Method and apparatus for managing uplink synchronization with non-terrestrial network base station in wireless communication system

Abstract

The present disclosure relates to a method and apparatus for managing uplink synchronization with a non-terrestrial network (NTN) base station in a wireless communication system, and the operation method of a terminal may include: establishing a connection with an NTN base station; receiving a message for imposing a restriction on uplink transmission to the NTN base station; in response to receiving the message, performing a procedure for acquiring second TA information different from first TA information currently in use; and performing communication on the basis of the second TA information.

Description

Method and device for managing uplink synchronization for a non-terrestrial network base station in a wireless communication system

[0001] The present disclosure relates to a non-terrestrial network (NTN) in a wireless communication system, and more particularly, to a method and apparatus for managing uplink synchronization for an NTN base station.

[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 preventing uplink synchronization errors in a wireless communication system supporting a non-terrestrial network (NTN).

[0008] The present disclosure can provide a device and method for correcting an uplink TA (timing advance) error in a wireless communication system.

[0009] The present disclosure can provide a device and method for limiting uplink transmission of a terminal having a TA error in a wireless communication system.

[0010] The present disclosure can provide a device and method for inducing a random access procedure of a terminal having a TA error in a wireless communication system.

[0011] The present disclosure can provide a device and method for inducing a random access procedure of a terminal based on a message indicating an RRC (radio resource control) state transition in a wireless communication system.

[0012] The present disclosure may provide a device and method for transmitting a message indicating the suspension of uplink transmission in a wireless communication system.

[0013] The present disclosure may provide a device and method for transmitting information for TA compensation in a wireless communication system.

[0014] 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.

[0015] 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.

[0016] According to one embodiment of the present disclosure, a method of operating a terminal in a wireless communication system may include establishing a connection with a non-terrestrial network (NTN) base station, receiving a message for restriction on uplink transmission to the NTN base station, performing a procedure for obtaining second TA information different from first TA information currently in use in response to receiving the message, and performing communication based on the second TA information.

[0017] According to one embodiment of the present disclosure, a method of operating a non-terrestrial network (NTN) base station in a wireless communication system may include establishing a connection with a terminal, and transmitting a message for restriction on uplink transmission to the terminal.

[0018] 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, wherein the operations may include establishing a connection with a non-terrestrial network (NTN) base station, receiving a message for restriction on uplink transmission to the NTN base station, performing a procedure for acquiring second TA information different from first TA information currently in use in response to receiving the message, and performing communication based on the second TA information.

[0019] 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 may include establishing a connection with the terminal and transmitting a message for a restriction on uplink transmission to the terminal.

[0020] According to the present disclosure, it is possible to prevent synchronization errors and uplink performance degradation due to TA (timing advance) pre-compensation errors in a wireless communication system, and to prevent coverage degradation and feeder link capacity waste.

[0021] 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.

[0022] FIG. 1A and FIG. 1B illustrate the structure of a transparent-based non-terrestrial network according to an embodiment of the present disclosure.

[0023] FIGS. 2A to 2C illustrate the structure of a regenerative-based non-terrestrial network according to an embodiment of the present disclosure.

[0024] FIG. 3 illustrates a block diagram of a communication node constituting a non-terrestrial network according to an embodiment of the present disclosure.

[0025] FIG. 4 illustrates a block diagram of a communication node according to an embodiment of the present disclosure.

[0026] 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.

[0027] FIG. 6 illustrates an example of a system frame in a wireless communication system according to an embodiment of the present disclosure.

[0028] FIG. 7 illustrates an example of a subframe in a wireless communication system according to an embodiment of the present disclosure.

[0029] FIG. 8 illustrates an example of a slot in a wireless communication system according to an embodiment of the present disclosure.

[0030] FIG. 9 illustrates the timing relationship between uplink and downlink in a wireless communication system according to an embodiment of the present disclosure.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] Figure 13 illustrates the timing relationship between objects included in NTN.

[0035] 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.

[0036] FIG. 14b illustrates an example of applying TA pre-compensation in a wireless communication system according to an embodiment of the present disclosure.

[0037] FIG. 15a illustrates an example of a procedure for performing communication during a connection mode in a wireless communication system according to an embodiment of the present disclosure.

[0038] FIG. 15b illustrates an example of a procedure for preventing uplink synchronization errors in a wireless communication system according to an embodiment of the present disclosure.

[0039] FIG. 16 illustrates an example of a random access induction procedure in a wireless communication system according to an embodiment of the present disclosure.

[0040] FIG. 17 illustrates an example of transmission of a random access induction signal in a wireless communication system according to an embodiment of the present disclosure.

[0041] FIG. 18 illustrates examples of a first type of random access induction signal transmission in a wireless communication system according to an embodiment of the present disclosure.

[0042] FIG. 19 illustrates examples of second type random access induction signal transmission in a wireless communication system according to an embodiment of the present disclosure.

[0043] FIG. 20 illustrates an example of a procedure for stopping uplink transmission in a wireless communication system according to an embodiment of the present disclosure.

[0044] FIG. 21 illustrates an example of a procedure for stopping uplink transmission using signaling in a wireless communication system according to an embodiment of the present disclosure.

[0045] FIG. 22 illustrates an example of a procedure for stopping uplink transmission without signaling in a wireless communication system according to an embodiment of the present disclosure.

[0046] FIG. 23 illustrates examples of uplink transmission interruption using signaling in a wireless communication system according to an embodiment of the present disclosure.

[0047] FIG. 24 illustrates examples of stopping uplink transmission without signaling in a wireless communication system according to an embodiment of the present disclosure.

[0048] FIG. 25 illustrates an example of a procedure for performing uplink transmission based on a long relative TAC in a wireless communication system according to an embodiment of the present disclosure.

[0049] FIG. 26 illustrates an example of a TAC-specific correction range in a wireless communication system according to an embodiment of the present disclosure.

[0050] FIG. 27 illustrates examples of uplink transmission based on a long relative TAC in a wireless communication system according to an embodiment of the present disclosure.

[0051] FIG. 28 illustrates an example of a procedure for performing uplink transmission based on TAC adjustment coefficient information in a wireless communication system according to an embodiment of the present disclosure.

[0052] FIG. 29 illustrates examples of application of the first type of TAC adjustment coefficient in a wireless communication system according to an embodiment of the present disclosure.

[0053] FIG. 30 illustrates examples of application of a second type of TAC adjustment coefficient in a wireless communication system according to an embodiment of the present disclosure.

[0054] FIGS. 31A and 31B 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.

[0055] FIG. 32 illustrates an example of available bits of absolute TAC in a wireless communication system according to an embodiment of the present disclosure.

[0056] FIG. 33 illustrates an example of bit allocation for a TAC adjustment coefficient within a TAC in an absolute wireless communication system according to an embodiment of the present disclosure.

[0057] 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.

[0058] 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.

[0059] 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.”

[0060] 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.”

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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)).

[0068] 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.”

[0069] 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.

[0070] 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."

[0071] FIG. 1A and FIG. 1B illustrate the structure of a transparent-based non-terrestrial network (NTN) according to an embodiment of the present disclosure.

[0072] 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.

[0073] 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.

[0074] In non-terrestrial networks, three types of service links can be supported:

[0075] - 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).

[0076] - 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).

[0077] - 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).

[0078] 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.

[0079] 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 a 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.

[0080] 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).

[0081] 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.

[0082] FIGS. 2A to 2C illustrate the structure of a regenerative-based non-terrestrial network according to an embodiment of the present disclosure.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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).

[0087] As in the embodiments of FIGS. 2b and 2c below, a “core network” may exist between the gateway (230) and the data network (240).

[0088] 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.

[0089] 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.

[0090] FIG. 3 illustrates a block diagram of a communication node constituting a non-terrestrial network according to an embodiment of the present disclosure.

[0091] 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.

[0092] 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).

[0093] 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).

[0094] 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.

[0095] 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.

[0096] 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).

[0097] 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.

[0098] FIG. 4 illustrates a block diagram of a communication node according to an embodiment of the present disclosure.

[0099] 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).

[0100] 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.

[0101] 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).

[0102] 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).

[0103] 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).

[0104] 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).

[0105] 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).

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] FIG. 6 illustrates an example of a system frame in a wireless communication system according to an embodiment of the present disclosure.

[0115] 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.

[0116] 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."

[0117] FIG. 7 illustrates an example of a subframe in a wireless communication system according to an embodiment of the present disclosure.

[0118] 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.

[0119] FIG. 8 illustrates an example of a slot in a wireless communication system according to an embodiment of the present disclosure.

[0120] 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.

[0121] 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].

[0122] 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

[0123] 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.

[0124] 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.

[0125] 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."

[0126] FIG. 9 illustrates the timing relationship between uplink and downlink in a wireless communication system according to an embodiment of the present disclosure.

[0127] 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.

[0128] 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.

[0129] is derived from the upper layer parameters ta-Common, ta-CommonDrift, ta-CommonDriftVariant, which if not configured am.

[0130] 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.

[0131] 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.

[0132]

[0133] 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].

[0134]

[0135] 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.

[0136] 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.

[0137] 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 ability 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.

[0138] Meanwhile, NTN reference scenarios can be defined as shown in [Table 4] below.

[0139] NTN shown in Fig. 1 NTNGEO shown in Fig. 2 Scenario A Scenario BLEO (steerable beam) Scenario C1 Scenario D1 LEO (beam moving with satellite) Scenario C2 Scenario D2

[0140] 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.”

[0141] 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.”

[0142] Parameters for the NTN reference scenarios defined in [Table 4] can be defined as shown in [Table 5] below.

[0143] 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

[0144] Additionally, in the NTN reference scenario defined in [Table 4], the delay constraint can be defined as in [Table 6] below.

[0145] 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

[0146] 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.

[0147] 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.

[0148] 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.

[0149] 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.

[0150] 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.

[0151] 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.

[0152] 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.

[0153] - NTN gateway can serve multiple NTN payloads.

[0154] - A single NTN payload can be served by multiple NTN gateways.

[0155] - NTN payloads can change carrier frequency before being retransmitted on the service link, or vice versa (on each feeder link).

[0156] In NTN, in addition to the network identifier, the following may apply:

[0157] - A tracking area corresponds to a fixed geographic area. Each mapping is configured in the RAN.

[0158] - Mapped cell ID as defined in Section 16.14.5.

[0159] Three types of service links are supported:

[0160] - 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).

[0161] - 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).

[0162] - 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).

[0163] 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.

[0164] Timing and synchronization are as follows:

[0165] 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.

[0166] - Common TA is a timing offset configured equal to the round trip time (RTT) between the RP and NTN payloads.

[0167] - 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.

[0168] - k mac is an offset that is configured to be approximately equal to the RTT between the RP and gNB.

