Method and apparatus for performing random access to non-terrestrial network base station in wireless communication system

Abstract

The present disclosure relates to a method and an apparatus for performing random access in a wireless communication system. This operation method of a terminal comprises: receiving system information including information related to random access to a non-terrestrial network (NTN) base station; transmitting a random access preamble to the NTN base station; receiving a random access response message from the NTN base station; transmitting a first message for a connection setup through a resource scheduled on the basis of the random access response message; and receiving a second message for the connection setup from the NTN base station, wherein the random access response message includes timing advance (TA) information, the system information or the random access response message includes information for TA compensation, and the first message may be transmitted at a timing determined by applying the TA information and the information for TA compensation.

Description

Method and device for performing random access to a non-terrestrial network base station in a wireless communication system

[0001] The present disclosure relates to a method and device for performing random access in a wireless communication system, and more specifically, to a random access method and device for a terminal supporting non-terrestrial network (NTN) communication.

[0002] Communication networks (e.g., 5G communication networks, 6G communication networks, etc.) are being developed to provide improved communication services compared to existing communication networks (e.g., long term evolution (LTE) and advanced LTE-A). 5G communication networks (e.g., new radio (NR) communication networks) can support frequency bands above 6 GHz as well as frequency bands below 6 GHz. That is, 5G communication networks can support FR1 bands and / or FR2 bands. 5G communication networks can support a variety of communication services and scenarios compared to LTE communication networks. For example, usage scenarios of 5G communication networks may include enhanced Mobile Broadband (eMBB), Ultra Reliable Low Latency Communication (URLLC), and massive Machine Type Communication (mMTC).

[0003] Compared to 5G, 6G communication networks can support a wider range of communication services and scenarios. 6G communication networks can meet requirements for ultra-high performance, ultra-high bandwidth, ultra-high space, ultra-high precision, ultra-intelligence, and / or ultra-reliability. 6G communication networks can support diverse and wide frequency bands and be applied to various usage scenarios (e.g., terrestrial communications, non-terrestrial communications, sidelink communications, etc.).

[0004] Compared to 5G, 6G communication networks can support a wider range of communication services and scenarios. 6G communication networks can meet requirements for ultra-high performance, ultra-high bandwidth, ultra-high space, ultra-high precision, ultra-intelligence, and / or ultra-reliability. 6G communication networks can support diverse and wide frequency bands and be applied to various usage scenarios (e.g., terrestrial communications, non-terrestrial communications, sidelink communications, etc.).

[0005] Communication networks (e.g., 5G communication networks, 6G communication networks, etc.) can provide communication services to terminals located on the ground. Demand for communication services for not only terrestrial but also non-terrestrial devices such as airplanes, drones, and satellites is increasing, and technologies for non-terrestrial networks (NTNs) are being discussed to meet this demand. Non-terrestrial networks can be implemented based on 5G communication technologies, 6G communication technologies, etc. For example, in a non-terrestrial network, communication between a satellite and a communication node located on the ground, or between a communication node located on the ground (e.g., airplanes, drones, etc.) can be performed based on 5G communication technologies, 6G communication technologies, etc. In a non-terrestrial network, a satellite can perform the function of a base station in a communication network (e.g., 5G communication networks, 6G communication networks, etc.).

[0006] Meanwhile, the technology that serves as the background for the invention is written to promote understanding of the background for the invention, and may include content that is not a prior art already known to a person with ordinary skill in the field to which the technology belongs.

[0007] The present disclosure may provide a device and method for performing a random access procedure in a wireless communication system supporting a non-terrestrial network (NTN).

[0008] The present disclosure may provide a device and method for pre-compensating an uplink TA (timing advance) during a random access procedure in a wireless communication system.

[0009] The present disclosure may provide a device and method for transmitting information for TA compensation in a wireless communication system.

[0010] The present disclosure can provide a device and method for determining an uplink TA based on information for TA compensation in a wireless communication system.

[0011] The present disclosure may provide a device and method for transmitting at least one of TAC (timing advance command) adjustment coefficient information or TA pre-compensation value information in a wireless communication system.

[0012] The present disclosure may provide a device and method for determining an uplink TA based on at least one of TAC adjustment coefficient information or TA pre-compensation value information in a wireless communication system.

[0013] The present disclosure may provide a device and method for determining an uplink TA based on TAC adjustment coefficient information and / or TA pre-compensation value information in a wireless communication system.

[0014] The present disclosure can provide a device and method for retransmitting a random access preamble by correcting a TA pre-compensation value when a random access procedure failure is detected in a wireless communication system.

[0015] The present disclosure may provide a device and method for transmitting random access suspension indication information in a wireless communication system.

[0016] The present disclosure can provide a device and method for terminating or temporarily waiting a random access procedure based on random access suspension indication information in a wireless communication system.

[0017] The technical objectives to be achieved in the present disclosure are not limited to those mentioned above, and other technical tasks not mentioned can be considered by a person having ordinary skill in the technical field to which the technical configuration of the present disclosure is applied from the embodiments of the present disclosure described below.

[0018] According to one embodiment of the present disclosure, a method of operating a terminal in a wireless communication system includes receiving system information including information on random access to a non-terrestrial network (NTN) base station, transmitting a random access preamble to the NTN base station, receiving a random access response message from the NTN base station, transmitting a first message for establishing a connection through a resource scheduled by the random access response message, and receiving a second message for establishing a connection from the NTN base station, wherein the random access response message includes TA (timing advance) information, the system information or the random access response message includes information for TA compensation, and the first message can be transmitted at a timing determined by applying the TA information and the information for TA compensation.

[0019] According to one embodiment of the present disclosure, a method for operating a non-terrestrial network (NTN) base station in a wireless communication system includes transmitting system information including information on random access to the NTN base station to a terminal, receiving a random access preamble from the terminal, transmitting a random access response message to the terminal, receiving a first message for establishing a connection through a resource scheduled by the random access response message, and transmitting a second message for establishing a connection to the terminal, wherein the random access response message includes timing advance (TA) information, the system information or the random access response message includes information for TA compensation, and the first message can be transmitted at a timing determined by applying the TA information and the information for TA compensation in the terminal.

[0020] According to one embodiment of the present disclosure, in a wireless communication system, a terminal includes at least one transceiver, at least one processor, and at least one memory operably connected to the at least one processor and storing instructions that, when executed by the processor, control the terminal to perform operations, the operations including receiving system information including information on random access to a non-terrestrial network (NTN) base station, transmitting a random access preamble to the NTN base station, receiving a random access response message from the NTN base station, transmitting a first message for establishing a connection through a resource scheduled by the random access response message, and receiving a second message for establishing a connection from the NTN base station, wherein the random access response message includes timing advance (TA) information, and the system information or the random access response message includes information for TA compensation, and the first message can be transmitted at a timing determined by applying the TA information and the information for TA compensation.

[0021] According to one embodiment of the present disclosure, in a wireless communication system, a non-terrestrial network (NTN) base station includes at least one transceiver, at least one processor, and at least one memory operably connected to the at least one processor and storing instructions that, when executed by the processor, control the terminal to perform operations, wherein the operations include transmitting system information including information on random access to the NTN base station to the terminal, receiving a random access preamble from the terminal and transmitting a random access response message to the terminal, receiving a first message for establishing a connection through a resource scheduled by the random access response message, and transmitting a second message for establishing a connection to the terminal, wherein the random access response message includes timing advance (TA) information, and the system information or the random access response message includes information for TA compensation, and the first message can be transmitted at a timing determined by applying the TA information and the information for TA compensation in the terminal.

[0022] According to the present disclosure, it is possible to prevent uplink performance degradation and resource waste due to TA (timing advance) pre-compensation error in a wireless communication system.

[0023] The effects that can be obtained from the embodiments of the present disclosure are not limited to the effects mentioned above, and other effects not mentioned can be clearly derived and understood by those skilled in the art to which the technical configuration of the present disclosure is applied, from the description of the embodiments of the present disclosure below. In other words, unintended effects resulting from implementing the configuration described in the present disclosure can also be derived by those skilled in the art from the embodiments of the present disclosure.

[0024] FIG. 1A and FIG. 1B illustrate the structure of a transparent-based non-terrestrial network according to an embodiment of the present disclosure.

[0025] FIGS. 2A to 2C illustrate the structure of a regenerative-based non-terrestrial network according to an embodiment of the present disclosure.

[0026] FIG. 3 illustrates a block diagram of a communication node constituting a non-terrestrial network according to an embodiment of the present disclosure.

[0027] FIG. 4 illustrates a block diagram of a communication node according to an embodiment of the present disclosure.

[0028] FIGS. 5A and 5B illustrate block diagrams of a transmission path and a reception path of a communication node according to an embodiment of the present disclosure.

[0029] FIG. 6 illustrates an example of a system frame in a wireless communication system according to an embodiment of the present disclosure.

[0030] FIG. 7 illustrates an example of a subframe in a wireless communication system according to an embodiment of the present disclosure.

[0031] FIG. 8 illustrates an example of a slot in a wireless communication system according to an embodiment of the present disclosure.

[0032] FIG. 9 illustrates the timing relationship between uplink and downlink in a wireless communication system according to an embodiment of the present disclosure.

[0033] FIG. 10A and FIG. 10B illustrate examples of protocol stacks of a user plane and a control plane in a non-terrestrial network based on transparent payload in a wireless communication system according to an embodiment of the present disclosure.

[0034] FIG. 11A and FIG. 11B illustrate examples of protocol stacks of a user plane and a control plane in a non-terrestrial network based on regenerative payload in a wireless communication system according to an embodiment of the present disclosure.

[0035] Figure 12 illustrates an example of an NTN providing non-terrestrial NR access to a UE by means of an NTN payload and an NTN gateway.

[0036] Figure 13 illustrates the timing relationship between objects included in NTN.

[0037] FIG. 14a illustrates an example of applying TA (timing advance) based on TAC (timing advance command) in a wireless communication system according to an embodiment of the present disclosure.

[0038] FIG. 4b illustrates an example of applying TA pre-compensation in an NTN system in a wireless communication system according to an embodiment of the present disclosure.

[0039] FIG. 14c illustrates an example of a random access procedure in a wireless communication system according to an embodiment of the present disclosure.

[0040] FIG. 15 illustrates an example of a procedure for performing random access to a base station in a wireless communication system according to an embodiment of the present disclosure.

[0041] FIG. 16 illustrates an example of a procedure for performing random access with a terminal in a wireless communication system according to an embodiment of the present disclosure.

[0042] FIG. 17 illustrates an example of a procedure for determining uplink transmission timing based on a TAC adjustment coefficient in a wireless communication system according to an embodiment of the present disclosure.

[0043] FIG. 18a and FIG. 18b illustrate examples of application of the first type of TAC adjustment coefficient in a wireless communication system according to an embodiment of the present disclosure.

[0044] FIG. 19a and FIG. 19b illustrate examples of application of a second type of TAC adjustment coefficient in a wireless communication system according to an embodiment of the present disclosure.

[0045] FIG. 20A and FIG. 20B illustrate examples of simultaneous application of a first type of TAC adjustment factor and a second type of TAC adjustment factor in a wireless communication system according to an embodiment of the present disclosure.

[0046] FIG. 21 illustrates an example of available bits of a random access response message in a wireless communication system according to an embodiment of the present disclosure.

[0047] FIG. 22 illustrates an example of bit allocation for a TAC adjustment coefficient in a random access response message in a wireless communication system according to an embodiment of the present disclosure.

[0048] FIG. 23 illustrates an example of a procedure for determining uplink transmission timing based on a TA pre-compensation value in a wireless communication system according to an embodiment of the present disclosure.

[0049] FIG. 24 is an example of transmission and application of a first type base station estimated TA pre-compensation value in a wireless communication system according to an embodiment of the present disclosure.

[0050] FIG. 25 illustrates an example of uplink TA determination according to application of a first type of base station estimated TA pre-compensation value in a wireless communication system according to an embodiment of the present disclosure.

[0051] FIG. 26 illustrates an example of transmission and application of a second type of base station estimated TA pre-compensation value in a wireless communication system according to an embodiment of the present disclosure.

[0052] FIG. 27 illustrates an example of uplink TA determination according to application of a second type of base station estimated TA pre-compensation value in a wireless communication system according to an embodiment of the present disclosure.

[0053] FIG. 28 illustrates an example of applying a first type base station estimated TA pre-compensation value and a second type base station pre-compensation value in a wireless communication system according to an embodiment of the present disclosure.

[0054] FIG. 29 illustrates an example of a procedure for correcting a TA pre-compensation value in a wireless communication system according to an embodiment of the present disclosure.

[0055] FIG. 30 illustrates an example of a procedure for correcting a TA pre-compensation value during a random access procedure in a wireless communication system according to an embodiment of the present disclosure.

[0056] FIGS. 31A to 31C illustrate examples of application of types for TA pre-compensation correction in a wireless communication system according to an embodiment of the present disclosure.

[0057] FIG. 32 illustrates an example of a random access procedure based on random access suspension indication information in a wireless communication system according to an embodiment of the present disclosure.

[0058] FIG. 33 illustrates an example of a first type of random access interruption information application procedure in a wireless communication system according to an embodiment of the present disclosure.

[0059] FIG. 34 illustrates an example of transmitting and applying a first type of random access interruption indication information in a wireless communication system according to an embodiment of the present disclosure.

[0060] FIG. 35 illustrates an example of a second type of random access interruption information application procedure in a wireless communication system according to an embodiment of the present disclosure.

[0061] FIG. 36 illustrates an example of transmitting and applying a second type of random access interruption indication information in a wireless communication system according to an embodiment of the present disclosure.

[0062] This disclosure may be subject to various modifications and various embodiments. Specific embodiments are illustrated and described in detail in the drawings. However, this is not intended to limit the disclosure to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the disclosure.

[0063] While terms such as "first" and "second" may be used to describe various components, these components should not be limited by these terms. These terms are used solely to distinguish one component from another. For example, without departing from the scope of the present disclosure, a first component could be referred to as a "second component," and similarly, a second component could also be referred to as a "first component." The term "and / or" may refer to a combination of multiple related items described herein or to any of multiple related items described herein.

[0064] In the present disclosure, “at least one of A and B” may mean “at least one of A or B” or “at least one of combinations of one or more of A and B.” Additionally, in the present disclosure, “at least one of A and B” may mean “at least one of A or B” or “at least one of combinations of one or more of A and B.”

[0065] In the present disclosure, (re)transmission may mean “transmission,” “retransmission,” or “transmission and retransmission,” (re)setting may mean “setting,” “resetting,” or “setting and resetting,” (re)connection may mean “connection,” “reconnection,” or “connection and reconnection,” and (re)connection may mean “connection,” “reconnection,” or “connection and reconnection.”

[0066] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0067] The terminology used in this disclosure is only used to describe specific embodiments and is not intended to limit the present disclosure. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this disclosure, it should be understood that the terms "comprises" or "has" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0068] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which this disclosure pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0069] Hereinafter, preferred embodiments of the present disclosure will be described in more detail with reference to the attached drawings. In order to facilitate an overall understanding in describing the present disclosure, the same reference numerals will be used for identical components in the drawings, and redundant descriptions of identical components will be omitted. In addition to the embodiments explicitly described in the present disclosure, operations may be performed according to combinations of embodiments, extensions of embodiments, and / or modifications of embodiments. The performance of some operations may be omitted, and the order of operation may be changed.

[0070] In an embodiment, even if a method (e.g., transmitting or receiving a signal) performed by a first communication node among communication nodes is described, a corresponding second communication node can perform a method (e.g., receiving or transmitting a signal) corresponding to the method performed by the first communication node. That is, if an operation of a UE (user equipment) is described, a corresponding base station can perform an operation corresponding to the operation of the UE. Conversely, if an operation of a base station is described, a corresponding UE can perform an operation corresponding to the operation of the base station.

[0071] A base station may be referred to as a NodeB, an evolved NodeB, a gNodeB (next generation node B), a gNB, a device, an apparatus, a node, a communication node, a BTS (base transceiver station), a RRH (radio remote head), a TRP (transmission reception point), a RU (radio unit), an RSU (road side unit), a radio transceiver, an access point, an access node, etc. A UE may be referred to as a terminal, a device, an apparatus, a node, a communication node, an end node, an access terminal, a mobile terminal, a station, a subscriber station, a mobile station, a portable subscriber station, an OBU (on-broad unit), etc.

[0072] In the present disclosure, signaling may be at least one of upper layer signaling, MAC signaling, or PHY (physical) signaling. A message used for upper layer signaling may be referred to as an "upper layer message" or an "upper layer signaling message." A message used for MAC signaling may be referred to as a "MAC message" or a "MAC signaling message." A message used for PHY signaling may be referred to as a "PHY message" or a "PHY signaling message." Upper layer signaling may refer to a transmission and reception operation of system information (e.g., a master information block (MIB), a system information block (SIB)) and / or an RRC message. MAC signaling may refer to a transmission and reception operation of a MAC control element (CE). PHY signaling may refer to a transmission and reception operation of control information (e.g., downlink control information (DCI), uplink control information (UCI), sidelink control information (SCI)).

[0073] In the present disclosure, “an operation (e.g., a transmission operation) is set” may mean that “setting information for the operation (e.g., an information element, a parameter)” and / or “information instructing the performance of the operation” is signaled. “An information element (e.g., a parameter) is set” may mean that the information element is signaled. In the present disclosure, “a signal and / or a channel” may mean a signal, a channel, or “a signal and a channel,” and a signal may be used to mean “a signal and / or a channel.”

