Method and apparatus for transmitting uplink channel in wireless communication system

Abstract

The present invention relates to a method and an apparatus for transmitting an uplink channel in a wireless communication system. The method performed by a terminal comprises the steps of: receiving resource information related to transmission of an uplink channel from a base station; detecting a downlink channel transmitted from the base station; and transmitting an uplink channel to the base station based on the resource information according to a result of detecting the downlink channel, in which the uplink channel is transmitted within a channel occupancy time (COT) initiated by the base station or within a COT initiated by the terminal.

Description

[0001] This application is a divisional application of a patent application with application number 202180057629.8 (PCT / KR2021 / 010529), which was submitted to the China Patent Office on February 2, 2023, with an international application date of August 9, 2021, and the invention name is “Method and device for sending uplink channels in a wireless communication system”. Technical Field

[0002] The present specification relates to a wireless communication system, and more particularly to a method and device for transmitting an uplink channel. Background Art

[0003] After the commercialization of the fourth generation (4G) communication system, in order to meet the increasing demand for wireless data services, efforts are being made to develop a new fifth generation (5G) communication system. The 5G communication system is referred to as an ultra-4G network communication system, a post-LTE system, or a new radio (NR) system. In order to achieve high data transmission rates, the 5G communication system includes a system operating in a millimeter wave (mmWave) band of 6 GHz or higher, and includes a communication system operating in a band of 6 GHz or lower in terms of ensuring coverage, so that the implementation in the base station and the terminal is under consideration.

[0004] The 3rd Generation Partnership Project (3GPP) NR system improves the spectrum efficiency of the network and enables communication providers to provide more data and voice services over a given bandwidth. Therefore, the 3GPP NR system is designed to meet the demand for high-speed data and media transmission in addition to supporting a large amount of voice. The advantages of the NR system are higher throughput and lower latency on the same platform, support for frequency division duplex (FDD) and time division duplex (TDD), and low operating costs due to an enhanced end-user environment and simple architecture.

[0005] For more efficient data processing, the dynamic TDD of the NR system can use a method for changing the number of orthogonal frequency division multiplexing (OFDM) symbols that can be used in the uplink and downlink according to the data service direction of the cell user. For example, when the downlink service of the cell is greater than the uplink service, the base station can allocate multiple downlink OFDM symbols to the time slot (or subframe). Information about the time slot configuration should be sent to the terminal.

[0006] In order to reduce the path loss of radio waves and increase the transmission distance of radio waves in the mmWave band, in the 5G communication system, beamforming, massive multiple input / output (massive MIMO), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, hybrid beamforming combining analog beamforming and digital beamforming, and massive antenna technology are discussed. In addition, for the network improvement of the system, in the 5G communication system, technology development related to evolved small cells, advanced small cells, cloud radio access networks (cloud RAN), ultra-dense networks, device-to-device communication (D2D), vehicle-to-everything communication (V2X), wireless backhaul, non-terrestrial network communication (NTN), mobile networks, cooperative communication, coordinated multipoint (CoMP), interference cancellation, etc. is being carried out. In addition, in the 5G system, hybrid FSK and QAM modulation (FQAM) and sliding window superposition coding (SWSC) as advanced coding modulation (ACM) schemes and filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA) and sparse code multiple access (SCMA) as advanced connection technologies are being developed.

[0007] Meanwhile, in a human-centered connection network where humans generate and consume information, the Internet has evolved into an Internet of Things (IoT) network that exchanges information between distributed components such as objects. Internet of Everything (IoE) technology, which combines IoT technology with big data processing technology through connection with a cloud server, is also emerging. In order to realize IoT, technical elements such as sensing technology, wired / wireless communication and network infrastructure, service interface technology and security technology are required, so that in recent years, technologies such as sensor networks, machine-to-machine (M2M) and machine type communication (MTC) have been studied to connect between objects. In the IoT environment, it is possible to provide intelligent Internet technology (IT) services that collect and analyze data generated from connected objects to create new value in human life. Through the integration and mixing of existing information technology (IT) and various industries, IoT can be applied to fields such as smart homes, smart buildings, smart cities, smart cars or connected cars, smart grids, health care, smart home appliances and advanced medical services.

[0008] Therefore, various attempts have been made to apply 5G communication systems to IoT networks. For example, technologies such as sensor networks, machine-to-machine (M2M), and machine type communications (MTC) are implemented through technologies such as beamforming, MIMO, and array antennas. The application of cloud RAN, which is the above-mentioned big data processing technology, is an example of the fusion of 5G technology and IoT technology. In general, mobile communication systems are developed to provide voice services while ensuring the activities of users.

[0009] However, mobile communication systems are gradually expanding not only voice services but also data services, and have now developed to the extent of providing high-speed data services. However, in the mobile communication systems currently providing services, due to resource shortages and users' high-speed service requirements, more advanced mobile communication systems are needed.

[0010] In recent years, with the surge in mobile traffic due to the popularity of smart devices, it has become increasingly difficult to cope with the increase in data usage for providing cellular communication services using only existing licensed spectrum or licensed frequency bands.

[0011] Under such circumstances, a method of providing a cellular communication service using an unlicensed spectrum or an unlicensed frequency band (eg, a 2.4 GHz band, a 5 GHz band, or a higher frequency band, etc.) is being discussed in order to solve the problem of lack of spectrum.

[0012] Unlike in licensed bands where telecommunications operators secure exclusive use rights through auctions and other procedures, in unlicensed bands, multiple communication devices can be used simultaneously without restriction, provided that only a certain level of adjacent band protection regulations are followed. For this reason, when unlicensed bands are used for cellular communication services, it is difficult to ensure communication quality to the level provided in licensed bands, and interference with existing wireless communication devices (e.g., wireless LAN devices) using the unlicensed bands is likely to occur.

[0013] In order to use LTE and NR technologies in unlicensed bands, research on coexistence with existing devices for unlicensed bands and effective sharing of wireless channels with other wireless communication devices will be conducted in advance. That is, a robust coexistence mechanism (RCM) needs to be developed so that devices using LTE and NR technologies in unlicensed bands do not affect existing devices for unlicensed bands. Summary of the invention

[0014] Technical issues

[0015] The present specification is to provide a method for determining in a wireless communication system whether to send an uplink channel based on a channel occupancy duration initiated by a base station or based on a channel occupancy duration initiated by a UE when a fixed frame duration is configured in each of a base station and a UE.

[0016] Technical Solution

[0017] The present specification provides a method for transmitting an uplink channel in a wireless communication system.

[0018] Specifically, a method performed by a UE includes: receiving resource information related to the transmission of an uplink channel from a base station; detecting a downlink channel sent from the base station; and sending an uplink channel to the base station based on the resource information according to a result of detecting the downlink channel, wherein the uplink channel is sent based on a shared channel occupancy time (COT) after being initiated by the base station or based on the COT initiated by the UE.

[0019] In addition, the method performed by the UE according to the present disclosure further includes: receiving dynamic signaling including scheduling information for transmission of an uplink channel from a base station, wherein resource information is included in the scheduling information; when the scheduling information includes information about the COT during which the uplink channel is sent, detection of the downlink channel is not performed, and the uplink channel is sent based on the information about the COT; when the scheduling information does not include information about the COT during which the uplink channel is sent, the uplink channel is sent based on the scheduling information according to a result of the detection of the downlink channel; and the information about the COT corresponds to information indicating whether the uplink channel is sent based on the COT shared after being initiated by the base station or based on the COT initiated by the UE.

[0020] In addition, a UE for sending an uplink transmission channel in a wireless communication system according to the present disclosure includes: a communication module; and a processor, which is configured to control the communication module, wherein the processor is configured to: receive resource information related to the transmission of the uplink channel from the base station; detect the downlink channel sent from the base station; and send the uplink channel to the base station based on the resource information according to the result of detecting the downlink channel, wherein the uplink channel is sent based on the shared channel occupancy time (COT) after being initiated by the base station or based on the COT initiated by the UE.

[0021] In addition, according to the present disclosure, an uplink channel is transmitted based on a configuration grant.

[0022] In addition, according to the present disclosure, as a result of detection of a downlink channel, when the UE detects the downlink channel, an uplink channel is sent based on the COT shared after being initiated by the base station, and when the UE fails to detect the downlink channel, the uplink channel is sent based on the COT initiated by the UE.

[0023] In addition, according to the present disclosure, the COT shared after being initiated by the base station corresponds to the duration within the fixed frame period (FFP) configured in the base station, and the COT initiated by the UE corresponds to the duration within the FFP configured in the UE.

[0024] In addition, according to the present disclosure, when an uplink channel is transmitted based on the COT shared after being initiated by the base station, the uplink channel is transmitted in a duration excluding an idle duration within the FFP configured in the base station.

[0025] In addition, according to the present disclosure, when an uplink channel is transmitted based on a COT initiated by a UE, the uplink channel is transmitted in a duration excluding an idle duration within an FFP configured in the UE.

[0026] In addition, according to the present disclosure, the FFP configured in the base station and the FFP configured in the UE are different from each other.

[0027] In addition, according to the present disclosure, when an uplink channel is transmitted based on a COT initiated by a UE, the uplink channel is transmitted regardless of whether a duration during which the uplink channel is transmitted is included in an idle duration within an FFP configured in a base station.

[0028] In addition, according to the present disclosure, when an uplink channel is transmitted based on the COT shared after being initiated by the base station, the uplink channel is transmitted in a duration excluding an idle duration within the FFP configured in the base station.

[0029] In addition, according to the present disclosure, the FFP configured in the UE is configured in the UE through dedicated RRC signaling information.

[0030] In addition, according to the present disclosure, information about the COT is included in a channel access related field of configuration dynamic signaling.

[0031] In addition, according to the present disclosure, a method for receiving an uplink channel in a wireless communication system is performed by a base station and includes: sending resource information related to the transmission of the uplink channel to a UE; and receiving an uplink channel from the UE based on the resource information, wherein the uplink channel is sent based on whether the UE has detected a downlink channel sent from the base station, and the uplink channel is sent within a channel occupancy time (COT) initiated by the base station or the uplink channel is sent within a COT initiated by the UE.

[0032] Beneficial Effects

[0033] The present specification provides a method for determining in a wireless communication system whether to send an uplink channel based on a channel occupancy duration initiated by a base station or based on a channel occupancy duration initiated by a UE when a fixed frame duration is configured for each of a base station and a UE, so as to enable efficient uplink channel transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1An example of a radio frame structure used in a wireless communication system is illustrated.

[0035] Figure 2 An example of a downlink (DL) / uplink (UL) slot structure in a wireless communication system is illustrated.

[0036] Figure 3 A diagram for explaining physical channels used in a 3GPP system and a typical signal transmission method using the physical channels.

[0037] Figure 4 Illustration of SS / PBCH blocks used for initial cell access in a 3GPP NR system.

[0038] Figure 5 Illustration of a procedure for transmitting control information and control channels in a 3GPP NR system.

[0039] Figure 6 Illustration of a control resource set (CORESET) in which a physical downlink control channel (PDCCH) can be transmitted in a 3GPP NR system.

[0040] Figure 7 A method for configuring a PDCCH search space in a 3GPP NR system is illustrated.

[0041] Figure 8 is a conceptual diagram illustrating carrier aggregation.

[0042] Fig. 9 It is a diagram for explaining single-carrier communication and multi-carrier communication.

[0043] Fig.10 is a diagram showing an example in which a cross-carrier scheduling technology is applied.

[0044] Fig.11 2 is a diagram illustrating locations of OFDM symbols occupied by SSB within multiple time slots of a licensed frequency band of an NR system according to an embodiment of the present invention.

[0045] Fig.12 2 is a diagram illustrating the position of a time slot occupied by SSB within a half radio frame, i.e., 5 ms, of an authorized frequency band of an NR system according to an embodiment of the present invention.

[0046] Fig.13 is a diagram illustrating positions of OFDM symbols occupied by SSB within a slot including 16 OFDM symbols according to an embodiment of the present invention.

[0047] Fig.14 is a block diagram illustrating a configuration of a user equipment and a base station according to an embodiment of the present invention.

[0048] Fig.15 is a diagram illustrating a downlink channel access procedure according to an embodiment of the present invention.

[0049] Fig.16 is a diagram illustrating scheduled uplink transmission according to an embodiment of the present invention.

[0050] Fig.17 FIG. 1 illustrates an FBE-based LBT operation process according to an embodiment of the present disclosure;

[0051] Fig.18 illustrates the FBE operation according to an embodiment of the present disclosure;

[0052] Fig.19 illustrates LBE operation according to an embodiment of the present disclosure;

[0053] Figure 20 to Figure 23 A method for performing uplink transmission and downlink transmission when different FFPs are configured in a base station and a UE according to an embodiment of the present disclosure is illustrated; and

[0054] Fig.24 A method for transmitting an uplink channel by a UE according to an embodiment of the present disclosure is illustrated. DETAILED DESCRIPTION

[0055] The terms used in the specification adopt the currently widely used general terms as much as possible by considering the functions in the present invention, but these terms may be changed according to the intentions, habits and emergence of new technologies of the technicians in the field. In addition, in certain cases, there are terms arbitrarily selected by the applicant, and in this case, their meanings will be described in the corresponding description part of the present invention. Therefore, it is intended to disclose that the terms used in the specification should not be analyzed based only on the names of the terms, but should be analyzed based on the substantial meanings of the terms and contents in the entire specification.

[0056] Throughout the specification and the claims that follow, when it is described that an element is "connected" to another element, the element may be "directly connected" to the other element or "electrically connected" to the other element through a third element. In addition, unless explicitly described to the contrary, the word "comprising" will be understood to imply the inclusion of the elements without implying the exclusion of any other elements. Furthermore, in some exemplary embodiments, limitations such as "greater than or equal to" or "less than or equal to" based on a specific threshold value may be appropriately replaced with "greater than" or "less than", respectively.

[0057] The following technologies can be used in various wireless access systems: such as code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier-FDMA (SC-FDMA), etc. CDMA can be implemented by wireless technologies such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA can be implemented by wireless technologies such as Global System for Mobile Communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE). OFDMA can be implemented by wireless technologies such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, Evolved UTRA (E-UTRA), etc. UTRA is part of Universal Mobile Telecommunications System (UMTS). The 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) is a part of Evolved UMTS (E-UMTS) using Evolved UMTS Terrestrial Radio Access (E-UTRA), and LTE Advanced (A) is an evolved version of 3GPP LTE. 3GPP New Radio (NR) is a system designed separately from LTE / LTE-A, and is a system for supporting enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC), and massive machine type communication (mMTC) services as requirements of IMT-2020. For the sake of clear description, 3GPP NR is mainly described, but the technical idea of ​​the present invention is not limited thereto.

[0058] Unless otherwise specified herein, the base station may include a next generation node B (gNB) defined in 3GPP NR. In addition, unless otherwise specified, the terminal may include a user equipment (UE). In the following, in order to help understand the description, each embodiment describes each content separately, but each embodiment may be used in combination with each other. In this specification, the configuration of the UE may indicate the configuration by the base station. In more detail, the base station may configure the value of a parameter used in the operation of the UE or the wireless communication system by sending a channel or a signal to the UE.

[0059] Figure 1 An example of a radio frame structure used in a wireless communication system is illustrated.