[0169] 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.

[0170] The network can configure HARQ operation as follows:

[0171] - 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.

[0172] - 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.

[0173] 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.

[0174] Mobility and state transitions for NTN are as follows.

[0175] For mobility in RRC_IDLE and RRC_INACTIVE states, the same principles as applied in TN (e.g., TS 38.300 clause 9.2.1) may apply to mobility in RRC_IDLE to NTN, and the same principles as applied in TN (e.g., TS 38.300 clause 9.2.2) may apply to mobility in RRC_INACTIVE to NTN.

[0176] The network can broadcast multiple tracking area codes (TACs) per public land mobile network (PLMN) in an NR NTN cell. TAC changes within the system information are under network control, and TAC changes may not be precisely synchronized with the real-time illumination of the ground beams.

[0177] For NTN-TN mobility, the network can broadcast cell information for NR TN and EUTRA TN coverage areas in SIB25. This is supported for geo-stationary, semi-geo-stationary, and geo-mobile cells. The coverage information consists of a list of geographical TN areas and also indicates associated frequency information. The UE can skip TN measurements based on the broadcast TN coverage information.

[0178] The UE can implicitly determine the network type (e.g., terrestrial or non-terrestrial) through the presence of cellBarredNTN in SIB1. The NTN ephemeris is provided in SIB19. An NTN cell may include the NTN payload ephemeris of the serving cell and, optionally, the NTN payload ephemeris of neighboring cells.

[0179] Mobility in RRC_CONNECTED can be viewed in terms of handover, conditional handover (CHO), satellite switch with re-sync, measurements, etc.

[0180] For handover, the same principles as those applied in the TN (e.g. TS 38.300 clause 9.2.3.2) may be applied to the NTN, unless otherwise specified. During movement between the NTN and the TN, the UE is not required to be connected to both the NTN and the TN simultaneously. An NTN TN handover means bidirectional mobility, i.e., movement from the NTN to the TN (e.g. hand-in) and from the TN to the NTN (e.g. hand-out). The UE may support mobility between gNBs operating with the NTN payload in different orbits (e.g. GSO, NGSO at different altitudes). The NTN may support RACH-less handover.

[0181] For conditional handovers, the same principles as those applied in TN (e.g., TS 38.300, clause 9.2.3.4) may be applied to NTN, unless otherwise specified. NTN supports additional trigger conditions for a UE to initiate a conditional handover to a candidate cell, such as radio resource management (RRM) measurement-based event A4, time-based trigger conditions, and / or location-based trigger conditions.

[0182] Time-based or location-based trigger conditions can be configured independently from the measurement conditions for conditional handover of the NTN in the minimal hard satellite switch case where the service discontinuity gap time length is assumed to be zero or negligible. Otherwise, the time-based or location-based trigger conditions are configured together with one of the measurement-based trigger conditions (e.g., conditional handover events A3 / A4 / A5). How the UE evaluates the time-based or location-based trigger conditions together with the RRM measurement-based events depends on the UE implementation. If a time-based trigger condition is used, the source BS can signal the corresponding parameters to a single target gNB via the Source NG-RAN Node to Target NG-RAN Node Transparent Container in an NG-C based handover (see TS 23.502). The source BS can signal the corresponding conditional handover configuration to the UE using an RRC reconfiguration message during the handover. If a time-based trigger condition is used, the source BS determines the start time of initial data transfer to the target BS by considering the time indicated to the UE. Additionally, time-based conditional handover can be performed in a RACH-less manner.

[0183] 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.

[0184] 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}

[0185] NTN-Config defined in [Table 7] may include information element(s) defined in [Table 8] below.

[0186] 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)}

[0187] EphemerisInfo defined in [Table 8] may include information element(s) defined in [Table 9] below.

[0188] 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 (-131072..131071)

[0189] 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.

[0190] 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}

[0191] The present disclosure relates to a device and method for preventing uplink synchronization errors and resource waste due to timing advance (TA) precompensation errors of a terminal in an RRC connected mode situation of a non-terrestrial network (NTN) environment.

[0192] In a mobile communication system, the uplink signals of each user must be synchronized so that they are received within a cyclic prefix (CP) from the base station's reception timing perspective. This ensures that the base station can receive each user's signals without interference. Therefore, in a terrestrial network (TN) system, the transmission timing of each user's uplink signals (e.g., PUSCH, PUCCH, SRS (Sounding Reference Signal), etc.) is adjusted by compensating for the TA based on a timing advance command (TAC) to synchronize the uplink signals.

[0193] 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).

[0194] 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.

[0195] 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.

[0196] 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.

[0197] 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.

[0198] In particular, if an uplink synchronization error occurs for PUSCH, PUCCH, and / or SRS due to TA error while the terminal is in RRC connected mode, the uplink throughput of the NTN cell may be significantly reduced. In addition, the interference caused by the uplink synchronization error may deteriorate the performance of terminals near cell edges with low SNR (Signal-to-Noise Ratio), which may lead to a degradation of NTN coverage. In an NTN environment, the feeder link capacity between satellites and base stations is limited due to the large number of users. However, the limited feeder link capacity may be wasted due to an uplink synchronization error caused by TA error. Therefore, immediate measures are required for terminals that have caused or are expected to cause an uplink synchronization error due to TA error in the future.

[0199] The present disclosure relates to a method and device for resolving uplink synchronization errors caused by a terminal with a TA error in connected mode. The present disclosure proposes various embodiments for resolving uplink synchronization errors, and at least two or more embodiments may be combined and applied, if necessary.

[0200] According to embodiments of the present disclosure, a base station and / or a network are required to determine whether a terminal has caused or will cause an uplink synchronization error due to a TA error, and at least one of the embodiments proposed in the present disclosure may be applied based on the determination result. For this determination, various pieces of information related to TA may be utilized. For example, a TA report transmitted by each terminal, an applicable TA estimate of each terminal estimated by the base station, a TA application range in which each terminal is expected not to cause an uplink synchronization error, a TA threshold, a TA error threshold, a future TA prediction value, an estimated SINR (Signal-to-Interference-Plus-Noise Ratio) for uplink transmission (e.g., PUSCH, PUCCH, SRS, etc.), a decoding error probability, or an estimated ISI (Inter-Symbol Interference) / ICI (Inter-Carrier Interference) power, etc. may be utilized. Here, the applied TA estimate for each terminal can be estimated based on the uplink signal transmitted by each terminal, such as PUSCH / PUCCH / SRS. Furthermore, the TA coverage can be calculated based on location information for each terminal. The TA threshold or TA error threshold refers to a reference point used to determine the occurrence or likelihood of an uplink synchronization error in the future. The future TA prediction can be determined based on observations of at least one of the TA application trends and history up to a specific point in time. Furthermore, these determinations can be performed based on an AI (Artificial Intelligence) / ML (Machine Learning) algorithm utilizing the information described above.

[0201]

[0202] FIG. 15A illustrates an example of a procedure for performing communication during a connected mode in a wireless communication system according to an embodiment of the present disclosure. FIG. 15A illustrates a method performed by a terminal. The terminal may be understood as a UE.

[0203] Referring to Figure 15a, in step S1501, the terminal establishes a connection with the NTN base station. The terminal can establish a connection with the NTN base station by performing an RRC connection procedure with the NTN base station.

[0204] In step S1503, the terminal receives a message for uplink transmission restriction. The terminal may receive a message for restricting uplink transmission to an NTN base station. According to one embodiment, the message for restricting uplink transmission may include a message for inducing performance of a random access procedure. The message for inducing performance of the random access procedure may include at least one of a message indicating a transition to an RRC idle mode or an RRC inactive mode, or a message including a triggering command for the random access procedure. According to one embodiment, the message for restricting uplink transmission may include a message for inducing suspension of uplink transmission. The message for restricting uplink transmission may be received via at least one of a PDSCH, a PDCCH, or a SIB.

[0205] In step S1505, the terminal performs a procedure for acquiring second TA information that is different from the first TA information currently in use. In response to receiving a message for uplink transmission restriction, the terminal may perform a procedure for acquiring second TA information that is different from the first TA information currently in use. The procedure for acquiring the second TA information may include a random access procedure. For example, the terminal may perform a random access procedure to receive a TAC from an NTN base station and acquire second TA information that is different from the first TA information currently in use based on the received TAC.

[0206] At step S1507, the terminal performs communication based on the second TA information. The terminal determines an uplink transmission timing based on the second TA information and can transmit an uplink signal at the determined transmission timing.

[0207]

[0208] Figure 15b illustrates an example of a procedure for preventing uplink synchronization errors in a wireless communication system according to an embodiment of the present disclosure. Figure 15b illustrates a method performed by a base station. The base station may be understood as an NTN base station.

[0209] Referring to Figure 15b, at step S1551, the base station establishes a connection with the terminal. The base station can establish a connection with the terminal by performing an RRC connection procedure with the terminal.

[0210] In step S1553, the base station transmits a message for limiting uplink transmission. The base station can detect that the terminal is a terminal with an uplink synchronization error. The terminal with an uplink synchronization error may include a terminal that has caused an uplink synchronization error or a terminal that is likely to cause an uplink synchronization error in the future. The base station can transmit a message for limiting uplink transmission to the terminal to the NTN base station. According to one embodiment, the message for limiting uplink transmission may include a message for inducing the performance of a random access procedure. The message for inducing the performance of the random access procedure may include at least one of a message indicating a transition to an RRC idle mode or an RRC inactive mode, or a message including a triggering command for the random access procedure. According to one embodiment, the message for limiting uplink transmission may include a message for inducing the suspension of uplink transmission. Here, whether a terminal is an uplink synchronization error terminal can be determined based on at least one of a TA report transmitted by each terminal, an applicable TA estimate of each terminal estimated by the base station, a TA application range, a TA threshold, a TA error threshold, a future TA prediction, an estimated SINR for PUSCH / PUCCH / SRS, a decoding error probability, or an estimated ISI / ICI. A message for uplink transmission restriction can be transmitted through at least one of a PDSCH, a PDCCH, or a SIB.

[0211]

[0212] Example #1: Inducing random access

[0213] According to Embodiment #1 of the present disclosure, a base station and / or a network induces random access of an individual terminal or a plurality of terminals that have or are expected to have an uplink synchronization error due to a TA error. This is because, when a terminal accesses a different cell and / or a different beam through a cell search process for random access, the TA error for the beam of the current cell can be corrected. In addition, even when accessing the same beam of the same cell through random access, the TA error can be corrected over a wide range based on the TAC. Since the TAC in the random access process consists of 12 bits, a wider range of TA errors can be corrected than a typical 6-bit TAC. In addition, by inducing random access, it is possible to prevent uplink transmission with an uplink synchronization error from being performed before transmitting an uplink signal in the random access procedure.