[0074] The communication system may include at least one of a terrestrial network, a non-terrestrial network, a 4G communication network (e.g., a long-term evolution (LTE) communication network), a 5G communication network (e.g., a new radio (NR) communication network), or a 6G communication network. Each of the 4G communication network, the 5G communication network, and the 6G communication network may include a terrestrial network and / or a non-terrestrial network. The non-terrestrial network may operate based on at least one communication technology among the LTE communication technology, the 5G communication technology, and the 6G communication technology. The non-terrestrial network may provide communication services in various frequency bands.

[0075] The communication networks to which the embodiments are applied are not limited to those described below, and the embodiments may be applied to various communication networks (e.g., 4G communication networks, 5G communication networks, and / or 6G communication networks). Here, the term "communication network" may be used interchangeably with the term "communication system."

[0076] FIG. 1A and FIG. 1B illustrate the structure of a transparent-based non-terrestrial network (NTN) according to an embodiment of the present disclosure.

[0077] Referring to FIG. 1A, the NTN may include a satellite (110), a communication node (120), a gateway (130), a data network (140), etc. The unit including the satellite (110) and the gateway (130) may be a remote radio unit (RRU). The satellite (110) 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 non-GEO satellite may be a LEO satellite and / or a MEO satellite.

[0078] The communication node (120) may include ground-based devices (e.g., UE, terminal) and non-ground-based devices (e.g., airplanes, drones). A service link may be established between the satellite (110) and the communication node (120), and the service link may be a radio link. The satellite (110) may be referred to as an NTN payload. The gateway (130) may support multiple NTN payloads. The satellite (110) may provide a communication service to the communication node (120) using one or more beams. The shape of the beam footprint of the satellite (110) may be elliptical or circular.

[0079] In non-terrestrial networks, three types of service links can be supported:

[0080] - Earth-fixed: The service link may be provided by beam(s) that continuously cover the same geographic area at all times (e.g. Geosynchronous Orbit (GSO) satellites).

[0081] - Quasi-earth-fixed: The service link may be provided by beam(s) that cover one geographic area for a limited period and another geographic area for a different period (e.g., NGSO (non-GSO) satellites that produce steerable beams).

[0082] - Earth-moving: The service link may be provided by beam(s) moving over the Earth's surface (e.g., NGSO satellites producing fixed beams or non-steerable beams).

[0083] The communication node (120) can perform communication (e.g., downlink communication, uplink communication) with the satellite (110) using 4G communication technology, 5G communication technology, and / or 6G communication technology. Communication between the satellite (110) and the communication node (120) can be performed using an NR-Uu interface and / or a 6G-Uu interface. When DC (dual connectivity) is supported, the communication node (120) can be connected to not only the satellite (110) but also other base stations (e.g., base stations supporting 4G functions, 5G functions, and / or 6G functions), and can perform DC operations based on technologies defined in the 4G standard, the 5G standard, and / or the 6G standard.

[0084] The gateway (130) may be located on the ground, and a feeder link may be established between the satellite (110) and the gateway (130). The feeder link may be a wireless link. The gateway (130) may be referred to as a "non-terrestrial network (NTN) gateway." Communication between the satellite (110) and the gateway (130) may be performed based on an NR-Uu interface, a 6G-Uu interface, or a satellite radio interface (SRI). The gateway (130) may be connected to a data network (140). A "core network" may exist between the gateway (130) and the data network (140). In this case, the gateway (130) may be connected to the core network, and the core network may be connected to the data network (140). The core network may support 4G communication technology, 5G communication technology, and / or 6G communication technology. For example, the core network may include an access and mobility management function (AMF), a user plane function (UPF), a session management function (SMF), etc. Communication between the gateway (130) and the core network may be performed based on a NG-C / U interface or a 6G-C / U interface.

[0085] As in the embodiment of Fig. 1b below, in a non-terrestrial network based on transparent payload, a base station and a core network may exist between a gateway (130) and a data network (140).

[0086] Referring to FIG. 1B, a gateway may be connected to a base station, the base station may be connected to a core network, and the core network may be connected to a data network. Each of the base station and the core network may support 4G communication technology, 5G communication technology, and / or 6G communication technology. Communication between the gateway and the base station may be performed based on a NR-Uu interface or a 6G-Uu interface, and communication between the base station and the core network (e.g., AMF, UPF, SMF) may be performed based on a NG-C / U interface or a 6G-C / U interface.

[0087] FIGS. 2A to 2C illustrate the structure of a regenerative-based non-terrestrial network according to an embodiment of the present disclosure.

[0088] Referring to FIG. 2A, the non-terrestrial network may include satellite #1 (211), satellite #2 (212), communication node (220), gateway (230), data network (1240), etc. The non-terrestrial network illustrated in FIG. 2A may be a regenerative payload-based non-terrestrial network. For example, each of satellite #1 (211) and satellite #2 (212) may perform a regenerative operation (e.g., a demodulation operation, a decoding operation, a re-encoding operation, a re-modulation operation, and / or a filtering operation) on a payload received from another entity constituting the non-terrestrial network (e.g., a communication node (220), a gateway (230)) and transmit the regenerated payload.

[0089] Each of satellite #1 (211) and satellite #2 (212) may be a LEO satellite, MEO satellite, GEO satellite, HEO satellite, or UAS platform. The UAS platform may include HAPS. Satellite #1 (211) may be connected to satellite #2 (212), and an inter-satellite link (ISL) may be established between satellite #1 (211) and satellite #2 (212). The ISL may operate in a radio frequency (RF) frequency or an optical band. The ISL may be configured as optional. The communication node (220) may include a ground-based communication node (e.g., UE, terminal) and a non-ground-based communication node (e.g., airplane, drone). A service link (e.g., wireless link) may be established between satellite #1 (211) and the communication node (220). Satellite #1 (211) may be referred to as an NTN payload. Satellite #1 (211) can provide communication services to a communication node (220) using one or more beams.

[0090] The communication node (220) can perform communication (e.g., downlink communication, uplink communication) with satellite #1 (211) using 4G communication technology, 5G communication technology, and / or 6G communication technology. Communication between satellite #1 (211) and the communication node (220) can be performed using an NR-Uu interface or a 6G-Uu interface. When DC is supported, the communication node (220) can be connected to other base stations (e.g., base stations supporting 4G functions, 5G functions, and / or 6G functions) as well as satellite #1 (211), and can perform DC operations based on technologies defined in the 4G standard, the 5G standard, and / or the 6G standard.

[0091] The gateway (230) may be located on the ground, and a feeder link may be established between satellite #1 (211) and the gateway (230), and a feeder link may be established between satellite #2 (212) and the gateway (230). The feeder link may be a wireless link. If an ISL is not established between satellite #1 (211) and satellite #2 (212), a feeder link between satellite #1 (211) and the gateway (230) may be established mandatorily. Communication between each of satellite #1 (211) and satellite #2 (212) and the gateway (230) may be performed based on an NR-Uu interface, a 6G-Uu interface, or SRI. The gateway (230) may be connected to a data network (240).

[0092] As in the embodiments of FIGS. 2b and 2c below, a “core network” may exist between the gateway (230) and the data network (240).

[0093] Referring to FIGS. 2B and 2C, a gateway may be connected to a core network, and the core network may be connected to a data network. The core network may support 4G communication technology, 5G communication technology, and / or 6G communication technology. For example, the core network may include AMF, UPF, SMF, etc. Communication between the gateway and the core network may be performed based on an NG-C / U interface or a 6G-C / U interface. The function of the base station may be performed by a satellite. That is, the base station may be located on a satellite. Payloads may be processed by a base station located on a satellite. Base stations located on different satellites may be connected to the same core network. A single satellite may have one or more base stations. In the non-terrestrial network of FIG. 2B, an ISL between satellites may not be established, and in the non-terrestrial network of FIG. 2C, an ISL between satellites may be established.

[0094] Meanwhile, entities (e.g., satellites, base stations, UEs, communication nodes, gateways, etc.) constituting the non-terrestrial network illustrated in FIGS. 1a, 1b, 2a, 2b, and / or 2c may be configured as follows. In the present disclosure, entities may be referred to as communication nodes.

[0095] FIG. 3 illustrates a block diagram of a communication node constituting a non-terrestrial network according to an embodiment of the present disclosure.

[0096] FIG. 3 illustrates an example of a wireless device (300) in a wireless communication system according to one embodiment of the present disclosure. The wireless device (300) according to the embodiment of the present disclosure may be a mobile terminal such as a smartphone, tablet PC, or wearable device, but is not limited thereto.

[0097] Referring to FIG. 3, the wireless device (300) may include at least one control unit (310), at least one memory (320), at least one power unit (330), at least one transceiver unit (340), at least one input unit (350), at least one output unit (360), and / or at least one antenna (370).

[0098] The control unit (310) can control the memory (320) and / or the transceiver (340), and can be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in the present disclosure. The memory (320) can be connected to the control unit (310) and can store various information related to the operation of the control unit (310). For example, the memory (320) can perform some or all of the controls controlled by the control unit (310), or store software code including commands for performing the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in the present disclosure. The configuration of the memory is not limited in a specific manner. For example, it can be configured as at least one of a read-only memory (ROM) and a random access memory (RAM).

[0099] At least one control unit (310) may be referred to as a controller, a microcontroller, a microprocessor, or a microcomputer. The descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure may be implemented using firmware or software in the form of codes, instructions, and / or a set of instructions. Here, the firmware or software may execute another program stored in the memory (320), such as an OS. The control unit (310) may be implemented to support beamforming or directional routing operations in which signals from at least one antenna (370) are weighted differently to effectively steer signals outgoing in a desired direction.

[0100] Additionally, at least one control unit (310) may be coupled to a backhaul or network interface. The wireless device (300) may communicate with other wireless devices through the backhaul or network interface. The control unit (310) may include at least one processor. The processor may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which methods according to embodiments of the present disclosure are performed.

[0101] At least one transceiver (340) may be connected to the control unit (310) and may transmit and / or receive a wireless signal via at least one antenna (370). The transceiver (340) may include a transmitter and / or a receiver. The at least one transceiver (340) may transmit user data, control information, wireless signals / channels, etc. mentioned in the methods and / or operation flowcharts of the present disclosure to at least one other device. For example, the at least one transceiver (340) may be connected to at least one control unit (310) and may transmit and receive wireless signals. In addition, the at least one control unit (310) may control the at least one transceiver (340) to transmit user data, control information, or wireless signals to at least one other device. The at least one transmitter (340) may receive a signal transmitted by another wireless device from at least one antenna (370). Additionally, at least one transceiver (340) may downconvert or upconvert the received signal to generate a baseband signal. At least one antenna (370) may be a plurality of physical antennas or a plurality of logical antennas (e.g., antenna ports).

[0102] The input unit (350) can obtain information such as user input, video, and audio, and may include various input means such as various mechanical / electronic input means, cameras, and microphones. The output unit (360) is for providing information to users by generating output related to sight, hearing, or touch, and may include a display, a speaker, a vibration module, and the like. The wireless device (300) supplies power through the power supply unit (330), and the power supply unit (330) may include a wired / wireless charging circuit, a battery, and the like.

[0103] FIG. 4 illustrates a block diagram of a communication node according to an embodiment of the present disclosure.

[0104] Referring to FIG. 4, each of the first communication node (400a) and the second communication node (400b) may be a base station or a UE. The first communication node (400a) may transmit a signal to the second communication node (400b). The transmission processor (411) included in the first communication node (400a) may receive data (e.g., a data unit) from a data source (410). The transmission processor (411) may receive control information from a controller (416). The control information may include at least one of system information, RRC configuration information (e.g., information configured by RRC signaling), MAC control information (e.g., MAC CE), or PHY control information (e.g., DCI, SCI).

[0105] The transmitting processor (411) may perform a processing operation (e.g., an encoding operation, a symbol mapping operation, etc.) on data to generate data symbol(s). The transmitting processor (411) may perform a processing operation (e.g., an encoding operation, a symbol mapping operation, etc.) on control information to generate control symbol(s). In addition, the transmitting processor (411) may generate synchronization / reference symbol(s) for a synchronization signal and / or a reference signal.

[0106] The Tx MIMO processor (412) may perform spatial processing operations (e.g., precoding operations) on data symbol(s), control symbol(s), and / or synchronization / reference symbol(s). The output (e.g., symbol stream) of the Tx MIMO processor (412) may be provided to modulators (MODs) included in the transceivers (413a to 413t). The modulators (MODs) may perform processing operations on the symbol streams to generate modulation symbols, and may perform additional processing operations (e.g., analog conversion operations, amplification operations, filtering operations, upconversion operations) on the modulation symbols to generate signals. The signals generated by the modulators (MODs) of the transceivers (413a to 413t) may be transmitted via the antennas (414a to 414t).

[0107] Signals transmitted by the first communication node (400a) may be received by antennas (464a to 464r) of the second communication node (400b). Signals received by the antennas (464a to 464r) may be provided to demodulators (DEMODs) included in transceivers (463a to 463r). The demodulator (DEMOD) may perform a processing operation (e.g., a filtering operation, an amplification operation, a downconversion operation, a digital conversion operation) on the signal to obtain samples. The demodulator (DEMOD) may perform an additional processing operation on the samples to obtain symbols. The MIMO detector (462) may perform a MIMO detection operation on the symbols. The receiving processor (461) may perform a processing operation (e.g., a deinterleaving operation, a decoding operation) on the symbols. The output of the receiving processor (461) may be provided to a data sink (460) and a controller (466). For example, data may be provided to the data sink (460) and control information may be provided to the controller (466).

[0108] Meanwhile, the second communication node (400b) can transmit a signal to the first communication node (400a). The transmitting processor (468) included in the second communication node (400b) can receive data (e.g., data units) from a data source (467) and perform a processing operation on the data to generate data symbol(s). The transmitting processor (468) can receive control information from the controller (466) and perform a processing operation on the control information to generate control symbol(s). In addition, the transmitting processor (468) can perform a processing operation on a reference signal to generate reference symbol(s).

[0109] The Tx MIMO processor (469) may perform spatial processing operations (e.g., precoding operations) on data symbol(s), control symbol(s), and / or reference symbol(s). The output (e.g., symbol stream) of the Tx MIMO processor (469) may be provided to modulators (MODs) included in the transceivers (463a to 463t). The modulators (MODs) may perform processing operations on the symbol streams to generate modulation symbols, and may perform additional processing operations (e.g., analog conversion operations, amplification operations, filtering operations, upconversion operations) on the modulation symbols to generate signals. The signals generated by the modulators (MODs) of the transceivers (463a to 463t) may be transmitted via the antennas (464a to 464t).

[0110] Signals transmitted by the second communication node (400b) may be received by the antennas (414a to 414r) of the first communication node (400a). The signals received by the antennas (414a to 414r) may be provided to demodulators (DEMODs) included in the transceivers (413a to 413r). The demodulator (DEMOD) may perform a processing operation (e.g., a filtering operation, an amplification operation, a downconversion operation, a digital conversion operation) on the signal to obtain samples. The demodulator (DEMOD) may perform an additional processing operation on the samples to obtain symbols. The MIMO detector (420) may perform a MIMO detection operation on the symbols. The receiving processor (419) may perform a processing operation (e.g., a deinterleaving operation, a decoding operation) on the symbols. The output of the receiving processor (419) may be provided to a data sink (418) and a controller (416). For example, data may be provided to the data sink (418) and control information may be provided to the controller (416).

[0111] Memories (415 and 465) can store data, control information, and / or program code. Scheduler (417) can perform scheduling operations for communication. Processors (411, 412, 419, 461, 468, 469) and controllers (416, 466) illustrated in FIG. 4 may be the processor (310) illustrated in FIG. 3 and may be used to perform the methods described in the present disclosure.

[0112] FIGS. 5A and 5B illustrate block diagrams of a transmission path and a reception path of a communication node according to an embodiment of the present disclosure.

[0113] Referring to FIGS. 5A and 5B, a transmission path (510) may be implemented in a communication node that transmits a signal, and a reception path (520) may be implemented in a communication node that receives a signal. The transmission path (510) may include a channel coding and modulation block (511), an S-to-P (serial-to-parallel) block (512), an N IFFT (Inverse Fast Fourier Transform) block (513), a P-to-S (parallel-to-serial) block (514), a CP (cyclic prefix) addition block (515), and an UC (up-converter) (UC) (516). The receiving path (520) may include a DC (down-converter) (521), a CP removal block (522), an S-to-P block (523), an N FFT block (524), a P-to-S block (525), and a channel decoding and demodulation block (526). Here, N may be a natural number.

[0114] In the transmission path (510), information bits may be input to a channel coding and modulation block (511). The channel coding and modulation block (511) may perform a coding operation (e.g., low-density parity check (LDPC) coding operation, polar coding operation, etc.) and a modulation operation (e.g., quadrature phase shift keying (QPSK), quadrature amplitude modulation (QAM), etc.) on the information bits. The output of the channel coding and modulation block (511) may be a sequence of modulation symbols.

[0115] The S-to-P block (512) can convert modulation symbols in the frequency domain into parallel symbol streams to generate N parallel symbol streams. N can be an IFFT size or an FFT size. The N IFFT block (513) can perform an IFFT operation on the N parallel symbol streams to generate signals in the time domain. The P-to-S block (514) can convert the output (e.g., parallel signals) of the N IFFT block (513) into a serial signal to generate a serial signal.

