KR20210001916A - Method and apparatus for controlling transmission and reception operations in non-terrestrial network - Google Patents

Abstract

Disclosed are a method for controlling a transceiving operation on a non-terrestrial network and an apparatus thereof. The method includes the following steps of: transmitting a first message including an RA preamble to a non-terrestrial node during a random access procedure; performing a downlink monitoring operation in an RA response window starting after a first offset from the moment of transmitting the first message; and receiving a second message which is in response to the first message from the non-terrestrial node by the downlink monitoring operation. The first offset is set considering the smallest transmission delay between the non-terrestrial node and terminals located on a cell formed by the non-terrestrial node, and the RA response window is set considering the difference between the smallest transmission delay and the largest transmission delay between the non-terrestrial node and the terminals. Therefore, the performance of a non-terrestrial network can be improved.

Description

Method and apparatus for control of transmission/reception operation in non-terrestrial network {METHOD AND APPARATUS FOR CONTROLLING TRANSMISSION AND RECEPTION OPERATIONS IN NON-TERRESTRIAL NETWORK}

The present invention relates to a communication technology in a non-terrestrial network, and more particularly, to a technology for controlling the transmission and reception operation of a terminal.

In order to process rapidly increasing radio data, a frequency band higher than the frequency band of LTE (long term evolution) (or LTE-A) (eg, a frequency band of 6 GHz or less) (eg, a frequency band of 6 GHz or higher) A communication network using (for example, a new radio (NR) communication network) is being considered. The NR communication network can support not only a frequency band of 6 GHz or lower but also a frequency band of 6 GHz or higher, and can support various communication services and scenarios compared to an LTE communication network. For example, the usage scenario of the NR communication network may include enhanced Mobile BroadBand (eMBB), Ultra Reliable Low Latency Communication (URLLC), and Massive Machine Type Communication (mMTC).

The NR communication network may provide communication services to terminals located on the terrestrial. Recently, the demand for communication services for non-terrestrial planes, drones, unmanned aerial vehicles (UAVs), UBS (UAN base stations), satellites, etc. is increasing. For this purpose, technologies for a non-terrestrial network (NTN) 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 (e.g., user equipment (UE)) located on the ground or a communication node (e.g., airplane, UAV, drone) located on the ground is NR It can be done based on technology. In a non-terrestrial network, a satellite may perform the function of a base station in an NR communication network. Here, the non-terrestrial network may mean a long-distance communication network in terms of a communication range.

Meanwhile, in a non-terrestrial network, the terminal may perform communication using a 6GHz~90GHz band. That is, high-speed data transmission can be performed using a wide bandwidth in a non-terrestrial network. In a non-terrestrial network, since a round trip delay (RTD) between a satellite and a terminal is long, a transmission/reception method and a control method according to a radio protocol taking this into account are required.

An object of the present invention for solving the above problems is to provide a transmission/reception method and a control method in consideration of transmission delay in a non-terrestrial network.

In order to achieve the above object, a method of operating a terminal according to a first embodiment of the present invention includes transmitting a first message including an RA preamble to a non-ground node in a random access procedure, and a transmission time point of the first message. Performing a downlink monitoring operation in an RA response window starting after a first offset from, and receiving a second message that is a response to the first message from the non-ground node by the downlink monitoring operation. Including, wherein the first offset is set in consideration of a minimum transmission delay between the non-ground node and terminals located in a cell formed by the non-ground node, and the RA response window is the minimum transmission delay and the It is set in consideration of the difference in the maximum transmission delay between the non-ground node and the terminals.

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

1 is a conceptual diagram showing a first embodiment of a communication network.
2 is a block diagram showing the first embodiment of a communication node constituting a communication network.
3 is a conceptual diagram illustrating a first embodiment of an operating state of a terminal in a communication network.
4 is a conceptual diagram showing a first embodiment of a non-terrestrial network.
5 is a conceptual diagram showing a second embodiment of a non-terrestrial network.
6 is a conceptual diagram showing a third embodiment of a non-terrestrial network.
7 is a timing diagram illustrating a first embodiment of a random access procedure in a non-terrestrial network.
8 is a timing diagram illustrating a first embodiment of a transmission procedure of SR information considering Ldelay_min in a non-terrestrial network.
9 is a timing diagram illustrating a first embodiment of a beam recovery procedure considering Ldelay_min in a non-terrestrial network.

In the present invention, various modifications may be made and various embodiments may be provided, and specific embodiments will be illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to a specific embodiment, it is to be understood to include all changes, equivalents, or substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. These terms are used only for the purpose of distinguishing one component from another component. For example, without departing from the scope of the present invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. The term and/or includes a combination of a plurality of related listed items or any of a plurality of related listed items.

When a component is referred to as being "connected" or "connected" to another component, it is understood that it may be directly connected or connected to the other component, but other components may exist in the middle. Should be. On the other hand, when a component is referred to as being "directly connected" or "directly connected" to another component, it should be understood that there is no other component in the middle.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof, does not preclude in advance.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms as defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and should not be interpreted as an ideal or excessively formal meaning unless explicitly defined in the present application. Does not.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings. In describing the present invention, in order to facilitate an overall understanding, the same reference numerals are used for the same elements in the drawings, and duplicate descriptions for the same elements are omitted.

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

The non-terrestrial network may operate based on LTE technology and/or NR technology. The non-terrestrial network can support communication in a frequency band of 6 GHz or higher as well as a frequency band of 6 GHz or less. The 4G communication network can support communication in a frequency band of 6 GHz or less. The 5G communication network can support communication in not only a frequency band below 6GHz but also a frequency band above 6GHz. The communication network to which the embodiments according to the present invention are applied is not limited to the contents described below, and the embodiments according to the present invention can be applied to various communication networks. Here, the communication network may have the same meaning as the communication system.

1 is a conceptual diagram showing a first embodiment of a communication network.

Referring to FIG. 1, the communication network 100 includes 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). A plurality of communication nodes are 4G communication (e.g., long term evolution (LTE), LTE-A (advanced)), 5G communication (e.g., new radio) specified in the 3rd generation partnership project (3GPP) standard. ), etc. 4G communication may be performed in a frequency band of 6 GHz or less, and 5G communication may be performed in a frequency band of 6 GHz or more as well as a frequency band of 6 GHz or less.

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

In addition, the communication network 100 may further include a core network. When the communication network 100 supports 4G communication, the core network may include a serving-gateway (S-GW), a packet data network (PDN)-gateway (P-GW), a mobility management entity (MME), and the like. have. When the communication network 100 supports 5G communication, the core network may include a user plane function (UPF), a session management function (SMF), an access and mobility management function (AMF), and the like.

Meanwhile, a plurality of communication nodes 110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130- constituting the communication network 100 4, 130-5, 130-6) Each may have the following structure.

2 is a block diagram showing the first embodiment of a communication node constituting a communication network.

Referring to FIG. 2, the communication node 200 may include at least one processor 210, a memory 220, and a transmission/reception device 230 connected to a network to perform communication. In addition, the communication node 200 may further include an input interface device 240, an output interface device 250, and a storage device 260. Each of the components included in the communication node 200 may be connected by a bus 270 to perform communication with each other.

However, each of the components included in the communication node 200 may be connected through an individual interface or an individual bus centering on the processor 210 instead of the common bus 270. For example, the processor 210 may be connected to at least one of the memory 220, the transmission/reception device 230, the input interface device 240, the output interface device 250, and the storage device 260 through a dedicated interface. .

The processor 210 may 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 configured with at least one of a volatile storage medium and a nonvolatile storage medium. For example, the memory 220 may be formed of at least one of a read only memory (ROM) and a random access memory (RAM).