[0214] FIG. 16 illustrates an example of a random access induction procedure in a wireless communication system according to an embodiment of the present disclosure. FIG. 16 illustrates signal exchange between a terminal (1610) and a base station (1620).

[0215] Referring to FIG. 16, in step S1601, the base station (1620) detects a terminal with an uplink synchronization error. The terminal with an uplink synchronization error may include an individual terminal or multiple terminals that have caused or are expected to cause an uplink synchronization error due to a TA error. The base station (1620) may determine whether the terminal is a terminal with an uplink synchronization error based on at least one of a previous uplink transmission or a TA report of the terminal (1610). For example, the base station (1620) may determine the TA error of the terminal based on the reception time of the previous uplink transmission of the terminal (1610) or the TA report. If the determined TA error is greater than or equal to a specified TA error threshold, the base station (1620) may determine the terminal as a terminal with an uplink synchronization error.

[0216] In step S1603, the base station (1620) transmits a random access induction message to the terminal (1610). That is, the base station (1610) may transmit the random access induction message to the terminal (1610) in order to cause the terminal (1610) to perform the random access procedure again. The random access induction message may include a message for restricting uplink transmission to the base station. For example, the random access induction message may include at least one of a message indicating a transition to an RRC standby mode or an RRC deactivation mode or a random access triggering command message.

[0217] FIG. 17 illustrates an example of transmitting a random access induction signal in a wireless communication system according to an embodiment of the present disclosure. Referring to FIG. 17, if random access induction is determined based on a previous uplink transmission or TA report of the terminal, the base station (1720) may induce random access of the terminal (1710) based on at least one of a PDSCH, a PDCCH, or a SIB, as in step S1701. The method of inducing random access can be divided into two types. Specifically, the method of inducing random access can be divided into a first type of transmitting an RRC state transition message, and a second type of transmitting a random access triggering command message.

[0218] As described above, the first type of transmitting an RRC state transition message is a method of inducing a terminal in RRC connected mode to perform random access again by transitioning the terminal to RRC idle mode or RRC inactive mode. A terminal operating in RRC idle mode or RRC inactive mode must be transitioned to RRC connected mode through an RRC setup request, an RRC resume request, etc. for uplink data transmission. The terminal must perform a random access procedure to transition to RRC connected mode. Accordingly, the network and / or base station of the present disclosure may transmit an RRC release message or an RRC release with suspendConfig message to a terminal experiencing an uplink synchronization error via a PDSCH. A terminal receiving an RRC release message transitions to the RRC idle mode, and a terminal receiving an RRC release message with suspendConfig transitions to the RRC inactive mode. The network and / or the base station may determine whether to transition the terminal to RRC standby mode or RRC inactive mode based on the NTN cell service time of the area where the terminal is located, etc. If the network determines the mode to which the terminal will transition, the base station may transmit information necessary for the network's decision to the corresponding network node. For example, the base station may provide the network node with at least one of a report on the terminal that has experienced an uplink error or TA error estimation information of the terminal. According to one embodiment, in case the terminal attempts random access through another base station in the future, the base station may transmit TAC-related information to be applied to the terminal to the other base station through the network.

[0219] A terminal in RRC standby mode does not perform uplink transmission. Therefore, if the terminal's mode is determined to be RRC standby mode, the base station and / or network can prevent uplink transmission by the terminal, which would cause uplink synchronization errors, by sending an RRC release message to the terminal without additional signaling.

[0220] On the other hand, a terminal in RRC disabled mode can perform SRS transmission for positioning, and an uplink synchronization error may occur due to the SRS transmission. That is, a terminal that has transitioned to RRC disabled mode may transmit an uplink signal before performing a random access procedure, which may cause an uplink synchronization error. Therefore, when the mode of the terminal is determined to be RRC disabled mode, the base station and / or the network need to restrict the terminal from performing uplink transmission before the random access procedure starts when the terminal transitions to RRC disabled mode. Therefore, the base station can restrict the terminal from performing uplink transmission before the random access procedure by transmitting an RRC release message with a separate signaling or suspension setting to the terminal. Here, the separate signaling may be performed using at least one of a PDSCH, a PDCCH, or a SIB. For example, the PDSCH may include at least one of an RRC message such as RRC release, or a MAC CE. Additionally, the PDCCH may include DCI, and the SIB may include at least one of cell-specific signaling or group signaling that is transmitted to multiple terminals. The separate signaling may be transmitted prior to the transmission of a message indicating an RRC deactivation mode transition, or may be transmitted together with the message indicating an RRC deactivation mode transition.

[0221] According to one embodiment, when an RRC release message having a pause setting is used to restrict SRS transmission for positioning in an RRC disabled mode, the RRC release message having a pause setting may not include SRS-related fields. For example, the SRS-related fields may not include at least one of srs-PosRRC-Inactive or srs-PosRRC-InactiveValidityAreaConfigList among the parameters related to SRS transmission defined in the specification. srs-PosRRC-Inactive indicates whether the terminal can perform SRS transmission in the RRC disabled state, and srs-PosRRC-InactiveValidityAreaConfigList may indicate a list of validity area configurations applied when the terminal transmits SRS in the RRC disabled state.

[0222] The long distance between the base station and the terminal in the NRN causes a time difference between the base station's transmission and the terminal's reception. Even if the base station sends a message instructing the terminal, which is determined to have an uplink synchronization error, to transition to RRC inactive mode, the terminal may transmit SRS due to the aforementioned time difference, which may result in an uplink synchronization error. To minimize the possibility of such terminals experiencing an uplink synchronization error, the base station can set the SRS offset and transmission period (e.g., SRS-PeriodicityAndOffset) to be as long as possible based on a given numerology.

[0223] FIG. 18 illustrates examples of transmitting a first type of random access induction signal in a wireless communication system according to an embodiment of the present disclosure. FIG. 18 discloses cases of inducing random access by transmitting an RRC state transition message.

[0224] Referring to Figure 18, a base station may determine whether to induce random access for a terminal based on the uplink transmission(s) and signaling(s) from the terminal in RRC connection mode. The base station that has determined to induce random access for the terminal may operate according to any one of Case 1, Case 2, or Case 3 described below.

[0225] According to Case 1, the base station can send an RRC release message to the terminal to induce random access. The terminal receiving the RRC release message can transition to RRC standby mode. The terminal in RRC standby mode can perform a random access procedure for uplink transmission.

[0226] According to case 2, the base station can send an RRC release with suspendConfig message to the terminal to induce random access of the terminal. The terminal that receives the RRC release with suspendConfig message can transition to RRC deactivation mode. The terminal in RRC deactivation mode can perform a random access procedure for uplink transmission. However, the terminal in RRC deactivation mode can perform SRS transmission before performing the random access procedure, which may cause uplink synchronization error. Therefore, the base station can set the SRS offset and transmission cycle as long as possible to prevent this.

[0227] According to case 3, the base station can transmit an RRC release with suspendConfig message to the terminal to induce random access of the terminal. At this time, the RRC release with suspendConfig message does not include a configuration for SRS signaling. The terminal that receives the RRC release with suspendConfig message can transition to RRC deactivation mode. Since the RRC release with suspendConfig message does not include a configuration for SRS signaling, the terminal does not transmit SRS in RRC deactivation mode. The terminal in RRC deactivation mode can perform a random access procedure for uplink transmission.

[0228] The second type of transmitting a random access triggering message is a method of inducing the terminal to perform random access again by transmitting a message directly instructing the terminal to perform random access in the current state. That is, the base station and / or the network can prevent the occurrence of uplink synchronization errors by instructing the terminal with uplink synchronization errors to perform a random access procedure, and additionally significantly correct the terminal's TA error based on the TAC through the random access response (RAR). In case the terminal with uplink synchronization errors attempts random access through another base station, the base station can transmit TAC-related information to be applied to the terminal to the other base station through the network.

[0229] If, in a situation where transmission of a dedicated preamble through an RRC message or DCI is possible and dedicated preamble resources that can be allocated exist, thereby enabling contention free random access (CFRA), and if it is determined that CFRA is applicable, the base station can control normal CFRA to proceed based on the PDCCH order. On the other hand, if it is determined that CFRA is not applicable, a signal including a contention based random access (CBRA) execution command can be transmitted to the terminal. Here, whether CFRA is applicable can be determined by considering the service time and downlink transmission status of the area where the terminal is located. For example, if a terminal has not yet incurred an uplink synchronization error and signaling and / or information that can be used for allocation of dedicated preamble resources, such as explicit and / or implicit status for available RACH opportunities, can be received from the terminal, but the terminal may be predicted to incur an uplink synchronization error even if the TA error is compensated based on the TAC. In this case, the base station can check whether CFRA is applicable to the terminal and, based on the result of the check, transmit a command indicating CFRA or CBRA. The terminal can immediately initiate a random access procedure including cell search based on the received command.

[0230] As described above, signaling based on 2-state information is required for the random access triggering command, which can be transmitted to the corresponding terminal via the PDSCH or the PDCCH. For example, the random access triggering command can be transmitted using a MAC CE or an RRC message of the PDSCH, or using a DCI of the PDCCH. Alternatively, the base station can transmit the random access triggering command to multiple terminals corresponding to the same beam using cell-specific signaling, such as SIB, or group signaling.

[0231] FIG. 19 illustrates examples of transmitting a second type of random access induction signal in a wireless communication system according to an embodiment of the present disclosure. FIG. 19 discloses cases of inducing random access by transmitting a random access triggering command.

[0232] Referring to Figure 19, the base station can determine whether to induce random access for a terminal based on the uplink transmission(s) and signaling(s) from the terminal. Once the random access induction for the terminal is determined, the base station can determine the random access type for the terminal based on the service time and downlink transmission status of the area where the terminal is located. That is, the base station that has determined to induce random access for the terminal can operate according to any one of Case 1, Case 2, or Case 3 described below.

[0233] According to Case 1, the base station can determine the random access type of the terminal as CFRA. For example, the base station can determine the CFRA of the terminal if the service time and downlink transmission status of the area where the terminal is located satisfy specified conditions. If the random access type is determined to be CFRA, the base station transmits a signal to the terminal indicating the execution of CFRA. The terminal can initiate CFRA based on the instruction from the base station.

[0234] According to case 2, the base station may determine the random access type of the terminal as CBRA. For example, if the service time and downlink transmission status of the area where the terminal is located do not satisfy the specified conditions and an uplink synchronization error is predicted to occur, the base station may determine the CBRA of the terminal. If the random access type is determined to be CBRA, the base station may transmit a random access triggering command signal to the terminal. The terminal may initiate CBRA for the current base station and / or the current cell based on the instruction of the base station.