[0116] The CP addition block (515) can insert a CP into a signal. The UC (516) can up-convert the frequency of the output of the CP addition block (515) to an RF (radio frequency) frequency. Additionally, the output of the CP addition block (515) can be filtered at the baseband before up-conversion.

[0117] A signal transmitted from a transmission path (510) may be input to a reception path (520). An operation in the reception path (520) may be the reverse operation of the operation in the transmission path (510). A DC (521) may down-convert the frequency of the received signal to a baseband frequency. A CP removal block (522) may remove a CP from a signal. The output of the CP removal block (522) may be a serial signal. An S-to-P block (523) may convert the serial signal into parallel signals. An NFFT block (524) may perform an FFT algorithm to generate N parallel signals. A P-to-S block (525) may convert the parallel signals into a sequence of modulation symbols. A channel decoding and demodulation block (526) may perform a demodulation operation on the modulation symbols and perform a decoding operation on the result of the demodulation operation to restore data.

[0118] In FIGS. 5A and 5B , Discrete Fourier Transform (DFT) and Inverse DFT (IDFT) may be used instead of FFT and IFFT. Each of the blocks (e.g., components) in FIGS. 5A and 5B may be implemented by at least one of hardware, software, or firmware. For example, in FIGS. 5A and 5B , some blocks may be implemented by software, and the remaining blocks may be implemented by hardware or a “combination of hardware and software.” In FIGS. 5A and 5B , a single block may be subdivided into multiple blocks, multiple blocks may be integrated into a single block, some blocks may be omitted, and blocks supporting other functions may be added.

[0119] FIG. 6 illustrates an example of a system frame in a wireless communication system according to an embodiment of the present disclosure.

[0120] Referring to Figure 6, time resources in a communication system can be divided into frame units. For example, system frames can be set consecutively in the time domain of the communication system. The length of a system frame can be 10 ms (milliseconds). The system frame number (SFN) can be set from #0 to #1023. In this case, 1024 system frames can be repeated in the time domain of the communication system. For example, the SFN of the system frame after system frame #1023 can be #0.

[0121] A system frame may include two half frames. A half frame may be 5 ms long. A half frame located at the beginning of the system frame may be referred to as "half frame #0," and a half frame located at the end of the system frame may be referred to as "half frame #1." A system frame may include 10 subframes. A subframe may be 1 ms long. The 10 subframes within a system frame may be referred to as "subframes #0-9."

[0122] FIG. 7 illustrates an example of a subframe in a wireless communication system according to an embodiment of the present disclosure.

[0123] Referring to Fig. 7, one subframe can include n slots, where n can be a natural number. Therefore, one subframe can be composed of one or more slots.

[0124] FIG. 8 illustrates an example of a slot in a wireless communication system according to an embodiment of the present disclosure.

[0125] Referring to Figure 8, a single slot may contain one or more symbols. A single slot, as illustrated in Figure A-8, may contain 14 symbols. The length of a slot may vary depending on the number and length of symbols contained in the slot. Alternatively, the length of a slot may vary depending on the numerology.

[0126] In a communication system, the numerology applied to physical signals and channels can be variable. The numerology can be variable to meet various technical requirements of the communication system. In a communication system applying CP (cyclic prefix)-based OFDM waveform technology, the numerology can include subcarrier spacing and CP length (or CP type). [Table 1] may be an embodiment of a method for configuring a numerology for a CP-OFDM-based communication system. At least some of the numerologies in [Table 1] may be supported depending on the frequency band in which the communication system operates. In addition, the communication system may additionally support numerologies not listed in [Table 1].

[0127] Subcarrier spacing 15kHz 30kHz 60kHz 120kHz 240kHz 480kHz OFDM symbol length [μs] 66.733.316.78.34.22.1 CP length [us] 4.762.381.190.600.300.151 Number of OFDM symbols in ms 142856112224448

[0128] When the subcarrier spacing is 15 kHz (e.g., μ=0), the slot length can be 1 ms. In this case, one system frame can contain 10 slots. When the subcarrier spacing is 30 kHz (e.g., μ=1), the slot length can be 0.5 ms. In this case, one system frame can contain 20 slots.

[0129] When the subcarrier spacing is 60 kHz (e.g., μ=2), the slot length can be 0.25 ms. In this case, one system frame can contain 40 slots. When the subcarrier spacing is 120 kHz (e.g., μ=3), the slot length can be 0.125 ms. In this case, one system frame can contain 80 slots. When the subcarrier spacing is 240 kHz (e.g., μ=4), the slot length can be 0.0625 ms. In this case, one system frame can contain 160 slots.

[0130] A symbol may be configured as a downlink (DL) symbol, a flexible (FL) symbol, or an uplink (UL) symbol. A slot consisting solely of DL symbols may be referred to as a "DL slot," a slot consisting solely of FL symbols may be referred to as an "FL slot," and a slot consisting solely of UL symbols may be referred to as a "UL slot."

[0131] FIG. 9 illustrates the timing relationship between uplink and downlink in a wireless communication system according to an embodiment of the present disclosure.

[0132] There is one frame set in the uplink and one frame set in the downlink for each carrier. The uplink frame number i for transmission from the UE is It must be started before, and must coincide with the start of the corresponding downlink frame observed at the UE.

[0133] Here, and can be provided by adjusting the transmission timing of the synchronization procedure. However, for msgA transmission on PUSCH (physical uplink shared channel), NTA = 0.

[0134] is derived from the upper layer parameters ta-Common, ta-CommonDrift, ta-CommonDriftVariant, which if not configured am.

[0135] is computed by the UE only if the UE's position and related upper layer parameters are configured according to the transmission timing adjustment of the synchronization procedure, otherwise am.

[0136] As previously mentioned, the timing of the downlink and uplink can be adjusted based on the transmission timing adjustment of the synchronization procedure. Section 4.2 of 3GPP TS 38.213 defines the timing adjustment procedure for the synchronization procedure, as shown in [Table 2] below.

[0137]

[0138] The aforementioned TA (timing advance) can be determined based on the signal transmission and reception times of the random access procedure. For example, the base station can determine the TA based on the arrival time of the preamble transmitted by the terminal. Sections 8.1 and 8.2 of 3GPP TS 38.213 define the random access procedure as shown in [Table 3].

[0139]

[0140] A terminal that has performed a random access procedure can receive configuration information from a base station and transmit a PUSCH based on the configuration information. Specifically, the terminal can identify uplink resources and determine uplink transmission power based on control information and / or configuration information received from the base station. Then, the terminal can transmit a PUSCH using the identified resources and the determined power.

[0141] The aforementioned PUSCH transmission can be controlled via a physical uplink control channel (PUCCH). In NR, a terminal transmits uplink control information (UCI) to a base station via the PUCCH. The control information may include at least one of a HARQ-ACK indicating whether demodulation / decoding was successful for a TB (transport block) received by the terminal via the PDSCH, a scheduling request (SR) requesting resource allocation from the PUSCH base station for uplink data transmission, and channel state information (CSI), which is information for reporting the channel status of the terminal.

[0142] PUCCH can be repeatedly transmitted. Depending on given conditions, the terminal can perform repeated PUCCH transmission based on configuration information from the base station. For example, if the terminal does not have a dedicated PUCCH resource configuration and has the capability to repeatedly transmit PUCCH containing HARQ-ACK information, the terminal can determine the number of slots for repeated PUCCH transmission containing HARQ-ACK information based on upper layer configuration (e.g., numberOfPUCCHforMsg4HARQACK-RepetitionsList) and / or control information (e.g., downlink assignment index (DAI) field of DCI), and perform repeated PUCCH transmission in the determined number of slots. In this case, the terminal can apply frequency hopping. Meanwhile, NTN reference scenarios can be defined as shown in [Table 4] below.

[0143] NTN shown in Fig. 1a NTNGEO shown in Fig. 2a Scenario A Scenario BLEO (steerable beam) Scenario C1 Scenario D1 LEO (beam moving with satellite) Scenario C2 Scenario D2

[0144] In the non-terrestrial network illustrated in FIG. 1a and / or FIG. 1b, if the satellite (110) is a GEO satellite (e.g., a GEO satellite supporting transparent functionality), this may be referred to as “Scenario A.” In the non-terrestrial network illustrated in FIG. 2a, FIG. 2b, and / or FIG. 2c, if each of satellite #1 (211) and satellite #2 (212) is a GEO satellite (e.g., a GEO supporting regeneration functionality), this may be referred to as “Scenario B.”

[0145] If the satellite (110) in the non-terrestrial network illustrated in FIG. 1a and / or FIG. 1b is a LEO satellite having steerable beams, this may be referred to as “Scenario C1.” If the satellite (110) in the non-terrestrial network illustrated in FIG. 1a and / or FIG. 1b is a LEO satellite having beams move with the satellite, this may be referred to as “Scenario C2.” If each of satellite #1 (211) and satellite #2 (212) in the non-terrestrial network illustrated in FIG. 2a, FIG. 2b, and / or FIG. 2c is a LEO satellite having steerable beams, this may be referred to as “Scenario D1.” In the non-terrestrial network illustrated in FIG. 2a, FIG. 2b, and / or FIG. 2c, if each of satellite #1 (211) and satellite #2 (212) is a LEO satellite having beams that travel with the satellite, this may be referred to as “Scenario D2.”

[0146] Parameters for the NTN reference scenarios defined in [Table 4] can be defined as shown in [Table 5] below.

[0147] Scenario A and B Scenario C and D Altitude 35,786 km 600 km 1,200 km Spectrum (service link) <6 GHz (e.g., 2 GHz) > 6 GHz (e.g., DL 20 GHz, UL 30 GHz) Maximum channel bandwidth capability (service link) 30 MHz for band < 6 GHz 1 GHz for band > 6 GHz Maximum distance between satellite and communication node (e.g., UE) at minimum elevation angle 40,581 km 1,932 km (600 km altitude) 3,131 km (1,200 km altitude) Maximum round trip delay (RTD) (propagation delay only) Scenario A: 541.46 ms (service and feeder links) Scenario B: 270.73 ms (service link only) Scenario C: (Transparent payload: service and feeder links) -25.77 ms (600 km) Altitude) -41.77ms (1200km altitude) Maximum differential delay within a cell 10.3m3.12ms (600km altitude) 3.18ms (1200km altitude) Service link NR or 6G Feeder link Radio interface defined in 3GPP or non-3GPP

[0148] Additionally, in the NTN reference scenario defined in [Table 4], the delay constraint can be defined as in [Table 6] below.

[0149] Scenario A Scenario B Scenario C1-2 Scenario D1-2 Satellite altitude 35,768 km 600 km Maximum RTD on the air interface between the base station and the UE 541.75 ms (worst case) 270.57 ms 28.41 ms 12.88 ms Minimum RTD on the air interface between the base station and the UE 477.14 ms 238.57 ms 8 ms 4 ms

[0150] FIG. 10A and FIG. 10B illustrate examples of protocol stacks of a user plane and a control plane in a non-terrestrial network based on transparent payload in a wireless communication system according to an embodiment of the present disclosure.

[0151] Referring to FIGS. 10A and 10B , user data may be transmitted and / or received between a UE and a core network (e.g., UPF), and control data (e.g., control information) may be transmitted and / or received between a UE and a core network (e.g., AMF). Each of the user data and the control data may be transmitted and / or received via a satellite and / or a gateway. The protocol stack of the user plane illustrated in FIG. 10A may be applied identically or similarly to a 6G communication network. The protocol stack of the control plane illustrated in FIG. 10B may be applied identically or similarly to a 6G communication network.

[0152] FIG. 11A and FIG. 11B illustrate examples of protocol stacks of a user plane and a control plane in a non-terrestrial network based on regenerative payload in a wireless communication system according to an embodiment of the present disclosure.

[0153] Referring to FIGS. 11A and 11B , user data and control data (e.g., control information) may be transmitted and / or received via an interface between a UE and a satellite (e.g., a base station). The user data may include a user protocol data unit (PDU). The protocol stack of the satellite radio interface (SRI) may be used to transmit and / or receive the user data and / or control data between the satellite and the gateway. The user data may be transmitted and / or received via a GPRS (general packet radio service) tunneling protocol (GTP)-U tunnel between the satellite and the core network.

[0154] In relation to NTN communication, an NTN may be configured to provide non-terrestrial NR access to the UE via an NTN payload and an NTN gateway. A service link refers to a connection between an NTN payload and the UE, and a feeder link refers to a link between an NTN gateway and an NTN payload. The configuration and procedures for the NTN, service link, and feeder link may be implemented in combination with, or in part performed or modified from, the configuration and procedures disclosed in section 16.14 of 3GPP TS 38.300.

[0155] Figure 12 illustrates an example of an NTN providing non-terrestrial NR access to a UE via an NTN payload and an NTN gateway. Figure 12 shows a service link between the NTN payload and the UE, and a feeder link between the NTN gateway and the NTN payload.

[0156] The NTN payload transparently transmits wireless protocols received from the UE via the service link to the NTN gateway via the feeder link, or vice versa. The connectivity supported by the NTN payload is as follows.

[0157] - NTN gateway can serve multiple NTN payloads.

[0158] - A single NTN payload can be served by multiple NTN gateways.

[0159] - NTN payloads can change carrier frequency before being retransmitted on the service link, or vice versa (on each feeder link).

[0160] In NTN, in addition to the network identifier, the following may apply:

[0161] - A tracking area corresponds to a fixed geographic area. Each mapping is configured in the RAN.

[0162] - Mapped cell ID as defined in Section 16.14.5.

[0163] Three types of service links are supported:

[0164] - Earth-fixed: The service link may be provided by beam(s) that continuously cover the same geographic area at all times (e.g. Geosynchronous Orbit (GSO) satellites).

[0165] - Quasi-earth-fixed: The service link may be provided by beam(s) that cover one geographic area for a limited period and another geographic area for another period (e.g., NGSO (non-GSO) satellites producing steerable beams).

[0166] - Earth-moving: The service link may be provided by beam(s) moving over the surface of the Earth (e.g., NGSO satellites producing fixed beams or non-steerable beams).

[0167] A gNB operating as an NGSO satellite can provide a quasi-Earth fixed service link or an Earth mobile service link, and a gNB operating as a GSO satellite can provide an Earth fixed service link.

[0168] Timing and synchronization are as follows:

[0169] Regarding scheduling and timing, downlink and uplink frames are aligned using an offset given by the NTA offset (see Section 4.2 of TS 38.213) from the uplink time synchronization reference point (RP). To accommodate the propagation delay of the NTN, some timing relationships are enhanced by a common timing advance (TA) and two offsets, K_offset and k_mac.

[0170] - Common TA is a timing offset configured equal to the round trip time (RTT) between the RP and NTN payloads.

[0171] - K offset is a configured scheduling offset that must be greater than or equal to the sum of the service link RTT and common TA.

[0172] - k mac is an offset that is configured to be approximately equal to the RTT between the RP and gNB.

[0173] Scheduling offset K offset is used to allow the UE sufficient processing time between downlink reception and uplink transmission (see TS 38.213). Offset k mac is used to delay the application of downlink configuration indicated by MAC CE command on PDSCH (see TS 38.213) and for estimation of UE-gNB RTT (see TS 38.321). If downlink and uplink frame timing are not aligned at the gNB, offset k mac can be provided by the network. Also, the offset k mac is used to determine the RAR window / MsgB window start time after sending Msg1 / MsgA in the random access procedure (see TS 38.213). Service link RTT, feeder link RTT, RP, common TA, k mac And TTA is as shown in Fig. 13. Fig. 13 shows the timing relationship between objects included in NTN.

[0174] The network can configure HARQ operation as follows:

[0175] - For downlink, HARQ feedback can be enabled or disabled on a per-HARQ process basis. Disabling HARQ feedback allows scheduling a HARQ process before one HARQ RTT has elapsed since the last scheduling.

[0176] - For uplink, HARQ modes (e.g., HARQ mode A or HARQ mode B) can be configured for each HARQ process. HARQ mode B allows scheduling a HARQ process before one HARQ RTT has elapsed since the last scheduling.

[0177] For HARQ processes configured to have HARQ feedback enabled / disabled, it is up to the network implementation to ensure the appropriate HARQ feedback configuration (e.g., all enabled or all disabled) for the HARQ processes used in the SPS configuration. For HARQ processes configured in HARQ mode, it is up to the network implementation to ensure the appropriate HARQ mode configuration (e.g., all HARQ mode A or all HARQ mode B) for the HARQ processes used in the configured grant (CG) configuration.

[0178] Meanwhile, in a non-terrestrial network, a base station may transmit system information (e.g., SIB19) containing satellite assistance information for NTN access. The UE may receive system information (e.g., SIB19) from the base station, verify the satellite assistance information included in the system information, and perform communication (e.g., non-terrestrial communication) based on the satellite assistance information. SIB19 may include the information element(s) defined in [Table 7] below.