Referring back to FIG. 1, the communication network 100 includes 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). 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) The containing communication network 100 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 may form a macro cell. Each of the fourth base station 120-1 and the fifth base station 120-2 may form a small cell. The fourth base station 120-1, the third terminal 130-3, and the fourth terminal 130-4 may belong to 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 belong to 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 belong within the cell coverage of the third base station 110-3. have. The first terminal 130-1 may belong to the cell coverage of the fourth base station 120-1. The sixth terminal 130-6 may belong to the cell coverage of the fifth base station 120-2.

Here, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 is a NodeB, an evolved NodeB, a base transceiver station (BTS), Radio base station, radio transceiver, access point, access node, RSU (road side unit), RRH (radio remote head), TP (transmission point), TRP ( transmission and reception point), eNB, gNB, and the like.

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

Meanwhile, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may operate in different frequency bands or may operate in the same frequency band. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to each other through an ideal backhaul link or a non-ideal backhaul link, , Information can be exchanged with each other through an ideal backhaul link or a non-ideal backhaul link. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to the core network through an ideal backhaul link or a non-ideal backhaul link. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 transmits a signal received from the core network to the corresponding terminal 130-1, 130-2, 130-3, 130 -4, 130-5, 130-6), and the signal received from the corresponding terminal (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) Can be transferred to.

In addition, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 transmits MIMO (e.g., single user (SU)-MIMO, multi-user (MU)- MIMO, massive MIMO, etc.), coordinated multipoint (CoMP) transmission, carrier aggregation (CA) transmission, transmission in an unlicensed band, direct communication between terminals (device to device communication, D2D) (or, ProSe ( proximity services)). Here, each of the plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 is a base station 110-1, 110-2, 110-3, 120-1 , 120-2) and operations supported by the base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be performed. For example, the second base station 110-2 may transmit a signal to the fourth terminal 130-4 based on the SU-MIMO scheme, and the fourth terminal 130-4 may transmit a signal to the fourth terminal 130-4 by the SU-MIMO scheme. A signal may be received from the second base station 110-2. Alternatively, the second base station 110-2 may transmit a signal to the fourth terminal 130-4 and the fifth terminal 130-5 based on the MU-MIMO method, and the fourth terminal 130-4 And each of the fifth terminal 130-5 may receive a signal from the second base station 110-2 by the MU-MIMO method.

Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 may transmit a signal to the fourth terminal 130-4 based on the CoMP scheme, and The terminal 130-4 may receive signals 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 plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 has terminals 130-1, 130-2, 130-3, and 130-4 belonging to their cell coverage. , 130-5, 130-6) and the CA method can transmit and receive signals. 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 may perform D2D under the control of the second base station 110-2 and the third base station 110-3, respectively. .

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

In the embodiments below, UPF (or S-GW) may refer to a terminal communication node of the core network that exchanges packets (eg, control information, data) with a base station, and AMF (or MME) is It may refer to a communication node of a core network that performs a control function in the wireless access section (or interface) of the terminal. Here, each of the S-GW, MME, AMF, and UPF may be referred to as different terms according to a function of a communication protocol (eg, a function of a core network) according to a radio access technology (RAT).

In a communication network supporting a dual connectivity function, a connection may be established between a terminal and a plurality of base stations. A plurality of base stations may provide services to the terminal. A plurality of base stations (eg, a plurality of base stations connected to a terminal) supporting the dual connectivity function may be classified into a master base station and a secondary base station. In the following embodiments, dual connectivity is a single-radio dual connectivity (SR-DC) by a plurality of base stations supporting the same RAT or a multi-radio (MR) by a plurality of base stations supporting different RATs. Can mean DC.

The master base station may be referred to as a “master node”. The master node may be a node that proactively performs an RRC function to support a dual connection function. The master node can provide a function of connecting the control plane with the core network. The master node may be composed of a plurality of cells. A plurality of cells included in the master node may be referred to as a master cell group (MCG). The MCG bearer may mean a bearer according to a logical channel configuration between the RLC layer and the MAC layer of a cell belonging to the MCG.

The secondary base station may be referred to as a “secondary node”. The secondary node may not provide a function of connecting the control plane to the core network. The secondary node may provide a service to the terminal by using additional radio resources. The secondary node may be composed of a plurality of cells. A plurality of cells included in the secondary node may be referred to as a secondary cell group (SCG). The split bearer may use a logical channel configuration between an RLC layer and a MAC layer of a cell belonging to an MCG and a logical channel configuration between an RLC layer and a MAC layer of a cell belonging to the SCG. The split bearer may be classified into a secondary node (SN) terminated bearer and a master node (MN) terminated bearer according to the type of a node performing the PDCP function. When the PDCP function for the split bearer is performed in the master node, the corresponding split bearer may be an MN end bearer. When the PDCP function for the split bearer is performed in the secondary node, the corresponding split bearer may be an SN termination bearer.

3 is a conceptual diagram illustrating a first embodiment of an operating state of a terminal in a communication network.

Referring to FIG. 3, the operating state of the terminal may be classified into an RRC connected state, an RRC inactive state, and an RRC idle state. When the terminal operates in the RRC connected state or in the RRC inactive state, the radio access network (RAN) (eg, a control function block of the RAN) and the base station are RRC connection configuration information and/or context information of the corresponding terminal (For example, RRC context information, AS (access stratum) context information) can be stored/managed. In addition, a terminal operating in an RRC connected state or an RRC inactive state may store RRC connection configuration information and/or context information.

"When the operating state of the terminal transitions from the RRC connected state to the RRC idle state" or ""When the operating state of the terminal transitions from the RRC inactive state to the RRC idle state", context information can be deleted from the RAN and the base station. The context information (eg, RRC context information) may include an identifier assigned to the terminal, PDU session information, encryption key (security key), capability information, and the like.

The UE operating in the RRC idle state monitors the downlink signal at the on-duration or active time according to the DRX (discontinuous reception) period set for the low power consumption operation (e.g., measurement Operation), it is possible to perform a cell selection operation or a cell reselection operation for camping to an optimum base station (eg, an optimum cell). In order to camp on a new base station (eg, a new cell), the terminal can obtain system information from the base station. In addition, when system information required by the terminal exists, the terminal may request transmission of system information. The terminal may perform an operation of receiving a paging message in on-duration or active time according to a paging occasion.

The terminal operating in the RRC connected state can set up a base station (eg, serving cell) and a radio bearer (eg, data radio bearer (DRB), signaling radio bearer (SRB)), and is required in the RRC connected state. Context information (eg, RRC context information) can be stored/managed. A terminal operating in an RRC connected state may perform a PDCCH monitoring operation using context information and connection configuration information. The terminal may receive downlink data from the base station through radio resources indicated by the DCI obtained by the PDCCH monitoring operation. In addition, the terminal may transmit uplink data to the base station using radio resources indicated by the DCI obtained by the PDCCH monitoring operation.

The mobility function for the terminal operating in the RRC connected state may be supported through a handover procedure when the base station is changed. For the handover procedure, the terminal may perform a measurement operation for a base station and/or an adjacent base station (eg, an adjacent cell) based on measurement and/or reporting parameters set by the base station, and the measurement result You can report to. In the following embodiments, the measurement operation may include an operation of reporting a measurement result. In addition, the terminal operating in the RRC connected state may perform a DRX operation based on DRX parameters set by the base station. For example, a terminal operating in an RRC connected state may perform a PDCCH monitoring operation in on-duration or active time according to the DRX cycle.