[0235] According to case 3, the base station may determine the random access type of the terminal as CBRA. For example, if the service time and downlink transmission status of the area where the terminal is located do not satisfy the specified conditions and an uplink synchronization error is predicted to occur, the base station may determine the CBRA of the terminal. If the random access type is determined to be CBRA, the base station may transmit a random access triggering command signal to the terminal. The terminal may initiate CBRA for other base stations and / or other cells based on the instructions of the base station.

[0236]

[0237] Example #2: Uplink Transmission Interruption

[0238] According to Embodiment #2 of the present disclosure, a base station and / or a network suspends uplink transmission of an individual terminal or a plurality of terminals that have caused or are expected to cause an uplink synchronization error due to a TA error (UL transmission pause). That is, the base station and / or the network can prevent an uplink synchronization error by stopping or pausing the uplink transmission of the corresponding terminal for a specified period of time. During the period in which the uplink transmission is stopped, the terminal can correct the TA error based on the downlink signal of the corresponding cell or attempt random access to another cell. For example, the terminal can correct the TA error based on the TAC received via the downlink while the uplink transmission is stopped or paused, or attempt random access to another cell considering the service time of the cell in which the terminal is located. Since only the uplink transmission is stopped or paused by the base station and / or the network, the terminal can smoothly receive the downlink signal from the network and / or the base station without an uplink synchronization error. At this time, the terminal can maintain the current state or perform random access to another cell, if necessary or based on conditions.

[0239]

[0240] FIG. 20 illustrates an example of a procedure for stopping uplink transmission in a wireless communication system according to an embodiment of the present disclosure. FIG. 20 illustrates signal exchange between a terminal (2010) and a base station (2020).

[0241] Referring to FIG. 20, in step S2001, the base station (2020) detects a terminal with an uplink synchronization error. The terminal with an uplink synchronization error may include an individual terminal or multiple terminals that have caused or are expected to cause an uplink synchronization error due to a TA error. The base station (2020) may determine whether the terminal is a terminal with an uplink synchronization error based on at least one of a previous uplink transmission or a TA report of the terminal (2010). For example, the base station (2020) may determine the TA error of the terminal based on the reception time of the previous uplink transmission of the terminal (2010) and / or the TA report. If the determined TA error is greater than or equal to a specified TA error threshold, the base station (2020) may determine the terminal as a terminal with an uplink synchronization error.

[0242] In step S2003, the base station (2020) transmits an uplink transmission stop message to the terminal (2010). The uplink transmission stop may include an uplink transmission stop. The base station (2010) may transmit a message to the terminal (2010) to stop or instruct the terminal (2010) to stop uplink transmission for a specified period of time in order to restrict uplink transmission to the base station. In response to the uplink transmission stop message, the terminal (2010) stops uplink transmission. The terminal (2010) may correct a TA error based on a downlink signal received during the uplink transmission stop. Alternatively, the terminal (2010) may perform a random access procedure to another cell during the uplink transmission stop.

[0243]

[0244] FIG. 21 illustrates an example of a procedure for stopping uplink transmission using signaling in a wireless communication system according to an embodiment of the present disclosure.

[0245] Referring to FIG. 21, in step 1, the base station can determine whether to suspend uplink transmission of at least one terminal. Whether to suspend uplink transmission of at least one terminal can be determined based on at least one of a TA report of at least one terminal or a TA estimation result obtained based on uplink transmission of at least one terminal.

[0246] In step 2, the base station may not grant uplink resources and / or uplink grants to at least one terminal. That is, if it is determined that at least one terminal will stop uplink transmission, the base station will no longer transmit UL grants to the terminal, regardless of whether a scheduling-related request or information is normally received from the at least one terminal. The scheduling-related request or information may include at least one of a scheduling request (SR) or a buffer status report (BSR).

[0247] In step 2, the base station can deactivate configured scheduling (CS) for uplink for at least one terminal. If configured scheduling (CS) for uplink for at least one terminal for which uplink transmission suspension is determined exists, the base station can release the UL grant for at least one terminal. For example, the base station can release the UL grant by transmitting an RRC message having an information element (IE) or logical channel configuration that does not have a parameter (e.g., configuredGrantType1Allowed) indicating whether the configured grant of the first type is allowed for the first type of configured grant (e.g., configuredGrantType1). Alternatively, the base station can release the UL grant by transmitting a DCI having a CRC scrambled by a configured scheduling-RNTI (CS-RNTI) for the configured grant of the second type (e.g., configuredGrantType2).

[0248] In step 3, the base station may transmit a signal to at least one terminal for uplink transmission pause. For example, the base station may transmit control information related to uplink transmission pause to at least one terminal. The signal for uplink transmission pause may be a signal for uplink transmission suspension.

[0249] In step 4, the terminal may stop all uplink transmissions in response to receiving a signal for stopping uplink transmissions and determine whether a specified stopping condition is satisfied. The stopping condition may include a delay time for remaining UL data and / or BSR, the last NTN cell service time after the suspension, a predefined value for signal reception and the suspension period, or a condition related to at least one of the following: a stopping function.

[0250] If the suspension condition is satisfied, in step 5, the terminal may suspend uplink transmission for a specified period of time and resume uplink transmission to the last cell. The terminal may correct the TA error based on the downlink signal received during the specified period of time and resume uplink transmission to the last cell based on the corrected TA error. For example, the terminal may correct the TA error based on the TAC received during the specified period of time. The terminal may transmit an SR at a transmission timing determined based on the corrected TA error.

[0251] If the suspension condition is not satisfied, in step 5, the terminal may initiate cell search for random access. Based on the cell search result, the terminal may perform random access to connect to a specific cell and initiate uplink transmission to the connected cell. Cases in which the suspension condition is not satisfied may include delay time limits for remaining UL data and / or BSR, expiration of the last NTN cell service time after the suspension, absence of a predefined value for signal reception and suspension period, or absence of suspension function. For example, the terminal may attempt random access to another cell based on the NTN cell service time or the buffer status of the terminal.

[0252] A terminal can request retransmission or transmission of new data by transmitting a hybrid automatic repeat request (HARQ) feedback signal in response to the base station's downlink transmission according to the HARQ technique. In this case, the base station determines whether to retransmit using the HARQ feedback signal based on the terminal's downlink decoding result. However, as described above, if the base station suspends or interrupts a specific terminal's uplink transmission, the base station will not be able to confirm the terminal's downlink decoding result.

[0253] Therefore, when a base station decides to stop uplink transmission of a specific terminal, a HARQ procedure and / or processing method different from the existing HARQ procedure is required for the HARQ feedback signal for downlink transmission of the base station.

[0254] In one embodiment, the base station may deactivate HARQ procedures for downlink transmission signals that remain untransmitted to the terminal until the time when the uplink transmission is stopped, or for new downlink transmission signals generated in the stopped or stopped state. For example, when the uplink transmission of the first terminal is stopped, the base station may not expect HARQ feedback from the first terminal and may operate under the assumption of a non-HARQ situation in which there is no retransmission for all downlink signals to the first terminal until the uplink transmission is resumed.

[0255] In one embodiment, the base station can operate by specifying a specific number of retransmissions for downlink transmissions. For example, if it is determined that the uplink transmission of the first terminal is to be interrupted, the base station can repeatedly transmit all downlink signals to the first terminal a fixed number of retransmissions until the uplink transmission is resumed, without expecting HARQ feedback from the first terminal. Here, after the base station determines to interrupt the uplink transmission, the fixed number of retransmissions used for downlink HARQ can be set to the maximum number of retransmissions assuming a worst-case scenario. In one embodiment, after it is determined that the uplink transmission of the terminal is to be interrupted, the fixed number of retransmissions can be applied regardless of whether the UCI including HARQ feedback for the downlink signal according to the existing HARQ procedure is normally received by the base station. According to one embodiment, when a UCI including HARQ feedback for a downlink signal according to an existing HARQ procedure is normally received at a base station after a decision is made to stop uplink transmission of a terminal, the existing HARQ procedure may be applied without applying a fixed number of retransmissions to the HARQ feedback.

[0256] The terminal can determine whether to use the existing HARQ procedure, non-HARQ, or HARQ with a fixed number of retransmissions by using at least one of the new data indicator of the DCI, the redundancy version, the HARQ process number, or whether the terminal transmits downlink HARQ feedback for the corresponding HARQ procedure. The use of HARQ with a fixed number of retransmissions or the non-HARQ situation can be released when the uplink transmission interruption of the terminal ends and the uplink transmission of the terminal to the corresponding base station resumes. In this case, the existing HARQ procedure can be applied to the downlink of the terminal.

[0257] According to the embodiment described with reference to FIG. 21, the base station transmits a signal to the terminal to stop or suspend the terminal's uplink transmission. However, the base station may not transmit a signal to the terminal to stop or suspend the uplink transmission.

[0258] FIG. 22 illustrates an example of a procedure for stopping uplink transmission without signaling in a wireless communication system according to an embodiment of the present disclosure.

[0259] Referring to FIG. 22, in step 1, the base station can determine whether to suspend uplink transmission of at least one terminal. Whether to suspend uplink transmission of at least one terminal can be determined based on at least one of a TA report of at least one terminal or a TA estimation result obtained based on uplink transmission of at least one terminal.

[0260] In step 2, the base station may not grant uplink resources and / or uplink grant to at least one terminal. That is, if it is determined that uplink transmission of at least one terminal is to be discontinued, the base station may no longer transmit an UL grant to the terminal, regardless of whether a scheduling-related request or information is normally received from the at least one terminal. The scheduling-related request or information may include at least one of a scheduling request (SR) or a buffer status report (BSR).

[0261] In step 2, the base station can deactivate the configured scheduling (CS) for the uplink for at least one terminal. If there is a configured scheduling (CS) for the uplink of at least one terminal for which uplink transmission suspension has been determined, the base station can release the UL grant for the at least one terminal. For example, if the CS type corresponds to a configured grant of the first type, the base station can release the UL grant by transmitting an RRC message having an information element (IE) or logical channel configuration that does not have a parameter indicating whether to allow the configured grant of the first type. Alternatively, if the CS type corresponds to a configured grant of the second type, the UL grant can be released by transmitting a DCI having a CRC scrambled by a configured scheduling-RNTI (CS-RNTI).