[0179] SIB19-r17 :: = SEQUENCE {ntn-Config-r17 NTN-Config-r17 OPTIONAL,t-service-r17 INTEGER(1..549755813887) OPTIONAL,referenceLocation-r17 ReferenceLocation-r17 OPTIONAL,distanceThresh-r17 INTEGER(1..65525) OPTIONAL,ntn-NeighCellConfigList-r17 NTN-NeighCellConfigList-r17 OPTIONAL,lateNonCRiticalExtension OCTET STRING...,[[ntn-NeighCellConfigListExt-v1720 NTN-NeighCellConfigList-r17 OPTIONAL,]],[[movingReferenceLocation-r18 ReferenceLocation-r17 OPTIONAL,satSwitchWithReSync-r18 SatSwitchWithReSync-r18 OPTIONAL,]]}NTN-NeighCellConfigList-r17 :: = SEQUENCE (SIZE(1..maxCellNTN-r17)) OFNTN-NeighCellConfig-r17NTN-NeighCellConfig-r17 :: = SEQUENCE {ntn-Config-r17 NTN-Config-r17 OPTIONAL,carrierFreq-r17 ARFCN-ValueNR OPTIONAL,physCellId-r17 PhysCellId OPTIONAL}SatSwitchWithReSync-r18 :: = SEQUENCE {ntn-Config-r18 NTN-Config-r17,t-ServiceStart-r18 INTEGER(1..549755813887) OPTIONAL,ssb-TimeOffset-r18 INTEGER(1..159) OPTIONAL}

[0180] NTN-Config defined in [Table 7] may include information element(s) defined in [Table 8] below.

[0181] NTN-Config-r17 ::= SEQUENCE {epochTime-r17 EpochTime-r17ntn-UISyncValidityDuration-r17 ENUMERATED {s5, s10, s15, s20, s25, s30, s35, s40, s45, s50, s55, s60, s120, s180, s240, s900}cellSpecificKoffset-r17 INTEGER(1..1023)kmac-r17 INTEGER(1..512)ta-Info-r17 TA-Info-r17ntn-PolarizationDL-r17 ENUMERATED {rhcp, lhcp, linear}ntn-PolarizationUL-r17 ENUMERATED {rhcp, lhcp, linear}ephemerisInfo-r17 EphemerisInfo-r17ta-Report-r17 ENUMERATED {enabled}...}EpochTime-r17 ::= SEQUENCE {sfn-r17 INTEGER(1..1023)subFrameNR-r17 INTEGER(1..9)}TA-Info-r17 ::= SEQUENCE {ta-Common-r17 INTEGER(1..66485757)ta-CommonDrift-r17 INTEGER(-257303..257303)ta-CommonDriftVarant-r17 INTEGER(0..28949)}

[0182] EphemerisInfo defined in [Table 8] may include information element(s) defined in [Table 9] below.

[0183] EphemerisInfo-r17 ::= CHOICE {positionVelocity-r17 PositionVelocity-r17,orbital-r17 Orbital-r17}PositionVelocity-r17 ::= SEQUENCE {positionX-r17 PositionStateVector-r17,positionY-r17 PositionStateVector-r17,positionZ-r17 PositionStateVector-r17, velocity V INTEGER (0..1048575),periapsis-r17 INTEGER (0..268435455),longitude-r17 INTEGER (0..268435455),incliating-r17 INTEGER (-67108864..67108863),meanAnomaly-r17 INTEGER (0..268435455)}PositionStateVector-r17 ::= INTEGER (-33554432..33554431)VelocityStateVector-r17 ::= INTEGER (-142172..142171)

[0184] Additionally, if there is a difference in the NTN connection setup compared to the TN connection, the NTN-parameter may include the information elements defined in [Table 10] below to convey the UE wireless connection capability parameters applicable to the NTN connection.

[0185] NTN-parameters-r17 ::= SEQUENCE {inactiveStateNTN-r17 ENUMERATED {supported} OPTIONAL,ra-SDT-NTN-r17 ENUMERATED {supported} OPTIONAL,srb-SDT-NTN-r17 ENUMERATED {supported} OPTIONAL,measAndMobParametersNTN-r17 MeasAndMobParameters OPTIONAL,mac-ParametersNTN-r17 Mac-Parameters OPTIONAL,phy-ParametersNTN-r17 Phy-Parameters OPTIONAL,fdd-ADD-UE-NR-CapabilitiesNTN-r17 UE-NR-CapabilityNTNAddXDD-Mode OPTIONAL,frl-ADD-UE-NR-CapabilitiesNTN-r17 UE-NR-CapabilityNTNAddFRX-Mode OPTIONAL,ue-BasedPerfMeas-ParametersNTN-r17 UE-BasedPerfMeas-Parameters-r16 OPTIONAL,son-ParametersNTN-r17 SON-Parameters-r16 OPTIONAL}

[0186] The present disclosure relates to a device and method for preventing uplink synchronization errors and resource waste due to timing advance (TA) pre-compensation errors of a terminal in a random access situation of a non-terrestrial network (NTN) environment.

[0187] In a mobile communication system, the uplink signals of each user must be synchronized to be received within a cyclic prefix (CP) from the base station's reception timing perspective. This ensures that the signals of each user can be received by the base station without interference. Therefore, terrestrial network (TN) systems adjust the transmission timing of each user's uplink signals (e.g., PUSCH, PUCCH, SRS, etc.) by compensating for the TA based on a timing advance command (TAC) to synchronize the uplink signals.

[0188] FIG. 14A illustrates an example of applying TAC-based TA in a wireless communication system according to an embodiment of the present disclosure. Referring to FIG. 14A, BS (1412) generates and transmits TACs for UE1 (1411-1) and UE2 (1411-2) based on distance and / or delay time information for each of UE1 (1411-1) and UE2 (1411-2) to synchronize uplink signals from UE1 (1411-1) and UE2 (1411-2). Each of UE1 (1411-1) and UE (1411-2) adjusts TAs based on the TAC from BS (1412), thereby transmitting uplink signals at different transmission timings. The uplink signals transmitted at different transmission timings from each of UE1 (1411-1) and UE2 (1411-2) are synchronized at the reception side of BS (1412).

[0189] Meanwhile, terminals in an NTN environment can communicate with base stations via satellite. Consequently, the distance between base stations and terminals in an NTN environment significantly increases compared to that in a TN environment. Furthermore, in an NTN environment, it is difficult for base stations to immediately obtain information about the distance and delay between terminals and satellites. Therefore, in an NTN system, in addition to compensating for TA based on TAC and / or TA offset, each terminal additionally performs TA pre-compensation to synchronize with the base station reception timing.

[0190] FIG. 14B illustrates an example of applying TA pre-compensation in an NTN system in a wireless communication system according to an embodiment of the present disclosure. Referring to FIG. 14B, a UE (1421) of the NTN system determines a TA based on a TAC (1431), a pre-specified TA offset (1433), and a TA pre-compensation (1435). The TA pre-compensation (1435) can be performed by obtaining a TA pre-compensation value based on information included in a system information block (SIB). Specifically, a terminal connected to an NTN cell, i.e., a UE (1421), derives a UE-specific TA pre-compensation value (1437) that reflects the propagation delay of a service link, which is a link between the UE (1421) and a satellite (1422), based on the ephemeris of the serving cell included in the SIB and the position estimation result of the UE. In addition, the UE (1421) derives a common TA pre-compensation value (1439) that reflects the propagation delay of the feeder link, which is a link between the BS (1423) and the satellite (1422), through the TA-related information included in the SIB. The UE (1421) determines its own TA based on the first value calculated by the TAC (1431), the TA offset (1433) according to the frequency band and / or uplink and downlink duplexing, the UE-specific TA pre-compensation value (1437), and the cell-common TA pre-compensation value (1439). The TA pre-compensation value, including the UE-specific TA pre-compensation value (1437) and the cell-common TA pre-compensation value (1439), can be reported to the BS (1423) during the RRC connection procedure. In addition, when the TA variation value according to the TA pre-compensation value increases in the RRC_CONNECTED state, the UE (1421) reports information related to the TA variation to the BS (1423). The BS (1423) monitors the TA pre-compensation value of the UE (1421) to additionally adjust the final TA of the terminal, and can transmit a TAC based on the TA pre-compensation value.

[0191] The TA mechanism in NTN, as described above, gradually improves TA errors. That is, if an error is determined in the TA pre-compensation value by the terminal, the error can be compensated for using TAC. However, the range of TAC limits the range of errors that can be corrected at once. Therefore, even if the terminal receives TAC from the base station, TA inaccuracy may continue to increase depending on the situation. For example, TA errors may accumulate due to inaccurate GNSS position information of the terminal caused by tunnel passage or inaccurate ephemeris due to low elevation angles. In this case, even if the terminal receives TAC, the accumulated TA error cannot be improved all at once. Another example is that abrupt changes, such as temporal uncorrelation of the terminal's position estimate information due to a period of inability to obtain position information due to tunnel passage or terminal power issues, can result in a large TA error. In this case, even if the terminal receives TAC, the large TA error cannot be improved all at once. Therefore, according to the existing TA mechanism, the TAC transmission and TA application process must be repeated multiple times in certain situations to gradually improve the TA error.

[0192] However, if the TA error exceeds a certain level, even if the TA error is gradually improved as described above, the TA error will persist. In particular, if the degree of error improvement is less than the degree of error accumulation, the TA error may increase or remain due to the accumulated error even if the error is improved. In this case, the uplink signal may deviate from the base station reception timing synchronization, which may degrade the uplink performance of terminals connected to the NTN cell and damage the coverage of the NTN cell. In addition, even though the terminal's uplink synchronization is difficult due to the TA error, time and frequency resources may be allocated to the terminal, which may result in a waste of resources. In particular, in situations where the length of the CP, which is the interval where synchronization is possible, is shortened due to the application of high-frequency bands higher than FR2 / 10 GHz, the aforementioned problems may occur more frequently.

[0193] Figure 14c illustrates an example of a random access procedure applicable to the present disclosure. Referring to Figure 14c, a terminal may perform a four-step random access procedure (1451) or a two-step random access procedure (1453) to access a base station. During the random access procedure, transmission of uplink resources, such as Msg3, Msg4 HARQ-ACK, MsgA, or MsgB HARQ-ACK, may fail. In this case, the terminal repeatedly attempts random access by retransmitting the failed message or restarting from the previous step. If the terminal repeatedly attempting random access in this way is a terminal that causes uplink synchronization errors due to TA errors, not only will available uplink resources be wasted during the random access procedure, but the uplink synchronization errors may also degrade the overall random access performance and coverage within the cell. Therefore, a solution to the aforementioned problems is needed.

[0194] Accordingly, the present disclosure proposes signaling and procedures for resolving uplink synchronization errors in a terminal with TA errors during a random access procedure. Specifically, the present disclosure describes a method and device for pre-compensating uplink TA during a random access procedure.

[0195]

[0196] FIG. 15 illustrates an example of a procedure for performing random access to a base station in a wireless communication system according to an embodiment of the present disclosure. FIG. 15 illustrates a method performed by a terminal. The terminal may be understood as a UE.

[0197] Referring to FIG. 15, in step S1501, a terminal receives system information. The system information may include information on random access to an NTN base station. The system information may be received using a master information block (MIB) and / or system information blocks (SIBs). According to one embodiment, the system information may further include information for TA compensation. The information for TA compensation may include coefficient information for compensating for a first value determined by a TAC. The information for TA compensation may include first coefficient information commonly applied to a plurality of terminals for TA compensation. The first coefficient information may include at least one of a common TAC adjustment coefficient for adjusting the first value determined by the TAC, or a first TA precompensation value estimated by the base station. The first TA precompensation value estimated by the base station may include a TA precompensation value commonly applicable to a plurality of terminals.

[0198] In step S1503, the terminal transmits a random access preamble. The terminal transmits a random access preamble for initial access to the NTN base station. For example, the terminal may transmit a message including a random access preamble to the NTN base station according to the random access procedure of step 4. The message including the random access preamble may be referred to as Msg1.

[0199] In step S1505, the terminal receives a random access response message. The terminal may receive the random access response message from the NTN base station. The random access response message may include TA information. The TA information may include information related to TA adjustment indicated by the TAC. According to one embodiment, the random access response message may further include information for TA compensation. The information for TA compensation may include coefficient information for compensating for a first value determined by the TAC. The information for TA compensation may include second coefficient information applied to each terminal for TA compensation. The second coefficient information may include at least one of a terminal-specific TAC adjustment coefficient for adjusting the first value determined by the TAC, or a second TA pre-compensation value estimated by the base station. The second TA pre-compensation value estimated by the base station may include a TA pre-compensation value applied to a specific terminal. The random access response message may be referred to as Msg2.

[0200] In step S1507, the terminal transmits a first message for connection establishment. The terminal may transmit the first message for connection establishment to the NTN base station through resources scheduled by the random access response message. The first message may be transmitted at a timing determined by applying TA information and information for TA compensation. In other words, the terminal may determine an uplink TA value based on the TA information and information for TA compensation included in the system information and / or the random access response message, and determine the transmission timing of the first message based on the determined uplink TA value. The first message may be referred to as Msg3.

[0201] In step S1509, the terminal receives a second message for connection establishment. The terminal may receive the second message for connection establishment from the NTN base station. According to one embodiment, the second message may include information for TA compensation. The information for TA compensation may include second coefficient information applied to each terminal for TA compensation. The second coefficient information may include at least one of a terminal-specific TAC adjustment coefficient for adjusting a first value determined by the TAC, or a second TA pre-compensation value estimated by the base station. The second message includes a contention resolution message and may be referred to as Msg4.

[0202]

[0203] Figure 16 illustrates an example of a procedure for performing random access with a terminal in a wireless communication system according to an embodiment of the present disclosure. Figure 16 illustrates a method performed by a base station. The base station may be understood as an NTN base station.

[0204] Referring to FIG. 16, in step S1601, the base station transmits system information. The system information may include information on random access to the NTN base station. The system information may be received using a master information block (MIB) and / or system information blocks (SIBs). According to one embodiment, the system information may further include information for TA compensation. The information for TA compensation may include coefficient information for compensating for a first value determined by the TAC. The information for TA compensation may include first coefficient information commonly applied to a plurality of terminals for TA compensation. The first coefficient information may include at least one of a common TAC adjustment coefficient for adjusting the first value determined by the TAC, or a first TA precompensation value estimated by the base station. The first TA precompensation value estimated by the base station may include a TA precompensation value commonly applicable to a plurality of terminals.

[0205] In step S1603, the base station receives a random access preamble. The base station receives a random access preamble for initial access from the terminal. For example, the base station may receive a message including a random access preamble from the terminal according to the random access procedure of step 4. The message including the random access preamble may be referred to as Msg1.

[0206] In step S1605, the base station transmits a random access response message. The base station may transmit the random access response message to the terminal. The random access response message may include TA information. The TA information may include information related to TA adjustment indicated by the TAC. According to one embodiment, the random access response message may further include information for TA compensation. The information for TA compensation may include coefficient information for compensating for a first value determined by the TAC. The information for TA compensation may include second coefficient information applied to each terminal for TA compensation. The second coefficient information may include at least one of a terminal-specific TAC adjustment coefficient for adjusting the first value determined by the TAC and a second TA pre-compensation value estimated by the base station. The second TA pre-compensation value estimated by the base station may include a TA pre-compensation value applied to a specific terminal. The random access response message may be referred to as Msg2. Information for TA compensation included in a random access response message can be determined or estimated based on a random access preamble received from the terminal.

[0207] In step S1607, the base station receives a first message for connection establishment. The base station may receive the first message for connection establishment from the terminal via resources scheduled by the random access response message. The first message may be transmitted at a timing determined by applying TA information and TA compensation information from the terminal. The first message may be referred to as Msg3.

[0208] In step S1609, the base station transmits a second message for connection establishment. The base station may transmit the second message for connection establishment to the terminal. According to one embodiment, the second message may include information for TA compensation. The information for TA compensation may include second coefficient information applied to each terminal for TA compensation. The second coefficient information may include at least one of a terminal-specific TAC adjustment coefficient for adjusting a first value determined by the TAC, or a second TA pre-compensation value estimated by the base station. The second message includes a contention resolution message and may be referred to as Msg4. The information for TA compensation included in the second message may be determined or estimated based on at least one of a random access preamble received from the terminal or the first message.

[0209]

[0210] In the embodiments described with reference to FIGS. 15 and 16, the terminal and / or base station adjust the uplink transmission timing of the terminal by pre-compensating for TA while operating according to a four-step random access procedure. However, the TA pre-compensation method of the present disclosure is not limited thereto. For example, the TA pre-compensation described in the present disclosure can also be applied when the terminal and / or base station performs a two-step random access procedure.

[0211]

[0212] The present disclosure below describes various embodiments for resolving uplink synchronization errors in terminals with TA errors during random access procedures. The embodiments described below may be applied independently, or two or more embodiments may be combined, as needed.

[0213]

[0214] Example #1: TAC Adjustment Factor Signaling and Procedure

[0215] According to embodiment #1 of the present disclosure, the terminal and / or the base station compensates for a first value determined by the TAC based on a TAC adjustment coefficient.

[0216] According to 3GPP TS 38.211, uplink frame i is time-dependent compared to downlink frame i. It must be transmitted at a point in time that is far in advance. is determined as shown in [Mathematical Formula 1] below.

[0217]

[0218] In [Equation 1], is the first value calculated by TAC, is a predefined TA offset value depending on the frequency band and uplink and downlink duplexing, is the cell-common TA pre-compensation value, is a UE-specific TA pre-compensation value, is the basic time unit. Here, is calculated as shown in [Mathematical Formula 2] below depending on the TAC transmission situation.

[0219]

[0220] In [Mathematical Formula 2], μ indicates the numerology of SCS (subcarrier spacing). is the value indicated by TAC, is the first value calculated by the previous TAC.

[0221] According to Embodiment #1 of the present disclosure, a base station transmits a TAC adjustment coefficient to a terminal to adjust an uplink TA of the terminal, and the terminal determines an uplink TA using the TAC adjustment coefficient. At this time, the TAC adjustment coefficient can be divided into a first type of TAC adjustment coefficient and a second type of TAC adjustment coefficient.