[0060] refer to Figure 1 , the radio frame (or radio frame) used in the 3GPP NR system may have a 10ms (Δf max N f / 100)*T c ) length. In addition, the wireless frame includes 10 subframes (SF) of equal size. Here, Δf max =480*10 3 Hz,Nf =4096,T c =1 / (Δf ref *N f,ref ), Δf ref =15*10 3 Hz, and N f,ref =2048. Numbers from 0 to 9 can be assigned to 10 subframes in one radio frame respectively. Each subframe has a length of 1 ms and can include one or more time slots according to the subcarrier spacing. More specifically, in the 3GPP NR system, the subcarrier spacing that can be used is 15*2 μ kHz, and μ can have values ​​of μ=0, 1, 2, 3, 4 as subcarrier spacing configuration. That is, 15kHz, 30kHz, 60kHz, 120kHz, and 240kHz can be used for subcarrier spacing. One subframe with a length of 1ms may include 2 μ time slots. In this case, the length of each time slot is 2 -μ ms. It can be from 0 to 2 μ -1 are assigned to the 2 μ In addition, the time slots from 0 to 10*2 μ Numbers of -1 are respectively allocated to time slots in a radio frame. Time resources may be distinguished by at least one of a radio frame number (also referred to as a radio frame index), a subframe number (also referred to as a subframe index), and a time slot number (or a time slot index).

[0061] Figure 2 An example of a downlink (DL) / uplink (UL) time slot structure in a wireless communication system is illustrated. In particular, Figure 2 The structure of the resource grid of the 3GPP NR system is shown.

[0062] There is one resource grid per antenna port. Figure 2 , a time slot includes multiple orthogonal frequency division multiplexing (OFDM) symbols in the time domain and multiple resource blocks (RBs) in the frequency domain. An OFDM symbol also refers to a symbol interval. Unless otherwise specified, an OFDM symbol may be referred to as a symbol. An RB includes 12 consecutive subcarriers in the frequency domain. Reference Figure 2 , the signal transmitted from each time slot can be composed of N size,μ grid,x *N RB sc subcarriers and N slot symb Here, when the signal is a DL signal, x=DL, and when the signal is a UL signal, x=UL. N size,μ grid,xrepresents the number of resource blocks (RBs) according to the subcarrier spacing component μ (x is DL or UL), and N slot symb N represents the number of OFDM symbols in a time slot. RB sc is the number of subcarriers constituting one RB and N RB sc = 12. The OFDM symbol may be called a cyclic shift OFDM (CP-OFDM) symbol or a discrete Fourier transform spread OFDM (DFT-s-OFDM) symbol according to a multiple access scheme.

[0063] The number of OFDM symbols included in one slot may vary depending on the length of the cyclic prefix (CP). For example, in the case of a normal CP, one slot includes 14 OFDM symbols, but in the case of an extended CP, one slot may include 12 OFDM symbols. In a specific embodiment, the extended CP may be used only at a 60kHz subcarrier spacing. Figure 2 In the embodiment, for the convenience of description, one time slot is configured with 14 OFDM symbols as an example, but the embodiments of the present disclosure can be applied to time slots with different numbers of OFDM symbols in a similar manner. Figure 2 , each OFDM symbol includes N size,μ grid,x *N RB sc subcarriers. The types of subcarriers can be divided into data subcarriers for data transmission, reference signal subcarriers for transmission of reference signals, and guard bands. The carrier frequency is also called the center frequency (fc).

[0064] An RB can be composed of N RB sc For reference, a resource configured with one OFDM symbol and one subcarrier may be referred to as a resource element (RE) or tone. Thus, one RB can be configured with N slot symb *N RB sc resource elements. Each resource element in the resource grid can be uniquely defined by a pair of indices (k, l) in a time slot. k can be a random number from 0 to N in the frequency domain. size,μ grid,x *N RB sc –1 is the assigned index, and l can be from 0 to N in the time domain slot symb –1 The assigned index.

[0065] In order for a UE to receive or send signals from or to a base station, the UE's time / frequency may be synchronized with that of the base station. This is because when the base station and the UE are synchronized, the UE is able to determine the time and frequency parameters necessary to demodulate the DL signal and send the UL signal at the correct time.

[0066] Each symbol of a radio frame used in a time division duplex (TDD) or unpaired spectrum may be configured with at least one of a DL symbol, a UL symbol, and a flexible symbol. A radio frame used as a DL carrier in a frequency division duplex (FDD) or paired spectrum may be configured with a DL symbol or a flexible symbol, and a radio frame used as a UL carrier may be configured with a UL symbol or a flexible symbol. In a DL symbol, DL transmission is possible, but UL transmission is unavailable. In a UL symbol, UL transmission is possible, but DL transmission is unavailable. A flexible symbol may be determined to be used as DL or UL according to a signal.

[0067] Information about the type of each symbol, i.e., information indicating any one of a DL symbol, a UL symbol, and a flexible symbol, may be configured using a cell-specific or common radio resource control (RRC) signal. In addition, information about the type of each symbol may be additionally configured using a UE-specific or dedicated RRC signal. The base station notifies, by using a cell-specific RRC signal, i) the period of the cell-specific time slot configuration, ii) the number of time slots having only DL symbols from the beginning of the period of the cell-specific time slot configuration, iii) the number of DL symbols from the first symbol of the time slot immediately following the time slot having only DL symbols, iv) the number of time slots having only UL symbols from the end of the period of the cell-specific time slot configuration, and v) the number of UL symbols from the last symbol of the time slot immediately preceding the time slot having only UL symbols. Here, a symbol that is not configured with any one of the UL symbol and the DL symbol is a flexible symbol.

[0068] When the information about the symbol type is configured with a UE-specific RRC signal, the base station may signal whether the flexible symbol is a DL symbol or a UL symbol with a cell-specific RRC signal. In this case, the UE-specific RRC signal cannot change the DL symbol or UL symbol configured with the cell-specific RRC signal to another symbol type. The UE-specific RRC signal may signal the N of the corresponding time slot for each time slot. slot symb The number of DL symbols among the symbols and the corresponding time slot N slot symbThe number of UL symbols among the symbols. In this case, the DL symbols of the time slot can be continuously configured with the first symbol to the i-th symbol of the time slot. In addition, the UL symbols of the time slot can be continuously configured with the j-th symbol to the last symbol of the time slot (where i < j). In a time slot, a symbol that is not configured with any of the UL symbols and DL symbols is a flexible symbol.

[0069] The type of symbol configured with the above RRC signal can be referred to as semi-static DL / UL configuration. In the semi-static DL / UL configuration previously configured with the RRC signal, the flexible symbol can be indicated as a DL symbol, a UL symbol indication, or a flexible symbol by the dynamic time slot format information (SFI) sent on the physical downlink control channel (PDCCH). In this case, the DL symbol or UL symbol configured with the RRC signal is not changed to another symbol type. Table 1 illustrates the dynamic SFI that the base station can indicate to the UE.

[0070] [Table 1]

[0071]

[0072] In Table 1, D represents a DL symbol, U represents a UL symbol, and X represents a flexible symbol. As shown in Table 1, up to two DL / UL switches in a time slot can be allowed.

[0073] Figure 3 is a diagram for explaining the physical channels used in a 3GPP system (e.g., NR) and a typical signal transmission method using the physical channel.

[0074] If the power of the UE is turned on or the UE camps on a new cell, the UE performs initial cell search (step S101). Specifically, the UE can synchronize with the BS during the initial cell search. To this end, the UE can receive the primary synchronization signal (PSS) and the secondary synchronization signal (SSS) from the base station to synchronize with the base station and obtain information such as the cell ID. Thereafter, the UE is able to receive the physical broadcast channel from the base station and obtain the broadcast information in the cell.

[0075] After the initial cell search is completed, the UE receives the physical downlink shared channel (PDSCH) according to the physical downlink control channel (PDCCH) and the information in the PDCCH, so that the UE can obtain more specific system information than the system information obtained through the initial cell search (S102). Here, the system information received by the UE is the cell common system information for the normal operation of the UE in the physical layer in radio resource control (RRC), and is referred to as the remaining system information or is referred to as system information block (SIB)1.

[0076] When the UE initially accesses the base station or does not have radio resources for signal transmission (i.e., the UE is in RRC_idle mode), the UE can perform a random access procedure on the base station (step operations S103 to S106). First, the UE can send a preamble through a physical random access channel (PRACH) (step S103) and receive a response message for the preamble from the base station through a PDCCH and a corresponding PDSCH (step S104). When the UE receives a valid random access response message, the UE sends data including an identifier of the UE, etc. to the base station through a physical uplink shared channel (PUSCH) indicated by a UL grant sent from the base station through the PDCCH (step S105). Next, the UE waits for the reception of the PDCCH as an indication of the base station for conflict resolution. If the UE successfully receives the PDCCH through the UE's identifier (step S106), the random access procedure is terminated. The UE can obtain UE-specific system information for normal operation of the UE in the physical layer in the RRC layer during the random access procedure. When the UE obtains the UE-specific system information, the UE enters the RRC connection mode (RRC_connection mode).

[0077] The RRC layer is used to generate or manage messages for controlling the connection between the UE and the radio access network (RAN). In more detail, in the RRC layer, the base station and the UE can perform broadcasting cell system information required for each UE in the cell, management of mobility and switching, measurement reporting of the UE, storage management including UE capability management and device management. Generally, because the update period of the signal transmitted in the RRC layer is longer than the transmission time interval (TTI) in the physical layer, the RRC signal is not changed and maintained for a relatively long interval.

[0078] After the above procedure, the UE receives PDCCH / PDSCH (step S107) and sends a physical uplink shared channel (PUSCH) / physical uplink control channel (PUCCH) (step S108) as a general UL / DL signal transmission procedure. In particular, the UE can receive downlink control information (DCI) through the PDCCH. The DCI may include control information such as resource allocation information for the UE. In addition, the format of the DCI may vary according to the intended use. The uplink control information (UCI) sent by the UE to the base station through the UL includes DL / UL ACK / NACK signals, channel quality indicators (CQI), precoding matrix indexes (PMI), rank indicators (RI), etc. Here, CQI, PMI and RI may be included in the channel state information (CSI). In the 3GPP NR system, the UE can send control information such as the above-mentioned HARQ-ACK and CSI through PUSCH and / or PUCCH.

[0079] Figure 4 Illustration of SS / PBCH blocks used for initial cell access in a 3GPP NR system.

[0080] When the power is turned on or when the UE wants to access a new cell, it can obtain time and frequency synchronization with the cell and perform an initial cell search process. During the cell search process, the UE can detect the physical cell identity N of the cell. cell ID To this end, the UE may receive a synchronization signal, such as a primary synchronization signal (PSS) and a secondary synchronization signal (SSS), from the base station and synchronize with the base station. In this case, the UE is able to obtain information such as a cell identity (ID).

[0081] refer to Figure 4 (a), the synchronization signal (SS) will be described in more detail. The synchronization signal can be classified into PSS and SSS. PSS can be used to obtain time domain synchronization and / or frequency domain synchronization, such as OFDM symbol synchronization and time slot synchronization. SSS can be used to obtain frame synchronization and cell group ID. Figure 4 (a) and Table 2, the SS / PBCH block can be configured with 20 consecutive RBs (=240 subcarriers) on the frequency axis, and can be configured with 4 consecutive OFDM symbols on the time axis. In this case, in the SS / PBCH block, the PSS is sent in the first OFDM symbol and the SSS is sent in the third OFDM symbol through the 56th to 182nd subcarriers. Here, the lowest subcarrier index of the SS / PBCH block is numbered from 0. In the first OFDM symbol in which the PSS is sent, the base station does not send signals through the remaining subcarriers, i.e., the 0th to 55th subcarriers and the 183rd to 239th subcarriers. In addition, in the third OFDM symbol in which the SSS is sent, the base station does not send signals through the 48th to 55th subcarriers and the 183rd to 191st subcarriers. The base station sends the physical broadcast channel (PBCH) through the remaining REs in the SS / PBCH block except for the above signals.

[0082] [Table 2]

[0083]

[0084] The SS allows a total of 1008 unique physical layer cell IDs to be grouped into 336 physical layer cell identifier groups, each group including three unique identifiers, through a combination of three PSS and SSS, specifically so that each physical layer cell ID will be part of only one physical layer cell identifier group. cell ID =3N (1) ID +N (2)ID The physical layer cell identifier group can be indicated by an index N ranging from 0 to 335. (1) ID and an index N ranging from 0 to 2 indicating a physical layer identifier in the physical layer cell identifier group (2) ID The UE can detect the PSS and identify one of the three unique physical layer identifiers. In addition, the UE can detect the SSS and identify one of the 336 physical layer cell IDs associated with the physical layer identifier. In this case, the sequence d of the PSS PSS (n) are as follows.

[0085] d PSS (n) = 1-2x(m)

[0086]

[0087] 0≤n<127

[0088] Here, x(i+7)=(x(i+4)+x(i))mod2 and is given as

[0089] [x(6) x(5) x(4) x(3) x(2) x(1) x(0)]=[1 1 1 0 1 1 0].

[0090] In addition, the sequence d of SSS SSS (n) are as follows.

[0091] d SSS (n)=[1-2x0((n+m0)mod127)[1-2x1((n+m1)mod127)]

[0092]

[0093] 0≤n<127

[0094] here,

[0095] and is given as

[0096] [x0(6) x0(5) x0(4) x0(3) x0(2) x0(1)0(0)]=[0 0 0 0 0 0 1]

[0097] [x1(6) x1(5) x1(4) x1(3) x1(2) x1(1) x1(0)]=[0 0 0 0 0 0 1].

[0098] A radio frame having a length of 10 ms may be divided into two half frames having a length of 5 ms. Figure 4 (b) The time slot in which the SS / PBCH block is sent in each half frame will be described. The time slot in which the SS / PBCH block is sent may be any one of cases A, B, C, D, and E. In case A, the subcarrier spacing is 15kHz and the starting time point of the SS / PBCH block is the ({2,8}+14*n)th symbol. In this case, at a carrier frequency of 3GHz or lower, n=0 or 1. In addition, at a carrier frequency higher than 3GHz and lower than 6GHz, it may be n=0, 1, 2, 3. In case B, the subcarrier spacing is 30kHz and the starting time point of the SS / PBCH block is {4,8,16,20}+28*n. In this case, at a carrier frequency of 3GHz or lower, n=0. In addition, at a carrier frequency higher than 3GHz and lower than 6GHz, it may be n=0, 1. In case C, the subcarrier spacing is 30kHz and the starting time point of the SS / PBCH block is the ({2,8}+14*n)th symbol. In this case, at a carrier frequency of 3 GHz or lower, n=0 or 1. In addition, at a carrier frequency higher than 3 GHz and lower than 6 GHz, it can be n=0, 1, 2, 3. In case D, the subcarrier spacing is 120 kHz and the starting time point of the SS / PBCH block is the ({4, 8, 16, 20} + 28*n)th symbol. In this case, at a carrier frequency of 6 GHz or higher, n=0, 1, 2, 3, 5, 6, 7, 8, 10, 11, 12, 13, 15, 16, 17, 18. In case E, the subcarrier spacing is 240 kHz and the starting time point of the SS / PBCH block is the ({8, 12, 16, 20, 32, 36, 40, 44} + 56*n)th symbol. In this case, at a carrier frequency of 6 GHz or higher, n=0, 1, 2, 3, 5, 6, 7, 8.