[0262] In step 4, the terminal may stop all uplink transmissions. The terminal may determine whether a specified condition for stopping uplink transmission in a connected mode is satisfied, and may stop uplink transmission if the specified condition for stopping uplink transmission is satisfied. For example, the specified condition for stopping uplink transmission may include a condition related to at least one of smoothness of downlink reception, variability of downlink reception, number of uplink SR rejections, uplink transmission unavailability due to a timer, or a downlink HARQ retransmission state. According to one embodiment, the terminal may determine whether a condition for stopping uplink transmission is satisfied based on a period of uplink transmission unavailability due to SR transmission (e.g., number of UCI transmissions including SR, whether grant-free release is performed, etc.) and a downlink reception continuity state during the period (e.g., number of DCI receptions, degree of change in RSRP / RSSI / RSRQ, etc.). In one embodiment, the terminal can determine whether an uplink transmission stop condition, which is set separately from a handover or RACH initiation condition, is satisfied, and the uplink transmission stop condition can be set for each terminal. In one embodiment, if a retransmission for a downlink transmission is repeated a specific number of times during a specified period or during a specified number of downlink transmissions, unlike the HARQ feedback it transmitted, the terminal can determine that the uplink transmission stop condition is satisfied. In this case, the terminal can determine whether to use the existing HARQ procedure, non-HARQ application, or HARQ with a fixed number of retransmissions based on a new data indicator of each DCI, a duplicate version, a HARQ procedure number, or whether the terminal transmits downlink HARQ feedback for the corresponding HARQ procedure.

[0263] If the specified conditions for uplink transmission suspension are not met or the terminal does not support uplink transmission suspension, the terminal may proceed with the existing procedure. If the specified conditions for uplink transmission suspension are not met, the terminal may perform uplink transmission (e.g., PUCCH and SRS) until the specified conditions for uplink transmission suspension are determined to be met.

[0264] The terminal can determine whether a specified interruption condition is satisfied while uplink transmission is suspended. The interruption condition may include a delay time for remaining UL data and / or BSR, the last NTN cell service time after the interruption, a predefined value for signal reception and interruption duration, or a condition related to at least one of the interruption functions.

[0265] If the suspension condition is satisfied, in step 5, the terminal may suspend uplink transmission for a specified period of time and resume uplink transmission to the last cell. The terminal may correct the TA error based on the downlink signal received during the specified period of time and resume uplink transmission to the last cell based on the corrected TA error. For example, the terminal may correct the TA error based on the TAC received during the specified period of time. The terminal may transmit an SR at a transmission timing determined based on the corrected TA error.

[0266] If the suspension condition is not satisfied, in step 5, the terminal may initiate cell search for random access. The terminal performs random access based on the cell search result to connect to a specific cell and initiates uplink transmission to the connected cell. Cases in which the suspension condition is not satisfied may include delay time limits for remaining UL data and / or BSR, expiration of the last NTN cell service time after the suspension, absence of a predefined value for signal reception and suspension period, or absence of the suspension function. For example, the terminal may attempt random access to another cell based on the NTN cell service time or the buffer status of the terminal.

[0267]

[0268] In the embodiment described with reference to FIG. 22, the base station does not transmit a signal for stopping uplink transmission. If, as in the embodiment described with reference to FIG. 21, the base station transmits a signal for stopping uplink transmission, the terminal may stop all uplink transmissions to which TA pre-compensation is applied, regardless of its own uplink transmission request and transmission situation, such as its SR. For example, the uplink transmissions to which TA pre-compensation is applied may include at least one of a PUSCH, a PUCCH from dedicated resources, a PUCCH from common resources, or an SRS. After stopping all uplink transmissions, the terminal may perform the remaining steps, for example, steps 4 and 5. That is, the terminal may temporarily wait for uplink transmissions for a specified period of time, and then resume uplink-related operations to the corresponding cell or initiate new cell search and random access based on at least one of the NTN cell service time, cell reference position, or BSR. This may be handled by the implementation of the terminal.

[0269]

[0270] A signal for stopping uplink transmission, i.e., an uplink transmission stop command, can be represented as 2-state information and can be transmitted to a UE through UE specific signaling. The signaling of the uplink transmission stop command can be transmitted using a DCI having reserved bits, such as DCI format 0_0 / DCI format 0_1 ​​having a CRC scrambled by CS-RNTI, DCI format 1_0 / DCI format 1_1 having a CRC scrambled by CS-RNTI, or DCI format 1_0 having a CRC scrambled by P-RNTI / SI-RNTI. Alternatively, it can be transmitted using a new field added to DCI format 0_0 / DCI format 0_1 ​​having a CRC scrambled by CS-RNTI, or a field that is not used in a specific situation. Alternatively, the signaling of the uplink transmission stop command may be transmitted using a new field in an RRC message such as LogicalChannelConfig if the UL grant is a semi-statically configured UL grant and is a configured grant of the first type (ConfiguredGrantType1). Alternatively, the signaling of the uplink transmission stop command may be transmitted using a specific value of the TAC when transmitted via MAC CE. For example, if the 6-bit TAC is set to the value “111111”, it may indicate that it is an uplink transmission stop command. Alternatively, the signaling of the uplink transmission stop command may be transmitted using reserved bits of the Absolute TAC MAC CE or transmitted via a new MAC CE.

[0271] According to one embodiment, the base station can support multiple methods for transmitting an uplink transmission stop command, thereby ensuring that the uplink transmission stop command is delivered to the corresponding terminal as quickly as possible. If it is necessary to transmit the uplink transmission stop command to multiple terminals, the uplink transmission stop command can be transmitted via group signaling or cell-specific signaling. If the uplink transmission stop command is transmitted via cell-specific signaling, the base station can control whether the uplink transmission stop command is applied to all terminals that have received the cell-specific signaling or to only some terminals according to conditions. For example, in order to ensure that the uplink transmission stop command is applied to some terminals according to conditions, conditions of the terminals that will perform the uplink transmission stop can be transmitted together. For example, the conditions of the terminals that will perform the uplink transmission stop can include at least one of a minimum distance, a maximum distance, a minimum TA pre-compensation value, a maximum TA pre-compensation value, a minimum TAC, or a maximum TAC value.

[0272]

[0273] According to one embodiment, the fixed number of retransmissions used for downlink HARQ in an uplink transmission interrupt state of a terminal may use a value defined in the standard. According to one embodiment, the fixed number of retransmissions may be transmitted through cell-specific signaling or group-specific signaling via SIB. According to one embodiment, the fixed number of retransmissions may be transmitted UE-specifically via DCI, MAC CE, or RRC message. According to one embodiment, the transmission of any fixed number of retransmissions other than absent may itself be regarded as an uplink transmission interrupt command. For example, when the fixed number of retransmissions is absent, it may indicate an uplink transmission availability state, and when the fixed number of retransmissions is set to a specific value, it may indicate an uplink transmission interrupt state. In this case, the use of a separate signaling or field for the uplink transmission interrupt command may not be necessary.

[0274] A terminal that receives an uplink transmission suspension signal or determines that an uplink transmission suspension condition is satisfied suspends uplink transmission for a predetermined period of time and performs a downlink reception operation regardless of the uplink transmission suspension. The waiting duration for the uplink transmission suspension, i.e., the suspension period, may be transmitted to each terminal via UE-specific signaling, or to multiple terminals via cell-specific signaling or group signaling via SIB, etc. In one embodiment, the suspension period may be defined without signaling according to a standard specification or terminal characteristics. In one embodiment, the suspension period may be transmitted together with a signal including an uplink transmission suspension command. The unit of the suspension period may be determined based on at least one of a slot, a symbol, the number of times a TAC command is received, or the number of times a DCI is received. A signal including a suspension period with a specific non-zero value may be regarded as an uplink transmission suspension command. In this case, the use of a separate signaling or field for the uplink transmission suspension command may not be necessary.

[0275]

[0276] FIG. 23 illustrates examples of uplink transmission interruption using signaling in a wireless communication system according to an embodiment of the present disclosure. FIG. 23 discloses instances of transmitting a signal for uplink transmission interruption.

[0277] Referring to Figure 23, the base station determines to suspend the uplink transmission of the terminal based on the uplink transmission(s) and signaling(s) from the terminal. The base station that determines to suspend the uplink transmission of the terminal may operate according to any of Case 1, Case 2, or Case 3 described below.

[0278] According to case 1, a terminal can transmit an SR to a base station. The base station can ignore the SR received from the terminal and transmit a downlink signal to the terminal for stopping uplink transmission. The terminal can stop uplink transmission in response to the downlink signal for stopping uplink transmission and determine whether a stop condition is satisfied. If the stop condition is satisfied, the terminal can update the TA based on the downlink signal received from the base station while the uplink transmission is stopped. When a pre-specified stop period has elapsed, the terminal can transmit an SR based on the updated TA.

[0279] According to case 2, the base station can transmit a downlink signal for stopping uplink transmission to the terminal. At this time, the downlink signal for stopping uplink transmission can include a downlink signal whose uplink transmission stopping period is not 0. That is, when the terminal receives a downlink signal whose uplink transmission stopping period is not 0, the terminal can determine that a command for stopping uplink transmission has been received. At this time, the terminal can stop uplink transmission and check whether the stopping condition is satisfied. If the stopping condition is not satisfied, the terminal can initiate cell search and random access. Based on the cell search result, the terminal can transmit Msg1 including a random access preamble to another base station.

[0280] According to case 3, the base station can transmit a signal to the terminal for deactivating the CS. The signal for deactivating the CS can include information on at least one of an uplink transmission suspension command or a suspension period. The terminal can suspend uplink transmission in response to the signal for deactivating the CS. While suspending uplink transmission during the suspension period, the terminal can update its TA based on a downlink signal received from the base station. When the signal for activating the CS is received from the base station, the terminal can transmit a PUSCH based on the updated TA.

[0281]

[0282] FIG. 24 illustrates examples of stopping uplink transmission without signaling in a wireless communication system according to an embodiment of the present disclosure. FIG. 24 discloses cases in which a signal for stopping uplink transmission is not transmitted.

[0283] Referring to Figure 24, the base station determines to suspend the uplink transmission of the terminal based on the uplink transmission(s) and signaling(s) from the terminal. The base station that determines to suspend the uplink transmission of the terminal may operate according to any one of Case 1, Case 2, or Case 3 described below.

[0284] According to case 1, a terminal can transmit an SR to a base station. The base station can ignore the SR received from the terminal and perform downlink transmission to the terminal. At this time, the base station can repeat the downlink transmission of the terminal a fixed number of times. The terminal can suspend uplink transmission based on the number of downlink transmissions and check whether the conditions for suspension are satisfied. If the conditions for suspension are satisfied, the terminal updates the TA based on the downlink signal received from the base station while the uplink transmission is suspended. When a pre-specified suspension period has elapsed, the terminal can transmit an SR based on the updated TA.

[0285] According to case 2, a terminal can transmit an SR to a base station. The base station can ignore the SR received from the terminal and perform downlink transmission to the terminal. At this time, the base station can repeat the downlink transmission of the terminal a fixed number of times. The terminal can stop uplink transmission based on the number of downlink transmissions and check whether the stop condition is satisfied. If the stop condition is not satisfied, the terminal can initiate cell search and random access. Based on the cell search result, the terminal can transmit Msg1 including a random access preamble to another base station.

