transmitting one or more of scheduling information (e.g., radio resource allocation information, modulation and coding scheme (MCS) information), feedback information (e.g., channel quality indication (CQI), precoding matrix indicator (PMI), HARQ ACK, HARQ NACK), resource request information (e.g., scheduling request (SR)), results of beam monitoring operations for beamforming function support, TCI status ID, and measurement information for an active beam (or inactive beam).

[0087] Wireless resource information may include parameter(s) indicating frequency domain resources (e.g., center frequency, system bandwidth, PRB index, number of PBRs, CRB index, number of CRBs, subcarrier index, frequency offset) and parameter(s) indicating time domain resources (e.g., radio frame index, subframe index, transmission time interval (TTI), slot index, mini-slot index, symbol index, time offset, period, length, window of the transmission interval (or reception interval)). Additionally, wireless resource information may further include resource information occupied according to the characteristics of the wireless resource hopping pattern, information for beamforming (e.g., beamforming) operation (e.g., beam configuration information, beam index), and code sequence (or bit sequence, signal sequence).

[0088] The names of physical layer channels and / or transport channels may vary depending on the type of data (or attributes), the type of control information (or attributes), the direction of transmission (e.g., uplink, downlink, sidelink), etc.

[0089] The reference signal for beam (or TCI state) or wireless link management may be a synchronization signal (e.g., PSS, SSS, SS / PBCH block), CSI-RS, PT-RS, SRS, DM-RS, etc. The reference parameter(s) for the reception quality of the reference signal for beam (or TCI state) or wireless link management may be a measurement time unit, a measurement time interval, a reference value indicating the degree of improvement in reception quality, a reference value indicating the degree of degradation in reception quality, etc. Each of the measurement time unit and measurement time interval may be set to an absolute time (e.g., millisecond, second), TTI, symbol, slot, frame, subframe, scheduling period, base station operation period, or terminal operation period unit.

[0090] The reference value indicating the degree of change in reception quality can be set as an absolute value (dBm) or a relative value (dB). Additionally, the reception quality of a reference signal for beam (or TCI status) or wireless link management can be expressed as RSRP (reference signal received power), RSRQ (reference signal received quality), RSSI (received signal strength indicator), SNR (signal-to-noise ratio), SIR (signal-to-interference ratio), SINR (signal-to-noise and interference ratio), etc.

[0091] Meanwhile, in NR communication systems using the millimeter frequency band, flexibility in channel bandwidth management for packet transmission can be ensured based on the concept of a bandwidth part (BWP). A base station can configure up to four BWPs with different bandwidths in a terminal. BWPs can be configured independently in the downlink and uplink. That is, the downlink BWP can be distinguished from the uplink BWP. Each BWP can have a different subcarrier spacing as well as a different bandwidth.

[0092] A terminal operating in an RRC connection state can measure the signal quality of the wireless link of a serving cell and a cell to be measured (e.g., adjacent cell, target cell, candidate cell, etc.) based on an SS / PBCH block and / or a reference signal (e.g., CSI-RS). Here, the signal quality may be the aforementioned beam (e.g., TCI state) or RSRP, RSRQ, RSSI, SNR, SIR, SINR, etc., mentioned in the description regarding the reception performance of the reference signal for wireless link management.

[0093] A terminal operating in an RRC inactive state or an RRC idle state can measure the signal quality (e.g., RSRP, RSRQ, RSSI, SINR) of a wireless link of a serving cell (e.g., camping cell) or a cell to be measured according to a DRX period (e.g., measurement period) set based on an SS / PBCH block. The terminal can perform a cell selection operation or a cell re-selection operation based on the measurement results. For measuring a serving cell (e.g., camping cell), the terminal can obtain the transmission period of an SS / PBCH block (e.g., ssb-PeriodicityServingCell) or configuration information of a wireless resource to which the SS / PBCH is transmitted (e.g., ssb-PositionsInBurst) from the system information of the cell.

[0094] In addition, for measuring a target cell (e.g., an adjacent cell), the terminal may obtain SMTC (signal measurement time configuration) window information, etc. from system information. A terminal operating in an RRC inactive state or RRC idle state may perform a cell selection operation or a cell re-selection operation based on the measurement results of SS / PBCH. During the execution of the cell selection operation or cell re-selection operation, the terminal may recognize that the RAN (radio access network) area or TA (tracking area) has changed based on an identifier included in the system information received from the cell. In this case, the terminal may perform an update procedure for the RAN area or TA.

[0095] FIG. 4 is a conceptual diagram illustrating a first embodiment of a non-ground network.

[0096] Referring to FIG. 4, the non-ground network may include a satellite (410), a communication node (420), a gateway (430), a data network (440), etc. The non-ground network illustrated in FIG. 4 may be a non-ground network based on a transparent payload. The satellite (410) may be a low earth orbit (LEO) satellite, a medium earth orbit (MEO) satellite, a geostationary earth orbit (GEO) satellite, a high elliptical orbit (HEO) satellite, or an unmanned aircraft system (UAS) platform. The UAS platform may include a high altitude platform station (HAPS). The satellite (410) may refer to an unmanned aerial vehicle (UAV) or a UAN base station (UBS).