[0222] When using the first type of TAC adjustment coefficient, the terminal is as shown in [Mathematical Formula 3] below. can be decided.

[0223]

[0224] In [Equation 3], is the first type of TAC adjustment coefficient, is the first value calculated by TAC, is a predefined TA offset value depending on the frequency band and uplink and downlink duplexing, Silver cell common TA pre-compensation, is a UE specific TA pre-compensation, is the basic unit of time.

[0225] When using the second type of TAC adjustment coefficient, the terminal is as follows [Mathematical Formula 4] can be decided.

[0226]

[0227] In [Equation 4], is the first value calculated by TAC, is the second type TAC adjustment factor, and μ indicates the numerology of the subcarrier spacing (SCS). is the value indicated by TAC, is the first value calculated by the previous TAC.

[0228]

[0229] FIG. 17 illustrates an example of a procedure for determining uplink transmission timing based on a TAC adjustment coefficient in a wireless communication system according to an embodiment of the present disclosure. FIG. 17 illustrates signal exchange between a terminal (1710) and a base station (1720).

[0230] Referring to FIG. 17, in step S1701, the base station (1720) transmits TAC adjustment coefficient information to the terminal (1710). The TAC adjustment coefficient information is a value for compensating for a first value determined by the TAC, and may include a common TAC adjustment coefficient applicable to multiple terminals, or a terminal-specific TAC adjustment coefficient applicable to a specific terminal. The TAC adjustment coefficient information may be transmitted using system information or a random access-related message. For example, the base station (1720) may transmit the TAC adjustment coefficient information to the terminal (1710) using SIB, MsgB, Msg2, or Msg4.

[0231] In step S1703, the terminal (1710) obtains a compensated first value based on the TAC adjustment coefficient. The compensated first value can be obtained in different ways based on the type of the TAC adjustment coefficient. If the type of the TAC adjustment coefficient is the first type, the terminal (1710) can obtain the compensated first value by determining the first value based on the TAC and then applying the first type of TAC adjustment coefficient to the determined first value. If the type of the TAC adjustment coefficient is the second type, the terminal (1710) can obtain the compensated first value by applying the second type of TAC adjustment coefficient when determining the first value based on the TAC.

[0232] In step S1705, the terminal (1710) can determine the uplink TA based on the compensated first value. The terminal uses the compensated first value, the pre-specified TA offset, and the TA pre-compensation value to determine the uplink TA, i.e., can be determined. Here, the TA pre-compensation value may include at least one of a UE-specific TA pre-compensation value or a cell-common TA pre-compensation value.

[0233] In step S1707, the terminal (1710) determines the transmission timing based on the uplink TA. For example, the terminal (1710) may determine the transmission timing so that the uplink frame i is transmitted at a point in time that is earlier than the downlink frame i by the uplink TA.

[0234] In step S1709, the terminal (1710) transmits a message to the base station (1720). The terminal (1710) may transmit a message for random access to the base station (1720) at a determined transmission timing. For example, the message may include at least one of Msg1, Msg3, or Msg5.

[0235]

[0236] FIGS. 18A and 18B illustrate examples of application of the first type of TAC adjustment coefficient in a wireless communication system according to an embodiment of the present disclosure. FIGS. 18A and 18B disclose cases related to the first type of TAC adjustment coefficient.

[0237] Referring to Figures 18a and 18b, case 1 (case 0) is the first type of TAC adjustment coefficient Here is an example for the case where the first type of TAC adjustment factor is not applied or is 1. The BS transmits an SIB to the UE and receives Msg1 from the UE. The BS checks the TA status of the UE based on Msg1, and may determine that the application of the first type of TAC adjustment factor is unnecessary based on the TA status, or may determine the TAC adjustment factor to be 1. Thereafter, the BS transmits a TAC through Msg2. The UE may determine a first value based on the TAC received through Msg2, and may calculate an uplink TA value based on the first value. The UE may calculate the uplink TA value, i.e., Msg3 can be transmitted at the uplink transmission timing determined based on .

[0238] Case 2 (case 1) is the common TAC adjustment factor of the first type Here is an example of applying the same. According to Case 2, the BS transmits a common TAC adjustment factor of the first type to the UE through SIB. At this time, the common TAC adjustment factor of the first type is a value commonly applied to multiple terminals in the corresponding cell. For example, the common TAC adjustment factor of the first type may be set to 2, and the present disclosure is not limited thereto. The UE obtains the common TAC adjustment factor of the first type through SIB and transmits Msg1 to the BS. The BS transmits the TAC through Msg2. The UE obtains the first value based on the TAC received through Msg2, and can calculate the uplink TA value by applying the common TAC adjustment factor of the first type to the first value. The UE may calculate the uplink TA value, i.e., Msg3 can be transmitted at the uplink transmission timing determined based on .

[0239] Case 3 (case 2) is the terminal-specific TAC adjustment factor of the first type. Here is an example of applying. According to Case 3, the BS checks the TA status of the UE based on Msg1 received from the UE, and determines a terminal-specific TAC adjustment factor of the first type based on the TA status. The BS transmits the TAC and the terminal-specific TAC adjustment factor of the first type to the UE through Msg2. At this time, the terminal-specific TAC adjustment factor of the first type is a value that is applied only to a specific terminal. For example, the terminal-specific TAC adjustment factor of the first type may be set to 3, but the present disclosure is not limited thereto. The UE may obtain the TAC and the terminal-specific TAC adjustment factor of the first type received through Msg2, determine a first value based on the TAC, and calculate an uplink TA value by applying the terminal-specific TAC adjustment factor of the first type to the first value. The UE may calculate the uplink TA value, i.e., Msg3 can be transmitted at the uplink transmission timing determined based on .

[0240] Case 4 (case 3) is the common TAC adjustment factor of the first type and terminal-specific TAC adjustment coefficients of the first type Here is an example of applying the same. According to Case 4, the BS transmits a common TAC adjustment factor of the first type to the UE via SIB. For example, the common TAC adjustment factor of the first type may be set to 2, but the present disclosure is not limited thereto. The UE obtains the common TAC adjustment factor of the first type via SIB and transmits Msg1 to the BS. The BS checks the TA state of the UE based on Msg1 received from the UE, and determines the terminal-specific TAC adjustment factor of the first type based on the TA state. The BS transmits the TAC and the terminal-specific TAC adjustment factor of the first type to the UE via Msg2. For example, the terminal-specific TAC adjustment factor of the first type may be set to 4, but the present disclosure is not limited thereto. The UE can obtain the TAC and the terminal-specific TAC adjustment factor of the first type received through Msg2, determine the first value based on the TAC, and calculate the uplink TA value by applying the terminal-specific TAC adjustment factor of the first type. That is, when both the common TAC adjustment factor of the first type and the terminal-specific TAC adjustment factor of the first type are received, the terminal-specific TAC adjustment factor of the first type can be used to calculate the first value. However, the present disclosure is not limited thereto. For example, the common TAC adjustment factor of the first type and the terminal-specific TAC adjustment factor of the first type can also be used to calculate the TA value. The UE calculates the uplink TA value, i.e., Msg3 can be transmitted at the uplink transmission timing determined based on .

[0241] As described with reference to FIGS. 18A and 18B, the UE may acquire a first type of TAC adjustment factor during a four-step random access procedure, and transmit Msg3 based on the acquired first type of TAC adjustment factor. At this time, the first type of TAC adjustment factor may be transmitted from the BS to the UE using at least one of SIB, Msg2, or Msg4. The BS may check the TA state of the UE based on the previous uplink transmission of the UE (e.g., at least one of Msg1, Msg3, or Msg3 TA report), and may determine whether the first type of TAC adjustment factor needs to be transmitted and / or the first type of TAC adjustment factor based on the TA state information. If the BS determines that the first type of TAC adjustment factor needs to be transmitted, the BS may determine the first type of TAC adjustment factor. The BS may transmit the determined first type TAC adjustment factor to the UE using at least one of Msg2 or Msg4.

[0242]

[0243] FIGS. 19A and 19B illustrate examples of application of a second type of TAC adjustment factor in a wireless communication system according to an embodiment of the present disclosure. FIGS. 19A and 19B disclose cases related to the second type of TAC adjustment factor.

[0244] Referring to Figures 19a and 19b, case 1 (case 0) is the second type of TAC adjustment coefficient Here is an example for the case where the second type of TAC adjustment factor is not applied or is 1. According to Case 1, the BS transmits an SIB to the UE and receives Msg1 from the UE. The BS checks the TA status of the UE based on Msg1, and may determine that the application of the second type of TAC adjustment factor is unnecessary based on the TA status, or may determine the second type of TAC adjustment factor to be 1. Thereafter, the BS transmits a TAC through Msg2. The UE may determine a first value based on the TAC received through Msg2, and may calculate an uplink TA value based on the first value. The UE may calculate the uplink TA value, i.e., Msg3 can be transmitted at the uplink transmission timing determined based on .

[0245] Case 2 (case 1) is the second type of common TAC adjustment factor Here is an example of applying the same. According to Case 2, the BS transmits a common TAC adjustment factor of the second type to the UE through the SIB. At this time, the common TAC adjustment factor of the second type is a value commonly applied to multiple terminals in the corresponding cell. For example, the common TAC adjustment factor of the second type may be set to 2, and the present disclosure is not limited thereto. The UE obtains the common TAC adjustment factor of the second type through the SIB and transmits Msg1 to the BS. The BS transmits the TAC through Msg2. When the UE obtains the first value based on the TAC received through Msg2, the UE can obtain a compensated first value by applying the common TAC adjustment factor of the second type. The UE determines an uplink TA value based on the compensated first value, and the uplink TA value, i.e., Msg3 can be transmitted at the uplink transmission timing determined based on .

[0246] Case 2 is a terminal-specific TAC adjustment factor of the second type. Here is an example of applying. According to Case 3, the BS checks the TA status of the UE based on Msg1 received from the UE, and determines a terminal-specific TAC adjustment factor of the second type based on the TA status. The BS transmits the TAC and the terminal-specific TAC adjustment factor of the second type to the UE through Msg2. At this time, the terminal-specific TAC adjustment factor of the second type is a value that is applied only to a specific terminal. For example, the terminal-specific TAC adjustment factor of the second type may be set to 3, and the present disclosure is not limited thereto. The UE may obtain the TAC and the terminal-specific TAC adjustment factor of the second type received through Msg2, and calculate a compensated first value based on the TAC and the terminal-specific TAC adjustment factor of the second type. The UE may calculate an uplink TA value based on the calculated first value, i.e., , and can transmit Msg3 at the uplink transmission timing determined based on the uplink TA value.

[0247] Case 4 (case 3) is the second type of common TAC adjustment factor and a second type of terminal-specific TAC adjustment factor. Here is an example of applying the same. According to Case 4, the BS transmits a common TAC adjustment factor of the second type to the UE via SIB. For example, the common TAC adjustment factor of the second type may be set to 2, but the present disclosure is not limited thereto. The UE obtains the common TAC adjustment factor of the second type via SIB and transmits Msg1 to the BS. The BS checks the TA state of the UE based on Msg1 received from the UE, and determines the terminal-specific TAC adjustment factor of the second type based on the TA state. The BS transmits the TAC and the terminal-specific TAC adjustment factor of the second type to the UE via Msg2. For example, the terminal-specific TAC adjustment factor of the second type may be set to 4, but the present disclosure is not limited thereto. The UE may obtain the TAC and the terminal-specific TAC adjustment factor of the second type received through Msg2, obtain a first value compensated based on the TAC and the terminal-specific TAC adjustment factor of the first type, and calculate the TA value using the obtained first value. That is, when both the common TAC adjustment factor of the second type and the terminal-specific TAC adjustment factor of the second type are received, the terminal-specific TAC adjustment factor of the second type may be used to calculate the first value. However, the present disclosure is not limited thereto. For example, the common TAC adjustment factor of the second type and the terminal-specific TAC adjustment factor of the second type may also be used to calculate the uplink TA value. The UE may obtain the uplink TA value, i.e., Msg3 can be transmitted at the uplink transmission timing determined based on .

[0248] As described with reference to FIGS. 19A and 19B, the UE may acquire a second type of TAC adjustment factor during a four-step random access procedure, and transmit Msg3 based on the acquired second type of TAC adjustment factor. At this time, the second type of TAC adjustment factor may be transmitted from the BS to the UE using at least one of SIB, Msg2, or Msg4. The BS may check the TA state of the UE based on the previous uplink transmission of the UE (e.g., at least one of Msg1, Msg3, or Msg3 TA report), and may determine whether to transmit the second type of TAC adjustment factor and / or the second type of TAC adjustment factor based on the TA state information. If the BS determines that the transmission of the second type of TAC adjustment factor is necessary, the BS may determine the second type of TAC adjustment factor. The BS may transmit the determined second type of TAC adjustment factor to the UE using at least one of Msg2 or Msg4.

[0249]

[0250] As described above, by setting the TAC adjustment coefficients to a natural number or real number greater than 1, the TA error correction range by TAC can be increased. Therefore, it can be applied when it is necessary to increase the TA error correction range by TAC for a specific terminal or multiple terminals based on the judgment of the base station and / or the network. The first type of TAC adjustment coefficient is the total TA pre-compensation value. Directly reflected in It acts as a coefficient of , and the second type of TAC adjustment coefficient is to decide It acts as a coefficient of. The present disclosure can prevent uplink synchronization failure due to TA error in each terminal by using TAC adjustment coefficient, and can also prevent uplink performance degradation and coverage degradation of a base station due to interference signals caused by TA error. In addition, if necessary, the first type of TAC adjustment coefficient and the second type of TAC adjustment coefficient can be applied simultaneously.

[0251] FIGS. 20A and 20B illustrate examples of simultaneous application of a first type of TAC adjustment factor and a second type of TAC adjustment factor in a wireless communication system according to an embodiment of the present disclosure. FIGS. 20A and 20B disclose cases related to the first type and the second type of TAC adjustment factor.

[0252] Referring to FIGS. 20A and 20B, case 1 is an example in which the second type of TAC adjustment factor has a default value. According to case 1, the BS transmits a first type of common TAC adjustment factor to the UE via SIB. The UE transmits Msg1 to the BS, and the BS transmits Msg2 including the TAC to the UE. The UE sets the first type of common TAC adjustment factor received from the SIB to the first type of TAC adjustment factor, and can determine a first TA value based on the first type of TAC adjustment factor and the second type of adjustment factor having a default value. The UE transmits Msg3 at an uplink transmission timing based on the determined first TA value. The BS can check the TA state of the UE based on Msg3, and determine the first type of UE-specific TAC adjustment factor based on the checked TA state. The BS transmits Msg4, which includes the determined first type of terminal-specific TAC adjustment factor, to the UE. The UE may set the first type of terminal-specific TAC adjustment factor as the first type of TAC adjustment factor, and determine a second TA value based on the newly set first type of TAC adjustment factor and the second type of adjustment factor having a default value. The UE transmits Msg4 HARQ-ACK at an uplink transmission timing based on the determined second TA value.

[0253] Case 2 is an example in which the first type of TAC adjustment factor has a default value. According to Case 2, the BS transmits the second type of common TAC adjustment factor to the UE via SIB. The UE transmits Msg1 to the BS, and the BS can check the TA state of the UE based on Msg1 and determine the second type of UE-specific TAC adjustment factor based on the checked TA state. The BS transmits Msg2 including the TAC and the first type of UE-specific TAC adjustment factor to the UE. The UE sets the second type of UE-specific TAC adjustment factor received from Msg2 to the second type of TAC adjustment factor, and can determine the first TA value based on the first type of TAC adjustment factor and the second type of TAC adjustment factor having a default value. The UE transmits Msg3 at an uplink transmission timing based on the determined first TA value. The BS can check the TA status of the terminal based on Msg3, and determine a terminal-specific TAC adjustment factor of the second type based on the checked TA status. The BS transmits Msg4 including the determined terminal-specific TAC adjustment factor of the second type to the UE. The UE can set the terminal-specific TAC adjustment factor of the second type as the TAC adjustment factor of the second type, and determine a second TA value based on the first type TAC adjustment factor having a default value and the newly set second type TAC adjustment factor. The UE transmits Msg4 HARQ-ACK at an uplink transmission timing based on the determined second TA value.

[0254] Case 3 is an example of a case without a default value. According to Case 3, the BS transmits an SIB to the UE, and the UE transmits Msg1 to the BS. The BS can check the TA state of the UE based on Msg1, and determine a first type of UE-specific TAC adjustment factor and a second type of UE-specific TAC adjustment factor based on the checked TA state. The BS transmits Msg2 including the TAC, the first type of UE-specific TAC adjustment factor, and the second type of UE-specific TAC adjustment factor to the UE. The UE can set the first type of UE-specific TAC adjustment factor and the second type of UE-specific TAC adjustment factor, respectively, received using Msg2 to the first type of TAC adjustment factor and the second type of TAC adjustment factor, and determine a first TA value based on the first type of TAC adjustment factor and the second type of TAC adjustment factor. The UE transmits Msg3 at an uplink transmission timing based on the determined first TA value. The BS can check the TA status of the terminal based on Msg3, and determine a terminal-specific TAC adjustment factor of the second type based on the checked TA status. The BS transmits Msg4 including the determined terminal-specific TAC adjustment factor of the second type to the UE. The UE can set the received terminal-specific TAC adjustment factor of the second type using Msg4 as the TAC adjustment factor of the second type, and determine a second TA value based on the previous first type TAC adjustment factor and the newly set second type TAC adjustment factor. The UE transmits Msg4 HARQ-ACK at an uplink transmission timing based on the determined second TA value.