[0286] According to case 3, the base station can transmit a signal to the terminal to deactivate CS for the terminal. The terminal can transmit an SR to the base station. The base station can ignore the SR received from the terminal and perform downlink transmission to the terminal. At this time, the downlink transmission can be repeated a fixed number of times. The terminal can stop uplink transmission based on the number of downlink transmissions and check whether a stop condition is satisfied. If the stop condition is satisfied, the terminal updates the TA based on a downlink signal received from the base station while uplink transmission is stopped. The terminal can receive a signal to activate CS from the base station.

[0287]

[0288] Example #3: Long relative TAC

[0289] According to the current standard, TAC is divided into 12-bit absolute TAC and 6-bit conventional TAC. Since absolute TAC consists of 12 bits, it has a wider correction range than conventional TAC, but it does not consider the TA correction value from the previous TAC. On the other hand, conventional TAC corrects the TA error by considering the TA correction value from the previous TAC, but has a limited correction range due to the limitation of the number of bits. Therefore, if the TA error of a terminal is so large that it cannot be corrected by a single absolute TAC transmission, it is impossible for the base station to correct the TA error of the terminal by transmitting the absolute TAC multiple times. Therefore, the base station must correct the TA error by transmitting the conventional TAC multiple times. However, because the range of TA error that can be corrected by a single conventional TAC is small, it may take a very long time to resolve the uplink synchronization error of a terminal with a large TA error.

[0290] Accordingly, the present disclosure proposes a long relative TAC. Long relative TAC is intended to address the shortcomings of absolute TAC, which cannot improve stepwise TA errors, and general TAC, which has a limited correction range. Compared to general TAC, long relative TAC offers a wider correction range, while, unlike absolute TAC, it offers stepwise TA error improvement.

[0291] FIG. 25 illustrates an example of a procedure for performing uplink transmission based on a long relative TAC in a wireless communication system according to an embodiment of the present disclosure. FIG. 25 illustrates signal exchange between a terminal (2510) and a base station (2520).

[0292] Referring to FIG. 25, in step S2501, the base station (2520) transmits a long relative TAC to the terminal (2510). According to one embodiment, the long relative TAC may indicate a TA compensation value based on the last TA value indicated by the previous TAC. The long relative TAC may be configured with a number of bits greater than the number of bits of a general TAC, i.e., an existing relative TAC. For example, the number of bits of the long relative TAC may be configured with 12 bits. That is, the number of bits of the long relative TAC may be set to be the same as the number of bits of the absolute TAC. According to one embodiment, the long relative TAC may include a plurality of general TACs. For example, a 12-bit long relative TAC may be configured with a first general TAC of 6 bits and a second general TAC of 6 bits. In this case, the first general TAC and the second general TAC may be transmitted together in a single message and / or signal, or may be transmitted in separate messages and / or signals. In one embodiment, the long relative TAC may be transmitted together with an indicator indicating that the TAC is a long relative TAC. Alternatively, the indicator indicating that the TAC is a long relative TAC may be transmitted prior to the transmission of the long relative TAC.

[0293] In step S2503, the terminal (2510) determines the TA based on the long relative TAC received from the base station (2520). The terminal (2510) can determine that the received TAC is a long relative TAC based on at least one of the eLCID, the LCID, or the TAC indicator of the received TAC. If the received TAC is a long relative TAC, at least one of the values ​​calculated by the previous TAC, the TA value indicated by the received TAC, or the values ​​determined based on the maximum and minimum values ​​of the TA indicated by the received TAC is used. Determines the value. The terminal is determined Uplink TA using the value Decide.

[0294] In step S2505, the terminal (2510) performs uplink transmission at a transmission timing determined based on the TA. For example, the terminal (2510) may transmit a PUCCH, a PUSCH, or an SRS at a transmission timing determined based on the TA.

[0295]

[0296] 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.

[0297]

[0298] 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.

[0299]

[0300] In [Equation 2], is the value indicated by TAC, is the first value calculated by the previous TAC, i.e., the last TAC, and μ is the numerology of the subcarrier spacing (SCS).

[0301] Referring to [Mathematical Formula 2], if the terminal receives the TAC and the absolute TAC applied to the RAR is calculated by the previous TAC, and does not reflect the absolute TAC. Using only new It can be seen that it is determined.

[0302] When a long relative TAC is applied according to Example #2, is calculated as shown in [Mathematical Formula 3] below.

[0303]

[0304] In [Equation 3], is the value indicated by TAC, is the first value calculated by the previous TAC, i.e., the last TAC, and μ is the numerology of the subcarrier spacing (SCS). In addition, is a value according to the range of long relative TAC, , , or It can be determined based on either of the following: is a ceiling function that indicates the smallest integer not less than x, is a flooring function that indicates the largest integer not greater than x.

[0305] Using long relative TAC When calculating , if it is set so that all numbers that can be expressed with the allocated bits can be expressed, [Equation 3] can be expressed as [Equation 4] below. For example, using L bits, from 0 to When set to express a number up to , [Mathematical Formula 3] can be expressed as [Mathematical Formula 4] below.

[0306]

[0307] In [Equation 4], is the value indicated by TAC, is the first value computed by the previous TAC, i.e. the last TAC, μ is the numerology of the subcarrier spacing (SCS), L is the long relative TAC. is the number of bits allocated for calculation.

[0308] Long relative TAC uses the same bits as absolute TAC using 12 bits and It has a mapping form, the same as the existing absolute TAC. The scope of When given as , [Equation 3] can be expressed as [Equation 5] below.

[0309]

[0310] In [Equation 5], is the value indicated by TAC, is the first value calculated by the previous TAC, i.e., the last TAC, and μ is the numerology of the subcarrier spacing (SCS).

[0311] TAC by changing the number of bits (e.g. increasing the number of bits) When the range changes, as described in [Equation 3], (minimum + Max ) / 2 can be used as the nearest integer value. (At least + Max ) / 2, one of the multiple integer values ​​can be used.

[0312]

[0313] A base station can transmit a long relative TAC to a terminal using various methods.

[0314] In the first method, the base station can transmit a long relative TAC using an extended logical channel ID (eLCID) separate from the absolute TAC MAC CE (codepoint 252, index 316). For example, the long relative TAC can be transmitted using any of the eLCIDs (codepoints 0 to 216, index 64 to 280) reserved for the DL-SCH in Release 18.

[0315] In a second way, the base station can transmit a long relative TAC to the terminal using the same eLCID as the absolute TAC MAC CE, but using 4 reserved bits out of the 16 bits of the absolute TAC MAC CE.

[0316] In a third approach, the base station can transmit a long relative TAC to the UE using a separate LCID from the regular TAC MAC CE (codepoint / index 61). For example, the long relative TAC can be transmitted using any of the LCIDs (codepoint / index 35-46) reserved for the DL-SCH in Release 18. In this case, the UE can combine multiple regular TAC MAC CEs and use the combined TAC MAC CEs as a single long relative TAC. For example, the UE can receive two 6-bit TACs with a new LCID, combine the bits of the two received TACs, and then interpret the combined 12-bit TAC as a long relative TAC.

[0317] In a fourth approach, the base station can indicate the application of a long relative TAC to multiple terminals by transmitting an indicator using cell-specific signaling, such as a SIB, or group signaling. In this case, the base station can transmit a long relative TAC using the same eLCID as the eLCID of the absolute TAC MAC CE, without using a separate eLCID or reserved bits. If necessary, an application timer or application wait time based on the reception of the SIB can be introduced.

[0318]

[0319] Fig. 26 illustrates an example of a correction range for each TAC in a wireless communication system according to an embodiment of the present disclosure. Referring to Fig. 26, the long relative TAC (2601) proposed in the present disclosure consists of 12 bits, thereby having a wider correction range than the existing relative TAC (2607) of 6 bits. In addition, the correction range of the absolute TAC (2603) is the last TA ( )(2605) does not reflect the value, but the correction range of the long relative TAC (2601) is the last TA ( calculated by the previous TAC) )(2605). Therefore, when a large TA error exceeding the TA error threshold occurs, it is expected that correcting the TA error using a long relative TAC (2601) will be more efficient in terms of time than correcting the TA error using an absolute TAC.

[0320]

[0321] FIG. 27 illustrates examples of uplink transmission based on a long relative TAC in a wireless communication system according to an embodiment of the present disclosure.

[0322] Referring to Figure 27, the terminal The PUSCH is transmitted at a transmission timing determined based on the base station. At this time, the base station can operate as in case 1 or case 2 described below.

[0323] According to case 1, the base station can transmit the proposed TAC to the terminal. At this time, the proposed TAC is a long relative TAC and can be composed of 12 bits. The proposed TAC can indicate a TA correction value determined based on the PUSCH. The terminal can transmit the proposed TAC based on the long relative TAC received from the base station. Calculate and calculate The PUCCH can be transmitted at a transmission timing determined based on the PUCCH. The base station can determine a TA correction value based on the PUCCH and transmit a proposed TAC indicating the determined TA correction value to the terminal. At this time, the proposed TAC is a long relative TAC and can be composed of 12 bits. The terminal can transmit the PUCCH based on the long relative TAC received from the base station. Calculate and calculate PUSCH can be transmitted at a transmission timing determined based on the value.

[0324] According to case 2, the base station can transmit the proposed TAC to the terminal. At this time, the proposed TAC is a TAC that includes a portion of a long relative TAC and can be composed of 6 bits. The proposed TAC can indicate only 6 bits, which are part of a 12-bit bit string indicating the TA correction value determined based on the PUSCH. The terminal can transmit the proposed TAC to the terminal. has the same value as The SRS can be transmitted at a transmission timing determined based on the determined TAC. This is because the terminal has received only a part of the long relative TAC. The base station can transmit the proposed TAC to the terminal. At this time, the proposed TAC is a TAC that includes another part of the long relative TAC and can be composed of 6 bits. For example, the proposed TAC can indicate only 6 bits, which are another part of a 12-bit bit string indicating a TA correction value determined based on the PUSCH. The terminal can combine the previously received TAC and the currently received TAC and process the combined TAC as a long relative TAC. That is, the terminal can process the combined TAC based on the combined long relative TAC. Calculate and calculate PUSCH can be transmitted at a transmission timing determined based on the value.

[0325]

[0326] Example #4: TAC Adjustment Factor

[0327] According to current standards, if a TA error exceeds a specified TA error threshold, the base station must transmit TAC multiple times to correct the large TA error, which can be time-consuming. Therefore, the present disclosure proposes a method to significantly correct the TA error with a small number of TAC transmissions.