[0097] The communication node (420) may include a communication node located on the ground (e.g., UE (user equipment), terminal) and a communication node located off the ground (e.g., airplane, drone). A service link may be established between the satellite (410) and the communication node (420), and the service link may be a radio link. The satellite (410) may provide communication services to the communication node (420) using one or more beams. The shape of the beam footprint of the satellite (410) may be elliptical. The satellite (410) may provide communication services to a specific area. For example, the satellite (410) may provide communication services to a specific area using a single beam. There may be one area per cell, and multiple beams may be used in one cell.

[0098] A communication node (420) can communicate with a satellite (410) (e.g., downlink communication, uplink communication) using LTE technology and / or NR technology. Communication between the satellite (410) and the communication node (420) can be performed using an NR-Uu interface. If dual connectivity (DC) is supported, the communication node (420) can be connected to the satellite (410) as well as other base stations (e.g., base stations supporting LTE and / or NR functions), and can perform DC operations based on technology defined in LTE and / or NR specifications.

[0099] The gateway (430) may be located on the ground, and a feeder link may be established between the satellite (410) and the gateway (430). The feeder link may be a wireless link. The gateway (430) may be referred to as a "non-terrestrial network (NTN) gateway." Communication between the satellite (410) and the gateway (430) may be performed based on an NR-Uu interface or a satellite radio interface (SRI). The gateway (430) may be connected to a data network (440). A "core network" may exist between the gateway (430) and the data network (440). In this case, the gateway (430) may be connected to the core network, and the core network may be connected to the data network (440). The core network may support NR technology. For example, the core network may include an access and mobility management function (AMF), a user plane function (UPF), a session management function (SMF), etc. Communication between the gateway (430) and the core network can be performed based on the NG-C / U interface.

[0100] Alternatively, a base station and a core network may exist between the gateway (430) and the data network (440). In this case, the gateway (430) may be connected to the base station, the base station may be connected to the core network, and the core network may be connected to the data network (440). The base station and the core network may support NR technology. Communication between the gateway (430) and the base station may be performed based on an NR-Uu interface, and communication between the base station and the core network (e.g., AMF, UPF, SMF) may be performed based on an NG-C / U interface.

[0101] FIG. 5 is a conceptual diagram illustrating a second embodiment of a non-ground network.

[0102] Referring to FIG. 5, the non-ground network may include satellite #1 (511), satellite #2 (512), a communication node (520), a gateway (530), a data network (540), etc. The non-ground network illustrated in FIG. 5 may be a regenerative payload-based non-ground network. For example, each of satellites #1-2 (511, 512) may perform a regenerative operation (e.g., demodulation, decoding, re-coding, re-modulation, and / or filtering) on ​​a payload received from other entities constituting the non-ground network (e.g., communication node (520), gateway (530)), and may transmit the regenerative payload.

[0103] Each of satellites #1-2 (511, 512) may be a LEO satellite, MEO satellite, GEO satellite, HEO satellite, or UAS platform. A UAS platform may include a HAPS. Each of satellites #1-2 (511, 512) may represent a UAV or a UBS. Satellite #1 (511) may be connected to satellite #2 (512), and an inter-satellite link (ISL) may be established between satellite #1 (511) and satellite #2 (512). The ISL may operate in a radio frequency (RF) band or an optical band. The ISL may be configured optionally. Communication nodes (520) may include communication nodes located on the ground (e.g., UE, terminal) and communication nodes located off the ground (e.g., airplane, drone). A service link (e.g., a wireless link) can be established between satellite #1 (511) and a communication node (520). Satellite #1 (511) can provide communication services to the communication node (520) using one or more beams.

[0104] The communication node (520) can communicate with satellite #1 (511) (e.g., downlink communication, uplink communication) using LTE technology and / or NR technology. Communication between satellite #1 (511) and the communication node (520) can be performed using an NR-Uu interface. If DC is supported, the communication node (520) can be connected to satellite #1 (511) as well as other base stations (e.g., base stations supporting LTE and / or NR functions) and can perform DC operations based on technology defined in the LTE and / or NR specifications.

[0105] The gateway (530) may be located on the ground, and a feeder link may be established between satellite #1 (511) and the gateway (530), and a feeder link may be established between satellite #2 (512) and the gateway (530). The feeder link may be a wireless link. If an ISL is not established between satellite #1 (511) and satellite #2 (512), a feeder link between satellite #1 (511) and the gateway (530) may be established mandatorily.

[0106] Communication between each of satellites #1-2 (511, 5122) and the gateway (530) can be performed based on an NR-Uu interface or SRI. The gateway (530) can be connected to a data network (540). A "core network" may exist between the gateway (530) and the data network (540). In this case, the gateway (530) can be connected to the core network, and the core network can be connected to the data network (540). The core network may support NR technology. For example, the core network may include AMF, UPF, SMF, etc. Communication between the gateway (530) and the core network can be performed based on an NG-C / U interface.

[0107] Alternatively, a base station and a core network may exist between the gateway (530) and the data network (540). In this case, the gateway (530) may be connected to the base station, the base station may be connected to the core network, and the core network may be connected to the data network (540). The base station and the core network may support NR technology. Communication between the gateway (530) and the base station may be performed based on an NR-Uu interface, and communication between the base station and the core network (e.g., AMF, UPF, SMF) may be performed based on an NG-C / U interface.

[0108] Meanwhile, in non-terrestrial networks, scenarios can be defined as shown in Table 1 below.