A terminal operating in the RRC inactive state may store/manage context information required for the RRC inactive state. A terminal operating in an RRC inactive state or an RRC idle state may perform a DRX operation based on DRX parameters set by the last base station (eg, serving cell). For example, a UE operating in an RRC inactive state may perform a monitoring operation or measurement operation of a downlink signal at an on-duration or active time according to the DRX cycle, and an optimal base station (e.g., an optimal cell ), a cell selection operation or a cell reselection operation may be performed based on a result of a monitoring operation or a measurement operation. The terminal may acquire system information to camp on a new base station (eg, a new cell) and, if necessary, may request transmission of system information (eg, system information required by the terminal). A terminal operating in an RRC inactive state or an RRC idle state may perform an operation of receiving a paging message in an on-duration or active time according to a paging occasion.

The communication procedure between the base station and the terminal may be performed based on a beamforming method. A signal transmitted from the terminal may be used to provide a mobility function between base stations or to select an optimal beam within the base station. A connection between the terminal and one or more base stations (eg, one or more cells) may be established, and one or more base stations may provide a service to the terminal. Connection establishment between the terminal and one or more base stations may be maintained. For example, one or more base stations may store/manage context information (eg, AS context information). Alternatively, the terminal may be located in the service area of the base station without establishing a connection with the base station.

When the beamforming method is used in the high frequency band, in the communication system, "beam level mobility function to change the set beam of the terminal", "mobility function to change the set beam between base stations (eg, cells)", "wireless A resource management function for changing the setting of a link" and the like may be supported.

In order to perform the mobility support function and the radio resource management function, the base station may transmit a synchronization signal (eg, a synchronization signal/physical broadcast channel (SS/PBCH) block) and/or a reference signal. In order to support multiple numerology, a frame format supporting symbols having different lengths may be set. In this case, the UE may perform a monitoring operation of a synchronization signal and/or a reference signal in a frame according to an initial neurology, a default neurology, or a default symbol length. Each of the initial neurology and default neurology is a frame format applied to a radio resource in which a UE-common search space is set, and a radio resource in which CORESET (control resource set) #0 of an NR communication system is set. The applied frame format and/or a synchronization symbol burst capable of identifying a cell in an NR communication system may be applied to a frame format applied to a radio resource to be transmitted.

The frame format is information of setting parameters for a subcarrier spacing, a control channel (e.g., CORESET), a symbol, a slot, and/or a reference signal in a radio frame (or subframe) (e.g. For example, it may mean a value of a setting parameter, an offset, an index, an identifier, a range, a period, an interval, and a duration. The base station may inform the terminal of the frame format using system information and/or a control message (eg, a dedicated control message).

The terminal connected to the base station may transmit a reference signal (eg, an uplink-only reference signal) to the corresponding base station using resources set by the corresponding base station. For example, the uplink-oriented reference signal may include a sounding reference signal (SRS). In addition, a terminal connected to a base station may receive a reference signal (eg, a downlink-oriented reference signal) from resources set by the base station from the base station. The downlink-oriented 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), or the like. Each of the base station and the terminal may perform a beam management operation by monitoring a configured beam or an active beam based on a reference signal.

For example, the base station may transmit a synchronization signal and/or a reference signal so that a terminal located in a communication service area can search for itself and perform a downlink synchronization maintenance operation, a beam setting operation, or a link monitoring operation. A terminal connected to a base station (eg, a serving base station) may receive radio resource configuration information of a physical layer for connection establishment and radio resource management from the base station. The radio resource configuration information of the physical layer may be configuration parameters included in the RRC control message in the LTE communication system and/or the NR communication system. For example, radio resource configuration information is 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 , and the like.

The radio resource setting information includes a setting period (or, an allocation period) of a signal (or radio 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, It may include parameter values such as transmission timing (or allocation timing). To support multiple neurology, a frame format of a base station (or transmission frequency) may mean a frame format having different symbol lengths according to a plurality of subcarrier intervals within one radio frame. For example, in one radio frame (eg, a frame having a length of 10 ms), the number of symbols constituting each of a mini-slot, a slot, and a subframe may be different.

● Setting information of the transmission frequency and frame format of the base station

■ Transmission frequency configuration information: all the transmission carriers of the base station (eg, transmission frequency per cell), bandwidth part (BWP), transmission reference time or time difference information between the transmission frequencies of the base station (For example, a transmission period or offset parameter indicating the transmission reference time (or time difference) of the synchronization signal), etc.

■ Frame format setting information: Setting parameters of mini-slots, slots, and subframes having different symbol lengths according to subcarrier intervals

● Setting information of a downlink reference signal (eg, CSI-RS, common RS, etc.)

■ The common RS configuration information is configuration parameters such as transmission period, transmission location, code sequence, masking sequence (or scrambling sequence) of a reference signal commonly applied in the coverage of the base station (or beam).

● Uplink control signal configuration information

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

● Downlink control channel (eg, PDCCH (physical downlink control channel)) configuration information

■ A reference signal for PDCCH demodulation, a beam common reference signal (eg, a reference signal that can be received by all terminals within the beam coverage), a reference signal for beam sweeping (or beam monitoring), a reference signal for channel estimation, etc.

● Uplink control channel (eg, PUCCH (physical uplink control channel)) configuration information

● Setting information of scheduling request signal

● Feedback (for example, ACK (acknowledgement) or NACK (negative ACK)) transmission resource configuration information in the HARQ (hybrid automatic repeat request) procedure

● The number of antenna ports, information on the antenna array, beam configuration and/or beam index mapping information for applying beamforming

● Setting information of a downlink signal and/or an uplink signal (or uplink access channel resource) for beam sweeping (or beam monitoring)

● Receive a beam that triggers a beam setup operation, a beam recovery operation, a beam reconfiguration operation, a radio link re-establishment operation, a beam change operation at the same base station, and a handover procedure to another base station. Setting information such as signals and control timers for the above-described operations

In a radio frame format supporting different symbol lengths to support multiple neurology, a setting period (or allocation period) of parameters constituting the above-described information, time resource allocation information, frequency resource allocation information, transmission timing, and /Or the allocation timing may be information set according to the corresponding symbol length (or subcarrier interval).

In the following embodiments, "Resource-Config information" may be a control message including one or more parameters among radio resource configuration information of a physical layer. In addition, "Resource-Config information" may mean a property and/or a setting value (or range) of an information element (or parameter) delivered by a control message. The information element (or parameter) delivered by the control message is radio resource configuration information that is commonly applied to the entire coverage of the base station (or beam) or dedicated to a specific terminal (or specific terminal group). It may be radio resource configuration information allocated to.

The configuration information included in the "Resource-Config information" may be transmitted through one control message or different control messages according to the properties of the configuration information. The beam index information may not clearly represent the index of the transmission beam and the index of the reception beam. For example, the beam index information may be expressed using a reference signal mapped or associated with a corresponding beam index, or an index (or identifier) of a transmission configuration indicator (TCI) state for beam management.

Accordingly, a terminal operating in an RRC connected state can receive a communication service through a beam (eg, a beam pair) established between the terminal and the base station (eg, serving cell). The UE uses a synchronization signal (eg, SS/PBCH block) and/or a reference signal (eg, CSI-RS) transmitted from a base station (eg, serving cell) to search or monitor a radio channel. The operation can be performed. Here, "providing a communication service through a beam (eg, a set beam)" may mean "transmitting and receiving a packet through an activation beam among one or more set beams". In the NR communication system, “the beam is activated” may mean “the configured TCI state is activated”.

The terminal may operate in an RRC idle state or an RRC inactive state. In this case, the UE may perform a downlink channel discovery operation (eg, a monitoring operation) using the parameter(s) obtained from system information or common Resource-Config information. In addition, a terminal operating in an RRC idle state or an RRC inactive state may attempt access using an uplink channel (eg, a random access channel or a physical layer uplink control channel). Alternatively, the terminal may transmit control information using an uplink channel.