[0099] Figure 5 This figure shows the process of sending control information and control channels in the 3GPP NR system. Figure 5(a), the base station may add a cyclic redundancy check (CRC) masked (e.g., XORed) with a radio network temporary identifier (RNTI) to control information (e.g., downlink control information (DCI)) (step S202). The base station may scramble the CRC with an RNTI value determined according to the purpose / target of each control information. The common RNTI used by one or more UEs can include at least one of a system information RNTI (SI-RNTI), a paging RNTI (P-RNTI), a random access RNTI (RA-RNTI), and a transmit power control RNTI (TPC-RNTI). In addition, the UE-specific RNTI may include at least one of a cell temporary RNTI (C-RNTI) and a CS-RNTI. Thereafter, the base station may perform rate matching according to the amount of resources used for PDCCH transmission after performing channel coding (e.g., polarity coding) (step S204) (step S206). Thereafter, the base station may multiplex DCI based on a PDCCH structure based on a control channel element (CCE) (step S208). In addition, the base station may apply additional processes such as scrambling, modulation (e.g., QPSK), interleaving, etc. to the multiplexed DCI (step S210), and then map the DCI to the resource to be transmitted. CCE is a basic resource unit for PDCCH, and one CCE may include multiple (e.g., six) resource element groups (REGs). One REG may be configured with multiple (e.g., 12) REs. The number of CCEs used for one PDCCH may be defined as an aggregation level. In a 3GPP NR system, an aggregation level of 1, 2, 4, 8, or 16 may be used. Figure 5 (b) is a diagram related to multiplexing of a CCE aggregation level and a PDCCH, and illustrates the type of CCE aggregation level for one PDCCH and CCEs transmitted in the control region accordingly.

[0100] Figure 6 Illustration of a control resource set (CORESET) in which a physical downlink control channel (PUCCH) can be transmitted in a 3GPP NR system.

[0101] CORESET is a time-frequency resource in which PDCCH (i.e., a control signal for UE) is transmitted. In addition, the search space to be described later can be mapped to one CORESET. Therefore, the UE can monitor the time-frequency domain designated as the CORESET instead of monitoring all frequency bands for PDCCH reception, and decode the PDCCH mapped to the CORESET. The base station can configure one or more CORESETs for each cell to the UE. The CORESET can be configured with a maximum of three consecutive symbols on the time axis. In addition, the CORESET can be configured in units of six consecutive PRBs on the frequency axis. Figure 5 In the embodiment of FIG. 1 , CORESET#1 is configured with continuous PRBs, while CORESET#2 and CORESET#3 are configured with discontinuous PRBs. A CORESET can be located in any symbol in a time slot. For example, in Figure 5 In an embodiment of the present invention, CORESET#1 starts at the first symbol of the time slot, CORESET#2 starts at the fifth symbol of the time slot, and CORESET#9 starts at the ninth symbol of the time slot.

[0102] Figure 7 A method for setting a PUCCH search space in a 3GPP NR system is illustrated.

[0103] In order to send the PDCCH to the UE, each CORESET may have at least one search space. In an embodiment of the present disclosure, the search space is a set of all time-frequency resources (hereinafter referred to as PDCCH candidates) that can be used to send the PDCCH of the UE. The search space may include a common search space that requires UEs of 3GPP NR to search together and a terminal-specific search space or a UE-specific search space that requires a specific UE to search. In the common search space, the UE may monitor the PDCCH that is set so that all UEs in the cell belonging to the same base station search together. In addition, a UE-specific search space may be set for each UE so that the UE monitors the PDCCH assigned to each UE at a search space position that is different according to the UE. In the case of a UE-specific search space, since the limited control region to which the PDCCH can be allocated can be allocated, the search space between the UEs may partially overlap and be allocated. Monitoring the PDCCH includes blind decoding of the PDCCH candidates in the search space. When the blind decoding is successful, it can be expressed as (successfully) detecting / receiving the PDCCH, and when the blind decoding fails, it can be expressed as not detecting / not receiving or not successfully detecting / receiving the PDCCH.

[0104] For convenience of explanation, a PDCCH that is scrambled with a group common (GC) RNTI previously known to one or more UEs in order to send DL control information to one or more UEs is referred to as a group common (GC) PDCCH or a common PDCCH. In addition, a PDCCH that is scrambled with an RNTI of a specific terminal that is already known to a specific UE in order to send UL scheduling information or DL ​​scheduling information to a specific UE is referred to as a PDCCH of a specific UE. A common PDCCH may be included in a common search space, and a UE-specific PDCCH may be included in a common search space or a UE-specific PDCCH.

[0105] The base station may signal each UE or UE group through the PDCCH about information related to resource allocation of the paging channel (PCH) and the downlink shared channel (DL-SCH) as transmission channels (i.e., DL grant) or information related to resource allocation of the uplink shared channel (UL-SCH) and the hybrid automatic repeat request (HARQ) (i.e., UL grant). The base station may send the PCH transport block and the DL-SCH transport block through the PDSCH. The base station may send data excluding specific control information or specific service data through the PDSCH. In addition, the UE may receive data excluding specific control information or specific service data through the PDSCH.

[0106] The base station can include information in the PDCCH about which UE (one or more UEs) the PDSCH data is sent to and how the PDSCH data will be received and decoded by the corresponding UE, and send the PDCCH. For example, assume that the DCI sent on a specific PDCCH is CRC-masked with RNTI "A", and the DCI indicates that the PDSCH is allocated to radio resources "B" (e.g., frequency position) and indicates transmission format information "C" (e.g., transport block size, modulation scheme, coding information, etc.). The UE monitors the PDCCH using the RNTI information that the UE has. In this case, if there is a UE that performs blind decoding on the PDCCH using the "A" RNTI, the UE receives the PDCCH and receives the PDSCH indicated by "B" and "C" through the information of the received PDCCH.

[0107] Table 3 shows an embodiment of a physical uplink control channel (PUCCH) used in a wireless communication system.

[0108] [Table 3]

[0109] PUCCH format OFDM symbol length Number of bits 0 1-2 ≤2 1 4-14 ≤2 2 1-2 >2 3 4-14 >2 4 4-14 >2

[0110] PUCCH can be used to transmit the following UL control information (UCI).

[0111] - Scheduling Request (SR): information for requesting UL UL-SCH resources.

[0112] -HARQ-ACK: A response to the PDCCH (indicating a DL SPS release) and / or a response to a DL transport block (TB) on the PDSCH. HARQ-ACK indicates whether the information successfully sent on the PDCCH or PDSCH is received. The HARQ-ACK response includes a positive ACK (abbreviated as ACK), a negative ACK (hereinafter referred to as NACK), a discontinuous transmission (DTX), or NACK / DTX. Here, the term HARQ-ACK is used in a mixed manner with HARQ-ACK / NACK and ACK / NACK. Generally, ACK can be represented by a bit value of 1, while NACK can be represented by a bit value of 0.

[0113] - Channel State Information (CSI): Feedback information about the DL channel. The UE generates it based on the CSI-Reference Signal (RS) sent by the base station. Multiple Input Multiple Output (MIMO) related feedback information includes Rank Indicator (RI) and Precoding Matrix Indicator (PMI). The CSI can be divided into CSI Part 1 and CSI Part 2 according to the information indicated by the CSI.

[0114] In the 3GPP NR system, five PUCCH formats can be used to support various service scenarios, various channel environments, and frame structures.

[0115] PUCCH format 0 is a format capable of delivering 1-bit or 2-bit HARQ-ACK information or SR. PUCCH format 0 can be transmitted through one or two OFDM symbols on the time axis and one PRB on the frequency axis. When PUCCH format 0 is transmitted in two OFDM symbols, the same sequence on the two symbols can be transmitted through different RBs. In this case, the sequence can be a sequence that is cyclically shifted (CS) from the base sequence used in PUCCH format 0. As a result, the UE can obtain frequency diversity gain. In more detail, the UE can obtain frequency diversity gain based on M bit BitUCI(M bit =1 or 2) to determine the cyclic shift (CS) value m cs In addition, the CS value m can be calculated by cs The cyclic shift sequence is mapped to one OFDM symbol and 12 REs of one RB to transmit a basic sequence of length 12. When the number of cyclic shifts available to the UE is 12 and M bit =1, 1-bit UCI 0 and 1 can be mapped to two cyclic shift sequences respectively, and the cyclic shift values ​​of the two cyclic shift sequences have a difference of 6. In addition, when M bit=2, 2-bit UCI 00, 01, 11 and 10 may be mapped to four cyclic shift sequences having a difference of 3 in cyclic shift value, respectively.

[0116] PUCCH format 1 can deliver 1-bit or 2-bit HARQ-ACK information or SR. PUCCH format 1 can be transmitted through continuous OFDM symbols on the time axis and one PRB on the frequency axis. Here, the number of OFDM symbols occupied by PUCCH format 1 can be one of 4 to 14. More specifically, M bit =1 UCI is BPSK modulated. The UE can use quadrature phase shift keying (QPSK) to modulate M bit =2 for UCI. The signal is obtained by multiplying the modulated complex-valued symbol d(0) by a sequence of length 12. In this case, the sequence may be the base sequence for PUCCH format 0. The UE extends the even-numbered OFDM symbols to which PUCCH format 1 is allocated by a time axis orthogonal cover code (OCC) to send the obtained signal. PUCCH format 1 determines the maximum number of different UEs multiplexed in one RB according to the length of the OCC to be used. The demodulation reference signal (DMRS) may be extended with the OCC and mapped to the odd-numbered OFDM symbols of PUCCH format 1.

[0117] PUCCH format 2 can deliver more than 2 bits of UCI. PUCCH format 2 can be sent through one or two OFDM symbols on the time axis and one or more RBs on the frequency axis. When PUCCH format 2 is sent in two OFDM symbols, the sequences sent in different RBs through the two OFDM symbols can be the same as each other. Here, the sequence can be a plurality of modulated complex-valued symbols d(0), ..., d(M symbol -1). Here, M symbol It can be M bit / 2. Through this, the UE can obtain frequency diversity gain. More specifically, for M bit UCI(M bit >2) Perform bit-level scrambling, QPSK modulation, and map it to RBs of one or two OFDM symbols. Here, the number of RBs can be one of 1 to 16.

[0118] PUCCH format 3 or PUCCH format 4 can deliver more than 2 bits of UCI. PUCCH format 3 or PUCCH format 4 can be transmitted through continuous OFDM symbols on the time axis and one PRB on the frequency axis. The number of OFDM symbols occupied by PUCCH format 3 or PUCCH format 4 can be one of 4 to 14. Specifically, the UE uses π / 2-binary phase shift keying (BPSK) or QPSK to transmit the OFDM symbol. bit UCI(M bit >2) is modulated to generate complex-valued symbols d(0) to d(M symb -1). Here, when π / 2-BPSK is used, M symb =M bit , and when using QPSK, M symb =M bit / 2. The UE may not apply block unit extension to PUCCH format 3. However, the UE may apply block unit extension to one RB (i.e., 12 subcarriers) using a PreDFT-OCC of length 12, so that PUCCH format 4 may have two or four multiplexing capabilities. The UE performs transmit precoding (or DFT precoding) on ​​the extended signal and maps it to each RE to transmit the extended signal.

[0119] In this case, the number of RBs occupied by PUCCH format 2, PUCCH format 3, or PUCCH format 4 may be determined according to the length of UCI transmitted by the UE and the maximum coding rate. When the UE uses PUCCH format 2, the UE may transmit HARQ-ACK information and CSI information together through the PUCCH. When the number of RBs that the UE may transmit is greater than the maximum number of RBs that may be used by PUCCH format 2, PUCCH format 3, or PUCCH format 4, the UE may not transmit some UCI information according to the priority of the UCI information, but may transmit only the remaining UCI information.

[0120] PUCCH format 1, PUCCH format 3, or PUCCH format 4 may be configured by RRC signaling to indicate frequency hopping in a time slot. When frequency hopping is configured, the index of the RB to be frequency hopped may be configured by RRC signaling. When PUCCH format 1, PUCCH format 3, or PUCCH format 4 is transmitted by N OFDM symbols of the time axis, the first hop may have floor(N / 2) OFDM symbols and the second hop may have ceiling(N / 2) OFDM symbols.

[0121] PUCCH format 1, PUCCH format 3 or PUCCH format 4 can be configured to be repeatedly transmitted in multiple time slots. In this case, the number K of time slots in which PUCCH is repeatedly transmitted can be configured by RRC signal. The repeatedly transmitted PUCCH must start at an OFDM symbol at a constant position in each time slot and have a constant length. When one OFDM symbol among the OFDM symbols of the time slot in which the UE should transmit the PUCCH is indicated as a DL symbol by RRC signal, the UE may not transmit the PUCCH in the corresponding time slot and delay the transmission of the PUCCH to the next time slot to transmit the PUCCH.

[0122] Meanwhile, in the 3GPP NR system, the UE can perform transmission / reception using a bandwidth equal to or less than the bandwidth of the carrier (or cell). To this end, the UE can receive a bandwidth portion (BWP) of a continuous bandwidth configured with some bandwidths in the carrier bandwidth. A UE operating according to TDD operation or in an unpaired spectrum can receive up to four DL / UL BWP pairs in one carrier (or cell). In addition, the UE can activate one DL / UL BWP pair. A UE operating according to FDD operation or in paired spectrum operation can receive up to four DL BWPs on a DL carrier (or cell) and up to four ULBWPs on a UL carrier (or cell). The UE can activate one DL BWP and one UL BWP for each carrier (or cell). The UE may not perform reception or transmission in time-frequency resources other than the activated BWP. The activated BWP may be referred to as an active BWP.

[0123] The base station may indicate the activated BWP among the BWPs configured by the UE through downlink control information (DCI). The BWP indicated by the DCI is activated, and the other configured BWPs are deactivated. In a carrier (or cell) operating with TDD, the base station may include a bandwidth part indicator (BPI) in the DCI for scheduling PDSCH or PUSCH, which indicates the BWP to be activated to change the DL / UL BWP pair of the UE. The UE may receive the DCI for scheduling PDSCH or PUSCH, and may identify the DL / UL BWP pair activated based on the BPI. For a DL carrier (or cell) operating with FDD, the base station may include a BPI indicating the BWP to be activated in the DCI for scheduling PDSCH to change the DL BWP of the UE. For a UL carrier (or cell) operating with FDD, the base station may include a BPI indicating the BWP to be activated in the DCI for scheduling PUSCH to change the UL BWP of the UE.

[0124] Figure 8 is a conceptual diagram illustrating carrier aggregation.

[0125] Carrier aggregation is a method in which a UE uses multiple frequency blocks or cells (in a logical sense) configured with UL resources (or component carriers) and / or DL ​​resources (or component carriers) as one large logical frequency band so that a wireless communication system uses a wider frequency band. One component carrier may also be referred to as a primary cell (PCell) or a secondary cell (SCell) or a primary SCell (PScell). However, hereinafter, for the convenience of description, the term "component carrier" is used.

[0126] refer to Figure 8 As an example of a 3GPP NR system, the entire system band may include up to 16 component carriers, and each component carrier may have a bandwidth of up to 400 MHz. A component carrier may include one or more physically contiguous subcarriers. Figure 8 In the figure, each component carrier is shown to have the same bandwidth, but this is only an example, and each component carrier may have a different bandwidth. In addition, although each component carrier is shown as being adjacent to each other on the frequency axis, the drawings are shown in a logical concept, and each component carrier may be physically adjacent to each other, or may be spaced apart.

[0127] A different center frequency may be used for each component carrier. Alternatively, a common center frequency may be used in physically adjacent component carriers. Figure 8 In the embodiment of the present invention, all component carriers are physically adjacent, then the center frequency A can be used in all component carriers. In addition, assuming that the respective component carriers are not physically adjacent to each other, the center frequency A and the center frequency B can be used in each component carrier.