[0109]

[0110] In the non-ground network shown in FIG. 4, if the satellite (410) is a GEO satellite (e.g., a GEO satellite supporting transparent functions), this may be referred to as “Scenario A”. In the non-ground network shown in FIG. 5, if satellites #1-2 (511, 512) are GEO satellites (e.g., GEO satellites supporting regenerative functions), this may be referred to as “Scenario B”.

[0111] In the non-ground network illustrated in FIG. 4, if the satellite (410) is an LEO satellite having steerable beams, this may be referred to as "Scenario C1". In the non-ground network illustrated in FIG. 4, if the satellite (410) is an LEO satellite having beams that move with the satellite, this may be referred to as "Scenario C2". In the non-ground network illustrated in FIG. 5, if satellite #1-2 (511, 512) is an LEO satellite having steerable beams, this may be referred to as "Scenario D1". In the non-ground network illustrated in FIG. 5, if satellite #1-2 (511, 512) is an LEO satellite having beams that move with the satellite, this may be referred to as "Scenario D2".

[0112] The parameters for the scenarios defined in Table 1 can be defined as shown in Table 2 below.

[0113]

[0114] In addition, in the scenarios defined in Table 1, the delay constraint can be defined as shown in Table 3 below.

[0115]

[0116] FIG. 6 is a conceptual diagram illustrating a third embodiment of a non-ground network.

[0117] Referring to FIG. 6, the non-ground network may include a non-ground node (610), terminal #1 (621), terminal #2 (622), and terminal #3 (623). The non-ground node (610) may mean a satellite, HAPS, UAV, or UBS. For example, the non-ground node (610) may be a satellite located between approximately 600 km and 35,000 km from the surface of the earth. Alternatively, the non-ground node (610) may be a HAPS, UAV, or UBS located between approximately 10 km and 600 km from the surface of the earth. The non-ground node (610) may perform the function of a base station or relay in a ground network (e.g., LTE communication network, NR communication network). The maximum length of the service area of ​​the non-ground node (610) on the surface (e.g., the diameter of the service area if the shape of the service area is a circle) may be 500 km. In FIG. 6, X may be the maximum length of the service area of ​​the non-ground node (100).

[0118] If the non-ground node (610) is a high-altitude geostationary satellite (e.g., a GEO satellite), a transmission delay of about 280 ms may occur in the radio interval (L1-L3) between the non-ground node (610) and the terminals (621-623). The transmission delay may be a round trip delay (RTD) or a propagation delay in the radio interval (L1-L3). The difference (hereinafter "Ldelay_diff") between the transmission delay in the radio interval (L2) between the non-ground node (610) and the nearest terminal #2 (622) and the transmission delay in the radio interval (L1 or L3) between the non-ground node (610) and the farthest terminal #1 (621) or terminal #3 (623) may be about 2 ms.

[0119] The transmission delay and Ldelay_diff between the non-ground node (610) and the terminals (621-623) can each be much larger than the transmission delay and Ldelay_diff in the ground network. Therefore, in the non-ground network, control signaling operations, downlink monitoring operations, downlink receiving operations, and uplink transmission operations can each be performed with the transmission delay and / or Ldelay_diff in mind.

[0120] In an OFDMA-based communication network, for a base station to receive uplink signals from multiple terminals without interference, uplink signals transmitted from multiple terminals must be aligned in the time domain. Here, an uplink signal may refer to a signal including an uplink channel and / or a signal. To support this operation, the base station can adjust the uplink transmission timing by transmitting TA (timing advance) information to the terminal(s). In a non-terrestrial network, a control signaling operation to transmit TA information may be performed to adjust the uplink transmission timing between a non-terrestrial node (610) and terminals (621-623). However, the transmission delay of the wireless section (L1-L3) must be taken into account in the control signaling operation.

[0121] To support this operation, the non-ground node (610) can transmit transmission delay information of the wireless section (L1-L3) to the corresponding terminals (621-623). Here, the transmission delay information may be minimum transmission delay information (hereinafter referred to as "Ldelay_min information") in the wireless section (L2) between the non-ground node (610) and the nearest terminal #2 (622). That is, Lelay_min information may be transmitted from the non-ground node (610) to the terminals (621-623). Lelay_min information (e.g., minimum transmission delay value) may be set in units of a symbol, mini slot, slot, subframe, or radio frame. Alternatively, Lelay_min information may be set in absolute time units (e.g., ms, sec).

[0122] Before receiving TA information from the non-ground node (610) (e.g., "when the random access procedure is not completed" or "when uplink synchronization is not obtained"), the terminal (621-623) may obtain uplink synchronization information from system information. Alternatively, the terminal (621-623) may adjust the uplink transmission timing using Ldelay_min estimated by the terminal itself or Ldelay_min calculated. In the embodiments, uplink synchronization may mean uplink physical layer synchronization, and uplink transmission timing may mean uplink physical layer transmission timing. After that, the terminal (621-623) may adjust the uplink transmission timing using the TA information received from the non-ground node (610).

[0123] The TA information transmitted by the non-ground node (610) may be adjustment information for uplink transmission timing considering Ldelay_min. For example, if the uplink transmission timing value that the terminal (621-623) needs to adjust is "10" and Ldelay_min is "8", the non-ground node (610) may transmit TA information to the terminal (621-623) instructing an adjustment of "2".