The terminal may detect or detect a problem of a radio link by performing a radio link monitoring (RLM) operation. Here, "a problem with the wireless link is detected" may mean "there is an abnormality in setting or maintaining the synchronization of the physical layer for the wireless link". For example, "a problem of a wireless link is detected" may mean "that the physical layer synchronization between the base station and the terminal is not matched during a preset time". When a radio link problem is detected, the terminal may perform a radio link recovery operation. When the radio link is not restored, the terminal may declare a radio link failure (RLF) and may perform a radio link re-establishment procedure.

The radio link physical layer problem detection procedure according to the RLM operation, the radio link recovery procedure, the radio link failure detection (or declaration) procedure, and the radio link re-establishment procedure include the layer of the radio protocol constituting the radio link ( layer) 1 (eg, physical layer), layer 2 (eg, MAC layer, RLC layer, PDCP layer, etc.) and/or layer 3 (eg, RRC layer) functions. have.

The physical layer of the terminal can monitor the radio link by receiving a downlink synchronization signal (eg, a primary synchronization signal (PSS), a secondary synchronization signal (SSS), an SS/PBCH block) and/or a reference signal). I can. In this case, the reference signal is a base station common reference signal, a beam common reference signal, or a dedicated reference signal allocated to a terminal (or terminal group) specific reference signal (eg, a terminal (or terminal group)). dedicated) reference signal). Here, the common reference signal may be used for a channel estimation operation of all terminals located within the coverage (or service area) of a corresponding base station or beam. The dedicated reference signal may be used for a channel estimation operation of a specific terminal or a specific terminal group within the coverage of the base station or the beam.

Accordingly, when the base station or the beam (eg, a set beam between the base station and the terminal) is changed, the dedicated reference signal for beam management may be changed. The beam may be changed based on the configuration parameter(s) between the base station and the terminal. A change procedure for the set beam may be required. “The beam is changed in the NR communication system” means “the index (or identifier) of the TCI state is changed to the index of another TCI state”, “the TCI state is newly set”, or “the TCI state is activated. It can mean "to change to state." The base station may transmit system information including configuration information of the common reference signal to the terminal. The terminal may acquire a common reference signal based on system information. In a handover procedure, a synchronization reconfiguration procedure, or a connection reconfiguration procedure, the base station may transmit a dedicated control message including configuration information of a common reference signal to the terminal.

Information for classifying a base station (eg, cell) may be transmitted to the terminal according to a configuration condition of a radio protocol of the base station. Information for classifying the base station may be delivered to the terminal using a control message of the RRC layer, a control message of the MAC layer, or a control channel of the physical layer according to the layer(s) included in the base station. In embodiments, the control message of the RRC layer may be referred to as "RRC control message" or "RRC message", the control message of the MAC layer may be referred to as "MAC control message" or "MAC message", and the physical layer The control channel may be referred to as “PHY control channel”, “PHY control message”, or “PHY message”.

Here, the information for identifying the base station may include one or more of a base station identifier, reference signal information, reference symbol information, configured beam information, and configuration TCI state information. The reference signal information (or reference symbol information) includes setting information (eg, radio resources, sequence, index) of a reference signal allocated for each base station and/or configuration information of a dedicated reference signal allocated to the terminal (eg, Radio resources, sequences, and indexes) may be included.

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

In the following embodiments, the reference signal information includes transmission period information of the reference signal, sequence information (eg, code sequence), masking information (eg, scrambling information), radio resource information, and/or index information. can do. The reference signal identifier may mean a parameter (eg, resource ID, resource set ID) used to distinguish each of a plurality of reference signal information. The reference signal information may mean setting information of a reference signal.

The configuration beam information includes a configuration beam index (or identifier), a configuration TCI state index (or identifier), configuration information of each beam (e.g., transmission power, beam width, vertical angle, horizontal angle), transmission of each beam, and /Or reception timing information (eg, subframe index, slot index, mini-slot index, symbol index, offset), reference signal information corresponding to each beam, and reference signal identifier. In 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 (eg, a drone), a manned aircraft, or a satellite.

The terminal may receive configuration information of the base station (eg, identification information of the base station) from the base station through one or more of an RRC message, a MAC message, and a PHY message, and a beam monitoring operation, a radio access ( access) operation and/or a control (or data) packet transmission/reception operation may be performed.

When a plurality of beams are configured, communication between the base station and the terminal may be performed using a plurality of 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.

The base station may obtain the result of the beam measurement operation or the beam monitoring operation from the terminal, and may change the attribute of the beam or the TCI state based on the result of the beam measurement operation or the beam monitoring operation. The beam may be classified into a primary beam, a secondary beam, a spare (or candidate) beam, an active beam, and an inactive beam according to properties. The TCI state may be classified into a primary TCI state, a secondary TCI state, a reserve (or candidate) TCI state, a serving TCI state, a set TCI state, an active TCI state, and an inactive TCI state according to attributes. The TCI state may be assumed to be an active TCI state and a serving TCI state. The reserve (or candidate) TCI state may be assumed to be an inactive TCI state or a set TCI state.

The procedure for changing the beam (or TCI state) attribute may be controlled by the RRC layer and/or the MAC layer. When the procedure for changing the beam (or TCI state) attribute is controlled by the MAC layer, the MAC layer may inform the upper layer of information on the change of the beam (or TCI state) attribute. Information on the change of the beam (or TCI state) attribute may be transmitted to the terminal through a MAC message and/or a physical layer control channel (eg, PDCCH). Information on the change of the beam (or TCI state) attribute may be included in downlink control information (DCI) or uplink control information (UCI). Information on the change of the beam (or TCI state) attribute may be expressed as a separate indicator or field.

The terminal may request a property change of the TCI state based on the result of the beam measurement operation or the beam monitoring operation. The terminal may transmit control information (or feedback information) for requesting the property change of the TCI state to the base station using one or more of a PHY message, a MAC message, and an RRC message. Control information (or feedback information, control message, and control channel) for requesting to change the TCI state attribute may be configured using one or more of the above-described configuration beam information.

Changing the properties of a beam (or TCI state) may mean "change from an active beam to an inactive beam". The procedure for changing the properties of the beam (or TCI state) may be controlled by the RRC layer and/or the MAC layer. The procedure for changing the properties of the beam (or TCI state) may be performed through partial cooperation between the RRC layer and the MAC layer.

When a plurality of beams are allocated, one or more of the plurality of beams may be set as beam(s) for transmitting a physical layer control channel. For example, the primary beam and/or the secondary beam may be used for transmission and reception of a physical layer control channel (eg, a PHY message). Here, the physical layer control channel may be a PDCCH or a PUCCH. The physical layer control channel is 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 (eg, SR (scheduling request)), a result of a beam monitoring operation for supporting a beamforming function, a TCI status ID, and measurement information for an active beam (or an inactive beam) Can be used for more than one transmission.

Radio resource information includes 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 time domain resources (For example, a radio frame index, a subframe index, a transmission time interval (TTI), a slot index, a mini-slot index, a symbol index, a time offset, a period of a transmission interval (or a reception interval), a length, Window) may include parameter(s) indicating. In addition, the radio resource information includes a hopping pattern of radio resources, information for beamforming (eg, beam shaping) operation (eg, beam configuration information, beam index), and a code sequence (or bit string). , Signal sequence) may further include resource information occupied according to the characteristics.

The name of the physical layer channel and/or the name of the transport channel is the type of data (or attribute), the type of control information (or attribute), and the transmission direction (e.g., uplink, downlink, sidelink). ), etc.