[0255] Case 4 is an example of a case without a default value. According to Case 4, the BS transmits a first type common TAC adjustment factor and a second type common TAC adjustment factor to the UE via SIB. The UE transmits Msg1 to the BS, and the BS transmits Msg2 including the TAC to the UE. The UE may set the first type common TAC adjustment factor and the second type common TAC adjustment factor, respectively, received via SIB to the first type TAC adjustment factor and the second type TAC adjustment factor, and may determine a first TA value based on the first type TAC adjustment factor and the second type TAC adjustment factor. The UE transmits Msg3 at an uplink transmission timing based on the determined first TA value. The BS may check the TA status of the UE based on Msg3, and may determine the first type UE-specific TAC adjustment factor based on the checked TA status. The BS transmits Msg4, which includes the determined first type of terminal-specific TAC adjustment factor, to the UE. The UE may use Msg4 to set the received first type of terminal-specific TAC adjustment factor to the first type of TAC adjustment factor, and determine a second TA value based on the newly set first type of TAC adjustment factor and the previously set second type of TAC adjustment factor. The UE transmits Msg4 HARQ-ACK at an uplink transmission timing based on the determined second TA value.

[0256] As in the embodiments described with reference to FIGS. 20A and 20B, when multiple types of TAC adjustment factors are supported simultaneously, signaling for a separate indicator may be required so that the terminal can determine which type to apply. Accordingly, the base station may transmit to the terminal information indicating the type of TAC adjustment factor to be applied or information indicating at least one of at least one type of TAC adjustment factor. For example, when the indicator is 00, it may indicate not applying the TAC adjustment factor or using the default value. When the indicator is 01, it may indicate that the value of the first type is transmitted through signaling and the value of the second type is not applied or uses the default value. When the indicator is 10, the value of the second type may indicate using the value transmitted through signaling and the value of the first type is not applied or uses the default value. When the indicator is 11, it may indicate that both the values ​​of the first type and the second type are transmitted through signaling.

[0257] In cases where only one type is supported according to various embodiments, it can be applied only through signaling for the TAC adjustment factor without signaling for a separate indicator. That is, the base station can transmit only information indicating the TAC adjustment factor to the terminal without transmitting information indicating the type of TAC adjustment factor to be applied.

[0258] As mentioned above, TAC adjustment factors can be transmitted as absolute values ​​or as exponents in power-of-two form for natural numbers to reduce signaling overhead. For example, when the maximum value is 8, a signal indicating any of the values ​​{1, 2, 3, 5, 6, 7, 8} is transmitted, or {2 0 , 2 1 , 2 2 , 2 3}={1, 2, 4, 8}, a signal indicating any one of the exponent values ​​{0, 1, 2, 3} can be transmitted.

[0259] The TAC adjustment factors may be applied UE-specifically by being included in Msg2, MsgB, and Msg4 for each terminal and transmitted, or may be applied to multiple terminals through cell-specific signaling included in SIB19 or other group signaling. According to one embodiment, the base station may transmit TAC adjustment factors commonly applied to multiple terminals through cell-specific signaling or group signaling, and thereafter provide TAC adjustment factors to specific terminals using UE-specific signaling as needed.

[0260] [Table 11] below shows examples of signaling methods for AC adjustment coefficients.

[0261] RACHCaseOrderMessagePossible Signaling Information4-StepRACH11Cell-specific: SIB1, SIB19, etc.1) TAC control coefficient(s)2) Indicator to select TAC control coefficient (if necessary)21UE-specific: Msg231UE-specific: Msg441Cell-specific: SIB1, SIB19, etc2UE-specific: Msg251Cell-specific: SIB1, SIB19, etc2UE-specific: Msg461UE-specific: Msg22UE-specific: Msg471Cell-specific: SIB1, SIB19, etc2UE-specific: Msg23UE-specific: Msg42-StepRACH81Cell-specific: SIB1, SIB19, etc91UE-specific: MsgB101Cell-specific: SIB1, SIB19, etc2UE-specific: MsgB

[0262] Information required for transmitting and / or applying TAC adjustment factors and indicators can be transmitted by adding new fields to existing signals such as IE (Information Elements) or modifying existing fields. At this time, the base station can apply different quantization levels to the TAC adjustment factors in SIB, Msg2, and / or Msg4 depending on the situation, so that the TAC adjustment factors transmitted through each message can have different ranges. For example, the base station can use 2-bit signaling to indicate any one of 0, 2, 4, and 8 through Msg2, and any one of 0, 1, 2, and 3 through Msg4. In addition, the base station can apply the ranges applied in each message repeatedly. For example, by using 2-bit signaling, one of 0, 10, 20, 30 can be indicated through Msg2, and one of 0, 2, 4, 8 can be indicated through Msg4, thereby applying them in addition to the applied value of Msg2.

[0263] When the TAC adjustment factor is transmitted using the random access response message of Msg2 or MsgB, the reserved bit of the TAC transmitted in Msg2 and / or MsgB may be utilized. In this case, since the reserved area of ​​the existing field is utilized, no additional field or signal for embodiment #1 will be required.

[0264] FIG. 21 illustrates an example of available bits of a random access response message in a wireless communication system according to an embodiment of the present disclosure. Referring to FIG. 21 , at least one of the reserved bits (2101, 2102, 2103, 2104) of the random access response message may be used for transmitting a TAC adjustment coefficient.

[0265] FIG. 22 illustrates an example of bit allocation for a TAC adjustment factor in a random access response message in a wireless communication system according to an embodiment of the present disclosure. Referring to FIG. 22, four cases of bit allocation for the TAC adjustment factor are disclosed. Case 1 (case 1) (2211) is an example in which one of four reserved bits is allocated for the TAC adjustment factor, and case 2 (case 2) (2212) is an example in which two of the four reserved bits are allocated for the TAC adjustment factor. In addition, case 3 (case 3) (2213) is an example in which three of the four reserved bits are allocated for the TAC adjustment factor, and case 4 (case 4) (2214) is an example in which all four reserved bits are allocated for the TAC adjustment factor.

[0266]

[0267] Example #2: Base Station Estimated TA Pre-Compensation Signaling and Procedure

[0268] According to embodiment #2 of the present disclosure, the base station and / or the network estimates a TA pre-compensation value and provides it to the terminal.

[0269] A base station and / or a network estimates a TA pre-compensation value for an individual terminal or a plurality of terminals, and transmits information about the estimated TA pre-compensation value to the terminal. The terminal determines an uplink transmission timing based on the information about the received TA pre-compensation value. In the present disclosure, the TA pre-compensation value estimated by the base station and / or the network may be referred to as a BS estimated TA pre-compensation value. That is, when the terminal estimates the TA pre-compensation value, the accuracy of the estimated TA pre-compensation value may be low, which may cause an uplink synchronization error. Therefore, in embodiment #2, in order to prevent an uplink synchronization error due to the terminal estimated TA pre-compensation value, the BS estimates the TA pre-compensation value, and transmits the estimated TA pre-compensation value to the terminal. The terminal receives the BS estimated TA pre-compensation value through signaling with the BS, and determines an uplink TA based on the received BS estimated TA pre-compensation value. The base station estimated TA pre-compensation value can be divided into a first type of base station estimated TA pre-compensation value commonly applied to multiple terminals and a second type of base station estimated TA pre-compensation value applied to individual terminals.

[0270]

[0271] FIG. 23 illustrates an example of a procedure for determining uplink transmission timing based on TA pre-compensation in a wireless communication system according to an embodiment of the present disclosure. FIG. 23 illustrates signal exchange between a terminal (2310) and a base station (2320).

[0272] Referring to FIG. 23, in step S2301, a base station (2320) estimates a TA pre-compensation value. The TA pre-compensation value may include a first type of base station estimated TA pre-compensation value commonly applied to multiple terminals, or a second type of base station estimated TA pre-compensation value applied to a specific terminal. Each of the first type of base station estimated TA pre-compensation value and the second type of base station estimated TA pre-compensation value may include a TA pre-compensation value for at least one of a service link or a feeder link.

[0273] In step S2303, the base station (2320) transmits base station estimated TA pre-compensation information to the terminal (2310). The TAC pre-compensation information may be transmitted using system information or a random access related message. For example, the base station (2320) may transmit the TAC pre-compensation information to the terminal (2310) using SIB, MsgB, Msg2, or Msg4. Specifically, the first type of base station estimated TA pre-compensation may be transmitted via SIB, and the second type of base station estimated TA pre-compensation may be transmitted using at least one of MsgB, Msg2, or Msg4.

[0274] In step S2305, the terminal (2310) can determine an uplink TA that reflects the base station estimated TA pre-compensation value. The terminal determines an uplink TA as shown in [Mathematical Formula 1] based on at least one of the first type of base station estimated TA pre-compensation value or the second type of base station estimated TA pre-compensation value received from the base station, i.e., According to one embodiment, the terminal may calculate or determine at least one of a cell common TA pre-compensation value or a UE specific TA pre-compensation value as shown in [Mathematical Formula 1] based on at least one of a first type of base station estimated TA pre-compensation value or a second type of base station estimated TA pre-compensation value received from the base station. For example, when a first type of base station estimated TA pre-compensation value including a TA pre-compensation value for a feeder link and a TA pre-compensation value for a service link is received, the terminal may determine the TA pre-compensation value for the feeder link as the cell common TA pre-compensation value and determine the TA pre-compensation value for the service link as the UE specific TA pre-compensation value. As another example, if only a second type of base station estimated TA precompensation including a TA precompensation for a service link is received, the terminal may determine the TA precompensation for the service link as a UE-specific TA precompensation and directly determine a cell-common TA precompensation based on information received from the base station (e.g., TA-related information included in the SIB). As another example, if only a first type of base station estimated TA precompensation including a TA precompensation for a feeder link is received, the terminal may determine the TA precompensation for the feeder link as a cell-common TA precompensation and directly determine a UE-specific TA precompensation based on information received from the base station (e.g., an ephemeris of a serving cell included in the SIB) and location information of the UE.

[0275] In step S2307, the terminal (2310) determines the transmission timing based on the uplink TA. For example, the terminal (2310) may determine the transmission timing so that the uplink frame i is transmitted at a point in time that is earlier than the downlink frame i by the uplink TA.

[0276] In step S2309, the terminal (2310) transmits a message to the base station (2320). The terminal (2310) can transmit the message to the base station (2320) at the determined transmission timing. The message can include at least one of Msg1, Msg3, or Msg5.

[0277]

[0278] FIG. 24 illustrates an example of transmitting and applying a first type of base station estimated TA pre-compensation in a wireless communication system according to an embodiment of the present disclosure. Referring to FIG. 24 , a base station (2420) transmits a first type of base station estimated TA pre-compensation to multiple terminals (2410-1, 2410-2, 2410-3) via cell-specific signaling (e.g., SIB19) or group signaling. At this time, the multiple terminals may include terminals predicted to have TA pre-compensation for similar service links, such as those in nearby areas, and the same feeder link.

[0279] In an NTN environment, a TA pre-compensation estimated by a terminal is configured based on the distances of the service link and the feeder link. Since terminals located in a nearby area have similar service links and the same feeder link, it is expected that the terminals will require similar TA pre-compensation. Therefore, a base station estimates and / or determines a first type of base station estimated TA pre-compensation for a plurality of terminals based on the locations of the terminals or a set of adjacent terminals, and provides information about the first type of base station estimated TA pre-compensation to the plurality of terminals through signaling. The first type of base station estimated TA pre-compensation can contribute to preventing uplink synchronization errors of a plurality of terminals requiring similar TA pre-compensation components with respect to a cell common TA pre-compensation and / or a UE specific TA pre-compensation.

[0280] The base station estimated TA pre-compensation value of the first type is transmitted in the same unit as the TAC, and is expressed as [Mathematical Formula 1]. And can be multiplied by each other. Alternatively, the base station estimated TA precompensation of the first type may be transmitted by dividing it into symbol transmission units, slot transmission time units, etc. For example, the base station estimated TA precompensation of the first type may be transmitted in symbol transmission time units, in which case the terminal must perform TA precompensation corresponding to x symbol transmission times separately from the TAC. As another example, the base station estimated TA precompensation of the first type may be transmitted in slot transmission time units, in which case the terminal must perform TA precompensation corresponding to x slot transmission times separately from the TAC. Depending on the embodiment, a single transmission time unit or multiple transmission time units may be applied. When multiple transmission time units are applied, a change in the transmission time unit may be indicated through separate signaling including an indicator related to the transmission time unit. For example, when the indicator is 0, it may indicate a symbol transmission time unit, and when the indicator is 1, it may indicate a slot transmission time unit.

[0281] The first type of base station estimated TA pre-compensation may include at least one of a TA pre-compensation for a service link, a TA pre-compensation for a feeder link, or a TA pre-compensation considering both the service link and the feeder link, depending on the situation. Here, the TA pre-compensation for the service link is can be expressed as, and the pre-compensation for the feeder link is TA pre-compensation considering both service link and feeder link can be expressed as can be expressed as

[0282] If the base station can dynamically change and transmit the first type of base station estimated TA pre-compensation according to a situation, the base station can change the application target of the first type of base station estimated TA pre-compensation through signaling including an application target indicator. For example, if the indicator is 0, it can be indicated that the application target is a feeder link, and if the indicator is 1, it can be indicated that the application target is the feeder link and the service link. If it is desired to transmit only the TA pre-compensation for the feeder link, the base station can transmit the first type of base station estimated TA pre-compensation including only the TA pre-compensation for the feeder link without estimating the location of each terminal or a set of adjacent terminals. The first type of base station TA pre-compensation can be applied as a cell common TA pre-compensation and a UE specific TA pre-compensation excluding the TAC and the TA offset.

[0283]

[0284] FIG. 25 illustrates an example of uplink TA determination according to application of a first type of base station estimated TA pre-compensation in a wireless communication system according to an embodiment of the present disclosure. Referring to FIG. 25, case 1 (2511) is an example of TA determination when the first type of base station estimated TA pre-compensation includes only a TA pre-compensation for a feeder link, and case 2 (2511) is an example of TA determination when the first type of base station estimated TA pre-compensation includes only a TA pre-compensation for a service link. In addition, case 3 (2531) is an example of TA determination when the first type of base station estimated TA pre-compensation includes TA pre-compensation for a feeder link and a service link.

[0285]

[0286] FIG. 26 illustrates an example of transmitting and applying a second type of base station estimated TA pre-compensation in a wireless communication system according to an embodiment of the present disclosure. Referring to FIG. 26, a base station (2620) individually transmits a second type of base station estimated TA pre-compensation for each of a plurality of terminals (2610-1, 2610-2, 2610-3) through UE-specific signaling. The base station identifies at least one terminal whose TA pre-compensation error is expected to be greater than or equal to a threshold, determines a second type of base station estimated TA pre-compensation for each of the at least one terminal, and individually transmits the determined second type of base station estimated TA pre-compensation to each of the at least one terminal, thereby preventing an uplink synchronization error of the corresponding terminal.

[0287] The second type of base station estimated TA pre-compensation value is transmitted in the same unit as the TAC, and is expressed as [Mathematical Formula 1]. And can be multiplied by each other. Alternatively, the second type base station estimated TA precompensation may be transmitted by dividing it into symbol transmission units, slot transmission time units, etc. For example, the second type base station estimated TA precompensation y may be transmitted in symbol transmission time units, in which case the terminal must perform TA precompensation corresponding to y symbol transmission times separately from the TAC. Depending on the embodiment, a single transmission time unit or multiple transmission time units may be applied. When multiple transmission time units are applied, a change in the transmission time unit may be indicated through separate signaling including an indicator related to the transmission time unit. For example, when the indicator is 0, it may indicate a symbol transmission time unit, and when the indicator is 1, it may indicate a slot transmission time unit.

[0288] The second type of base station estimated TA pre-compensation may include a TA pre-compensation for at least one of a feeder link and a service link. For example, the second type of base station estimated TA pre-compensation is a cell common TA pre-compensation excluding the TAC and TA offset in [Mathematical Formula 1]. and UE specific TA pre-compensation It may contain at least one of the following: This may change dynamically depending on the standard and circumstances.

[0289] When the second type base station estimated TA pre-compensation is transmitted, the second type base station estimated TA pre-compensation may be determined based on the values ​​of the remaining elements excluding the TAC, TA offset, and elements affecting the first type base station estimated TA pre-compensation. Alternatively, only the second type base station estimated TA pre-compensation may be used instead of the first type base station estimated TA pre-compensation. The terminal may receive information related to the first type and / or second type base station estimated TA pre-compensation, TAC, and TA offset, and determine the total TA pre-compensation based on the received information.

[0290] FIG. 27 illustrates an example of uplink TA determination according to application of a second type of base station estimated TA pre-compensation in a wireless communication system according to an embodiment of the present disclosure. Referring to FIG. 27, case 1 (2711) is an example of TA determination when the second type of base station estimated TA pre-compensation includes only a TA pre-compensation for a feeder link, and case 2 (2711) is an example of TA determination when the second type of base station estimated TA pre-compensation includes only a TA pre-compensation for a service link. In addition, case 3 (2731) is an example of TA determination when the second type of base station estimated TA pre-compensation includes TA pre-compensation for a feeder link and a service link.