[0124] The terminals (621-623) can adjust the uplink transmission timing based on Ldelay_min and / or TA information received from the non-ground node (610). The parameters for managing the uplink transmission timing are " timeAlignmentTimer It can be set to ". When a message containing TA information (e.g., a MAC message or a random access (RA) response message) is received from a non-ground node (610), the terminal timeAlignmentTimer You can (re)start it. timeAlignmentTimer If a message containing TA information is not received before the expiration of the period, the terminal (621-623) may determine that uplink synchronization has failed. In this case, the terminal (621-623) may perform a synchronization acquisition procedure (e.g., RA procedure) for uplink transmission.

[0125] Ldelay_min information may be set differently depending on the type, altitude, etc. of the non-ground node (610). The non-ground node (610) may transmit system information or other control messages (e.g., MAC control message or PHY control message) containing Ldelay_min information to the terminal (621-623). That is, Ldelay_min information may be signaled in an explicit manner through the system information. Alternatively, the terminal (621-623) may estimate or calculate Ldelay_min in an implicit manner. For example, the non-ground node (610) may transmit system information containing its type information, altitude information, etc. to the terminal (621-623). The terminal (621-623) may receive system information from the non-ground node (610) and estimate or calculate Ldelay_min based on the information included in the system information (e.g., type information and altitude information of the non-ground node (610)). The type information of the non-ground node (610) may indicate that the non-ground node (610) is a satellite, HAPS, UAV, or UBS.

[0126] Terminals (621-623) can determine that the non-ground node (610) is a GEO satellite, a non-GEO satellite (e.g., LEO satellite, MEO satellite, HEO satellite), HAPS, UAV, or UBS based on the configuration information (e.g., type information, altitude information) of the non-ground node (610). Information used to identify the non-ground node (610) may be transmitted from the non-ground node (610) to the terminals (621-623) via system information and / or control messages. The altitude information of the non-ground node (610) may be "information indicating the actual altitude of the non-ground node (610)" or "information indicating the altitude classification to which the actual altitude of the non-ground node (610) belongs (e.g., low altitude, medium altitude, high altitude)." Altitude information of the non-ground node (610) can be transmitted from the non-ground node (610) to the terminal (621-623) via system information and / or control messages. The terminal (621-623) can estimate or calculate Ldelay_min based on the configuration information (e.g., type information, altitude information) received from the non-ground node (610).

[0127] Alternatively, terminals (621-623) can estimate or calculate Ldelay_min using the identifier of the non-ground node (610) (e.g., an identifier for cell differentiation (e.g., PCI (physical cell identifier)), an identifier for beam differentiation). The PCI may be set differently depending on the type and / or altitude of the non-ground node (610). Thus, terminals (621-623) can identify the type and / or altitude of the non-ground node (610) based on the PCI received from the non-ground node (610), and can estimate or calculate Ldelay_min based on the identified information. That is, terminals (621-623) can estimate or calculate Ldelay_min using the configuration information and / or identifier of the non-ground node (610). The non-ground node (610) can provide communication services to terminals (621-623) using multiple beams or multiple frequency resources. In this case, the Ldelay_min of non-ground nodes located at the same altitude or non-ground nodes of the same type can have the same value.

[0128] Meanwhile, the terminal (621-623) may perform a random access procedure to connect to a non-ground node (610) (e.g., a base station). In the four-step random access procedure, the terminal (621-623) may transmit an RA preamble (e.g., PRACH (physical random access channel), msg1) to the non-ground node (610) and receive a RAR (random access response) message (e.g., msg2) which is a response to the RA preamble from the non-ground node (610). After that, the transmission and reception of msg3 and msg4 may be performed between the terminal (621-623) and the non-ground node (610). In the two-stage random access procedure, the terminal (621-623) can transmit msgA to the non-ground node (610) and receive msgB, which is a response to msgA, from the non-ground node (610). System information including resource configuration information and common parameters for the above-described random access procedure can be transmitted from the non-ground node (610) to the terminal (621-623).

[0129] FIG. 7 is a timing diagram illustrating a first embodiment of a random access procedure in a non-terrestrial network.

[0130] Referring to FIG. 7, a non-ground network may include a non-ground node and a terminal. In FIG. 7, the non-ground node may be the non-ground node (610) shown in FIG. 6, and in FIG. 7, the terminal may be one of the terminals (621-623) shown in FIG. 6. The non-ground node may transmit system information including configuration information for a random access procedure (e.g., resource configuration information, common parameters). The terminal may obtain configuration information for a random access procedure from the non-ground node and transmit msg1 or msgA to the non-ground node based on the obtained configuration information (S701).

[0131] A non-ground node may receive msg1 or msgA from a terminal. If msg1 is received from the terminal, the non-ground node may send msg2 (e.g., a RAR message) to the terminal in response to msg1 (S702). Alternatively, if msgA is received from the terminal, the non-ground node may send msgB to the terminal in response to msgA (S702). The terminal may perform a downlink monitoring operation in the RA response window to receive msg2 or msgB. That is, the terminal may receive msg2 or msgB from the non-ground node within the RA response window.

[0132] To prevent the terminal from performing unnecessary downlink monitoring operations for the reception of msg2 or msgB, the start time of the RA response window may be set to time B instead of time A. In this case, the RA response window may start at time B, which is a RAR offset after the transmission time of msg1 or msgA. That is, the timer related to the RA response window may start at time B. The RAR offset may be set in units of symbols, mini-slots, slots, subframes, or radio frames. Alternatively, the RAR offset may be set in absolute time units (e.g., ms, sec).