[0328] Specifically, according to embodiment #4 of the present disclosure, the base station transmits a TAC adjustment coefficient to the terminal through separate signaling, and the terminal corrects a first value determined by the TAC using the TAC adjustment coefficient and determines an uplink TA based on the corrected first value. 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.

[0329] When using the first type of TAC adjustment coefficient, the terminal is as shown in [Mathematical Formula 6] below. can be decided.

[0330]

[0331] In [Equation 6], 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.

[0332] When using the second type of TAC adjustment coefficient, the terminal is as shown in [Mathematical Formula 7] below. can be decided.

[0333]

[0334] 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.

[0335]

[0336] FIG. 28 illustrates an example of a procedure for performing uplink transmission based on TAC adjustment coefficient information in a wireless communication system according to an embodiment of the present disclosure. FIG. 28 illustrates signal exchange between a terminal (2810) and a base station (2820).

[0337] Referring to FIG. 28, in step S2801, the base station (2820) transmits TAC adjustment coefficient information to the terminal (2810). 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 via system information, PDSCH, or PDCCH. For example, the TAC adjustment coefficient information may be transmitted using SIB, DCI, MAC CE, or RRC signaling.

[0338] In step S2803, the terminal (2810) 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 (2810) 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 (2810) can obtain the compensated first value by applying the second type of TAC adjustment coefficient when determining the first value based on the TAC.

[0339] In step S2805, the terminal (2810) 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.

[0340] In step S2807, the terminal (2810) determines the transmission timing based on the uplink TA. For example, the terminal (2810) 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.

[0341] At step S2809, the terminal (2810) transmits a message to the base station (2820). The terminal (2810) can perform uplink transmission (e.g., PUSCH, PUCCH, SRS, etc.) to the base station (1720) at the determined transmission timing.

[0342]

[0343] FIG. 29 illustrates examples of application of the first type of TAC adjustment coefficient in a wireless communication system according to an embodiment of the present disclosure.

[0344] Referring to Figure 29, case 1 is the first type of TAC adjustment coefficient Here is an example of when the first type of TAC adjustment factor is 1 or not applied. The UE receives an SIB from a BS and performs uplink transmission. The BS checks the TA state of the UE based on the uplink transmission of the UE, and may determine that the application of the first type of TAC adjustment factor is unnecessary based on the TA state, or may determine the TAC adjustment factor to be 1. Thereafter, the BS transmits the TAC through the PDSCH. The UE may determine the first value based on the TAC received through the PDSCH, and may calculate a new uplink TA value based on the first value. The UE may determine the uplink TA value, i.e., Uplink transmission can be performed at a timing determined based on .

[0345] Case 2: Common TAC adjustment factor of type 1 Here is an example of applying the same. According to Case 2, the BS transmits a PDSCH to the UE, and the UE performs uplink transmission. The BS can check the TA state of the UE based on the uplink transmission of the UE, and determine a first type common TAC adjustment coefficient based on the TA state. The first type common TAC adjustment coefficient is a value commonly applied to multiple terminals in the corresponding cell. For example, the first type common TAC adjustment coefficient may be set to 2, but the present disclosure is not limited thereto. The BS transmits the first type common TAC adjustment coefficient through the SIB, and the UE can calculate a new uplink TA value by applying the first type common TAC adjustment coefficient as a coefficient of the first value. The UE calculates the new uplink TA value, i.e., Uplink transmission can be performed at a timing determined based on .

[0346] Case 3 is the terminal-specific TAC adjustment factor of the first type. Here is an example of applying the same. According to Case 3, the UE receives an SIB from the BS and performs uplink transmission. The BS can check the TA state of the UE based on the uplink transmission of the UE and determine a first type of terminal-specific TAC adjustment coefficient based on the TA state. The first type of terminal-specific TAC adjustment coefficient is a value that is applied only to a specific terminal. For example, the first type of terminal-specific TAC adjustment coefficient may be set to 3, but the present disclosure is not limited thereto. Thereafter, the BS transmits the first type of terminal-specific TAC adjustment coefficient through the PDSCH. The UE can calculate a new uplink TA value by applying the first type of terminal-specific TAC adjustment coefficient received through the PDSCH as a coefficient of the first value. The UE calculates the uplink TA value, i.e., Uplink transmission can be performed at a timing determined based on .

[0347] Case 4 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 performs uplink transmission. The BS checks the TA state of the UE based on the uplink transmission of the UE, and determines the terminal-specific TAC adjustment factor of the first type based on the TA state. The BS transmits the terminal-specific TAC adjustment factor of the first type to the UE via PDCCH. 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 calculate a new uplink TA value by applying the terminal-specific TAC adjustment factor of the first type received via PDCCH as a coefficient of the first value. That is, when both the first type common TAC adjustment factor and the first type terminal-specific TAC adjustment factor are received, the first type terminal-specific TAC adjustment factor can be used for uplink TA calculation. However, the present disclosure is not limited thereto. For example, both the first type common TAC adjustment factor and the first type terminal-specific TAC adjustment factor can be used for uplink TA value calculation. The UE calculates the new uplink TA value, i.e., Uplink transmission can be performed at a timing determined based on .

[0348] As described with reference to FIG. 29, the base station can check the TA state of the UE based on the previous uplink transmission of the UE (e.g., PUSCH, PUCCH, SRS, or TA report, etc.), and determine whether transmission of the first type of TAC adjustment factor is necessary and / or the first type of TAC adjustment factor based on the TA state information. If the BS determines that transmission of the first type of TAC adjustment factor is necessary, the BS can determine the first type of TAC adjustment factor. The BS can transmit the first type of TAC adjustment factor to at least one UE using at least one of SIB, DCI of PDCCH, MAC CAE of PDSCH, or RRC signaling of PDSCH.

[0349]

[0350] FIG. 30 illustrates examples of application of a second type of TAC adjustment coefficient in a wireless communication system according to an embodiment of the present disclosure.

[0351] Referring to Figure 30, case 1 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 UE receives an SIB from a BS and performs uplink transmission. The BS checks the TA state of the UE based on the uplink transmission of the UE, and may determine that the application of the second type of TAC adjustment factor is unnecessary based on the TA state, or may determine the second type of TAC adjustment factor to be 1. Thereafter, the BS transmits the TAC through the PDSCH. The UE may determine the first value based on the TAC received through the PDSCH, and may calculate a new uplink TA value based on the first value. The UE may calculate the new uplink TA value, i.e., Uplink transmission can be performed at a timing determined based on .

[0352] Case 2 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 PDSCH to the UE, and the UE performs uplink transmission. The BS can check the TA state of the UE based on the uplink transmission of the UE, and determine a second type of common TAC adjustment factor based on the TA state. The second type of common TAC adjustment factor is a value commonly applied to multiple terminals in the corresponding cell. For example, the second type of common TAC adjustment factor may be set to 2, but the present disclosure is not limited thereto. The BS transmits the second type of common TAC adjustment factor through the SIB, and the UE obtains a corrected first value using the second type of common TAC adjustment factor, and can calculate a new uplink TA value based on the corrected first value. The UE may determine the new uplink TA value, i.e., Uplink transmission can be performed at a timing determined based on .

[0353] Case 3 is the second type of terminal-specific TAC adjustment factor. Here is an example of applying the same. According to Case 3, the UE receives an SIB from the BS and performs uplink transmission. The BS can check the TA state of the UE based on the uplink transmission of the UE and determine a second type of terminal-specific TAC adjustment factor based on the TA state. The second type of terminal-specific TAC adjustment factor is a value that is applied only to a specific terminal. For example, the second type of terminal-specific TAC adjustment factor may be set to 3, but the present disclosure is not limited thereto. Thereafter, the BS transmits the second type of terminal-specific TAC adjustment factor through a PDCCH. The UE can obtain a corrected first value using the second type of terminal-specific TAC adjustment factor received through the PDCCH and calculate a new uplink TA value based on the corrected first value. The UE can obtain the new uplink TA value, i.e., Uplink transmission can be performed at a timing determined based on .

[0354] Case 4 is the common TAC adjustment factor of the second type 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 performs uplink transmission. The BS checks the TA state of the UE based on the uplink transmission of the UE, and determines the terminal-specific TAC adjustment factor of the second type based on the TA state. The BS transmits the terminal-specific TAC adjustment factor of the second type to the UE via PDSCH. 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 obtains a corrected first value using the terminal-specific TAC adjustment factor of the second type received via PDSCH, and calculates a new uplink TA value based on the corrected 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 for uplink TA calculation. However, the present disclosure is not limited thereto. For example, both the common TAC adjustment factor of the second type and the terminal-specific TAC adjustment factor of the second type may be used for uplink TA value calculation. The UE may receive a new uplink TA value, i.e., Uplink transmission can be performed at a timing determined based on .

[0355] As described with reference to FIG. 30, the base station can check the TA state of the UE based on the previous uplink transmission of the UE (e.g., PUSCH, PUCCH, SRS, or TA report, etc.), and determine whether transmission of the second type of TAC adjustment factor is necessary and / or the second type of TAC adjustment factor based on the TA state information. If the BS determines that transmission of the second type of TAC adjustment factor is necessary, the BS can determine the second type of TAC adjustment factor. The BS can transmit the second type of TAC adjustment factor to at least one UE using at least one of SIB, DCI of PDCCH, MAC CAE of PDSCH, or RRC signaling of PDSCH.

[0356]

[0357] 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. If necessary, the first type of TAC adjustment coefficient and the second type of TAC adjustment coefficient can be applied simultaneously.

[0358] FIGS. 31A and 31B 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.

[0359] Referring to FIGS. 31A and 31B, 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 sets the first type of common TAC adjustment factor received from the SIB as the first type of TAC adjustment factor, and determines an uplink TA based on the first type of common TAC adjustment factor and the second type of TAC factor having a default value. The UE performs a first uplink transmission at a timing based on the determined uplink TA. The BS determines a first type of terminal-specific TAC adjustment factor based on the first uplink transmission of the UE, and transmits the first type of terminal-specific TAC adjustment factor to the UE via PDSCH. The UE sets a terminal-specific TAC adjustment factor of the first type to the TAC adjustment factor of the first type, and determines an uplink TA based on the TAC adjustment factor of the first type and a second type adjustment factor having a default value. The UE performs a second uplink transmission at a timing based on the determined uplink TA.

[0360] 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 through the SIB, and transmits the second type of terminal-specific TAC adjustment factor to the UE through the PDSCH. The UE sets the second type of terminal-specific TAC adjustment factor received from the SIB as the second type of TAC adjustment factor, and determines an uplink TA based on the first type of adjustment factor having a default value and the second type of TAC adjustment factor. The UE performs a first uplink transmission at a timing based on the determined uplink TA. The BS determines the second type of terminal-specific TAC adjustment factor based on the first uplink transmission of the UE, and transmits the second type of terminal-specific TAC adjustment factor to the UE through the PDSCH. The UE sets the terminal-specific TAC adjustment factor of the second type to the TAC adjustment factor of the second type, and determines an uplink TA based on the TAC adjustment factor of the first type having a default value and the adjustment factor of the second type. The UE performs a second uplink transmission at a timing based on the determined uplink TA.