[0128] When the total system frequency band is extended by carrier aggregation, the frequency band used to communicate with each UE can be defined in units of component carriers. UE A can use 100MHz as the total system frequency band and use all five component carriers to perform communication. UE B1~B5 can use only 20MHz bandwidth and use one component carrier to perform communication. UE C1 and C2 can use 40MHz bandwidth and use two component carriers to perform communication respectively. The two component carriers can be logically / physically adjacent or non-adjacent. UE C1 represents the case of using two non-adjacent component carriers, and UE C2 represents the case of using two adjacent component carriers.

[0129] Fig. 9 is a diagram for explaining single carrier communication and multi-carrier communication. In particular, Fig. 9 (a) shows a single carrier subframe structure and Fig. 9 (b) shows a multi-carrier subframe structure.

[0130] refer to Fig. 9 (a), in FDD mode, a general wireless communication system can perform data transmission or reception through a DL frequency band and a UL frequency band corresponding thereto. In another specific embodiment, in TDD mode, a wireless communication system can divide a radio frame into a UL time unit and a DL time unit in the time domain, and perform data transmission or reception through the UL / DL time unit. Fig. 9 (b), three 20MHz component carriers (CCs) can be aggregated into each of UL and DL, so that a bandwidth of 60MHz can be supported. Each CC may be adjacent or non-adjacent to each other in the frequency domain. Fig. 9 (b) shows the case where the bandwidth of the ULCC and the bandwidth of the DL CC are the same and symmetrical, but the bandwidth of each CC can be determined independently. In addition, asymmetric carrier aggregation with different numbers of UL CCs and DL CCs is possible. The DL / UL CC allocated / configured to a specific UE through RRC may be referred to as a serving DL / UL CC for the specific UE.

[0131] The base station can perform communication with the UE by activating some or all of the UE's serving CCs or deactivating some CCs. The base station is able to change the CCs to be activated / deactivated and change the number of CCs to be activated / deactivated. If the base station allocates CCs available to the UE as cell-specific or UE-specific, at least one of the allocated CCs will not be deactivated unless the CC allocation for the UE is completely reconfigured or the UE is switched. One CC that is not deactivated by the UE is called a primary CC (PCC) or a primary cell (PCell), and a CC that the base station can freely activate / deactivate is called a secondary CC (SCC) or a secondary cell (SCell).

[0132] At the same time, 3GPP NR uses the concept of cells to manage radio resources. A cell is defined as a combination of DL resources and UL resources, that is, a combination of DL CCs and UL CCs. A cell may be configured with DL resources alone, or may be configured with a combination of DL resources and UL resources. When carrier aggregation is supported, the link between the carrier frequency of the DL resources (or DL ​​CC) and the carrier frequency of the UL resources (or UL CC) may be indicated by system information. The carrier frequency refers to the center frequency of each cell or CC. The cell corresponding to the PCC is called the PCell, and the cell corresponding to the SCC is called the SCell. The carrier corresponding to the PCell in the DL is the DL PCC, and the carrier corresponding to the PCell in the UL is the UL PCC. Similarly, the carrier corresponding to the SCell in the DL is the DL SCC, and the carrier corresponding to the SCell in the UL is the UL SCC. Depending on the UE capabilities, the serving cell may be configured with one PCell and zero or more SCells. In the case of a UE that is in the RRC_CONNECTED state but is not configured for carrier aggregation or does not support carrier aggregation, only one serving cell is configured with only the PCell.

[0133] As described above, the term "cell" used in carrier aggregation is distinguished from the term "cell" referring to a certain geographical area where communication services are provided by one base station or one antenna group. That is, one component carrier may also be referred to as a scheduling cell, a scheduled cell, a primary cell (PCell), a secondary cell (SCell), or a primary SCell (PScell). However, in order to distinguish between a cell representing a certain geographical area and a cell of carrier aggregation, in the present disclosure, a cell of carrier aggregation is referred to as a CC, and a cell of a geographical area is referred to as a cell.

[0134] Fig.10 is a diagram showing an example in which cross-carrier scheduling technology is applied. When cross-carrier scheduling is set, the control channel sent through the first CC can use the carrier indicator field (CIF) to schedule the data channel sent through the first CC or the second CC. The CIF is included in the DCI. In other words, a scheduling cell is set, and the DL grant / UL grant sent in the PDCCH area of ​​the scheduling cell schedules the PDSCH / PUSCH of the scheduled cell. That is, there is a search area for multiple component carriers in the PDCCH area of ​​the scheduling cell. The PCell can basically be a scheduling cell, and a specific SCell can be designated as a scheduling cell by an upper layer.

[0135] exist Fig.10In the embodiment of the present invention, it is assumed that three DL CCs are merged. Here, it is assumed that DL component carrier #0 is DL PCC (or PCell), and DL component carrier #1 and DL component carrier #2 are DL SCC (or SCell). In addition, it is assumed that DL PCC is set as a PDCCH monitoring CC. When cross-carrier scheduling is not configured by UE-specific (or UE group-specific or cell-specific) higher layer signaling, CIF is disabled, and each DL CC is able to send only the PDCCH for scheduling its PDSCH without CIF according to the NR PDCCH rule (non-cross-carrier scheduling, self-carrier scheduling). At the same time, if cross-carrier scheduling is configured by UE-specific (or UE group-specific or cell-specific) higher layer signaling, CIF is enabled, and a specific CC (e.g., DL PCC) can use CIF to send not only the PDCCH for scheduling the PDSCH of DL CC A but also the PDCCH for scheduling the PDSCH of another CC (cross-carrier scheduling). On the other hand, PDCCH is not sent in another DL CC. Therefore, the UE monitors a PDCCH not including a CIF to receive a PDSCH scheduled by a self-carrier, or monitors a PDCCH including a CIF to receive a PDSCH scheduled by a cross-carrier, according to whether cross-carrier scheduling is configured for the UE.

[0136] on the other hand, Fig. 9 and Fig.10 The subframe structure of the 3GPP LTE-A system is shown in the figure, and the same or similar configuration can be applied to the 3GPP NR system. However, in the 3GPP NR system, Fig. 9 and Fig.10 The subframes may be replaced by time slots.

[0137] As mentioned above, since existing communications in unlicensed bands are mainly operated based on LBT, channel access in the NR-U system also performs LBT to coexist with existing devices. Specifically, according to the presence / absence / application method of LBT, channel access methods on unlicensed bands in NR can be classified into the following four categories.

[0138] ●Category 1: No LBT

[0139] - The Tx entity does not perform the LBT procedure for transmission.

[0140] ●Category 2: LBT without random fallback

[0141] -The Tx entity senses whether the channel is idle during the first interval to perform transmission without random backoff. That is, the Tx entity may perform transmission through the channel immediately after sensing that the channel is idle during the first interval. The first interval is an interval of a predetermined length immediately before the Tx entity performs transmission. According to an embodiment, the first interval may be an interval of 25 μs in length, but the present invention is not limited thereto.

[0142] ● Category 3: LBT with random backoff using fixed-size CW

[0143] -The Tx entity obtains a random value within the fixed size CW, sets it as the initial value N of the backoff counter (or backoff timer), and performs backoff by using the set backoff counter N. In the backoff process, whenever the channel is detected to be in an idle state within a predetermined time slot period, the Tx entity reduces the backoff counter by 1. Here, the predetermined time slot period may be 9 μs, but the present invention is not limited thereto. The backoff counter N is reduced by 1 from the initial value, and when the value of the backoff counter N reaches 0, the Tx entity may perform transmission. At the same time, in order to perform backoff, the Tx entity first senses the first time interval (i.e., the delay duration T d ) during the second interval. According to an embodiment of the present invention, the Tx entity can sense (determine) whether the channel is idle during the second interval based on whether the channel is idle in at least some time periods (e.g., a time slot period) within the second interval. The second interval can be set based on the channel access priority level of the Tx entity and consists of a period of 16μs and m consecutive time slot periods. Here, m is a value set according to the channel access priority level. When the channel is sensed to be idle during the second interval, the Tx entity performs channel sensing to reduce the backoff counter. On the other hand, when the channel is sensed to be busy during the backoff process, the backoff process stops. After stopping the backoff process, when it is sensed that the channel is idle in the additional second interval, the Tx entity can resume the backoff. In this way, in addition to the second interval, the Tx entity can also perform transmission when the channel is idle during the time slot period of the backoff counter N. In this case, the initial value of the backoff counter N is obtained within a CW of a fixed size.

[0144] ● Category 4: LBT performs random backoff by using variable-sized CWs

[0145] -The Tx entity obtains a random value within a variable-sized CW, sets the random value as an initial value of a backoff counter (or backoff timer) N, and performs backoff by using the set backoff counter N. More specifically, the Tx entity may adjust the size of the CW based on the HARQ-ACK information for the previous transmission, and obtain the initial value of the backoff counter N within the CW of the adjusted size. The specific process of performing backoff by the Tx entity is as described in Category 3. In addition to the second interval, the Tx entity may perform transmission when the channel is idle during the time slot period of the backoff counter N. In this case, the initial value of the backoff counter N is obtained within the variable-sized CW.

[0146] In the above categories 1 to 4, the Tx entity may be a base station or a UE. According to an embodiment of the present invention, the first type of channel access may refer to category 4 channel access, and the second type of channel access may refer to category 2 channel access.

[0147] Fig.11 2 is a diagram illustrating locations of OFDM symbols occupied by SSB within multiple time slots of a licensed frequency band of an NR system according to an embodiment of the present invention.

[0148] SSB may include four OFDM symbols and 20 RBs. In detail, PSS may occupy one OFDM symbol, SSS may occupy one OFDM symbol, and PBCH may occupy two OFDM symbols and one OFDM symbol multiplexed with SSS by FDM. The OFDM symbol position may be changed in a time slot occupied by SSB according to a subcarrier spacing (SCS). Fig.11 (a) shows an SSB pattern when the value of the subcarrier spacing used for SSB transmission is 15 KHz and 30 KHz. Fig.11 (b) shows the SSB pattern when the value of the subcarrier spacing for SSB transmission is 120KHz and 240KHz. When the subcarrier spacing is 30KHz, the SSB pattern for eMBB transmission or the SSB pattern considering URLLC can be used. Fig.11 In FIG. 1 , the shaded OFDM symbols indicate the OFDM symbol positions in the time slot occupied by the SSB.

[0149] Fig.12 2 is a diagram illustrating the position of a time slot occupied by SSB within a half radio frame, i.e., 5 ms, of an authorized frequency band of an NR system according to an embodiment of the present invention.

[0150] exist Fig.12In FIG. 1 , the shaded time slot indicates the position of the time slot including the SSB within the half radio frame. One time slot may include two SSBs. Two SSBs in one time slot may have different SSB indexes. In addition, SSBs located in different time slots may also have different SSB indexes. The SSB index will be described again later. In addition, in Fig.12 In , L represents the maximum number of SSBs that can be sent by the base station in half a radio frame.

[0151] The NR system specifies that a subcarrier spacing is defined for each frequency band in order to reduce the complexity of the UE searching for the SSB for initial cell access. In particular, when using frequency bands below 6 GHz, the NR system specifies that a subcarrier spacing between 15 KHz and 30 KHz is used for SSB. In addition, when using frequency bands above 6 GHz, the NR system specifies that a subcarrier spacing between 120 KHz and 240 KHz is used for SSB.

[0152] The LBT process can be used in the case where a wireless communication device performs channel access in an unlicensed band. Therefore, if the channel is not idle, the wireless communication device may not be able to perform channel access. Even when the base station performs channel access in order to send an SSB, the channel access may fail. Therefore, SSB transmission may not be performed at the location configured by the base station. Ultimately, even if the base station configures the location where the SSB is sent for the UE so that the UE can assume the location where the SSB is sent, the UE may not be able to receive the SSB. The SSB is sent periodically. Therefore, even if the UE fails to receive the SSB at one point in time, the UE can receive the SSB after one cycle from the corresponding point in time. However, in the case where the UE receives the SSB as described above, delays may occur in the RRM measurement and the measurement of the neighboring cells. Ultimately, the delay will increase in the entire system.

[0153] In addition, SSB is used for beam link configuration and beam management. Specifically, the base station sends multiple SSBs corresponding to different SSB indexes in different time zones. The UE configures multiple beam links by using multiple SSBs. The base station performs beam scanning. The UE can configure the beam link based on whether the UE has received SSBs sent through different beams in different time zones. If the base station channel access fails, resulting in the inability to send SSB, the problem of the UE being unable to configure the beam link occurs. Ultimately, due to the failure of channel access, the delay of the beam link will increase. Therefore, a method is needed to reduce the number of SSB transmission failures and expand the SSB transmission opportunities.

[0154] In the case of using an NR system in an unlicensed band, a 60kHz subcarrier spacing can be used for SSB transmission to increase channel access opportunities. 15kHz or 30kHz subcarrier spacing can be used for SSB transmission in licensed bands below 6GHz. In addition, 15kHz, 30kHz or 60kHz subcarrier spacing can be used for data transmission in licensed bands below 6GHz. In addition, 120kHz or 240kHz subcarrier spacing can be used for SSB transmission in licensed bands above 6GHz. In addition, 60KHz or 120KHz subcarrier spacing can be used for data transmission in licensed bands above 6GHz. When the NR system is used in an unlicensed band below 7GHz (such as below 7.125GHz), a 15kHz or 30kHz subcarrier spacing can be considered, which is the same as the subcarrier spacing used in the licensed band below 6GHz. However, if a 60kHz subcarrier spacing is used for SSB transmission in an unlicensed band, the OFDM symbol duration is 1 / 4 of that when a 15kHz subcarrier spacing is used. Therefore, in the case where 60kHz subcarrier spacing is used for the NR system in the unlicensed band, the transmission opportunities of SSB and data channels in symbol units after channel access can be increased. When 60kHz subcarrier spacing is used, the time for the base station to transmit the reservation signal when successfully performing channel access in one OFDM symbol may be less than the time for transmitting the reservation signal when 15kHz subcarrier spacing and 30kHz subcarrier spacing are used.

[0155] NR-U DRS (or DRS) configuration

[0156] In the unlicensed band of the NR system, the base station may send a signal including at least one SSB transmission or at least one SSB burst set transmission. The SSB burst set indicates that the SSB is continuously transmitted within a predetermined time interval. In this case, the signal may correspond to a discovery signal burst (DRS burst). The base station may send a DRS burst according to the following principles. The base station may send a DRS burst so that a gap is not included in the time interval for sending a DRS burst in a beam. The base station may send a DRS burst to meet an occupied channel bandwidth (OCB) condition. However, the base station may send a DRS burst that does not meet the occupied channel bandwidth condition in some cases. In addition, the base station may consider a method of minimizing the channel occupancy time of the DRS burst and performing fast channel access. For ease of explanation, DRS will be used instead of a DRS burst.

[0157] The DRS transmitted in the unlicensed band may include a PDSCH containing SSB-related residual system information (RMSI), i.e., system information block 1 (SIB1). In addition, the DRS may include an RMSI-CORESET, which is a time and frequency resource region related to a control channel for transmitting scheduling information for transmitting RMSI. That is, the DRS may include a CORESET, which is a time and frequency region of a PDCCH for transmitting a PDCCH that schedules a PDCSH including SIB1. In addition, the DRS may include a CSI-RS. In addition, the DRS may include different types of signals. Specifically, the DRS may include other system information (OSI) or paging. As described above, when the base station transmits the DRS in the unlicensed band, the base station may multiplex the DRS with a physical channel or signal. In this case, the method by which the base station performs channel access is problematic. Specifically, which method is used by the base station in the various channel access methods described above, and by which method are parameters for channel access configured? In addition, the DRS may include the transmission of an SSB or an SSB burst set.