[0133] A terminal that has transmitted msg1 or msgA at time A can receive msg2 or msgB transmitted from a non-terrestrial node by performing a downlink monitoring operation in the RA response window that starts at time B, which is after the RAR offset from time A. The terminal may not perform a downlink monitoring operation for receiving msg2 or msgB during the time interval (e.g., the RAR offset) from time A to time B. The size of the RAR offset may be at least twice Ldelay_min. Alternatively, the size of the RAR offset may be set to a specific value considering Ldelay_min, and the non-terrestrial node may transmit RAR offset setting information to the terminal using system information or other control messages.

[0134] The size of the RA response window can be set by taking into account the difference (Ldelay_diff) between the transmission delay (e.g., minimum transmission delay) in the wireless interval (L2) between the non-ground node (610) shown in FIG. 6 and the nearest terminal #2 (622), and the transmission delay (e.g., maximum transmission delay) in the wireless interval (L1 or L3) between the non-ground node (610) and the farthest terminal #1 (621) or terminal #3 (623). For example, the size of the RA response window can be set to a value equal to Ldelay_diff, a multiple of Ldelay_diff, or a value greater than Ldelay_diff.

[0135] The RAR offset and Ldelay_diff, respectively, may be set differently depending on the type and / or elevation of the non-ground node. The non-ground node may transmit system information including the RAR offset and / or Ldelay_diff to the terminal. The terminal may determine the RAR offset and / or Ldelay_diff by receiving system information from the non-ground node. That is, the RAR offset and / or Ldelay_diff may be specified by an explicit method. Alternatively, the terminal may estimate or calculate the RAR offset and Ldelay_diff, respectively, based on an implicit method. For example, the terminal may estimate or calculate the RAR offset and Ldelay_diff, respectively, based on the type and / or elevation of the non-ground node.

[0136] For example, the terminal may determine that a non-ground node is a GEO satellite, a non-GEO satellite (e.g., LEO satellite, MEO satellite, HEO satellite), HAPS, UAV, or UBS based on the configuration information of the non-ground node (e.g., type information, altitude information). The information used to identify the non-ground node may be transmitted from the non-ground node to the terminal via system information and / or control messages. The altitude information of the non-ground node may be "information indicating the actual altitude of the non-ground node" or "information indicating the altitude classification to which the actual altitude of the non-ground node belongs (e.g., low altitude, medium altitude, high altitude)." The altitude information of the non-ground node may be transmitted from the non-ground node to the terminal via system information and / or control messages. The terminal may estimate or calculate the RAR offset and Ldelay_diff, respectively, based on the configuration information (e.g., type information, altitude information) received from the non-ground node.

[0137] Alternatively, the terminal can estimate or calculate the RAR offset and Ldelay_diff, respectively, using the identifier of the non-ground node (e.g., an identifier for cell separation (e.g., PCI), an identifier for beam separation). The PCI may be set differently depending on the type and / or elevation of the non-ground node. Therefore, the terminal can determine the type and / or elevation of the non-ground node based on the PCI received from the non-ground node, and can estimate or calculate the RAR offset and Ldelay_diff, respectively, based on the determined information. That is, the terminal can estimate or calculate the RAR offset and Ldelay_diff, respectively, using the configuration information and / or identifier of the non-ground node.

[0138] Meanwhile, if msg2 is successfully received from a non-ground node within the RA response window, the terminal can transmit msg3 to the non-ground node using the uplink resources allocated by the non-ground node (S703). The non-ground node can receive msg3 from the terminal and transmit msg4 to the terminal (S704). The terminal can receive msg4 from the non-ground node and determine that the contention is resolved if the identifier included in msg4 is the same as its own identifier. In this case, the random access procedure can be terminated.

[0139] A timer used to determine contention resolution ra-ContentionResolutionTimer " can be set. ra- ContentionResolutionTimer It can start at the time when the terminal transmits msg3 (e.g., time C). ra-ContentionResolutionTimer If msg4 is received from a non-terrestrial node before the expiration of, the terminal may determine that the contention has been resolved. In this case, the random access procedure may be terminated. ra-ContentionResolutionTimer If msg4 is not received from a non-ground node before the expiration of" or "ra- ContentionResolutionTimer If the terminal's identifier is not included in the msg4 received from the non-ground node before the expiration of the, the terminal may determine that the random access procedure has failed. In this case, the terminal may perform the random access procedure again.

[0140] ra- ContentionResolutionTimer It can be configured to start at time D instead of time C. For example, the terminal at time D, which is a contention offset after the transmission time of msg3. ra- ContentionResolutionTimer ...can start. Therefore, the terminal may not perform downlink monitoring operations for receiving msg4 during the time interval from time C to time D (e.g., contention offset), and from time D ra-ContentionResolutionTimer Downlink monitoring operations can be performed until the expiration of. ra- ContentionResolutionTimer can be set to a value equal to Ldelay_diff, a multiple of Ldelay_diff, or a value greater than Ldelay_diff.

[0141] The contention offset can be set and / or signaled in the same manner as the RAR offset described above. The size of the contention offset may be at least twice Ldelay_min. Alternatively, the size of the contention offset may be set to a specific value in consideration of Ldelay_min. The size of the contention offset may be set to be equal to the size of the RAR offset. The contention offset and the RAR offset may be set by a single parameter. In this case, the contention offset and the RAR offset may not be set independently. That is, only one of the contention offset and the RAR offset may be set, and the single set offset may be applied to both the contention offset and the RAR offset.