[0361] 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 transmits a first type of terminal-specific TAC adjustment factor and a second type of terminal-specific TAC adjustment factor to the UE via a PDCCH. The UE sets the first type of terminal-specific TAC adjustment factor and the second type of terminal-specific TAC adjustment factor received via the PDCCH to the first type of TAC adjustment factor and the second type of TAC adjustment factor, respectively, and determines an uplink TA based on the first type of TAC adjustment factor and the second type of TAC adjustment factor. The UE performs a first uplink transmission at a timing based on the determined uplink TA. The BS determines the second type of terminal-specific TAC adjustment factor based on the first uplink transmission of the UE and transmits the second type of terminal-specific TAC adjustment factor to the UE via the PDCCH. The UE sets the second type of terminal-specific TAC adjustment factor received via the PDCCH to a new type of TAC adjustment factor, and determines an uplink TA based on the previously set first type of TAC adjustment factor and the newly set second type of adjustment factor. The UE performs a second uplink transmission at a timing based on the determined uplink TA.

[0362] 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 through SIB, and transmits a PDSCH to the UE. The UE sets the first type terminal-specific TAC adjustment factor and the second type terminal-specific TAC adjustment factor received through SIB to the first type TAC adjustment factor and the second type TAC adjustment factor, respectively, and determines an uplink TA based on the first type TAC adjustment factor and the second type TAC adjustment factor. The UE performs a first uplink transmission at a timing based on the determined uplink TA. The BS determines the first type terminal-specific TAC adjustment factor based on the first uplink transmission of the UE, and transmits the first type terminal-specific TAC adjustment factor to the UE through PDSCH. The UE sets the first type of terminal-specific TAC adjustment factor received via the PDSCH to a second type of TAC adjustment factor, and determines an uplink TA based on the newly set first type of TAC adjustment factor and the previously set second type of adjustment factor. The UE performs a second uplink transmission at a timing based on the determined uplink TA.

[0363] As described with reference to FIGS. 31A and 31B , 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, if the indicator is 00, it may indicate not applying the TAC adjustment factor or using the default value. If the indicator is 01, the value of the first type may be transmitted through signaling and the value of the second type may be indicated not applying or using the default value. If the indicator is 10, the value of the second type may be indicated using the value transmitted through signaling and the value of the first type may be indicated not applying or using the default value. If the indicator is 11, it may indicate that both the values ​​of the first type and the second type are transmitted through signaling.

[0364] 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.

[0365] 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.

[0366] The TAC adjustment coefficient of Example #4 and the long relative TAC of Example #3 can be combined and used. When the second type of TAC adjustment coefficient and the long relative TAC of Example #3 are combined, [Mathematical Formula 7] can be changed to [Mathematical Formula 8], [Mathematical Formula 9], or [Mathematical Formula 10] below. [Mathematical Formula 7] can be changed to [Mathematical Formula 8] below based on [Mathematical Formula 3] of Example #3, or can be changed to [Mathematical Formula 9] below based on [Mathematical Formula 4] of Example #3, or can be changed to [Mathematical Formula 10] below based on [Mathematical Formula 5] of Example #3.

[0367]

[0368] In [Equation 8], is the second type of TAC adjustment coefficient, is the value indicated by TAC, is the previous TAC, i.e., the first value calculated by the last TAC, μ is the numeral of SCS). In addition, is a value according to the range of long relative TAC, , , or It can be determined based on either of the following: is a ceiling function that indicates the smallest integer not less than x, is a flooring function that indicates the largest integer not greater than x.

[0369]

[0370] In [Equation 9], Is is the value indicated by TAC, is the first value computed by the previous TAC, i.e. the last TAC, μ is the numerology of the subcarrier spacing (SCS), L is the long relative TAC. is the number of bits allocated for calculation.

[0371]

[0372] In [Equation 10], is the value indicated by TAC, is the first value calculated by the previous TAC, i.e., the last TAC, and μ is the numerology of the SCS.

[0373]

[0374] The TAC adjustment factors as described above may be applied UE-specifically by being included in the DCI, MAC CE, and RRC signaling of the PDSCH or PDCCH for each UE and transmitted, or may be applied to multiple UEs through cell-specific signaling or other group signaling included in the SIB. According to one embodiment, the base station may transmit the TAC adjustment factors commonly applied to multiple UEs through cell-specific signaling or group signaling, and thereafter provide the TAC adjustment factors to specific UEs using UE-specific signaling as needed.

[0375] Information required for transmitting and / or applying TAC adjustment coefficients 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 coefficients depending on the situation, so that the TAC adjustment coefficients can have different ranges. For example, the TAC adjustment coefficients can be signaled using 2 bits of the absolute TAC, and the TAC adjustment coefficients can be signaled using 4 bits of the general TAC.

[0376]

[0377] FIG. 32 illustrates an example of available bits of an absolute TAC in a wireless communication system according to an embodiment of the present disclosure. Referring to FIG. 32 , at least one of the reserved bits (3201, 3202, 3203, 3204) of the absolute TAC can be used for transmitting a TAC adjustment coefficient.

[0378] FIG. 33 illustrates examples of bit allocation for a TAC adjustment coefficient within an absolute TAC in a wireless communication system according to an embodiment of the present disclosure. Referring to FIG. 32, four cases of bit allocation for the TAC adjustment coefficient are disclosed. Case 1 (case 1) (3311) is an example in which one of four reserved bits is allocated for the TAC adjustment coefficient, and case 2 (case 2) (3312) is an example in which two of the four reserved bits are allocated for the TAC adjustment coefficient. In addition, case 3 (case 3) (3313) is an example in which three of the four reserved bits are allocated for the TAC adjustment coefficient, and case 4 (case 4) (3314) is an example in which all four reserved bits are allocated for the TAC adjustment coefficient.

[0379]

[0380] 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.

[0381] 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.

[0382] 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.

[0383] 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.

[0384] 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, Establishing a connection with a non-terrestrial network (NTN) base station; Receiving a message for restriction of uplink transmission to the NTN base station; In response to receiving the above message, performing a procedure for obtaining second TA information different from the first TA information currently in use; and A method comprising performing communication based on the second TA information.

2. In claim 1, Receiving the above message, A method comprising receiving a message that induces performance of a random access procedure.

3. In claim 2, A method wherein the message comprises at least one of a message indicating a transition to RRC standby mode or RRC deactivation mode, or a message including a triggering command for the random access procedure.

4. In claim 2, A method wherein the above message includes a message indicating a transition to an RRC disabled mode and restricting transmission of an SRS (sounding reference signal) in the RRC disabled mode.

5. In claim 1, Performing the procedure for obtaining the above second TA information is as follows: A method comprising performing the random access procedure in response to receiving the above message.

6. In claim 1, Receiving the above message, A method comprising receiving a message that induces an interruption of the above uplink transmission.

7. In claim 6, Performing the procedure for obtaining the above second TA information is as follows: suspending the uplink transmission in response to receiving the above message; and A method comprising obtaining the second TA information based on a downlink signal received from the NTN base station while the uplink transmission is interrupted.

8. In claim 6, Performing the procedure for obtaining the above second TA information is as follows: suspending the uplink transmission in response to receiving the above message; and A method comprising performing a random access procedure to another cell.

9. In claim 1, Receiving TA information from the above NTN base station; Obtaining third TA information based on the above TA information; and Further comprising performing communication with the NTN base station based on the third TA information, A method wherein the above TA information consists of 12 bits and indicates a correction range based on the previous TA.

10. In claim 1, Receiving first TA information from the NTN base station; Receiving second TA information from the NTN base station; Obtaining third TA information based on the first TA information and the second TA information; and Further comprising performing communication with the NTN base station based on the third TA information, The above first TA information and the above second TA information are each composed of 6 bits, A method in which the information combining the first TA information and the second TA information indicates a correction range based on a previous TA.

11. In claim 1, Receiving information for TA compensation from the above NTN base station; Obtaining third TA information based on the information for the above TA compensation; and Further comprising performing communication with the NTN base station based on the third TA information, A method in which the information for the above TA compensation includes coefficient information for compensating for a value determined by a TAC (timing advance command).

12. In a method of operating a NTN (non-terrestrial network) base station in a wireless communication system, Establishing a connection with the terminal; and A method comprising transmitting a message for restriction of uplink transmission to the terminal.

13. In claim 12, Sending the above message is: Including transmitting a message that induces the performance of a random access procedure, A method wherein the message comprises at least one of a message indicating a transition to RRC standby mode or RRC deactivation mode, or a message including a triggering command for the random access procedure.

14. In claim 12, Sending the above message is: A method comprising transmitting a message that induces an interruption of the above uplink transmission.

15. In claim 12, Transmitting a message for limiting the above uplink transmission is: Determining whether the terminal is a terminal that causes an uplink synchronization error; and Including transmitting a message for limiting the uplink transmission based on the terminal causing the uplink synchronization error, A method in which whether a terminal causes the above-mentioned uplink synchronization error is determined based on at least one of a TA (timing advance) report, an applied TA estimate of the terminal estimated by the NTN base station, a TA application range in which an uplink synchronization error is expected not to occur by the terminal, a TA threshold, a TA error threshold, a future TA prediction for the terminal, an estimated SINR based on the uplink transmission of the terminal, a decoding error probability, an inter-symbol interference (ISI) power, or an inter-carrier interference (ICI) power.

16. In claim 12, Further comprising transmitting TA information to the terminal, A method wherein the above TA information consists of 12 bits and indicates a correction range based on the previous TA.

17. In claim 12, Transmitting first TA information to the terminal; and Further comprising transmitting second TA information to the terminal, The above first TA information and the above second TA information are each composed of 6 bits, A method in which the information combining the first TA information and the second TA information indicates a correction range based on a previous TA.

18. In claim 12, Further comprising transmitting information for TA compensation to the terminal, A method in which the information for the above TA compensation includes coefficient information for compensating for a value determined by a TAC (timing advance command).

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, Establishing a connection with a non-terrestrial network (NTN) base station; Receiving a message for restriction of uplink transmission to the NTN base station; In response to receiving the above message, performing a procedure for obtaining second TA information different from the first TA information currently in use; and A terminal comprising performing communication based on the above second TA information.

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, Establishing a connection with the terminal; and An NTN base station, comprising transmitting a message for restriction of uplink transmission to the terminal.

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