[0158] In an embodiment of the present invention, when a base station multiplexes DRS with unicast data, the base station may perform channel access in which a random backoff is performed using a CW of a variable size and the size of the CW is determined according to a channel access priority level, so as to perform transmission of the multiplexed DRS and unicast data. The UE may perform channel access according to the channel access priority level of the multiplexed unicast data. Specifically, the channel access method may correspond to the first type of channel access described above.

[0159] In these embodiments, a case where the base station multiplexes DRS with signals or information other than unicast data will be described. Signals or information other than unicast data may indicate a signal or channel that is not a data service, so it is impossible to configure a channel access priority level for the signal or channel. Signals or information other than unicast data may include control messages associated with initial access, random access, mobility, or paging. In addition, signals or information other than unicast data may include transmissions that include only reference signals. In addition, signals or information other than unicast data may include transmissions that include only PDCCH. Transmissions that include only PDCCH may include at least one of RACH message 4, handover commands, group common PDCCH, short paging messages, other system information (OSI), paging, and random access responses (RAR) under a random access procedure. In addition, signals or information other than unicast data may also be sent via PDCCH and PDSCH. For ease of explanation, signals or information other than unicast data are referred to as non-unicast data. In addition, in this specification, the multiplexed DRS and non-unicast data may indicate that unicast data is not included in the corresponding transmission. In a detailed embodiment, in the case where the base station multiplexes DRS with non-unicast data, the base station may perform channel access in which only LBT based on a single time interval is performed so as to perform transmission of the multiplexed DRS and non-unicast data. The channel access in which only LBT based on a single time interval is performed may be the second type of channel access described above. The duration of a single time interval may be 25 μs or 34 μs.

[0160] In another detailed embodiment, in the case where the base station multiplexes DRS with non-unicast data, the base station may perform channel access in which a random backoff is performed using a CW of variable size and the size of the CW is determined according to the channel access priority level, so as to perform the transmission of the multiplexed DRS and non-unicast data. In this embodiment, it is considered that LBT based on a single time interval is performed only when the entire duration of the transmission including only DRS is less than or equal to 1ms and the duty cycle of the DRS transmission is less than or equal to 1 / 20. In this embodiment, the base station can use the channel access priority level with the highest priority (e.g., channel access priority level #1). Therefore, the base station can assign a higher channel access priority to non-unicast data than to unicast data. In addition, the base station can use the channel access priority level with the highest priority and use the minimum CW size among the CW sizes allowed in the channel access priority level. In another detailed embodiment, the base station can use the channel access priority level with the highest priority and use the largest CW size among the CW sizes allowed in the channel access priority level.

[0161] In another detailed embodiment, in the case where the base station multiplexes DRS with non-unicast data, the base station may perform channel access in which random backoff is performed using a CW of a fixed size in order to perform transmission of the multiplexed DRS and non-unicast data. The channel access method may be the above-mentioned category 3 channel access. In this embodiment, the base station may use a channel access priority level with the highest priority (e.g., channel access priority level #1). Therefore, the base station may assign a higher channel access priority to non-unicast data than to unicast data. In addition, the base station may use a channel access priority level with the highest priority and use the minimum CW size among the CW sizes allowed in the channel access priority level. In another detailed embodiment, the base station may use a channel access priority level with the highest priority and use the maximum CW size among the CW sizes allowed in the channel access priority level.

[0162] In the case where the base station sends non-unicast data that is not multiplexed with the DRS, the base station may perform channel access for transmitting the non-unicast data by using the channel access method used when multiplexing the non-unicast data and the DRS. Specifically, in the case where the base station sends non-unicast data that is not multiplexed with the DRS, the base station may use the channel access type and channel access parameters used when multiplexing the non-unicast data and the DRS.

[0163] In another detailed embodiment, in the case where the base station sends non-unicast data that is not multiplexed with DRS, the base station may perform channel access in which a random backoff is performed using a CW of variable size and the size of the CW is determined according to a channel access priority level, so as to perform transmission of non-unicast data. Specifically, the channel access method may correspond to the above-mentioned first type of channel access. In this embodiment, the base station may use a channel access priority level with the highest priority (e.g., channel access priority level #1). Therefore, the base station may assign a higher channel access priority to non-unicast data than to unicast data. In addition, the base station may use a channel access priority level with the highest priority and use the minimum CW size among the CW sizes allowed in the channel access priority level. In another detailed embodiment, the base station may use a channel access priority level with the highest priority and use the maximum CW size among the CW sizes allowed in the channel access priority level.

[0164] In another detailed embodiment, in the case where the base station sends non-unicast data that is not multiplexed with DRS, the base station may perform a channel access in which a random backoff is performed using a CW of a fixed size in order to perform the transmission of the non-unicast data. The channel access method may be the above-mentioned category 3 channel access. In this embodiment, the base station may use a channel access priority level with the highest priority (e.g., channel access priority level #1). Therefore, the base station can assign a higher channel access priority to non-unicast data than to unicast data. In addition, the base station may use a channel access priority level with the highest priority and use the minimum CW size among the CW sizes allowed in the channel access priority level. In another detailed embodiment, the base station may use a channel access priority level with the highest priority and use the maximum CW size among the CW sizes allowed in the channel access priority level.

[0165] In the above embodiment, the base station determines the channel access method for transmitting multiplexed DRS and non-unicast data or unicast data, regardless of the duration of the transmission of the multiplexed DRS and non-unicast data or unicast data and the duty cycle of the DRS transmission. When the base station determines the channel access method, the base station may assume that the transmission of only DRS and the transmission of multiplexed DRS and non-unicast data are the same. Specifically, the base station may determine the channel access method for transmitting multiplexed DRS and non-unicast data or unicast data based on the duration of the transmission of the multiplexed DRS and non-unicast data or unicast data and the duty cycle of the DRS transmission. The base station may determine the channel access method for transmitting multiplexed DRS and non-unicast data or unicast data based on whether the duration of the transmission of the multiplexed DRS and non-unicast data or unicast data is less than or equal to 1ms, and whether the duty cycle of the DRS transmission is less than or equal to 1 / 20.

[0166] When the base station performs transmission of multiplexed DRS and non-unicast data, the base station can select one of two channel access types according to whether two conditions are met, and the two conditions are that the duration of transmission of multiplexed DRS and non-unicast data is less than or equal to 1ms, and the duty cycle of DRS transmission is less than or equal to 1 / 20. One of the two channel access types indicates a channel access in which only LBT based on a single time interval is performed, and the other indicates a channel access in which a random backoff is performed using a CW of a variable size to determine the size of the CW according to the channel access priority level. In a detailed embodiment, if the duration of transmission of multiplexed DRS and non-unicast data is less than or equal to 1ms, or the duty cycle of DRS transmission is less than or equal to 1 / 20, the base station can perform a channel access in which only LBT based on a single time interval is performed in order to perform transmission of multiplexed DRS and non-unicast data. The duration of a single time interval may be 25μs. In addition, LBT based on a single time interval may correspond to the above-mentioned second type of channel access. In another detailed embodiment, if the duration of transmission of multiplexed DRS and non-unicast data is greater than 1ms, or the duty cycle of DRS transmission is greater than 1 / 20, the base station may perform a channel access in which a CW of variable size is used to perform a random backoff and the size of the CW is determined according to the channel access priority level, so as to perform transmission of multiplexed DRS and non-unicast data. In addition, the base station may select a random channel access priority level. The base station may randomly select one of the channel access priority levels that satisfies the MCOT length condition according to the duration of transmission of multiplexed DRS and non-unicast data. The base station may use the selected channel access priority level for channel access in order to transmit multiplexed DRS and non-unicast data. That is, the base station may use the CW size according to the selected channel access priority level for channel access. For example, the base station may use the channel access priority level with the highest priority (e.g., channel access priority level #1). Therefore, compared with unicast data, the base station can assign a higher channel access priority to non-unicast data. In addition, the base station may use the channel access priority level with the highest priority and use the minimum CW size among the CW sizes allowed in the channel access priority level. In another detailed embodiment, the base station may use a channel access priority class having the highest priority and use a maximum CW size among CW sizes allowed in the channel access priority class.

[0167] In the above embodiment, when the base station is able to determine whether the UE receives non-unicast data and whether it is successfully received, the base station can adjust the CW size based on the ratio between ACK and NACK. Specifically, the base station can convert feedback information about non-unicast data received from the UE according to the reception of the UE into ACK and NACK, and can adjust the CW size based on the ratio between ACK and NACK. The channel access method in which a variable-sized CW is used to perform random backoff and the size of the CW is determined according to the channel access priority level can correspond to the first type of channel access.

[0168] As described above, the base station and the UE can control the CW size based on HARQ feedback when using the channel access of CW. However, the base station and the UE may not expect HARQ feedback for all or part of the non-unicast data. In addition, the base station and the UE may not be able to determine whether the UE or the base station receives all or part of the non-unicast data. In addition, in the case where the base station and the UE are required to perform the initial access process, the base station and the UE may not be able to determine the HARQ-ACK feedback for part of the downlink signals and channels and uplink signals and channels used in the initial access process. In addition, the base station and the UE may not perform transmissions associated with a specific channel access priority level, and therefore may not be able to determine the HARQ-ACK feedback corresponding to the transmission associated with the corresponding channel access priority level. In this case, a method for the base station and the UE to determine a CW will be described, which will be used for channel access when transmitting channels and signals including all or part of the non-unicast data for which HARQ feedback cannot be expected. For ease of explanation, the base station is interpreted as the subject, but the embodiments to be described below can also be applied to the UE in the same manner.

[0169] When the base station cannot determine that there is HARQ-ACK feedback for a transmission associated with a channel access priority level that determines the CW size, the base station may perform channel access in which a random backoff is performed in a CW corresponding to the channel access priority. The base station may use the minimum CW size among the CW sizes allowed in the corresponding channel access priority level. In another detailed embodiment, the base station may use the channel access priority level with the highest priority and use the maximum CW size among the CW sizes allowed in the channel access priority level.

[0170] In addition, in the case where the base station cannot determine whether the UE receives all or part of the non-unicast data for which HARQ feedback cannot be expected, the base station may perform a channel access in which a random fallback is performed in a fixed CW size to send multiplexed non-unicast data and DRS. Specifically, the base station may use a CW corresponding to a channel access priority level during the above-mentioned first type of channel access. In a detailed embodiment, the base station may use one of the channel access priority levels that satisfies the MCOT length condition according to the duration of the transmission of the multiplexed DRS and non-unicast data during the first type of channel access. The base station may use a channel access priority level with the highest priority. In a detailed embodiment, the base station may use a channel access priority level with the highest priority among the channel access priority levels that satisfy the MCOT length condition according to the duration of the transmission of the multiplexed DRS and non-unicast data during the first type of channel access. In addition, the base station may use a channel access priority level with the highest priority and use the minimum CW size in the CW size allowed by the channel access priority level. In another detailed embodiment, the base station may use a channel access priority level with the highest priority and use the maximum CW size in the CW size allowed in the channel access priority level.

[0171] In another detailed embodiment, when the base station cannot determine whether the UE has received all or part of the non-unicast data for which HARQ feedback cannot be expected, the base station can perform the above-mentioned Category-3 channel access to send multiplexed non-unicast data and DRS. The base station can use the channel access priority level with the highest priority. The base station can use the channel access priority level with the highest priority among the channel access priority levels that meet the MCOT length condition based on the duration of the transmission of the multiplexed DRS and non-unicast data. In addition, the base station can use the channel access priority level with the highest priority and use the minimum CW size among the CW sizes allowed in the channel access priority level. In another detailed embodiment, the base station can use the channel access priority level with the highest priority and use the maximum CW size among the CW sizes allowed in the channel access priority level.

[0172] The base station may not be able to send an SSB due to a failure in the channel access (e.g., LBT) process. When the base station cannot send an SSB at a configured location, an SSB transmission window may be defined so that the SSB can be sent at another location. The SSB transmission window is a time interval in which the base station can send an SSB, and includes multiple SSB transmission position candidates. When the base station fails to start SSB transmission at a certain SSB transmission position candidate, the base station may attempt to send the SSB at an SSB transmission position candidate later than a certain SSB transmission position candidate within the SSB transmission window. The SSB transmission position candidate is a time point at which the base station can start transmission of the SSB. When a user device fails to receive an SSB at a certain SSB transmission position candidate within the SSB transmission window, the user device may receive the SSB at an SSB transmission position candidate later than a certain SSB transmission position candidate within the SSB transmission window. Here, the user equipment can determine whether the base station cannot start SSB transmission or the SSB transmission of the base station has failed at the SSB transmission position candidate. In a specific embodiment, when the user equipment fails to receive the SSB at a certain SSB transmission position candidate within the SSB transmission window, the user equipment may attempt to receive the SSB at an SSB transmission position candidate next to the certain SSB transmission position candidate within the SSB transmission window. After completing the reception of the SSB after starting to receive the SSB at the certain SSB transmission position candidate, the user equipment may not expect to receive an additional SSB within the corresponding SSB transmission window. In detail, after completing the reception of the SSB after starting to receive the SSB at the certain SSB transmission position candidate, the user equipment may not attempt to receive an additional SSB within the corresponding SSB transmission window.

[0173] In another specific embodiment, when the user equipment fails to receive a specific SSB at a certain SSB transmission position candidate within the SSB transmission window, the user equipment may attempt to receive the specific SSB at an SSB transmission position candidate next to the certain SSB transmission position candidate within the SSB transmission window. After completing the reception of the specific SSB after starting to receive the specific SSB at a certain SSB transmission position candidate, the user equipment may not perform reception of the specific SSB within the corresponding SSB transmission window. In detail, after receiving the specific SSB at a certain SSB transmission position candidate, the user equipment may not additionally attempt to receive the specific SSB within the corresponding SSB transmission window.

[0174] In another specific embodiment, even after reception of a specific SSB is completed at a certain SSB transmission position candidate, the user equipment may attempt to receive the specific SSB within the corresponding SSB transmission window. This is because the user equipment can additionally receive the specific SSB and can obtain a combined gain by the additionally received specific SSB. These embodiments can be applied not only to a case where a plurality of SSBs corresponding to different beam indices are transmitted for beam operation, but also to a case where an omni-TX scheme is used. In detail, the embodiments can also be applied to a case where the same SSB is repeatedly transmitted.

[0175] DRS’s LBT approach

[0176] Fig.13 is a diagram illustrating positions of OFDM symbols occupied by SSB within a slot including 14 OFDM symbols according to an embodiment of the present invention.

[0177] In the following, reference will be made to Fig.13 A channel access method for a DRS including at least one SSB is described. In detail, described below is a channel access method performed by a base station before transmitting the DRS according to the number of SSBs included in the DRS to be transmitted from the base station, that is, a configuration method for performing different LBTs.

[0178] Fig.13 The diagram shows the position of the OFDM symbol occupied by the SSB in a slot configured with 14 OFDM symbols. SSB pattern A is the same as the position of the OFDM symbol occupied by the SSB of the NR system defined in 3GPP Rel.15. In SSB pattern B, the OFDM symbol occupied by the SSB in the second half of the slot in one slot is positioned one symbol later than SSB pattern A. Therefore, SSB pattern B is configured so that the positions of the OFDM symbols occupied by the SSB in one slot are symmetrical to each other in units of half slots.