[0142] To estimate or calculate the transmission delay in the wireless segment between a non-ground node and a terminal, which serves as a reference for setting the aforementioned Ldelay_min, RAR offset, and / or contention offset, the non-ground node may provide the terminal with absolute time information (e.g., time according to GPS (global positioning system) time, time according to UTC (coordinated universal time), etc.). For example, the non-ground node may transmit absolute time information regarding the creation time of a transport block for downlink transmission, a code block for encoding, and / or a MAC message to the terminal using downlink resources. The absolute time information may be transmitted from the non-ground node to the terminal via one or more combinations of system information, RRC messages, MAC messages, and PHY messages. When the absolute time information is transmitted via a MAC message, the MAC message containing the absolute time information may be generated in the form of an RA response message. In this case, the non-ground node may transmit an RA response message containing the absolute time information at the necessary time.

[0143] The terminal may receive absolute time information from a non-ground node and, based on the absolute time information, estimate or calculate the transmission delay in the wireless interval between the non-ground node and the terminal (e.g., transmission delay in the wireless interval including processing time at the non-ground node). In this case, the terminal may set Ldelay_min, RAR offset, and / or contention offset based on the transmission delay in the wireless interval obtained using the absolute time information. The terminal may report information regarding the transmission delay in the wireless interval obtained using the absolute time information to the non-ground node. Information regarding the transmission delay in the wireless interval obtained using the absolute time information may be transmitted from the terminal to the non-ground node via one or more combinations of RRC messages, MAC messages, and PHY messages. In particular, the terminal may transmit information regarding the transmission delay to the non-ground node using specific messages (e.g., msg1, msg3, msgA) in a random access procedure.

[0144] To estimate or calculate transmission delay in the wireless interval between a non-ground node and a terminal (e.g., transmission delay in the wireless interval including processing time at the non-ground node), the non-ground node may instruct or request the terminal to report (e.g., transmit) transmission time information. Transmission time information may refer to absolute time information regarding the transmission time (e.g., GPS time, time according to UTC) or relative time information regarding the transmission time (e.g., index of a wireless frame). At the transmission time, the index of the wireless frame may consist of a system frame number (SFN), a subframe index, a slot index, a mini-slot index, and / or a symbol index.

[0145] When a report of transmission time information (e.g., transmission) is requested or directed by a non-terrestrial node, the terminal may transmit to the non-terrestrial node, using uplink resources, a transmission block for uplink transmission, a code block for encoding, and / or time information regarding the creation time of a control message (e.g., absolute time information). Here, the time information may be transmitted from the terminal to the non-terrestrial node through a combination of one or more of system information, RRC messages, MAC messages, and PHY messages.

[0146] A non-ground node can obtain time information (e.g., absolute time information) from a terminal and use the time information to estimate or calculate a transmission delay in the wireless interval between the terminal and the non-ground node (e.g., transmission delay in the wireless interval including processing delay at the terminal). Based on the time information obtained from the terminal, the non-ground node can set or adjust Ldelay_min, RAR offset, and / or contention offset using the estimated transmission delay or the calculated transmission delay.

[0147] Absolute time information transmitted by a non-terrestrial node or terminal may consist of information representing the entire absolute time or partial information representing a part of the absolute time (e.g., time information in units of seconds or less). Partial information may refer to time information expressed as absolute time in seconds, milliseconds, or microseconds.

[0148] Meanwhile, to provide communication services, a terminal operating in an RRC connection state may transmit scheduling request (SR) information requesting uplink resource allocation to a non-terrestrial node. One or more SR information may be configured depending on the configuration of the logical channel. One or more SR information includes a scheduling request identifier (hereinafter, " schedulingRequestId It can be distinguished using ""). The terminal that transmitted the SR information is a preset timer (hereinafter, " sr- ProhibitTimer Before the expiration of (referred to as "") the same schedulingRequestId It may not be able to transmit SR information containing. That is, the terminal sr-ProhibitTimer The same after it expires schedulingRequestId SR information containing can be transmitted.

[0149] Meanwhile, the terminal may perform the random access procedure illustrated in FIG. 7 for beam recovery. However, "a preset timer (hereinafter, " beamFailureRecoveryTimer "If set" or " beamFailureRecoveryTimer When [it] is in operation, the terminal may perform a contention-based random access procedure. In a contention-based random access procedure, uplink resources for the transmission of msg1 or msgA may be allocated exclusively to the terminal.

[0150] In the non-terrestrial network illustrated in FIG. 6, "when the terminal transmits SR information" or "when the terminal performs a random access procedure for beam recovery", sr- ProhibitTimer or beamFailureRecoveryTimer It can operate by taking Ldelay_min into account.

[0151] FIG. 8 is a timing diagram illustrating a first embodiment of a transmission procedure of SR information considering Ldelay_min in a non-terrestrial network.