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

The reference value representing the degree of change in reception quality may be set as an absolute value (dBm) or a relative value (dB). In addition, the reception quality of a beam (or a TCI state) or a reference signal for radio link management is a reference signal received power (RSRP), a reference signal received quality (RSRQ), a received signal strength indicator (RSSI), and a signal-to-signal (SNR). -noise ratio), signal-to-interference ratio (SIR), signal-to-noise and interference ratio (SINR), and the like.

Meanwhile, in an NR communication system using a millimeter frequency band, flexibility in channel bandwidth operation for packet transmission can be secured based on the concept of a bandwidth part (BWP). The base station may set up to 4 BWPs having different bandwidths in the terminal. The BWP can be independently configured in downlink and uplink. That is, the downlink BWP can be distinguished from the uplink BWP. Each of the BWPs may have different bandwidths as well as different subcarrier spacings.

The UE operating in the RRC connected state is a serving cell and a measurement target cell (eg, a neighbor cell, a target cell, a candidate cell, etc.) based on an SS/PBCH block and/or a reference signal (eg, CSI-RS). You can measure the signal quality of your wireless link. Here, the signal quality may be RSRP, RSRQ, RSSI, SNR, SIR, SINR, etc. mentioned in the description related to reception performance of a reference signal for management of the above-described beam (eg, TCI state) or radio link.

The UE operating in the RRC inactive state or the RRC idle state is a serving cell (eg, a camping cell) or a radio link of a measurement target cell according to a DRX period (eg, a measurement period) set based on the SS/PBCH block. The signal quality (eg, RSRP, RSRQ, RSSI, SINR) of can be measured. The terminal may perform a cell selection operation or a cell reselection operation based on the measurement result. For measurement of a serving cell (eg, a camping cell), the UE sets the transmission period of the SS/PBCH block (eg, ssb-PeriodicityServingCell) or the radio resource through which the SS/PBCH is transmitted from the system information of the cell. Information (eg, ssb-PositionsInBurst) may be obtained.

In addition, in order to measure a measurement target cell (eg, a neighboring cell), the terminal may obtain signal measurement time configuration (SMTC) window information from system information. A terminal operating in an RRC inactive state or an RRC idle state may perform a cell selection operation or a cell reselection operation based on a measurement result of SS/PBCH. During the cell selection operation or the cell reselection operation, the terminal may recognize that a radio access network (RAN) area or a tracking area (TA) has changed based on an identifier included in system information received from the cell. In this case, the UE may perform an update procedure of the RAN region or TA.

4 is a conceptual diagram showing a first embodiment of a non-terrestrial network.

Referring to FIG. 4, the non-terrestrial network may include a satellite 410, a communication node 420, a gateway 430, a data network 440, and the like. The non-terrestrial network illustrated in FIG. 4 may be a non-terrestrial 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 mean an unmanned aerial vehicle (UAV) or a UAN base station (UBS).

The communication node 420 may include a communication node (eg, user equipment (UE), terminal) located on the ground and a communication node (eg, airplane, drone) located on the ground. A service link may be established between the satellite 410 and the communication node 420, and the service link may be a radio link. Satellite 410 may provide communication services to communication node 420 using one or more beams. The shape of the footprint of the beam of the satellite 410 may be an elliptical shape. The satellite 410 may provide a communication service to a specific area. For example, the satellite 410 may provide a communication service to a specific area using one beam. One area may exist for each cell, and a plurality of beams may be used in one cell.

The communication node 420 may perform communication (eg, downlink communication, uplink communication) with the satellite 410 using LTE technology and/or NR technology. Communication between the satellite 410 and the communication node 420 may be performed using the NR-Uu interface. When DC (dual connectivity) is supported, the communication node 420 may be connected with not only the satellite 410 but also other base stations (eg, a base station supporting LTE and/or NR functions), and LTE and/or NR DC operation can be performed based on the technology defined in the standard.

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 the 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 can 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), and the like. Communication between the gateway 430 and the core network may be performed based on the NG-C/U interface.

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 can support NR technology. Communication between the gateway 430 and the base station may be performed based on the NR-Uu interface, and communication between the base station and the core network (eg, AMF, UPF, SMF) is performed based on the NG-C/U interface. I can.

5 is a conceptual diagram showing a second embodiment of a non-terrestrial network.

Referring to FIG. 5, the non-terrestrial network may include satellite #1 511, satellite #2 512, a communication node 520, a gateway 530, a data network 540, and the like. The non-terrestrial network shown in FIG. 5 may be a non-terrestrial network based on a regenerative payload. For example, satellite #1-2 (511, 512) each of the payload received from another entity (entity) (for example, communication node 520, gateway 530) constituting a non-terrestrial network For example, a regeneration operation (eg, a demodulation operation, a decoding operation, a re-encoding operation, a re-modulation operation, and/or a filtering operation) may be performed, and the regenerated payload may be transmitted.

Each of satellites #1-2 (511, 512) may be an LEO satellite, a MEO satellite, a GEO satellite, a HEO satellite, or a UAS platform. The UAS platform may include HAPS. Each of satellites #1-2 (511, 512) may mean UAV or 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 can operate in a radio frequency (RF) frequency or an optical band. ISL can be set as optional. The communication node 520 may include a communication node (eg, UE, terminal) located on the ground and a communication node (eg, airplane, drone) located on the ground. A service link (eg, a radio link) may be established between the satellite #1 511 and the communication node 520. Satellite #1 511 may provide a communication service to the communication node 520 using one or more beams.

The communication node 520 may perform communication (eg, downlink communication, uplink communication) with satellite #1 511 using LTE technology and/or NR technology. Communication between the satellite #1 511 and the communication node 520 may be performed using the NR-Uu interface. When DC is supported, the communication node 520 may be connected to the satellite #1 511 as well as other base stations (eg, a base station supporting LTE and/or NR functions), and comply with the LTE and/or NR standards. DC operation may be performed based on the defined technology.

The gateway 530 may be located on the ground, a feeder link may be established between the satellite #1 511 and the gateway 530, and a feeder link may be established between the satellite #2 512 and the gateway 530. have. The feeder link may be a wireless link. When the ISL is not set between the satellite #1 511 and the satellite #2 512, a feeder link between the satellite #1 511 and the gateway 530 may be set mandatory.

Communication between each of the satellites #1-2 511 and 5122 and the gateway 530 may be performed based on the NR-Uu interface or SRI. The gateway 530 may be connected to the data network 540. 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 core network, and the core network may be connected to the data network 540. The core network can support NR technology. For example, the core network may include AMF, UPF, SMF, and the like. Communication between the gateway 530 and the core network may be performed based on the NG-C/U interface.

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 can support NR technology. Communication between the gateway 530 and the base station may be performed based on the NR-Uu interface, and communication between the base station and the core network (eg, AMF, UPF, SMF) is performed based on the NG-C/U interface. I can.

Meanwhile, scenarios in a non-terrestrial network may be defined as shown in Table 1 below.

In the case where the satellite 410 in the non-terrestrial network shown in FIG. 4 is a GEO satellite (eg, a GEO satellite supporting a transparent function), it may be referred to as “scenario A”. In the non-terrestrial network shown in FIG. 5, when satellites #1-2 (511, 512) are GEO satellites (eg, GEO supporting regenerative function), this will be referred to as “scenario B”. I can.