[0179] In case the total duration of transmission including the DRS is greater than or equal to 1 ms, the base station may perform a plurality of transmissions and may determine a channel access method for each of the plurality of DRS transmissions.

[0180] If an unlicensed band (such as the 5 GHz band or the 6 GHz band) is used, the base station can send a maximum of n SSBs in the DRS. The value of n can be 2, 4, or 8. In addition, the subcarrier spacing used for DRS transmission can be 15 KHz or 30 KHz. If the subcarrier spacing is 15 KHz, the duration of a time slot can be 1 ms, and the number of SSBs that can be included in the 1 ms interval can be 2. In addition, if the subcarrier spacing is 30 KHz, the duration of a time slot can be 0.5 ms, and the number of SSBs that can be included in the 1 ms interval may be 4. The length of the total duration of a DRS transmission with a duty cycle of 1 / 20 may change depending on the DRS transmission cycle configuration.

[0181] As described above, the total duration of the transmission including DRS may be less than or equal to 1ms, and the duty cycle of the DRS transmission may be less than or equal to 1 / 20. In the case where the base station performs transmission including only DRS or multiplexed DRS and non-unicast data, for the corresponding transmission, the base station may perform a channel access in which only LBT based on a single time interval is performed. The channel access in which only LBT based on a single time interval is performed may be the above-mentioned second type of channel access. The total duration of the transmission including DRS may be greater than 1ms, and the duty cycle of the DRS transmission may be greater than 1 / 20. In the case where the base station performs transmission including only DRS or multiplexed DRS and non-unicast data, the base station may perform a channel access in which random backoff is performed using a CW of a variable size, and the size of the CW is determined according to the channel access priority level, so as to perform the corresponding transmission. The channel access method in which random backoff is performed using a CW of a variable size, and the size of the CW is determined according to the channel access priority level may correspond to the first type of channel access.

[0182] In an embodiment of the present disclosure, taking into account the characteristics of transmissions including DRS, a method in which a base station performs LBT based on a single time interval may be used. If the total duration of transmissions including DRS is greater than 1ms, the base station may determine the channel access method in units of 1ms duration. Specifically, if the total duration of transmissions including DRS is greater than 1ms, the base station may perform multiple transmissions, each of which has a duration less than or equal to 1ms, and may perform channel access including only LBT based on a single time interval for each of the multiple transmissions. The base station may apply this embodiment only to situations where the duty cycle of DRS transmission is less than or equal to 1 / 20. This is because, in the case where transmissions are performed without LBT, there is an ETSI provision that requires short control signals to not exceed 5% of the corresponding transmissions. Through the above-mentioned embodiments, the base station and the UE can quickly perform initial access and RRM measurements through the SSB included in the DRS sent from the base station. For example, when the period of DRS transmission is configured to be equal to or greater than 40ms, and the base station performs DRS transmission in each 5ms interval configured as a DRS transmission window in a minimum 40ms period unit, the total duration of transmission of DRS including the condition that the duty cycle of DRS transmission is less than or equal to 1 / 20 may be less than or equal to 2ms. Under the restriction that the total duration of transmission including DRS is less than or equal to 2ms, the base station may perform multiple DRS transmissions, and the duration of each DRS transmission is less than or equal to 1ms. The base station may perform a second type of channel access before performing each transmission of multiple transmissions. Through this embodiment, the base station can quickly perform DRS transmission to the UE. In addition, when the period of DRS transmission is configured to be greater than or equal to 80ms, and the base station performs DRS transmission in each 5ms interval configured as a DRS transmission window in a minimum 80ms period unit, the total duration of transmission of DRS including the condition that the duty cycle of DRS transmission is less than or equal to 1 / 20 may be less than or equal to 4ms. Under the constraint that the total duration of transmissions including DRS is less than or equal to 4 ms, the base station may perform multiple DRS transmissions, each DRS transmission having a duration less than or equal to 1 ms. The base station may perform the second type channel access before performing each of the multiple transmissions.

[0183] In addition, if the total duration of the transmission including the DRS is greater than 1 ms and the duty cycle of the DRS transmission is greater than 1 / 20, the base station may perform a channel access in which a random backoff is performed using a variable size CW and the size of the CW is determined according to the channel access priority level in order to perform the transmission including the DRS. The channel access method may correspond to the first type of channel access.

[0184] In another detailed embodiment, a portion of the intervals of the transmission including the DRS may have a transmission duty cycle less than or equal to 1 / 20. The base station may perform channel access in which only LBT based on a single time interval is performed for a portion of the transmission intervals of the transmission including the DRS whose duty cycle is less than or equal to 1 / 20. In addition, in this embodiment, the base station may perform multiple transmissions, each of which has a duration less than or equal to 1ms, and may perform channel access including only LBT based on a single time interval for each of the multiple transmissions. Wherein the channel access in which LBT based only on a single time interval is performed may be a second type of channel access. In addition, the base station may perform channel access in which random backoff is performed using a CW of a variable size, and the size of the CW is determined according to a channel access priority level, for the remaining transmission intervals in the transmission interval including the DRS transmission. Wherein the channel access in which random backoff is performed using a CW of a variable size and the size of the CW is determined according to a channel access priority level may be a first type of channel access. For example, the period of DRS transmission may be a multiple of 20ms. Specifically, if the period of DRS transmission is 20ms, the duration of the transmission interval in which the duty cycle of DRS transmission is less than or equal to 1 / 20 is 1ms. If the period of DRS transmission is 40ms, the duration of the transmission interval in which the duty cycle of DRS transmission is less than or equal to 1 / 20 is 2ms. If the period of DRS transmission is 60ms, the duration of the transmission interval in which the duty cycle of DRS transmission is less than or equal to 1 / 20 is 3ms. If the period of DRS transmission is 80ms, the duration of the transmission interval in which the duty cycle of DRS transmission is less than or equal to 1 / 20 is 4ms. The base station may perform the second type of channel access for part of the transmission intervals including the transmission of DRS whose duty cycle is 1 / 20, and may perform the first type of channel access for the remaining transmission intervals in the transmission interval including the transmission of DRS.

[0185] The maximum number of SSBs included in the DRS may be 8. The following description is given assuming that the number of SSBs included in the DRS is 8. If the period of DRS transmission is 20ms, the duration of the transmission interval in which the duty cycle of DRS transmission is less than or equal to 1 / 20 is 1ms. Therefore, if the subcarrier spacing is 15KHz, two SSBs are included in the transmission interval in which the duty cycle of DRS transmission is less than or equal to 1 / 20. The base station may perform the second type of channel access before performing the first transmission, and if the channel access is successful, the base station may send two SSBs. In addition, the base station may perform the first type of channel access before performing the second transmission, and if the channel access is successful, the base station may send 6 SSBs. In addition, if the period of DRS transmission is 20ms, the duration of the transmission interval in which the duty cycle of DRS transmission is less than or equal to 1 / 20 is 1ms. Therefore, if the subcarrier spacing is 30KHz, four SSBs may be included in the transmission interval in which the duty cycle of DRS transmission is less than or equal to 1 / 20. The base station may perform the second type of channel access before performing the first transmission, and if the channel access is successful, the base station may send four SSBs. In addition, the base station may perform the first type of channel access before performing the second transmission, and if the channel access is successful, the base station may send four SSBs.

[0186] If the period of DRS transmission is 40ms, the duration of the transmission interval in which the duty cycle of DRS transmission is less than or equal to 1 / 20 is 2ms. Therefore, if the subcarrier spacing is 15KHz, 4 SSBs may be included in the transmission interval in which the duty cycle of DRS transmission is less than or equal to 1 / 20. The base station may perform a transmission of 1ms duration twice, and may send two SSBs through each transmission. The base station may perform a second type of channel access before performing the first transmission, and if the channel access is successful, the base station may send two SSBs. In addition, the base station may perform a second type of channel access before performing the second transmission, and if the channel access is successful, the base station may send two SSBs. In addition, the base station may perform a first type of channel access before performing the third transmission, and if the channel access is successful, the base station may send the remaining 4 SSBs. In addition, if the period of DRS transmission is 40ms, the duration of the transmission interval in which the duty cycle of DRS transmission is less than or equal to 1 / 20 is 2ms. Therefore, if the subcarrier spacing is 30KHz, 8 SSBs can be included in a transmission interval in which the duty cycle of DRS transmission is less than or equal to 1 / 20. The base station can perform a second type of channel access before performing the first transmission, and if the channel access is successful, the base station can send 4 SSBs. In addition, the base station can perform a second type of channel access before performing the second transmission, and if the channel access is successful, the base station can send 4 SSBs.

[0187] In another detailed embodiment, a partial transmission interval including a DRS may have a duration less than or equal to 1 ms and a DRS transmission duty cycle less than or equal to 1 / 20. The base station may perform a channel access in which only LBT based on a single time interval is performed for a partial interval including transmission of a DRS having a duty cycle less than or equal to 1 / 20 and a duration less than or equal to 1 ms. Performing a channel access in which only LBT based on a single time interval is performed may be a second type of channel access. In addition, the base station may perform a channel access in which a random backoff is performed using a CW of a variable size and the size of the CW is determined according to a channel access priority level for the remaining transmission intervals. A channel access in which a random backoff is performed using a CW of a variable size and the size of the CW is determined according to a channel access priority level may be a first type of channel access.

[0188] The maximum number of SSBs that can be included in the DRS may be 8. The following description is given assuming that the number of SSBs included in the DRS is 8.

[0189] If the period of DRS transmission is 20ms, the duration of the transmission interval in which the duty cycle of DRS transmission is less than or equal to 1 / 20 is 1ms. Therefore, if the subcarrier spacing is 15KHz, two SSBs may be included in the transmission interval in which the duty cycle of DRS transmission is less than or equal to 1 / 20. The base station may perform the second type of channel access before performing the first transmission, and if the channel access is successful, the base station may send two SSBs. In addition, the base station may perform the first type of channel access before performing the second transmission, and if the channel access is successful, the base station may send 6 SSBs. In addition, if the period of DRS transmission is 20ms, the duration of the transmission interval in which the duty cycle of DRS transmission is less than or equal to 1 / 20 is 1ms. Therefore, if the subcarrier spacing is 30KHz, four SSBs may be included in the transmission interval in which the duty cycle of DRS transmission is less than or equal to 1 / 20. The base station may perform the second type of channel access before performing the first transmission, and if the channel access is successful, the base station may send 4 SSBs. In addition, the base station can perform a first type of channel access before performing the second transmission, and if the channel access is successful, the base station can send four SSBs.

[0190] If the period of DRS transmission is 40ms, the duration of the transmission interval in which the duty cycle of DRS transmission is less than or equal to 1 / 20 is 2ms. If the subcarrier spacing is 15KHz, two SSBs may be included in a transmission interval with a duration of 1ms and a DRS transmission duty cycle less than or equal to 1 / 20. The base station may perform a second type of channel access before performing the first transmission, and if the channel access is successful, the base station may send two SSBs. In addition, the base station may perform a first type of channel access before performing the second transmission, and if the channel access is successful, the base station may send the remaining 6 SSBs. In addition, if the period of DRS transmission is 40ms, the duration of the transmission interval in which the duty cycle of DRS transmission is less than or equal to 1 / 20 is 2ms. If the subcarrier spacing is 30KHz, four SSBs may be included in a transmission interval with a duration of 1ms and a DRS transmission duty cycle less than or equal to 1 / 20. The base station may perform a second type of channel access before performing the first transmission, and if the channel access is successful, the base station may send 4 SSBs. In addition, the base station can perform a first type of channel access before performing the second transmission, and if the channel access is successful, the base station can send four SSBs.

[0191] In addition, the DRS transmission window duration may be configured as Tms. T may be a natural number greater than or equal to 1. T may be 5 or 6. Alternatively, T may be configured as a multiple of the minimum time interval in which the maximum available number of SSBs included in the DRS may be included. If the duration of the DRS transmission window is greater than or equal to 1ms, the base station may perform channel access in which only LBT based on a single time interval is performed before the last 1ms of the DRS transmission window. If the DRS transmission duty cycle of the last 1ms of the DRS transmission window is less than or equal to 1 / 20, the base station may perform channel access in which only LBT based on a single time interval is performed before the last 1ms of the DRS transmission window. Performing channel access in which only LBT based on a single time interval is performed may be the second type of channel access described above. In addition, the base station may perform the first type of channel access or the second type of channel access before the last 1ms of the DRS transmission window. Through these embodiments, the UE can quickly perform initial access and RRM measurements.

[0192] Fig.14 is a block diagram illustrating a configuration of a user equipment and a base station according to an embodiment of the present invention.

[0193] In an embodiment of the present disclosure, the UE may be implemented using various types of wireless communication devices or computing devices that ensure portability and mobility. The UE may be referred to as a user equipment (UE), a station (STA), a mobile subscriber (MS), etc. In addition, in an embodiment of the present invention, a base station controls and manages a cell (e.g., a macro cell, a femto cell, a micro cell, etc.) corresponding to a service area, and performs functions such as signal transmission, channel designation, channel monitoring, self-diagnosis, relaying, etc. The base station may be referred to as a next generation Node B (gNB) or an access point (AP).

[0194] As shown in the drawings, the UE 100 according to an embodiment of the present disclosure may include a processor 110 , a communication module 120 , a memory 130 , a user interface 140 , and a display unit 150 .

[0195] First, the processor 110 may execute various instructions or programs within the UE 100 and process data. In addition, the processor 110 may control the entire operation of each unit including the UE 100, and may control the transmission / reception of data between the units. Here, the processor 110 may be configured to perform operations according to the embodiments described in the present invention. For example, the processor 110 may receive time slot configuration information, determine the time slot configuration based on the time slot configuration information, and perform communication according to the determined time slot configuration.

[0196] Next, the communication module 120 may be an integrated module that performs wireless communication using a wireless communication network and performs wireless LAN access using a wireless LAN. To this end, the communication module 120 may include a plurality of network interface cards (NICs) such as cellular communication interface cards 121 and 122 and an unlicensed band communication interface card 123 in an internal or external form. In the drawings, the communication module 120 is shown as an integrally integrated module, but unlike the drawings, each network interface card can be independently arranged according to a circuit configuration or usage.

[0197] The cellular communication interface card 121 may send or receive a radio signal with at least one of the base station 200, the external device, and the server by using a mobile communication network and provide a cellular communication service in a first frequency band based on an instruction from the processor 110. According to an embodiment, the cellular communication interface card 121 may include at least one NIC module using a frequency band less than 6 GHz. At least one NIC module of the cellular communication interface card 121 may independently perform cellular communication with at least one of the base station 200, the external device, and the server in accordance with a cellular communication standard or protocol in a frequency band below 6 GHz supported by the corresponding NIC module.

[0198] The cellular communication interface card 122 may send or receive a radio signal with at least one of the base station 200, the external device, and the server by using a mobile communication network and provide a cellular communication service in the second frequency band based on an instruction from the processor 110. According to an embodiment, the cellular communication interface card 122 may include at least one NIC module using a frequency band greater than 6 GHz. At least one NIC module of the cellular communication interface card 122 may independently perform cellular communication with at least one of the base station 200, the external device, and the server in accordance with a cellular communication standard or protocol in a frequency band greater than 6 GHz supported by the corresponding NIC module.