[0152] Referring to FIG. 8, a non-terrestrial network may include a non-terrestrial node and a terminal. In FIG. 8, the non-terrestrial node may be the non-terrestrial node (610) shown in FIG. 6, and the terminal in FIG. 8 may be one of the terminals (621-623) shown in FIG. 6. In the procedure for transmitting SR information, the terminal may transmit SR information to the non-terrestrial node at time A (S801). The non-terrestrial node may receive SR information from the terminal and may generate uplink resource allocation information based on the SR information. The non-terrestrial node may transmit uplink resource allocation information to the terminal (S802). The terminal may receive uplink resource allocation information from the non-terrestrial node and may transmit an uplink signal / channel to the non-terrestrial node using the uplink resource indicated by the uplink resource allocation information.

[0153] However, "if a non-terrestrial node has not received SR information" or "if a terminal has not received uplink resource allocation information," the terminal sr- ProhibitTimer The same after point C when it expired schedulingRequestId SR information having can be transmitted (S803). Step S803 may be performed when uplink resource allocation information is not received from a non-ground node. In this case, considering the transmission delay between the non-ground node and the terminal, the terminal at time B, which is Ldelay_min after time A (e.g., the time of transmission of SR information). sr-ProhibitTimer You can (re)start it.

[0154] In the time interval from point A to point B sr- ProhibitTimer Even if it is not operating, a control signal indicating that SR information has been transmitted (or triggered) may be set. If the control signal is set, the terminal that transmitted the SR information at time A is "the same schedulingRequestId Transmission operation of SR information having" or "identical schedulingRequestId The "triggering operation for the transmission of SR information having" may not be performed. That is, the terminal (re)started at time B, which is the end time of Ldelay_min sr- ProhibitTimer After it expires, "the same schedulingRequestId Transmission operation of SR information having" or "identical schedulingRequestId It can perform a "triggering operation for transmitting SR information having".

[0155] Meanwhile, in the BSR (buffer status report) procedure, the terminal can transmit BSR information to a non-ground node. In the transmission procedure of the SR information described above sr- ProhibitTimer The operation and management method is a timer for the BSR procedure retxBSR -Timer It can be applied for the operation and management of.

[0156] The terminal can transmit BSR information to a non-ground node at time A (S801). The non-ground node can receive BSR information from the terminal and generate uplink resource allocation information based on the BSR information. The non-ground node can transmit the uplink resource allocation information to the terminal (S802). The terminal can receive the uplink resource allocation information from the non-ground node. The terminal that transmitted the BSR information at time A retxBSR -Timer The same BSR information can be (re)transmitted after time C, when it has expired (S803). Step S803 may be performed when uplink resource allocation information is not received from a non-ground node. In this case, considering the transmission delay between the non-ground node and the terminal, the terminal [can be] at time B, which is Ldelay_min after time A. retxBSR-Timer You can (re)start it.

[0157] In the time interval from point A to point B retxBSR -TimesEven if it is not operating, a control signal indicating that BSR information has been transmitted (or triggered) may be set. If the control signal is set, the terminal that transmitted BSR information at time A may not perform the "transmission operation of BSR information" or the "triggering operation for the transmission of BSR information." That is, the terminal that (re)started at time B, which is the end time of Ldelay_min retxBSR -Times After it expires, the "transmission of BSR information" or the "triggering operation for the transmission of BSR information" can be performed.

[0158] FIG. 9 is a timing diagram illustrating a first embodiment of a beam recovery procedure considering Ldelay_min in a non-ground network.

[0159] Referring to FIG. 9, the non-terrestrial network may include non-terrestrial nodes and terminals. In FIG. 9, the non-terrestrial node may be the non-terrestrial node (610) shown in FIG. 6, and in FIG. 9, the terminal may be one of the terminals (621-623) shown in FIG. 6. If a contention-based random access procedure for beam failure recovery (BFR) is established, the terminal may trigger the BFR procedure at time A and start the contention-based random access procedure (S901). In step S901, the terminal may transmit msg1 or msgA using uplink resources exclusively allocated for itself. If msg1 is received from the terminal, the non-terrestrial node may transmit msg2 (e.g., a RAR message) to the terminal in response to msg1 (S902). When msgA is received from the terminal, the non-ground node may send msgB to the terminal in response to msgA (S902).

[0160] The terminal may receive msg2 or msgB from a non-ground node. If the transmission and reception operations of msg3 and msg4 between the non-ground node and the terminal are completed in a contention-free four-stage random access procedure, the terminal may determine that BFR has been successfully performed. If msgB is successfully received from the non-ground node in a contention-free two-stage random access procedure, the terminal may determine that BFR has been successfully performed. If "the non-ground node has not received msg1 or msgA" or "the terminal has not received msg2 or msgB", the terminal beamFailureRecoveryTimer A contention-based random access procedure for BFR can be performed after time D, which is the expiration time of (S903). In this case, considering the transmission delay between the non-terrestrial node and the terminal, the terminal performs a contention-based random access procedure at time B, which is Ldelay_min after time A. beamFailureRecoveryTimer You can (re)start it.

[0161] In the time interval from point A to point B beamFailureRecoveryTimer Even if it is not operating, a control signal indicating that a contention-based random access procedure is being performed may be set. If the control signal is set, a terminal that triggered a contention-based random access procedure for BFR at time A may not trigger a new contention-based random access procedure for BFR. However, at time B, which is the end time of the RAR offset (or Ldelay_min), the (re)started beamFailureRecoveryTimer The RA response window may be terminated before the expiration time (e.g., time D). In this case, the terminal may transmit msgA by triggering a contention-based random access procedure for BFR during the time interval from time C, which is the end time of the RA response window, to time D.