[0291] FIG. 28 illustrates an example of applying a first type base station estimated TA pre-compensation value and a second type base station pre-compensation value in a wireless communication system according to an embodiment of the present disclosure.

[0292] Referring to FIG. 28, case 1 is an example in which a first type of base station estimated TA pre-compensation includes a TA pre-compensation for a feeder link, and a second type of base station estimated TA pre-compensation includes a TA pre-compensation for a service link. According to case 1, a BS transmits a first type of base station estimated TA pre-compensation including a TA pre-compensation for a feeder link via SIB. Thereafter, the BS calculates a TA pre-compensation for a service link based on Msg1 received from a UE, and transmits a second type of base station estimated TA pre-compensation including a TA pre-compensation for the service link via Msg2. The UE can calculate an uplink TA value based on the first type and second type of base station estimated TA pre-compensation received via SIB and Msg2. The UE calculates an uplink TA value, i.e., Msg3 can be transmitted at the uplink transmission timing determined based on .

[0293] Case 2 is an example in which the first type of base station estimated TA pre-compensation includes the TA pre-compensation for the feeder link, and the second type of base station estimated TA pre-compensation includes the TA pre-compensation for the service link. According to Case 2, the BS transmits the first type of base station estimated TA pre-compensation including the TA pre-compensation for the feeder link via SIB. Thereafter, the BS receives Msg1 from the UE and transmits Msg2 in response thereto. The UE can calculate an uplink TA value based on the first type of base station estimated TA pre-compensation received via SIB. The UE calculates the calculated uplink TA value, i.e., The BS may transmit Msg3 at an uplink transmission timing determined based on Msg1 or Msg3. The BS calculates a TA pre-compensation for the service link based on at least one of Msg1 and Msg3, and transmits a second type of base station estimated TA pre-compensation including the TA pre-compensation for the service link through Msg4. The UE may recalculate the uplink TA value based on the first type and second type of base station estimated TA pre-compensation received through SIB and Msg4. The UE may recalculate the recalculated uplink TA value, i.e., Msg4 HARQ-ACK can be transmitted at the uplink transmission timing determined based on .

[0294] Case 3 is an example in which a first type of base station estimated TA precompensation includes a TA precompensation for a feeder link, and a second type of base station estimated TA precompensation includes a TA precompensation for a service link. According to Case 3, a BS transmits a first type of base station estimated TA precompensation including a TA precompensation for a feeder link via a SIB. Thereafter, the BS calculates a TA precompensation for a service link based on Msg1 received from a UE, and transmits a second type of base station estimated TA precompensation including a TA precompensation for the service link via Msg2. The UE can calculate an uplink TA value based on the first type and second type of base station estimated TA precompensation received via the SIB and Msg2. The UE calculates the calculated TA value, i.e., The UE may transmit Msg3 at an uplink transmission timing determined based on the SIB. Thereafter, the BS recalculates a TA pre-compensation for the service link based on at least one of Msg1 and Msg3, and transmits a second type of base station estimated TA pre-compensation including the recalculated TA pre-compensation for the service link through Msg4. The UE may recalculate an uplink TA value based on the first type and second type of base station estimated TA pre-compensation received through SIB and Msg4. The UE may recalculate the recalculated uplink TA value, i.e., Msg4 HARQ-ACK can be transmitted at the uplink transmission timing determined based on .

[0295] Case 4 is an example in which the first type of base station estimated TA precompensation includes TA precompensation for a feeder link and a service link, and the second type of base station estimated TA precompensation includes TA precompensation for a feeder link or TA precompensation for a service link, depending on the situation. According to Case 4, the BS transmits the first type of base station estimated TA precompensation including TA precompensation for the feeder link and the service link via SIB. Thereafter, the BS calculates the TA precompensation for the feeder link based on Msg1 received from the UE, and transmits the second type of base station estimated TA precompensation including the TA precompensation for the feeder link via Msg2. The UE can calculate the TA value based on the first type and second type of base station estimated TA precompensation received via SIB and Msg2. The UE calculates the calculated TA value, i.e., The UE may transmit Msg3 at an uplink transmission timing determined based on the SIB. Thereafter, the BS calculates a TA pre-compensation for the service link based on at least one of Msg1 and Msg3, and transmits a second type of base station estimated TA pre-compensation including the calculated TA pre-compensation for the service link through Msg4. The UE may recalculate the uplink TA value based on the first type and second type of base station estimated TA pre-compensation received through SIB and Msg4. The UE may recalculate the recalculated uplink TA value, i.e., Msg4 HARQ-ACK can be transmitted at the uplink transmission timing determined based on .

[0296]

[0297] Example #3: Pre-compensation correction in Msg1 or MsgA

[0298] According to embodiment #3 of the present disclosure, the TA pre-compensation value is corrected to prevent random access from failing due to TA pre-compensation error of Msg1 or MsgA.

[0299] During the random access procedure, the TAC is transmitted to the terminal via Msg2 and / or MsgB. Therefore, Msg1 and / or MsgA transmitted by the terminal before Msg2 or MsgB do not reflect the latest TAC. Embodiment #3 is to prevent random access failure that may occur due to Msg1 and / or MsgA not reflecting the latest TAC. Specifically, Embodiment #3 can correct the TA pre-compensation value and retransmit the random access preamble based on the corrected TA pre-compensation value.

[0300] FIG. 29 illustrates an example of a procedure for correcting a TA pre-compensation value in a wireless communication system according to an embodiment of the present disclosure. FIG. 29 illustrates signal exchange between a terminal (2910) and a base station (2920).

[0301] Referring to FIG. 29, in step S2901, a terminal (2910) transmits a random access preamble to a base station (2920). The terminal (2910) may receive an SIB from the base station (2920) and transmit the random access preamble to access the base station (2920). According to one embodiment, the terminal (2910) may transmit the random access preamble at an uplink transmission timing determined based on an initial TA pre-compensation value. The initial TA pre-compensation value may be a value determined by the terminal itself based on information obtained through the SIB, or an initial value predefined through a standard, etc.

[0302] In step S2903, the terminal (2910) detects a failure in receiving a random access response. If, after transmitting a random access preamble to the base station (2920), a random access response having a RAPID (random access preamble ID) corresponding to the random access preamble is not received within a specified time, the terminal may determine that reception of the random access response has failed. For example, if a random access response is not received within a specified time, or a random access response received within a specified time does not include a RAPID corresponding to the random access preamble, the terminal may determine that reception of the random access response has failed.

[0303] In step S2905, the terminal (2910) corrects the TA pre-compensation value. The terminal (2910) corrects the TA pre-compensation value used in the failed random access preamble transmission. For example, the terminal (2910) may correct the TA pre-compensation value using at least one of a correction value indicated by the base station via SIB, an arbitrary correction value, or a correction value based on a previously received TAC.

[0304] In step S2907, the terminal (2910) retransmits the random access preamble at an uplink transmission timing determined based on the corrected TA precompensation. Thereafter, the terminal (2910) can check whether a random access response to the retransmitted random access preamble is successfully received. The terminal (2910) can repeatedly perform the TA precompensation correction and the random access preamble retransmission operation based on the corrected TA precompensation as described above until the random access response is successfully received.

[0305] FIG. 30 illustrates an example of a procedure for correcting a TA pre-compensation value during a random access procedure in a wireless communication system according to an embodiment of the present disclosure.

[0306] Referring to Figure 30, at step S3001, the UE Based on this, Msg1 or MsgA is transmitted to the BS. At this time, is determined based on the TA pre-compensation value estimated by the terminal. It can be. After transmitting Msg1 or MsgA to the BS, the UE can wait for receiving Msg2 or MsgB within a specified time.

[0307] If reception failure of Msg2 or MsgB is detected, in step S3003, the UE corrects the TA pre-compensation value and, based on the corrected TA pre-compensation value, can be decided. At this time, the decided Is It can be. The UE is calibrated Based on this, Msg1 or MsgA is retransmitted to the BS. After the UE retransmits Msg1 or MsgA to the BS, it may wait for Msg2 or MsgB to be received within a specified time.

[0308] If reception failure of Msg2 or MsgB is detected, in step S3005, the UE recalibrates the corrected TA pre-compensation and, based on the recalibrated TA pre-compensation, can be decided. At this time, Is It can be. The UE is recalibrated Based on this, send Msg1 or MsgA to BS.

[0309] As described above, if Msg2 or MsgB is not received, the terminal may repeatedly perform an operation of correcting the TA pre-compensation value and retransmitting Msg1 or MsgA based on the corrected TA pre-compensation value. This operation may be repeatedly performed until reception of Msg2 or MsgB is successful.

[0310]

[0311] In the embodiment described with reference to FIG. 30, correction for the TA pre-compensation value can be performed based on various types.

[0312] Type 1: The base station can transmit the application unit for the TA pre-compensation using cell-specific signaling. In this case, the terminal can additionally apply the application unit for the TA pre-compensation received from the base station to the transmission of the next Msg1 or MsgA. For example, the compensation value for the TA pre-compensation transmitted cell-specifically by the base station through SIB , and the TA pre-compensation value of the i-th transmission is In this case, the TA pre-compensation value of the i+1th transmission is It could be. At this time, can have a range of real numbers, for example, positive, zero, and negative. The absolute value of can be signaled and expressed in the same form as the TAC in the random access response. For example, can be expressed in 12 bits. Or, can be quantized and signaled according to a standardized range.

[0313] Type 2: The terminal can compensate the TA pre-compensation using a given random value in the next transmission. For example, the random compensation value for the i-th transmission attempt is , and the TA pre-compensation value of the i-th transmission is In this case, the TA pre-compensation value of the i+1th transmission is It could be. can have a range of real numbers, for example, positive, zero, and negative. can be set to the same value N for each transmission. Or, may be calculated by a standard specification or by the terminal, or may be a predefined value.

[0314] Type 3: If the terminal has a pre-compensation based on the previous TAC, it can use the pre-compensation based on the previous TAC to compensate the TA pre-compensation for the next transmission. For example, if the pre-compensation based on the most recently received TAC is , and the TA pre-compensation value of the i-th transmission is In this case, the TA pre-compensation value of the i+1th transmission is It can be. The application of Type 3 may be limited to specific situations, such as when performing random access within a certain time period from the time of acquiring the pre-compensation value by the previous TAC, or when transmitting TAC in the same NTN cell and / or beam. For example, even if a previous TAC has been acquired, if a random access is attempted in another NTN cell or a certain time period has passed, the terminal may determine that the accuracy of the previous TAC pre-compensation value is low and may not apply Type 3.

[0315]

[0316] The three types described above can be applied in combination. In this case, the three types can be applied based on priorities according to the number of repeated transmissions. For example, if all three types are applicable, Type 1 or Type 3 can be applied based on priorities. If repeated transmissions do not proceed to the next stage of random access, i.e., if random access response reception continues to fail, the terminal can change from the currently used type to another type and adjust the TA pre-compensation based on the changed type. At least one type, either Type 1 or Type 2, must always be defined or available for application by the terminal.

[0317] Figures 31a to 31c illustrate examples of application of types for TA pre-compensation correction in a wireless communication system according to an embodiment of the present disclosure. Figures 31a to 31c assume a case where random access preamble transmission is attempted up to five times. Referring to Figures 31a to 31c, Cases 1 to 3 are cases where only one of the three types is applied. Cases 4 to 9 are cases where two or more types are applied, and it can be seen that the type to be applied when attempting random access preamble transmission is determined based on the priority of each type.

[0318] In embodiment #3, the next transmission attempt of Msg1 or Msg B including the random access preamble may be performed sequentially when a random access failure due to a reception failure of Msg2 or MsgB is confirmed. Considering that the latency between the transmission of Msg1 or MsgA and the reception of Msg2 or MsgB in an NTN environment may be significantly increased compared to the latency in a TN environment, multiple transmission attempts may be performed simultaneously. That is, in an environment where the use of a total of L preambles is allowed for one terminal, each terminal L Msg1s or MsgAs having TAs can be transmitted without waiting for Msg2 or MsgB. At this time, the total number of preambles simultaneously available to one terminal and related information can be signaled cell-specifically via SIB acquired before transmitting Msg1 or MsgA. In addition, based on this, a RACH Occasion (RO) for each preamble available to one terminal can be implicitly or explicitly determined. At this time, the base station can transmit Msg2 or MsgB including RAR to the terminal for an RO determined to have the best reception power or SNR among the received L Msg1s or MsgAs.

[0319]

[0320] Example #4: Random Access Suspension Information, Signaling, and Procedures

[0321] According to embodiment #4 of the present disclosure, the base station and / or the network transmits information related to the suspension of the random access procedure to individual or multiple terminals.

[0322] A base station and / or a network may transmit information indicating the suspension of a random access procedure to at least one terminal expected to experience an uplink synchronization error. When the terminal receives the information indicating the suspension of the random access procedure, the terminal suspends the random access procedure. Here, the suspension of the random access procedure may include terminating or waiting for an ongoing random access procedure. This prevents terminals that may experience a synchronization error due to a TA precompensation error from performing retransmission for random access or restarting a previous step, thereby preventing waste of uplink resources and degradation of uplink performance of existing terminals.

[0323]

[0324] FIG. 32 illustrates an example of a random access procedure based on random access suspension indication information in a wireless communication system according to an embodiment of the present disclosure. FIG. 32 illustrates signal exchange between a terminal (3210) and a base station (3220).

[0325] Referring to FIG. 32, in step S3201, the base station (3220) transmits random access termination indication information to the terminal (3210). The base station (3220) may transmit the random access termination indication information to at least one terminal (3210) that satisfies a specified condition. For example, when the uplink TA error of the terminal (3210) is greater than a specified threshold error, the base station (3220) may transmit the random access termination indication information to the terminal (3210). The specified conditions herein are merely examples for better understanding and are not limited thereto. The random access termination indication information may include a first type of random access termination indication information that indicates immediate termination of an ongoing random access procedure, or a second type of random access termination indication information that initiates temporary waiting and conditional resumption of an ongoing random access procedure. According to an embodiment, the random access suspension information may be transmitted using any one of Msg2, MsgA, or Msg4, or may be transmitted using separate signaling.

[0326] In step S3203, the terminal (3210) determines whether to terminate or wait for the random access procedure based on the random access stop instruction information. The terminal (3210) may receive random access stop instruction information from the base station (3220) while performing the random access procedure, and may determine whether to terminate the ongoing random access procedure or temporarily wait without further performing the ongoing random access procedure based on the received random access stop instruction information.

[0327] If it is determined that the random access procedure is to be terminated, in step S3211, the terminal (3210) immediately terminates, i.e., stops, the random access procedure currently in progress. Thereafter, in step S3213, the terminal (3210) restarts from the cell search step or the random access preamble transmission step. The terminal (3210) may perform a cell search or retry the random access preamble transmission based on at least one of whether cell search is possible for other cells and / or other beams other than the existing cell and / or existing beam on which the existing random access procedure was performed, or whether a retry is possible for the existing cell and / or existing beam. When retrying the random access preamble transmission, the terminal (3210) may apply a corrected TA precompensation value. The corrected TA precompensation value is a value obtained by correcting the TA precompensation value used in the existing random access procedure, and may be obtained, for example, based on embodiment #3.

[0328] If waiting for a random access procedure is determined, in step S3221, the terminal (3210) temporarily waits for the random access procedure currently in progress. For example, the terminal (3210) may wait without further performing the random access procedure for a specified period of time or until a specified condition is satisfied. The specified period of time or the specified condition may be preset or may be instructed by the base station (3220). The specified period of time or the specified condition may be determined based on the standard or terminal characteristics. In step S3223, the terminal (3210) resumes the random access procedure based on the condition. That is, when the specified period of time has elapsed or the specified condition is satisfied, the terminal (3210) may resume the existing random access procedure.

[0329]

[0330] FIG. 33 illustrates an example of a first type of random access interruption information application procedure in a wireless communication system according to an embodiment of the present disclosure.

[0331] Referring to FIG. 33, in step S3301, the terminal receives first type random access interruption information from the base station. According to an embodiment, the first type random access interruption information may be received using any one of Msg2, MsgA, or Msg4, or may be received using separate signaling.

[0332] In step S3303, the terminal immediately terminates the ongoing RACH procedure. In response to the first type of random access termination information, the terminal may immediately terminate the ongoing random access procedure.

[0333] In step S3305, the terminal determines whether to exclude existing cells in which the existing RACH procedure has been suspended for cell search or existing beams of the existing cells. In other words, the terminal can select targets to be excluded from cell search among existing cells and beams in which the existing RACH procedure has been performed.

[0334] If the UE wishes to exclude an existing beam for which the existing RACH procedure has been performed, in step S3307, the UE determines whether the UE can exclude the existing beam. If the UE can exclude the existing beam, in step S3311, the UE performs a cell search based on the remaining beams excluding the existing beam. That is, the UE can start a cell search using the remaining beams excluding the last beam of the last cell for which the existing RACH procedure has been performed in order to restart the RACH procedure.

[0335] If the existing cell for which the existing RACH procedure has been performed is excluded or if the terminal is a terminal that cannot exclude the existing beam, in step S3309, the terminal determines whether the terminal is a terminal that can exclude the existing cell. If the terminal is a terminal that can exclude the existing cell, in step S3313, the terminal performs a cell search for the remaining cells excluding the existing cell. That is, the terminal can start a cell search for the remaining cells excluding the last cell for which the existing RACH procedure has been performed in order to restart the RACH procedure.