[0199] The unlicensed band communication interface card 123 transmits or receives a radio signal with at least one of the base station 200, the external device, and the server by using the third frequency band as the unlicensed frequency band, and provides an unlicensed frequency band communication service based on an instruction from the processor 110. The unlicensed band communication interface card 123 may include at least one NIC module using the unlicensed frequency band. For example, the unlicensed frequency band may be a frequency band above 2.4 GHz, 5 GHz, 6 GHz, 7 GHz, or 52.6 GHz. At least one NIC module of the unlicensed band communication interface card 123 may independently or non-independently perform wireless communication with at least one of the base station 200, the external device, and the server according to the unlicensed frequency band communication standard or protocol of the frequency band supported by the corresponding NIC module.

[0200] The memory 130 stores a control program and various data thereof used in the UE 100. Such a control program may include a prescribed program required to perform wireless communication with at least one of the base station 200, an external device, and a server.

[0201] Next, the user interface 140 includes various input / output means provided in the UE 100. In other words, the user interface 140 may receive user input using various input means, and the processor 110 may control the UE 100 based on the received user input. In addition, the user interface 140 may perform output based on instructions from the processor 110 using various output means.

[0202] Next, the display unit 150 outputs various images on the display screen. The display unit 150 may output various display objects such as content or a user interface executed by the processor 110 based on a control instruction from the processor 110.

[0203] In addition, the base station 200 according to the embodiment of the present invention may include a processor 210 , a communication module 220 , and a memory 230 .

[0204] First, the processor 210 may execute various instructions or programs and process the internal data of the base station 200. In addition, the processor 210 may control the entire operation of each unit in the base station 200 and control the transmission and reception of data between the units. Here, the processor 210 may be configured to perform the operations according to the embodiments described in the present invention. For example, the processor 210 may signal a time slot configuration and perform communication according to the time slot configuration notified by the signal.

[0205] Next, the communication module 220 may be an integrated module that performs wireless communication using a wireless communication network and performs wireless LAN access using a wireless LAN. To this end, the communication module 220 may include a plurality of network interface cards such as cellular communication interface cards 221 and 222 and an unlicensed band communication interface card 223 in an internal or external form. In the drawings, the communication module 220 is shown as an integrally integrated module, but unlike the drawings, each network interface card can be independently arranged according to a circuit configuration or usage.

[0206] The cellular communication interface card 221 may send or receive a radio signal with at least one of the UE 100, the external device, and the server by using a mobile communication network and provide a cellular communication service in a first frequency band based on an instruction from the processor 210. According to an embodiment, the cellular communication interface card 221 may include at least one NIC module using a frequency band less than 6 GHz. At least one NIC module of the cellular communication interface card 221 may independently perform cellular communication with at least one of the UE 100, the external device, and the server in a frequency band less than 6 GHz supported by the corresponding NIC module in accordance with a cellular communication standard or protocol.

[0207] The cellular communication interface card 222 may send or receive a radio signal with at least one of the UE 100, the external device, and the server by using a mobile communication network and provide a cellular communication service in the second frequency band based on an instruction from the processor 210. According to an embodiment, the cellular communication interface card 222 may include at least one NIC module using a frequency band of 6 GHz or higher. At least one NIC module of the cellular communication interface card 222 may independently perform cellular communication with at least one of the UE 100, the external device, and the server in accordance with a cellular communication standard or protocol in a frequency band of 6 GHz or higher supported by the corresponding NIC module.

[0208] The unlicensed band communication interface card 223 transmits or receives a radio signal with at least one of the UE 100, the external device, and the server by using a third frequency band as an unlicensed frequency band, and provides an unlicensed frequency band communication service based on an instruction from the processor 210. The unlicensed band communication interface card 223 may include at least one NIC module using an unlicensed frequency band. For example, the unlicensed frequency band may be a frequency band above 2.4 GHz, 5 GHz, 6 GHz, 7 GHz, or 52.6 GHz. At least one NIC module of the unlicensed band communication interface card 223 may independently or dependently perform wireless communication with at least one of the UE 100, the external device, and the server in accordance with an unlicensed frequency band communication standard or protocol of a frequency band supported by the corresponding NIC module.

[0209] Fig.14 1 is a block diagram illustrating a UE 100 and a base station 200 according to an embodiment of the present invention, and the blocks shown separately are logically divided elements of the device. Therefore, the aforementioned elements of the device can be installed in a single chip or multiple chips according to the design of the device. In addition, a part of the configuration of the UE 100, for example, a user interface 140, a display unit 150, etc., can be selectively provided in the UE 100. In addition, the user interface 140, the display unit 150, etc. can be additionally provided in the base station 200 when necessary.

[0210] Hereinafter, in the present specification, a channel access method performed by a base station before transmitting a downlink channel on an unlicensed frequency band in a wireless communication system is described. More specifically, a channel access priority level (CAPC) to be used when the base station performs channel access for transmission of a downlink control channel (e.g., PDCCH) will be described.

[0211] When the base station performs channel access before sending a downlink control channel, it is necessary to apply the channel access priority level differently according to the various information sent through the downlink control channel and the time point of the downlink control channel transmission. Generally, when a PDSCH including unicast data scheduled by a PDCCH is sent on the same time slot of the same carrier as the carrier of the PDCCH, the base station can configure the CAPC according to the service type of the unicast data included in the PDSCH. In addition, according to the configured CAPC, the base station can perform channel access to send PDCCH and PDSCH on the same time slot of the same carrier. However, with respect to the transmission of other PDCCHs excluding the PDCCH for scheduling the PDSCH including unicast data sent on the same time slot of the same carrier as the carrier of the PDCCH, it may be ambiguous which CAPC the base station should select to perform channel access. Therefore, the present disclosure describes the CAPC that should be selected by the base station to perform channel access for PDCCH transmission based on the information sent through the PDCCH, the scheduling time of the PDCCH and the PDSCH, whether the PDSCH scheduled by the PDCCH is sent through the same carrier as the carrier of the PDCCH or through a carrier different from the carrier of the PDCCH, etc.

[0212] When the base station transmits a downlink control channel (e.g., PDCCH) to the UE, the information transmitted through the PDCCH may correspond to the following various information. Here, the base station may transmit each PDCCH including various information individually, or the base station may transmit a plurality of PDCCHs each including information within one control resource set (CORESET). CORESET may indicate a resource region in which the PDCCH is transmitted.

[0213] Various information transmitted through the PDCCH will be described. That is, various DCI formats that can be transmitted through the PDCCH will be described.

[0214] 1. DCI format for transmission of downlink shared channel (PDSCH) sent via PDCCH

[0215] 1-A. A DCI format for scheduling a PDSCH including unicast data, which is transmitted on one or more time slots including the same time slot as the time point of PDCCH transmission on the same carrier as the PDCCH

[0216] 1-B. DCI format for scheduling PDSCH including unicast data, which is transmitted on the same carrier as the carrier of PDCCH at a different time slot from the time point of PDCCH transmission

[0217] 1-C. DCI format for scheduling PDSCH including unicast data, which is transmitted on a slot of a carrier different from that of the PDCCH

[0218] 1-D. DCI format indicating reception of semi-persistent scheduling (SPS) PDSCH

[0219] 1-E. DCI format indicating release of SPS PDSCH reception

[0220] 2. DCI format for transmission of uplink shared channel (PUSCH) sent via PDCCH

[0221] 2-A. A DCI format for scheduling a PUSCH including unicast data, which is transmitted by the UE on one or more time slots including the same carrier as the carrier of the PDCCH as the same time point as the PDCCH transmission time point

[0222] 2-B. DCI format for scheduling PUSCH including unicast data, which is sent by the UE on a time slot different from the time point of PDCCH transmission on the same carrier as the PDCCH

[0223] 2-C. DCI format for scheduling PUSCH including unicast data, which is sent by the UE on a slot of a carrier different from that of the PDCCH

[0224] 2-D. DCI format indicating activation of configuration grant PUSCH

[0225] 2-E. DCI format indicating release of configuration grant PUSCH

[0226] 2-F. DCI format indicating downlink feedback information for configuring a granted PUSCH

[0227] 3. Transmitted via PDCCH for other purposes (excluding uplink / downlink shared channels (PUSCH / PDSCH) transmission purpose) DCI format

[0228] 3-A. DCI format for notifying a group of UEs of the slot format, available RB set, channel occupancy time (COT) duration, and search space set group switching

[0229] 3-B. Notification of DCI formats for PRBs and OFDM symbols in which the UE may assume that no transmission is intended for the UE

[0230] 3-C. DCI format for notifying a group of UEs of transmission of transmit power control (TPC) commands for PUCCH and PUSCH

[0231] 3-D. DCI format for notifying one or more UEs of a set of TPC commands for sounding reference signal (SRS) transmission

[0232] In the case where the DCI formats transmitted through the PDCCHs of 1 to 3 above are multiplexed with the PDSCH including unicast data, the base station may select the CAPC according to the service type of the unicast data included in the PDSCH.

[0233] However, as in 1-B to 1-E, 2-A to 2-F, and 3-A to 3-D above, when a DCI format is independently transmitted on a time slot via PDCCH instead of being multiplexed with a PDSCH including unicast data transmitted in a time slot different from the time slot in which the PDCCH is transmitted, or when a DCI format scheduling a PUSCH including unicast data is transmitted on a time slot via PDCCH (for example, 2-A to 2-F above), it is necessary to define which CAPC should be selected to perform channel access when the base station accesses the channel for PDCCH transmission.

[0234] When the DCI format is not multiplexed with a PDSCH including unicast data transmitted in a time slot different from the time slot in which the PDCCH is transmitted, the base station can select the highest priority CAPC to perform channel access for transmission of the PDCCH. If the base station uses the highest priority CAPC to perform channel access, the channel access priority for transmission of the control channel (ie, PDCCH) can be increased.

[0235] If the DCI format is not multiplexed with a PDSCH including unicast data sent in a time slot different from the time slot in which the PDCCH is sent, the base station can select the lowest priority CAPC to perform channel access for transmission of the PDCCH. If the base station uses the lowest priority CAPC to perform channel access, the base station can use the longest maximum channel occupancy time (MCOT) among the CAPCs to perform channel access. This is because the longest MCOT is configured in the lowest priority CAPC. Therefore, it is possible to multiplex and send control channels and data channels having the same CAPC as the lowest priority CAPC or a CAPC with a priority higher than its priority within the MCOT configured by the lowest priority CAPC in the time slot after channel access.

[0236] There may be a method for the base station to select a CAPC for each of the above DCI formats 1 to 3. Specifically, when the DCI format sent through the PDCCH is multiplexed with the PDSCH including unicast data, the CAPC will be selected according to the service type of the unicast data included in the PDSCH. For example, when the above DCI format 2 sent through the PDCCH schedules a PUSCH including unicast data, the base station may select a CAPC according to the service type of the unicast data included in the PUSCH.

[0237] In the case of the above-mentioned DCI format 3 sent by PDCCH according to a specific purpose, the base station can use the highest priority CAPC to perform channel access in order to increase the channel access priority. This is because information for a specific purpose should be sent by DCI. At the same time, when the above-mentioned DCI format 3 is sent by PDCCH according to a specific purpose, the base station can use the lowest priority CAPC when performing channel access. If the base station uses the lowest priority CAPC to perform channel access, the base station can use the longest maximum channel occupancy time (MCOT) among the CAPCs to perform channel access. This is because the longest MCOT is configured in the lowest priority CAPC. Therefore, it is possible to multiplex and transmit the control channel and data channel of the CAPC with the same CAPC as the lowest priority CAPC or the CAPC with a priority higher than its priority in the MCOT configured by the lowest priority CAPC in the time slot after channel access. In other words, the above-mentioned DCI format 3 can represent a DCI format that does not include information for scheduling uplink / downlink channels (e.g., PUSCH or PDSCH).

[0238] When each of the above-mentioned DCI formats 1 to 3 is transmitted through the PDCCH, the base station may select a CAPC for performing channel access according to each DCI format.

[0239] [Table 4]

[0240]

[0241]

[0242]

[0243] Each of the above-mentioned DCI formats 1 to 3 can be transmitted through one PDCCH, and one or more PDCCHs can be multiplexed in the CORESET and transmitted from the base station to the UE. Therefore, when one or more PDCCHs are multiplexed in the CORESET, the base station needs to select a CAPC to perform channel access when accessing a channel in order to transmit one or more PDCCHs in the time domain and frequency domain including one or more PDCCHs.

[0244] When one or more PDCCHs are multiplexed in a CORESET, the base station can perform channel access using the lowest priority CAPC among the CAPCs configured for each PDCCH. If the base station uses the lowest priority CAPC to perform channel access, the base station can use the longest maximum channel occupancy time (MCOT) among the CAPCs to perform channel access. This is because the longest MCOT is configured in the lowest priority CAPC. Therefore, control channels and data channels having the same CAPC as the lowest priority CAPC or having a priority higher than that of the CAPC within the MCOT configured by the lowest priority CAPC can be multiplexed and transmitted in the time slot after channel access.

[0245] On the other hand, when one or more PDCCHs are multiplexed in CORESET, the base station can perform channel access using the CAPC configured when a specific PDCCH schedules a PDSCH or PUSCH including unicast data, or the base station can perform channel access using the CAPC configured when PDCCH and PDSCH are multiplexed.

[0246] The highest priority CAPC and the lowest priority CAPC may refer to the highest priority CAPC (eg, p=1) and the lowest priority CAPC (eg, p=4) among a plurality of preconfigured CAPCs (see Table 4).

[0247] Fig.15 is a diagram illustrating a downlink channel access procedure according to an embodiment of the present invention.

[0248] Fig.15 is a diagram illustrating a downlink channel access procedure used in UE-initiated channel occupancy time (COT) sharing. Fig.15 (a) illustrates an example of a downlink channel access procedure when the gap is less than 16 μs, Fig.15 (b) illustrates an example of a downlink channel access procedure when the gap is 16 μs, and Fig.15 (c) illustrates an example of a downlink channel access procedure when the gap is 25 μs.

[0249] To perform uplink (eg, PUSCH) transmissions on scheduled resources or configured resources, the user equipment may use a category 4 channel access procedure to obtain channel occupancy initiated by the user equipment. In addition, the user equipment may share channel occupancy with the base station for base station transmissions.

[0250] When information about the Energy Detect (ED) threshold is configured

[0251] The user equipment may receive from the base station a threshold value of ED to be applied when obtaining channel occupancy. For example, the base station may configure the threshold value of ED by sending 'ULtoDL-CO-SharingED-Threshold-r16', an RRC parameter as a threshold value for ED, to the user equipment. When the user equipment shares channel occupancy with the base station, the base station may send a specific channel or a specific signal. Here, the uplink transmission may be a configuration grant (CG)-PUSCH or a scheduled uplink (e.g., a scheduled grant PUSCH) transmission. After the uplink transmission of the user equipment, a downlink transmission of the base station may be performed. In the present specification, a CG uplink transmission (e.g., CG-PUSCH) may be an uplink transmission (e.g., CG-PUSCH) that is semi-statically configured in advance for uplink transmission by the base station for the user equipment and is performed by the user equipment on the pre-configured resources.