In the case where the satellite 410 in the non-terrestrial network shown in FIG. 4 is an LEO satellite having steerable beams, this may be referred to as “scenario C1”. In the case where the satellite 410 in the non-terrestrial network shown in FIG. 4 is an LEO satellite having beams move with satellite, it may be referred to as “scenario C2”. In the case where satellite #1-2 (511, 512) in the non-terrestrial network shown in FIG. 5 is an LEO satellite having adjustable beams, this may be referred to as “scenario D1”. In the case where satellite #1-2 (511, 512) in the non-terrestrial network shown in FIG. 5 is an LEO satellite having beams moving together with the satellite, this may be referred to as “scenario D2”.

Parameters for the scenarios defined in Table 1 may be defined as shown in Table 2 below.

In addition, in the scenarios defined in Table 1, delay constraints may be defined as shown in Table 3 below.

6 is a conceptual diagram showing a third embodiment of a non-terrestrial network.

Referring to FIG. 6, a non-terrestrial network may include a non-terrestrial node 610, terminal #1 621, terminal #2 622, and terminal #3 623. The non-ground node 610 may mean satellite, HAPS, UAV, or UBS. For example, the non-ground node 610 may be a satellite located between about 600 km to 35,000 km from the ground surface. Alternatively, the non-ground node 610 may be a HAPS, UAV, or UBS located between about 10 km to 600 km from the ground surface. The non-ground node 610 may perform a function of a base station or a relay in a terrestrial network (eg, an LTE communication network, an NR communication network). The maximum length of the service area of the non-ground node 610 on the ground surface (eg, the diameter of the service area when 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.

When the non-terrestrial node 610 is a high altitude geostationary orbit satellite (eg, GEO satellite), approximately in the radio section (L1-L3) between the non-terrestrial node 610 and the terminals 621-623 A transmission delay of 280 ms may occur. The transmission delay may be a round trip delay (RTD) or a propagation delay in the radio section L1-L3. Transmission delay in the radio section (L2) between the non-ground node 610 and the closest terminal #2 (622) and between the non-ground node 610 and the farthest terminal #1 (621) or terminal #3 (623) The difference between transmission delays (hereinafter, "Ldelay_diff") in the radio section L1 or L3 may be about 2 ms.

Each of the transmission delay and Ldelay_diff between the non-ground node 610 and the terminals 621-623 may be much greater than the transmission delay and Ldelay_diff in the terrestrial network. Accordingly, in a non-terrestrial network, each of a control signaling operation, a downlink monitoring operation, a downlink reception operation, and an uplink transmission operation may be performed in consideration of transmission delay and/or Ldelay_diff.

In order for a base station to receive uplink signals of a plurality of terminals without interference in an OFDMA-based communication network, uplink signals transmitted from a plurality of terminals must be aligned in the time domain. Here, the uplink signal may mean a signal including an uplink channel and/or signal. In order to support this operation, the base station may adjust the uplink transmission timing by transmitting timing advance (TA) information to the terminal(s). In a non-terrestrial network, in order to adjust the uplink transmission timing between the non-terrestrial node 610 and the terminals 621-623, a control signaling operation for transmitting TA information may be performed. However, the transmission delay of the radio section (L1-L3) should be considered in the corresponding control signaling operation.

To support this operation, the non-ground node 610 may transmit transmission delay information of the radio section L1-L3 to the corresponding terminal 621-623. Here, the transmission delay information may be minimum transmission delay information (hereinafter referred to as “Ldelay_min information”) in the radio section L2 between the non-ground node 610 and the nearest terminal #2 622. That is, the 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, a mini slot, a slot, a sub frame, or a radio frame. have. Alternatively, the Lelay_min information may be set in absolute time units (eg, ms, sec).

Before receiving TA information from the non-ground node 610 (for example, "when a random access procedure is not completed" or "when uplink synchronization is not obtained"), the terminals 621-623 are Uplink synchronization information can be obtained from the information. Alternatively, the UEs 621-623 may adjust the uplink transmission timing using Ldelay_min or calculated Ldelay_min estimated by the UE itself. In embodiments, uplink synchronization may mean uplink physical layer synchronization, and uplink transmission timing may mean uplink physical layer transmission timing. Thereafter, the UEs 621-623 may adjust the uplink transmission timing using the TA information received from the non-ground node 610.

The TA information transmitted by the non-ground node 610 may be adjustment information of uplink transmission timing in consideration of Ldelay_min. For example, when the uplink transmission timing value to be adjusted by the terminals 621-623 is "10" and Ldelay_min is "8", the non-ground node 610 instructs to adjust by "2" TA information may be transmitted to the terminals 621-623.

The terminals 621-623 may adjust the uplink transmission timing based on the Ldelay_min and/or TA information received from the non-ground node 610. A parameter for management of uplink transmission timing may be set to " timeAlignmentTimer ". When a message including TA information (eg, a MAC message or a random access (RA) response message) is received from the non-ground node 610, the terminal may (re)start the timeAlignmentTimer . If a message including TA information is not received before the expiration of timeAlignmentTimer , the UEs 621-623 may determine that uplink synchronization maintenance has failed. In this case, the UEs 621-623 may perform a synchronization acquisition procedure (eg, an RA procedure) for uplink transmission.

The Ldelay_min information may be set differently according to the type and altitude of the non-ground node 610. The non-ground node 610 may transmit system information including Ldelay_min information or another control message (eg, a MAC control message or a PHY control message) to the terminals 621-623. That is, the Ldelay_min information may be signaled in an explicit manner through system information. Alternatively, the terminals 621-623 may estimate or calculate Ldelay_min by using an implicit method. For example, the non-ground node 610 may transmit system information including its type information, altitude information, and the like to the terminals 621-623. The terminals 621-623 may receive system information from the non-ground node 610, and are based on information included in the system information (eg, type information of the non-ground node 610, altitude information). Thus, Ldelay_min can be estimated or calculated. The type information of the non-ground node 610 may indicate that the non-ground node 610 is a satellite, HAPS, UAV, or UBS.

Terminals 621-623 based on the setting information (eg, type information, altitude information) of the non-ground node 610, the non-ground node 610 is a GEO satellite, non-GEO satellite ( For example, it may be determined as LEO satellite, MEO satellite, HEO satellite), HAPS, UAV, or UBS. Information used to identify the non-ground node 610 may be transmitted from the non-ground node 610 to the terminals 621-623 through system information and/or control messages. The altitude information of the non-ground node 610 is “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 (for example, For example, it could be "low altitude, medium and high altitude)". The altitude information of the non-ground node 610 may be transmitted from the non-ground node 610 to the terminals 621-623 through system information and/or control messages. The terminals 621-623 may estimate or calculate Ldelay_min based on configuration information (eg, type information, altitude information) received from the non-ground node 610.

Alternatively, the terminal (621-623) is the identifier of the non-ground node 610 (for example, an identifier for cell classification (for example, PCI (physical cell identifier)), an identifier for beam classification) Can be used to estimate or calculate Ldelay_min. PCI may be set differently according to the type and/or altitude of the non-ground node 610. Accordingly, the terminals 621-623 can check the type and/or altitude of the non-ground node 610 based on the PCI received from the non-ground node 610, and estimate Ldelay_min based on the checked information or Can be calculated. That is, the terminals 621-623 may estimate or calculate Ldelay_min using the configuration information and/or the identifier of the non-ground node 610. The non-ground node 610 may provide a communication service to the terminals 621-623 using a plurality of beams or a plurality of frequency resources. In this case, Ldelay_min of non-ground nodes located at the same altitude or non-ground nodes of the same type may have the same value.