[0162] Additionally, in a contention-based RA transmission procedure for SR transmission, BSR transmission, and Beam Failure Recovery (BFR), a separate offset parameter, such as the offset of FIG. 7 (e.g., RAR offset or contention offset), may be set for path delay compensation by the Ldelay_min described above. The offset value for the contention-based RA transmission procedure for SR transmission, BSR transmission, and Beam Failure Recovery (BFR) may be set to Ldelay_min, a multiple of Ldelay_min, or a value obtained by adding a constant to Ldelay_min. However, in this case, the unit of the offset parameter may be set to a unit such as a symbol, mini-slot, slot, subframe, or radio frame. Alternatively, the unit of the offset parameter may be set to an absolute time unit such as a microsecond, millisecond, or second (or second).

[0163] Meanwhile, the aforementioned non-ground node (e.g., non-ground cell) may be a base station. The non-ground node may be referred to as Node B, evolved Node B, base transceiver station (BTS), radio base station, radio transceiver, access point, access node, road side unit (RSU), radio remote head (RRH), transmission point (TP), transmission & reception point (TRP), or gNB.

[0164] In the present invention, the terminal may be referred to as a UE, terminal, access terminal, mobile terminal, station, subscriber station, mobile station, portable subscriber station, node, device, IoT (Internet of Thing) device, or mounted module / device / terminal or on board device / terminal.

[0165] The methods according to the present invention may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, etc., either alone or in combination. The program instructions recorded on the computer-readable medium may be those specifically designed and configured for the present invention, or they may be those known and available to those skilled in the art of computer software.

[0166] Examples of computer-readable media include hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, and flash memory. Examples of program instructions include machine code, such as that produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter, etc. The aforementioned hardware devices may be configured to operate as at least one software module to perform the operation of the present invention, and vice versa.

[0167] Although the invention has been described with reference to the above embodiments, those skilled in the art will understand that various modifications and changes can be made to the invention without departing from the spirit and scope of the invention as described in the following claims.

Claims

Claim 1 A method of operation of a terminal in a non-terrestrial network, comprising: transmitting a first message including a random access (RA) preamble to a non-terrestrial node in a random access procedure; performing a first downlink monitoring operation in an RA response window that starts after a first offset from the time of transmission of the first message; and receiving a second message that is a response to the first message from the non-terrestrial node by means of the first downlink monitoring operation, wherein the first offset is set considering the minimum transmission delay between the non-terrestrial node and terminals located in a cell formed by the non-terrestrial node. Claim 2 The method of operation of the terminal according to claim 1 further comprises: a step of transmitting a third message to the non-ground node using an uplink resource allocated by the non-ground node after the step of receiving the second message; a step of starting a first timer; a step of performing a second downlink monitoring operation for a fourth message transmitted from the non-ground node in response to the third message before the first timer expires; and a step of determining whether the random access procedure is successful based on the result of the second downlink monitoring operation for the fourth message. Claim 3 A method of operation of a terminal according to claim 2, wherein the step of starting the first timer includes the step of starting the first timer after a second offset from the time of transmission of the third message, and the second offset is set considering the minimum transmission delay. Claim 4 A method of operation of a terminal according to claim 1, wherein the first offset is set to have a size greater than or equal to twice the minimum transmission delay. Claim 5 A method of operation of a terminal according to claim 1, wherein the RA response window is set by considering the difference between the minimum transmission delay and the maximum transmission delay between the non-ground node and the terminals. Claim 6 A method of operation of a terminal in a non-terrestrial network, comprising: transmitting a first message to a non-terrestrial node containing first information for a first procedure for performing communication between a non-terrestrial node and said terminal; starting a first timer after a first offset from the time of transmission of said first message; and checking whether a second message transmitted from the non-terrestrial node in response to said first message is received during the operation of said first timer, wherein the first offset is set considering the minimum transmission delay between said non-terrestrial node and terminals located in a cell formed by said non-terrestrial node, and determining whether to transmit a third message corresponding to said first message based on whether the second message is received during the operation of said first timer. Claim 7 In claim 6, the first procedure is a scheduling request (SR) procedure, and the method of operation of the terminal further comprises the step of transmitting the third message containing second information to the non-ground node after the first timer has expired, if the second message is not received during the operation of the first timer, and the first information and the second information include the same scheduling request identifier. Claim 8 In claim 6, the first procedure is a buffer status report (BSR) procedure, and the method of operation of the terminal further includes the step of transmitting the third message containing second information to the non-ground node after the first timer has expired, when the second message is not received during the operation of the first timer, and the first information and the second information are the same BSR information. Claim 9 A method of operation of a terminal according to claim 6, wherein the first procedure is a contention-based random access procedure for beam failure recovery (BFR), and the method of operation of the terminal further comprises the step of transmitting the third message to the non-ground node to re-trigger the first procedure after the first timer has expired, if the second message is not received during the operation of the first timer. Claim 10 In claim 6, the first procedure is a contention-based random access procedure for BFR, the first message is a message that includes a random access (RA) preamble and triggers the first procedure, and the method of operation of the terminal further includes the step of transmitting the third message that triggers a contention-based random access procedure to the non-ground node after the second timer, which started simultaneously with the first timer, has expired, when the second message is not received during the operation of the first timer, and the size of the second timer is set considering the minimum transmission delay.

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