[0336] If the terminal cannot exclude the existing cell and the existing beam, in step S3315, the terminal can check whether a random access retry to the existing cell and the existing beam is possible. If a random access retry to the existing cell and the existing beam is not possible, in step S3317, the terminal starts a cell search for all cells and all beams. If a random access retry to the existing cell and the existing beam is possible, in step S3319, the terminal transmits Msg1 for the existing cell and the existing beam based on the corrected TA pre-compensation value. That is, if a random access retry to the existing cell and the existing beam is possible, the terminal can correct the existing TA pre-compensation value and determine the uplink transmission timing of Msg1 based on the corrected TA pre-compensation value. The terminal transmits Msg1 including a random access preamble at an uplink transmission timing determined based on a corrected TA pre-compensation value, and waits for reception of Msg2 having a RAPID (random access preamble ID) corresponding to the transmitted random access preamble. If Msg2 is not received within a specified time, or if Msg2 is received within a specified time but the corresponding PRPID is not detected, the terminal may determine that normal reception of Msg2 has failed. In this case, the terminal may transmit Msg1 again, and at this time, the TA pre-compensation value may be corrected based on Example #3.

[0337]

[0338] FIG. 34 illustrates an example of transmitting and applying a first type of random access suspension indication information in a wireless communication system according to an embodiment of the present disclosure. Referring to FIG. 34 , the first type of random access suspension indication information may be provided to a terminal via SIB, Msg2, or Msg4. Upon receiving the first type of random access suspension indication information, the terminal may immediately terminate the random access procedure and restart from the cell search phase to restart the random access procedure based on another cell and / or another beam.

[0339]

[0340] The first type of random access suspension indication information as described above may be transmitted as binary 2-state information. In addition, when the first type of random access suspension indication information is received, the cells and / or beams to be excluded from the cell search of the terminal may be determined by cell and / or beam exclusion selection indication information transmitted to the base station, or may be determined by a standard specification or terminal selection. In addition, whether a retry is possible from Msg1 or MsgA may be determined by retry-possible indication information transmitted by the base station, or may be determined by a standard specification or terminal selection. The cell and / or beam exclusion selection indication information and / or retry-possible indication information as described above may be transmitted as binary 2-state information. In some embodiments, when the random access suspension indication information, the cell and / or beam exclusion selection indication information, and the retry-possible indication information are combined and transmitted, the indication information may be transmitted as 8-state information. According to an embodiment, the above-described indication information may be transmitted via SIB, Msg2, Msg4, or MsgB, and may be transmitted via separate signaling. For example, the first type of random access suspension indication information may be transmitted via UE-specific signaling, and the cell or beam exclusion selection information and the information regarding whether a retry is possible may be transmitted via cell-specific signaling.

[0341]

[0342] FIG. 35 illustrates an example of a second type of random access interruption information application procedure in a wireless communication system according to an embodiment of the present disclosure.

[0343] Referring to FIG. 35, in step S3501, the terminal receives second type random access interruption information from the base station. According to an embodiment, the second type random access interruption information may be received using any one of Msg2, MsgA, or Msg4, or may be received using separate signaling after receiving Msg2, MsgA, or Msg4.

[0344] In step S3503, the terminal immediately suspends the ongoing RACH procedure. In response to the second type of random access suspension information, the terminal may suspend the transmission of Msg3, the transmission of Msg4 HARQ-ACK, or the transmission of MsgB HARQ-ACK. For example, if the second type of random access suspension information is received using Msg2 or is received using separate signaling after receiving Msg2, the terminal may suspend the ongoing random access procedure without transmitting Msg3. In this case, the suspended step of the random access procedure may be the Msg3 transmission step. As another example, if the second type of random access suspension information is received using Msg4 or is received using separate signaling after receiving Msg4, the terminal may suspend the ongoing random access procedure without transmitting Msg4 HARQ-ACK. In this case, the suspended step of the random access procedure may be the Msg4 HARQ-ACK transmission step.

[0345] In step S3505, the terminal waits for a given time interval for suspension. The given time interval may be predetermined based on the standard or terminal characteristics.

[0346] In step S3507, the terminal checks whether the conditions for resumption are satisfied. The conditions for resumption may include conditions related to a state before the RACH procedure was suspended. For example, the conditions for resumption may include a condition regarding whether any of Msg3, Msg4 HARQ-ACK, or MsgB HARQ-ACK was to be transmitted or retransmitted before the RACH procedure was suspended. Here, the state in which Msg3 must be transmitted or retransmitted may include a state in which reception of Msg3 has been completed, the state in which Msg4 HARQ-ACK must be transmitted or retransmitted may include a state in which reception of Msg4 has been completed, and the state in which MsgB HARQ-ACK must be transmitted or retransmitted may include a state in which reception of MsgB has been completed. Conditions for resumption may include conditions for whether the base station of the cell in question reserves the RAPID of the terminal in question and may not transmit RAR if it is determined that a collision will occur between terminals attempting random access through the same RAPID.

[0347] If the conditions for resumption are satisfied, in step S3515, the terminal decides whether to resume the RACH procedure to the same cell from the previously suspended step or from the step preceding the suspended step.

[0348] If it is decided to resume from the interrupted step, in step S3517, the terminal can resume the RACH procedure by performing the interrupted step. For example, the terminal can perform Msg3 transmission, Msg4 HARQ-ACK transmission, or MsgB HARQ-ACK transmission.

[0349] If it is determined to resume from a previous step prior to the interrupted step, the terminal can resume the RACH procedure at step S3519 by restarting from the step prior to the interrupted step. For example, if the interrupted step is the Msg3 transmission step, the terminal can retry receiving Msg2 from the base station.

[0350] If the conditions for resumption are not satisfied, the terminal may operate in the same manner as when the first type of random access suspension indication information is received. According to an embodiment, if the terminal confirms through SIB19 that the NGSO satellite-based NTN cell no longer serves the area at the time of resumption, the terminal may determine that resumption is not possible because the resumption conditions are not satisfied. At this time, the terminal may perform steps S3305 to S3319 described in FIG. 33. Specifically, in step 3509, the terminal determines whether to exclude the existing cell in which the existing RACH procedure has been performed for cell search or the existing beam of the existing cell. That is, the terminal may select a target to be excluded from the cell search among the existing cell and the existing beam in which the existing RACH procedure has been performed.

[0351] If the UE wishes to exclude an existing beam for which the existing RACH procedure has been performed, in step S3511, the UE determines whether the UE can exclude the existing beam. If the UE can exclude the existing beam, in step S3521, the UE performs a cell search based on the remaining beams excluding the existing beam. That is, the UE can start a cell search using the remaining beams excluding the last beam of the last cell for which the existing RACH procedure has been performed in order to restart the RACH procedure.

[0352] If the existing cell for which the existing RACH procedure has been performed is excluded or if the terminal is a terminal that cannot exclude the existing beam, in step S3513, the terminal determines whether the terminal is a terminal that can exclude the existing cell. If the terminal is a terminal that can exclude the existing cell, in step S3523, the terminal performs a cell search for the remaining cells excluding the existing cell. That is, the terminal can initiate a cell search for the remaining cells excluding the last cell for which the existing RACH procedure has been performed in order to restart the RACH procedure.

[0353] If the terminal cannot exclude the existing cell and the existing beam, in step S3525, the terminal can check whether a random access retry to the existing cell and the existing beam is possible. If a random access retry to the existing cell and the existing beam is not possible, in step S3527, the terminal starts a cell search for all cells and all beams. If a random access retry to the existing cell and the existing beam is possible, in step S3529, the terminal transmits Msg1 for the existing cell and the existing beam based on the corrected TA pre-compensation. That is, if a random access retry to the existing cell and the existing beam is possible, the terminal can correct the existing TA pre-compensation and determine the uplink transmission timing of Msg1 based on the corrected TA pre-compensation. The terminal transmits Msg1 including a random access preamble at an uplink transmission timing determined based on a corrected TA pre-compensation value, and waits for reception of Msg2 having a RAPID (random access preamble ID) corresponding to the transmitted random access preamble. If Msg2 is not received within a specified time, or if Msg2 is received within a specified time but the corresponding PRPID is not detected, the terminal may determine that normal reception of Msg2 has failed. In this case, the terminal may transmit Msg1 again, and at this time, the TA pre-compensation value may be corrected based on Example #3.

[0354]

[0355] FIG. 36 illustrates an example of transmitting and applying a second type of random access suspension indication information in a wireless communication system according to an embodiment of the present disclosure. Referring to FIG. 36, the second type of random access suspension indication information may be provided to a terminal via Msg2 or Msg4. When the second type of random access suspension indication information is received, the terminal temporarily suspends the random access procedure. When a resumption condition is satisfied, the terminal can resume the random access procedure by performing the suspended step or re-performing a step preceding the suspended step.

[0356]

[0357] The second type of random access suspension information described above can be transmitted as binary 2-state information. Conditions for resumption can be predefined by the standard. In addition, when conditions such as a specific TA pre-compensation value change, the base station can transmit the changed conditions to the terminal through signaling. The resumption operation can be predefined by the standard, and, if necessary, the base station can transmit instruction information for the resumption operation through signaling. For example, when resuming a suspended random access procedure, whether to resume from the existing suspended step or from the previous step can be defined by the standard or signaled by the base station. The duration for suspension can be predefined by the standard or indicated through additional signaling, etc. The suspension time can be defined and transmitted as a symbol unit or slot unit time. The cells and / or beams to be excluded when resumption is not possible can be determined by cell and / or beam exclusion selection instruction information transmitted from the base station, or by rules or terminal selection predefined in the standard. The cell and / or beam exclusion selection indication information can be transmitted as binary 2-state information. Whether a retry from Msg1 or MsgA is possible is determined by the retry-possible indication information transmitted by the base station, or can be determined by the standard specification or terminal selection. The retry-possible indication information can be transmitted as binary 2-state information. The information as described above can be transmitted via SIB, Msg2, Msg4, or MsgB, and can be transmitted via separate signaling. For example, the second type of random access suspension indication information can be transmitted via UE-specific signaling, and the indication information for the resumption operation can be transmitted via cell-specific signaling.

[0358]

[0359] As described above, the random access interruption information and / or information related to the waiting time may be transmitted via UE-specific signaling for individual terminals, or via cell-specific signaling or group signaling for multiple terminals. For example, if the error in the ephemeris transmitted via SIB19 is large, or if an uplink synchronization error is likely to occur during the random access procedure due to a TA error of the random access in a specific beam and a specific area, the random access interruption information and / or information related to the waiting time may be transmitted for multiple terminals via cell-specific signaling or group signaling.

[0360]

[0361] The methods according to the present disclosure may be implemented in the form of program instructions that can be executed by various computer means and recorded on a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, etc., either singly or in combination. The program instructions recorded on the computer-readable medium may be those specifically designed and configured for the present disclosure or may be known and available to those skilled in the computer software art.

[0362] Examples of computer-readable media include hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, and flash memory. Examples of program instructions include machine language code, such as that produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter, etc.

[0363] While some aspects of the present disclosure have been described in the context of a device, they may also represent a description of a corresponding method, wherein a block or device corresponds to a method step or a feature of a method step. Similarly, aspects described in the context of a method may also be described as a corresponding block or item or a feature of a corresponding device. Some or all of the method steps may be performed by (or using) a hardware device, such as, for example, a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, at least one or more of the most significant method steps may be performed by such a device.

[0364] A programmable logic device (e.g., a field-programmable gate array) may be used to perform some or all of the functions of the methods described in this disclosure. The field-programmable gate array may operate in conjunction with a microprocessor to perform one of the methods described in this disclosure. In general, the methods are preferably performed by some hardware device.

[0365] Although the present disclosure has been described with reference to the above embodiments, it will be understood by those skilled in the art that various modifications and changes can be made to the present disclosure without departing from the spirit and scope of the present disclosure as set forth in the claims below.

Claims

1. In a method of operating a terminal in a wireless communication system, Receiving system information including information about random access to a non-terrestrial network (NTN) base station; Transmitting a random access preamble to the NTN base station; Receiving a random access response message from the NTN base station; Transmitting a first message for establishing a connection through a resource scheduled by the above random access response message; comprising receiving a second message for establishing a connection from the NTN base station; The above random access response message includes TA (timing advance) information, The above system information or the random access response message includes information for TA compensation, A method in which the first message is transmitted at a timing determined by applying the TA information and the information for the TA compensation.

2. In claim 1, The above TA information includes information related to TA adjustment directed by TAC (timing advance command), A method in which the information for the above TA compensation includes coefficient information for compensating for the first value determined by the TAC.

3. In claim 2, A method in which the coefficient information for compensating for the first value determined by the TAC includes at least one of coefficient information commonly applied to a plurality of terminals or coefficient information applied to a specific terminal.

4. In claim 1, A method in which the information for the above TA compensation includes a TA pre-compensation value estimated by the base station.

5. In claim 4, A method in which the TA pre-compensation value estimated by the base station includes at least one of a TA pre-compensation value commonly applied to a plurality of terminals or a TA pre-compensation value applied to a specific terminal.

6. In claim 4, A method wherein the TA pre-compensation value estimated by the base station includes at least one of a TA pre-compensation value reflecting the propagation delay of the service link between the terminal and the satellite, or a TA pre-compensation value reflecting the propagation delay of the feeder link between the satellite and the base station.

7. In claim 1, Transmitting a random access preamble to the above NTN base station is: Determining failure to receive the above random access response; Correcting the TA pre-compensation applied to the above random access preamble; and A method comprising transmitting the random access preamble at a timing determined based on a corrected TA pre-compensation value.

8. In claim 1, A method further comprising receiving an instruction to discontinue the random access from the NTN base station.

9. In claim 8, Aborting an ongoing random access procedure based on an instruction to suspend the above random access; and Determining at least one of the cells or beams for cell search based on at least one of the cells or beams corresponding to the random access procedure; Performing a cell search based on at least one of the determined cells or beams; and A method further comprising restarting a random access procedure based on the cell search results.

10. In claim 8, Aborting an ongoing random access procedure based on an instruction to suspend the above random access; and Correcting the TA pre-compensation applied to the above random access preamble; and A method further comprising transmitting the random access preamble at a timing determined based on a corrected TA pre-compensation value.

11. In claim 8, Suspending the random access procedure based on the instruction to suspend the above random access; and Further comprising resuming the suspended random access procedure based on the resumption conditions, A method in which the above random access procedure is resumed by performing the interrupted step or a step preceding the interrupted step.

12. In a method of operating a NTN (non-terrestrial network) base station in a wireless communication system, Transmitting system information including information on random access to an NTN base station to a terminal; Receiving a random access preamble from the terminal; Transmitting a random access response message to the terminal; Receiving a first message for establishing a connection through a resource scheduled by the above random access response message; Including transmitting a second message for establishing a connection to the terminal, The above random access response message includes TA (timing advance) information, The above system information or the random access response message includes information for TA compensation, A method in which the first message is transmitted at a timing determined by applying the TA information and the information for the TA compensation from the terminal.

13. In claim 12, The above TA information includes information related to TA adjustment directed by TAC (timing advance command), A method in which the information for the above TA compensation includes coefficient information for compensating for the first value determined by the TAC.

14. In claim 13, A method in which the coefficient information for compensating for the first value determined by the TAC includes at least one of coefficient information commonly applied to a plurality of terminals or coefficient information applied to a specific terminal.

15. In claim 12, A method in which the information for the above TA compensation includes a TA pre-compensation value estimated by the base station.

16. In claim 15, A method in which the TA pre-compensation value estimated by the base station includes at least one of a TA pre-compensation value commonly applied to a plurality of terminals or a TA pre-compensation value applied to a specific terminal.

17. In claim 15, A method wherein the TA pre-compensation value estimated by the base station includes at least one of a TA pre-compensation value reflecting the propagation delay of the service link between the terminal and the satellite, or a TA pre-compensation value reflecting the propagation delay of the feeder link between the satellite and the base station.

18. In claim 12, A method further comprising transmitting an instruction to the terminal to discontinue the random access.

19. In a wireless communication system, at a terminal, At least one transmitter / receiver; at least one processor; and At least one memory operably connected to said at least one processor and storing instructions that, when executed by said processor, control said terminal to perform operations; The above actions are, Receiving system information including information about random access to a non-terrestrial network (NTN) base station; Transmitting a random access preamble to the NTN base station; Receiving a random access response message from the NTN base station; Transmitting a first message for establishing a connection through a resource scheduled by the random access response message; and comprising receiving a second message for establishing a connection from the NTN base station; The above random access response message includes TA (timing advance) information, The above system information or the random access response message includes information for TA compensation, The terminal, wherein the first message is transmitted at a timing determined by applying the TA information and the information for the TA compensation.

20. In a non-terrestrial network (NTN) base station in a wireless communication system, At least one transmitter / receiver; at least one processor; and At least one memory operably connected to said at least one processor and storing instructions that, when executed by said processor, control said terminal to perform operations; The above actions are, Transmitting system information including information on random access to the NTN base station to the terminal; Receiving a random access preamble from the terminal; Transmitting a random access response message to the terminal; Receiving a first message for establishing a connection through a resource scheduled by the random access response message; and Including transmitting a second message for establishing a connection to the terminal, The above random access response message includes TA (timing advance) information, The above system information or the random access response message includes information for TA compensation, An NTN base station, wherein the first message is transmitted at a timing determined by applying the TA information and the information for the TA compensation from the terminal.

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