Meanwhile, the terminals 621-623 may perform a random access procedure to access the non-ground node 610 (eg, a base station). In the step 4 random access procedure, the UEs 621-623 may transmit an RA preamble (e.g., PRACH (physical random access channel), msg1) to the non-ground node 610, and the RA preamble A response to the RAR (random access response) message (eg, msg2) may be received from the non-ground node 610. After that, the MSg3 and msg4 transmission/reception operations may be performed between the terminals 621-623 and the non-ground node 610. In the second-stage random access procedure, the terminals 621-623 may transmit msgA to the non-ground node 610 and may 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 may be transmitted from the non-ground node 610 to the terminals 621-623.

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

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

The non-ground node may receive msg1 or msgA from the terminal. When msg1 is received from the terminal, the non-ground node may transmit msg2 (eg, RAR message) to the terminal in response to msg1 (S702). Alternatively, when msgA is received from the terminal, the non-ground node may transmit msgB to the terminal in response to msgA (S702). The UE 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 a non-ground node within the RA response window.

In order to prevent the UE from performing an unnecessary downlink monitoring operation for 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 after the RAR offset from the time of transmission of msg1 or msgA. That is, a timer related to the RA response window may be started 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 (eg, ms, sec).

A terminal that has transmitted msg1 or msgA at time A may receive msg2 or msgB transmitted from a non-ground node by performing a downlink monitoring operation in an RA response window starting at time B after the RAR offset from time A. The UE may not perform a downlink monitoring operation for reception of msg2 or msgB in a time interval from time A to time B (eg, RAR offset). The size of the RAR offset may be more than twice the Ldelay_min. Alternatively, the size of the RAR offset may be set to a specific value in consideration of Ldelay_min, and the non-ground node may transmit RAR offset configuration information to the terminal using system information or other control message.

The size of the RA response window is a transmission delay (eg, minimum transmission delay) and a non-ground node in the radio section L2 between the non-ground node 610 and the nearest terminal #2 622 shown in FIG. It can be set in consideration of the difference (Ldelay_diff) between the transmission delay (e.g., the maximum transmission delay) in the radio section (L1 or L3) between 610 and the farthest terminal #1 621 or terminal #3 623 have. For example, the size of the RA response window may be set to a value equal to Ldelay_diff, a multiple of Ldelay_diff, or a value larger than Ldelay_diff.

Each of the RAR offset and Ldelay_diff may be set differently according to the type and/or altitude 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 check 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 indicated by an explicit method. Alternatively, the UE may estimate or calculate each of the RAR offset and Ldelay_diff based on the implicit method. For example, the terminal may estimate or calculate each of the RAR offset and Ldelay_diff based on the type and/or altitude of the non-ground node.

For example, the terminal is based on the setting information of the non-ground node (eg, type information, altitude information), the non-ground node is a GEO satellite, a non-GEO satellite (eg, LEO satellite, MEO satellite, HEO satellite), HAPS, UAV, or UBS. Information used to identify the non-ground node may be transmitted from the non-ground node to the terminal through system information and/or control messages. The altitude information of the non-ground node is “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 (eg, low altitude, medium altitude, high altitude )" can be. Altitude information of the non-ground node may be transmitted from the non-ground node to the terminal through system information and/or control messages. The terminal may estimate or calculate each of the RAR offset and Ldelay_diff based on configuration information (eg, type information, altitude information) received from a non-ground node.

Alternatively, the UE may estimate or calculate each of the RAR offset and Ldelay_diff using the identifier of the non-ground node (e.g., an identifier for cell classification (e.g., PCI), an identifier for beam classification). . PCI may be configured differently depending on the type and/or altitude of the non-ground node. Accordingly, the terminal may check the type and/or altitude of the non-ground node based on the PCI received from the non-ground node, and estimate or calculate each of the RAR offset and Ldelay_diff based on the confirmed information. That is, the terminal may estimate or calculate each of the RAR offset and Ldelay_diff using the configuration information and/or the identifier of the non-ground node.

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

" Ra-ContentionResolutionTimer ", which is a timer used to determine contention resolution, may be set. ra- ContentionResolutionTimer may be started at a time point when the terminal transmits msg3 (eg, time point C). When msg4 is received from a non-ground node before the expiration of ra-ContentionResolutionTimer , the terminal may determine that the contention has been resolved. In this case, the random access procedure may be terminated. "If it is not received from the ground node msg4 prior to the expiration of ra-ContentionResolutionTimer ratio" or "non-prior to the expiration of the ra- ContentionResolutionTimer - if the msg4 received from the ground node that does not include the terminal identifier", the mobile station random access It can be determined that the procedure has failed. In this case, the terminal may perform the random access procedure again.

ra- ContentionResolutionTimer may be set to start at time D instead of at time C. For example, the UE may start ra- ContentionResolutionTimer at a time point D after a contention offset from the time point of transmission of msg3 . Therefore, the UE may not perform a downlink monitoring operation for reception of msg4 in a time interval from time C to time D (eg, contention offset), and a downlink monitoring operation from time D until the expiration of ra-ContentionResolutionTimer Can be done. ra- ContentionResolutionTimer may be set to a value equal to Ldelay_diff, a multiple of Ldelay_diff, or a value greater than Ldelay_diff.

The contention offset may be set and/or signaled in the same manner as the RAR offset described above. The size of the contention offset may be more than twice the 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 equal to the size of the RAR offset. The contention offset and RAR offset may be set by one parameter. In this case, each of the contention offset and the RAR offset may not be independently set. That is, only one of the contention offset and the RAR offset may be set, and the set one offset may be applied to both the contention offset and the RAR offset.

In order to estimate or calculate the transmission delay in the radio section between the non-ground node and the terminal, which is a criterion for setting the aforementioned Ldelay_min, RAR offset, and/or contention offset, the non-ground node provides absolute time information (e.g., GPS (global positioning system) time, UTC (coordinated universal time) time, etc.) can be informed to the terminal. For example, the non-ground node uses downlink resources for absolute time information on the generation time of a transport block for downlink transmission, a code block for encoding, and/or a MAC message. Can be transmitted to the terminal. The absolute time information may be transmitted from the non-ground node to the terminal through a combination of one or more of system information, RRC message, MAC message, and PHY message. When the absolute time information is transmitted by the MAC message, the MAC message including 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 including absolute time information at a necessary time point.

The terminal may receive absolute time information from the non-ground node, and transmission delay in the radio section between the non-ground node and the terminal based on the absolute time information (e.g., processing time in the non-ground node) It is possible to estimate or calculate a transmission delay in a radio section including a). In this case, the terminal may set Ldelay_min, RAR offset, and/or contention offset based on a transmission delay in a radio section acquired using absolute time information. The terminal may report the information of the transmission delay in the radio section obtained using the absolute time information to the non-ground node. The information on the transmission delay in the radio section obtained using the absolute time information may be transmitted from the terminal to the non-ground node through a combination of one or more of an RRC message, a MAC message, and a PHY message. In particular, the terminal may transmit information of a transmission delay to a non-ground node by using a specific message (eg, msg1, msg3, msgA) in a random access procedure.

In order to estimate or calculate the transmission delay in the radio section between the non-ground node and the terminal (e.g., the transmission delay in the radio section including the processing time in the non-ground node), the non-ground node reports the transmission time information It is possible to instruct or request the terminal to (for example, transmit). The transmission time information may mean absolute time information about a transmission time (eg, GPS time, time according to UTC) or relative time information about a transmission time (eg, an index of a radio frame). At the time of transmission, the index of the radio frame may be composed of a system frame number (SFN), a subframe index, a slot index, a mini slot index, and/or a symbol index.

When reporting (e.g., transmission) of transmission time information is requested or indicated by a non-ground node, the UE is Time information for (eg, absolute time information) can be transmitted to a non-ground node using uplink resources. Here, the time information may be transmitted from the terminal to the non-ground node through a combination of one or more of system information, RRC message, MAC message, and PHY message.

The non-ground node can obtain time information (e.g., absolute time information) from the terminal, and transmission delay in the wireless section between the terminal and the non-ground node by using the time information (e.g., processing delay in the terminal It is possible to estimate or calculate a transmission delay in a radio section including a). The non-ground node may set or adjust Ldelay_min, RAR offset, and/or contention offset by using the estimated transmission delay or the calculated transmission delay based on the time information obtained from the terminal.

Absolute time information transmitted by a non-ground node or terminal may be composed of information representing the entire absolute time or partial information representing a part of the absolute time (eg, time information in units of seconds or less). . The partial information may mean time information expressed as an absolute time in seconds, milliseconds, or microseconds.

Meanwhile, in order to provide a communication service, a terminal operating in an RRC connected state may transmit scheduling request (SR) information requesting uplink resource allocation to a non-ground node. One or more SR information may be configured according to the configuration of a logical channel. One or more SR information may be identified using a scheduling request identifier (hereinafter, referred to as " schedulingRequestId "). The UE that has transmitted the SR information may not be able to transmit SR information having the same schedulingRequestId before expiration of a preset timer (hereinafter, referred to as “ sr- ProhibitTimer ”). That is, the UE may transmit SR information having the same schedulingRequestId after the sr-ProhibitTimer expires.

Meanwhile, the UE may perform the random access procedure shown in FIG. 7 for beam recovery. However, in "when a preset timer (hereinafter referred to as " beamFailureRecoveryTimer ") is set" or "when the beamFailureRecoveryTimer operates", the terminal may perform a contention-free random access procedure. In the contention-free random access procedure, uplink resources for transmission of msg1 or msgA may be dedicated to the terminal.

In the non-terrestrial network shown 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 may operate in consideration of Ldelay_min. have.

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

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

However, "when the non-ground node does not receive SR information" or "when the terminal does not receive uplink resource allocation information", the terminal SR information having the same schedulingRequestId after the point C when sr- ProhibitTimer expires 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, in consideration of the transmission delay between the non-ground node and the terminal, the terminal may (re)start the sr-ProhibitTimer at a time B after Ldelay_min from time A (eg, transmission time of SR information).

Even when the sr- ProhibitTimer does not operate in the time interval from time A to time B, a control signal indicating that SR information has been transmitted (or triggered) may be set. If the control signal is set, the terminal which has transmitted the SR information from point A may not perform the "transmission behavior of the SR information having the same schedulingRequestId" or "trigger operation for transmission of the SR information having the same schedulingRequestId". That is, the UE "information transfer operations of the SR have the same schedulingRequestId" after the point B at the end of the Ldelay_min (re) started sr- ProhibitTimer expires, or "triggering operation for transmission of the SR information having the same schedulingRequestId" Can be done.

Meanwhile, in a buffer status report (BSR) procedure, the UE may transmit BSR information to a non-ground node. In the above-described transmission procedure of SR information, the operation and management method of sr- ProhibitTimer may be applied for operation and management of retxBSR- Timer , which is a timer for the BSR procedure.

The terminal may transmit BSR information to the non-ground node at point A (S801). The non-ground node may receive BSR information from the terminal and may generate uplink resource allocation information based on the BSR information. The non-ground node may transmit uplink resource allocation information to the terminal (S802). The terminal may receive uplink resource allocation information from a non-ground node. The terminal transmitting the BSR information at time A may (re)transmit the same BSR information after time C when retxBSR- Timer expires (S803). Step S803 may be performed when uplink resource allocation information is not received from a non-ground node. In this case, in consideration of the transmission delay between the non-ground node and the terminal, the terminal may (re)start the retxBSR-Timer at time B after Ldelay_min from time A.

A case in point is not a retxBSR -Timer operation in a time interval of B and the time from the control signal is information indicating that the BSR transmission (or activated) can be set. When the control signal is set, the terminal transmitting the BSR information at point A may not perform the “transmission operation of BSR information” or “triggering operation for transmission of BSR information”. That is, the UE may perform the "transmission behavior of the BSR information" or "trigger operation for transmission of the BSR information" after the point B at the end of the Ldelay_min (re) started retxBSR -Timer expires.

9 is a timing diagram illustrating a first embodiment of a beam recovery procedure considering Ldelay_min in a non-terrestrial network.

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

The terminal may receive msg2 or msgB from a non-ground node. When the transmission/reception operation of msg3 and msg4 between the non-ground node and the terminal in the contention-free 4-step random access procedure is completed, the terminal may determine that the BFR has been successfully performed. When msgB is successfully received from a non-ground node in a contention-free two-step random access procedure, the terminal may determine that the BFR has been successfully performed. "When the non-ground node does not receive msg1 or msgA" or "When the terminal does not receive msg2 or msgB", the terminal is contention-based for BFR after time D, which is the expiration time of beamFailureRecoveryTimer A random access procedure of may be performed (S903). In this case, in consideration of the transmission delay between the non-ground node and the terminal, the terminal may (re)start the beamFailureRecoveryTimer at time B after Ldelay_min from time A.

Even when the beamFailureRecoveryTimer does not operate in a time interval from time A to time B, a control signal indicating that a contention-free random access procedure is being performed may be set. When the control signal is configured, the terminal triggering the contention-free random access procedure for BFR at point A may not trigger a new contention-free-based random access procedure for BFR. However, the RA response window may be terminated before the expiration time (eg, time D) of the beamFailureRecoveryTimer (re)started at time B, which is the end time of the RAR offset (or Ldelay_min). In this case, the UE may transmit msgA by triggering a contention-free random access procedure for BFR in a time interval from time C to time D, which is the end time of the RA response window.

In addition, in the contention-free RA transmission procedure for SR transmission, BSR transmission, and beam failure recovery (BFR), the offset of FIG. 7 (for example, RAR offset or contention offset) for path delay compensation by Ldelay_min described above. A separate offset parameter such as may be set. The offset value for the contention-free 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 constant to Ldelay_min. However, in this case, the unit of the offset parameter may be set in a unit such as a symbol, a mini slot, a slot, a subframe, or a radio frame. Alternatively, the unit of the offset parameter may be set in absolute time units such as microseconds, milliseconds, or seconds (or seconds).

Meanwhile, the above-described non-ground node (eg, non-ground cell) may be a base station. Non-ground nodes are NodeB, evolved NodeB, base transceiver station (BTS), radio base station, radio transceiver, access point, and access node. It may be referred to as (node), road side unit (RSU), radio remote head (RRH), transmission point (TP), transmission & reception point (TRP), or gNB.

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

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 in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like alone or in combination. The program instructions recorded on the computer-readable medium may be specially designed and configured for the present invention, or may be known and usable to those skilled in computer software.

Examples of computer-readable media include hardware devices specially configured to store and execute program instructions, such as rom, ram, flash memory, and the like. Examples of program instructions include not only machine language codes such as those produced by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The above-described hardware device may be configured to operate as at least one software module to perform the operation of the present invention, and vice versa.

Although described with reference to the above embodiments, those skilled in the art will understand that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention described in the following claims. I will be able to.

Claims (1)

As a method of operating a terminal in a non-terrestrial network,
Transmitting a first message including a random access (RA) preamble to a non-ground node in a random access procedure;
Performing a downlink monitoring operation in an RA response window starting after a first offset from a transmission point of the first message; And
Receiving a second message in response to the first message from the non-ground node by the downlink monitoring operation,
The first offset is set in consideration of a minimum transmission delay between the non-ground node and terminals located in a cell formed by the non-ground node, and the RA response window is the minimum transmission delay and the non-ground node And the maximum transmission delay difference between the terminals.

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