[0252] When the uplink transmission performed by the user equipment is CG-PUSCH, the user equipment can receive a table for sharing channel occupancy from the base station. In detail, the user equipment can receive from the base station the configuration of a table for sharing channel occupancy related information (e.g., channel occupancy time (COT)) between the base station and the user equipment through the RRC parameter 'COT-SharingList-r16'. In addition, the user equipment can receive channel occupancy information corresponding to each row of the table from the base station. For example, the channel occupancy information corresponding to each row of the table can be provided by the RRC parameter 'cg-COT-Sharing-r16'. Here, one of the rows of the table can be configured to indicate that the channel occupancy is not shared. When the user equipment shares with the base station the channel occupancy of the CG-PUSCH initiated by the user equipment, the user equipment can indicate the index (row index) corresponding to a row of the table configured from the base station by the COT sharing information included in the CG-uplink control information (UCI) of the CG-PUSCH. That is, when the user equipment indicates an index corresponding to a row of a table providing channel occupancy information, the base station can perform downlink transmission by assuming one or more values ​​corresponding to the channel occupancy information indicated by the row of the table indicated by the index. In detail, the channel occupancy information may include duration, offset, CAPC, etc. The duration may represent the number of time slots available (assumed) in downlink transmission within the time of channel occupancy initiated by the user equipment. The offset represents the time interval (difference) from the end of the time slot in which the base station has detected the CG-UCI to the time slot in which the downlink transmission performed by the base station is started. CAPC represents the CAPC assumed when the user equipment shares the channel occupancy initiated by the user equipment with the base station.

[0253] When information about the Energy Detect (ED) threshold is not configured

[0254] It may happen that the base station does not configure the threshold of ED for the user equipment. In other words, it may happen that the user equipment cannot receive the threshold of ED from the base station. That is, the base station may not configure 'ULtoDL-CO-SharingED-Threshold-r16' as the RRC parameter for the threshold of ED, and may not configure the threshold of ED for the user equipment. Here, when the uplink transmission performed by the user equipment is CG-PUSCH, the CG-UCI of the CG-PUSCH may include 'COT sharing information' indicating whether the channel occupancy is shared. When the user equipment indicates that the channel occupancy is shared by the CG-UCI (for example, when the value of the COT sharing information is 1), the user equipment may allow the X symbols configured from the base station to be used for the downlink transmission performed by the base station. In detail, the user equipment may receive the RRC parameter 'cg-COT-SharingOffset-r16' indicating X symbols for downlink transmission from the base station, and the base station may allow X symbols for shared channel occupancy for downlink transmission. Here, X symbols represent X symbols from the end of slot n (Slot #n) in which the base station has detected the CG-UCI.

[0255] Here, the downlink transmission of the base station may be performed after the uplink transmission of the user equipment, wherein the length of the downlink transmission may be limited to a maximum of 2 symbols, 4 symbols, or 8 symbols according to the subcarrier spacing. The downlink transmission may be limited to a maximum of 2 symbols when the subcarrier spacing is 15KHz, may be limited to a maximum of 4 symbols when the subcarrier spacing is 30KHz, and may be limited to a maximum of 8 symbols when the subcarrier spacing is 60KHz.

[0256] Hereinafter, the downlink transmission performed by the base station after the uplink transmission of the user equipment will be described. Here, the downlink transmission performed by the base station may correspond to both the case where the base station has sent (configured) the RRC parameter for the threshold value of ED to the user equipment and the case where the base station has not sent (configured) the RRC parameter for the threshold value of ED.

[0257] i) When the base station has configured the threshold of ED by configuring 'ULtoDL-CO-SharingED-Threshold-r16' as the RRC parameter for the threshold of ED for the user equipment, the base station may perform a downlink transmission including only DRS after the user equipment performs an uplink (e.g., PUSCH) transmission on the scheduled or configured resources. In the present specification, the DRS may include at least one SSB, the at least one SSB including a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a physical broadcast channel (PBCH), and a DR-RS for the PBCH. In addition, the DRS may include a CORESET for a PDSCH carrying system information block 1 (SIB1) and a PDCCH scheduling the PDSCH. In addition, the DRS may include a non-zero power CSI reference signal.

[0258] Meanwhile, when the threshold of ED has not been configured because the base station has not configured the RRC parameter 'ULtoDL-CO-SharingED-Threshold-r16' as the threshold of ED for the user equipment, downlink transmission including only DRS can be performed only when the subcarrier spacing is at least 30 KHz. This is because the number of symbols occupied by the SSB included in the DRS is at least 4.

[0259] ii) The base station may perform downlink transmission including DRS after the user equipment performs uplink (eg, PUSCH) transmission on the scheduled or configured resources. Here, in the downlink transmission of the base station, non-unicast transmission of any user equipment may be multiplexed.

[0260] iii) The base station may perform downlink transmission after the user equipment performs uplink (e.g., PUSCH) transmission on the scheduled or configured resources. Here, the downlink transmission performed by the base station may include reference signals (e.g., CSI-RS, tracking RS, etc.) for the user equipment that has initiated channel occupancy and non-unicast transmission for any user equipment.

[0261] iv) The base station may perform downlink transmission after the user equipment performs uplink (e.g., PUSCH) transmission on the scheduled or configured resources. Here, the downlink transmission performed by the base station may not include user plane data for the user equipment that has initiated channel occupancy, but may include unicast transmission containing control plane data (e.g., data for RRC configuration) and non-unicast transmission for any user equipment.

[0262] When the channel occupancy initiated by the user equipment is shared with the base station, the base station can perform channel access based on a specific gap or a gap smaller than the specific gap after the uplink transmission performed by the user equipment and perform the downlink transmission of the above i) to iv). Hereinafter, the channel access process of the base station will be described.

[0263] When the gap is less than 16 μs, the base station may perform downlink transmission after performing a type 2C downlink channel access procedure. The type 2C downlink channel access procedure instructs the base station to perform downlink transmission without performing channel sensing before performing downlink transmission. The duration for downlink transmission may be limited to a maximum of 584 μs (refer to 3GPP TS37.213).

[0264]

[0265] When the gap is 16μs, the base station may perform downlink transmission after performing a type 2B downlink channel access procedure. The type 2B downlink channel access procedure instructs the base station to perform downlink transmission immediately after sensing whether the channel is idle for a duration of 16μs (T_f) before performing downlink transmission. 16μs (T_f) may include a sensing slot within the last 9μs of 16μs. When the channel is sensed to be idle during the entire interval (e.g., at least 5μs) including the interval in which sensing is performed in the sensing slot (e.g., at least 4μs), the channel may be considered to be idle (see 3GPP TS 37.213).

[0266]

[0267]

[0268] When the gap is 25μs, the base station may perform downlink transmission after performing a type 2A downlink channel access procedure. The type 2A downlink channel access procedure instructs the base station to perform downlink transmission immediately after sensing whether the channel is idle during a sensing interval of 25μs (T_short_dl) before performing downlink transmission. The sensing interval of (T_short_dl) may be configured with a 16μs (T_f) interval and a sensing slot (9μs) immediately after the 16μs (T_f) interval. The 16μs (T_f) interval may include one sensing slot (9μs). When a sensing interval of 25μs (T_short_dl) (i.e., the entire sensing slot) is sensed as idle, the channel may be considered to be idle during an interval of 25μs (T_short_dl) (see 3GPP TS37.213).

[0269]

[0270] Fig.16 is a diagram illustrating scheduled uplink transmission according to an embodiment of the present invention.

[0271] In detail, Fig.16 It is illustrated that when the user equipment is scheduled from the base station to continuously perform uplink transmission without a gap after resources configured for autonomous transmission or CG-PUSCH, the user equipment performs scheduled uplink transmission.

[0272] When the user equipment is configured to perform scheduled uplink transmission, the user equipment may perform scheduled uplink transmission without performing channel access when the following conditions are met: Uplink transmission on resources configured for autonomous transmission or CG-PUSCH may be discarded at the last symbol of a time slot (e.g., (n-1)th time slot) before the start time of a time slot (e.g., nth time slot) for scheduled uplink transmission.

[0273] Hereinafter, conditions for a user equipment to perform scheduled uplink transmission without performing channel access will be described.

[0274] a) The user equipment shall perform a category 4 channel access (e.g., a type 1 uplink channel access) for uplink transmission on resources configured for autonomous transmission or CG-PUSCH. In addition, the user equipment shall perform uplink transmission on resources configured for autonomous transmission or CG-PUSCH before the start time of the scheduled uplink transmission.

[0275] b) For frequency domain resources for scheduled uplink transmission, all resource blocks (RBs) of the LBT bandwidth (e.g., 20 MHz) that may be occupied by the first scheduled time slot among the time domain resources configured for the scheduled uplink transmission should be scheduled. Alternatively, all RBs of the uplink bandwidth part (BWP) configured for the user equipment should be scheduled. Here, the starting symbol index of the first scheduled time slot among the time domain resources configured for CG-PUSCH can be 0. Alternatively, multiple LBT bandwidths may exist within one BWP. Here, resources for autonomous transmission or resources configured for CG-PUSCH are allocated to at least one LBT bandwidth within one BWP, and frequency domain resources for scheduled uplink transmission may occupy all RBs of a subset of at least one of the LBT bandwidths or all RBs of all LBT bandwidths including resources for autonomous transmission or resources configured for CG-PUSCH.

[0276] c) The CAPC used by a user equipment when performing a category 4 channel access (e.g., type 1 uplink channel access) for uplink transmission on resources configured for autonomous transmission or CG-PUSCH should be greater than or equal to the CAPC indicated by the base station for scheduled uplink transmission.

[0277] d) The sum of the length of uplink transmission on resources configured for autonomous transmission or CG-PUSCH and the length of scheduled uplink transmission should not exceed the maximum channel occupancy time (MCOT). Here, MCOT is the MCOT configured when the user equipment performs category 4 channel access (e.g., type 1 uplink channel access) for uplink transmission on resources configured for autonomous transmission or CG-PUSCH.

[0278] When all of the above conditions a) to d) are not satisfied, uplink transmission on resources configured for autonomous transmission or CG-PUSCH may be discarded at the last symbol of a time slot (e.g., the (n-1)th time slot) before the start time of the time slot (e.g., the nth time slot) for scheduled uplink transmission. Alternatively, the user equipment may discard uplink transmission on resources configured for autonomous transmission or CG-PUSCH at as many time slots (e.g., the (n-1)th time slot) as at least one time slot before the start time of the time slot (e.g., the nth time slot) for scheduled uplink transmission. At the same time, when the time during which discarding of uplink transmission is allowed (cancellation guarantee time) has not passed, the user equipment may discard uplink transmission on resources configured for autonomous transmission or CG-PUSCH at as many time slots (e.g., the (n-1)th time slot) as at least one time slot before the start time of the time slot (e.g., the nth time slot) for scheduled uplink transmission. However, the time during which the uplink transmission is allowed to be discarded has passed, and the user equipment can perform the scheduled uplink transmission at the next time slot (e.g., the (n+1)th time slot) after the start time of the time slot for scheduled uplink transmission (e.g., the nth time slot). Here, in the channel access process for performing the scheduled uplink transmission at the next time slot (e.g., the (n+1)th time slot), category 4 channel access (e.g., type 1 uplink channel access) can be used. Alternatively, when the resources for the scheduled uplink transmission are included in the MCOT configured when the user equipment performs category 4 channel access (e.g., type 1 uplink channel access) to perform uplink transmission on resources configured for autonomous transmission or CG-PUSCH, the user equipment can perform the scheduled uplink transmission based on category 2 channel access (e.g., type 2A uplink channel access).

[0279] When a user equipment has been scheduled from a base station to continuously perform uplink transmission without gaps after resources configured for autonomous transmission or CG-PUSCH, the user equipment may perform scheduled uplink transmission without channel access according to the type of scheduled uplink transmission. The type of scheduled uplink transmission may include PUSCH containing an uplink shared channel (UL-SCH), PUSCH without UL-SCH, PUCCH for sending uplink control information, uplink transmission related to a random access procedure (e.g., PRACH preamble, Msg3), sounding reference signal (SRS), etc. Here, PUCCH may include HARQ-ACK, scheduling request (SR), beam failure recovery request (BFR), or channel state information (CSI).

[0280] When the above conditions a) to d) are satisfied, the user equipment may perform scheduled uplink transmission without performing channel access (eg, LBT) regardless of the type of scheduled uplink transmission.

[0281] When the scheduled uplink transmission is uplink transmission excluding the PUSCH and the above conditions of a), c) and d) are satisfied, the user equipment may perform the scheduled uplink transmission without performing channel access.

[0282] When the scheduled uplink transmission is uplink transmission excluding the PUSCH including the UL-SCH and the above conditions of a), c) and d) are satisfied, the user equipment may perform the scheduled uplink transmission without performing channel access.

[0283] The scheduled uplink transmission may be a PUCCH including at least one of HARQ-ACK, SR or BFR. Here, when PUCCH transmission has been scheduled by extending to the LBT bandwidth by means of interleaved PUCCH transmission configured for PUCCH transmission by RRC, if the above conditions of a), c) and d) are met, the user equipment may perform scheduled PUCCH transmission without performing channel access. This is to ensure transmission on scheduled resources as much as possible, because in the case of a PUCCH including at least one of HARQ-ACK, SR or BFR, the delay caused by link failure may increase significantly or the data transfer rate of uplink / downlink transmission may be reduced due to failure in the channel access process. In addition, the CAPC for PUCCH transmission may generally be set to 1. Therefore, the CAPC for PUCCH transmission may always be less than or equal to the CAPC used by the user equipment when performing category 4 channel access (e.g., type 1 uplink channel access) to perform uplink transmission on resources configured for autonomous transmission or CG-PUSCH, so the above condition of c) may be met.

[0284] When the scheduled uplink transmission is SRS excluding PUSCH, PUCCH, PUSCH excluding UL-SCH, and transmission related to the random access procedure (e.g., PRACH preamble, Msg3), if the above conditions a), c), and d) are met, the user equipment can perform the scheduled uplink transmission without performing the channel access procedure. Here, for SRS excluding PUSCH, PUCCH, PUSCH excluding UL-SCH, and transmission related to the random access procedure (e.g., PRACH preamble, Msg3), a category 4 channel access (e.g., type 1 uplink channel access) process can be performed, and at this time, the CAPC can be set to 1.

[0285] A frame-based device (FBE)-based LBT operation in an unlicensed band, i.e., a channel access method and process for semi-static channel occupancy when a semi-static channel access mode is used, will be described. Specifically, a base station and a UE may perform FBE operation using UE-initiated channel occupancy. A method for transmitting or receiving a channel between a base station and a UE by using UE-initiated channel occupancy will be described.

[0286] Since most devices operating in unlicensed bands are based on listen-before-talk (LBT) operation, a clear channel assessment (CCA) for sensing the channel before data transmission is performed. A communication device (e.g., an AP or STA) checks whether the channel is busy by performing carrier sensing before sending data. When a radio signal of a predetermined strength or higher is detected in a channel for data transmission, the channel is determined to be busy, and the communication device delays access to the channel. This process is called clear channel assessment, and the signal level that determines whether a signal is detected is called a CCA threshold. On the other hand, when no radio signal is detected in the corresponding channel or when a radio signal with a strength less than the CCA threshold is detected, the channel is determined to be in an idle state. If the channel is determined to be idle, the UE with data to be sent performs a backoff process after a postponement period (e.g., arbitration interframe space (AIFS), PCF IFS (PIFS), etc.). The postponement period represents the minimum time that the UE should wait after the channel is in an idle state. The backoff process causes the UE to wait for a longer random period of time after the postponement period. For example, the UE waits while reducing the slot time by as much as a random number assigned to the UE within a contention window (CW) when the channel is in an idle state, and the UE that has used up all the slot times may attempt to access the corresponding channel.

[0287] Fig.17 The FBE-based LBT operation process according to an embodiment of the present disclosure is shown.

[0288] LBT can be divided into FBE scheme LBT and load-based equipment (LBE) scheme LBT (see ETSI) according to the operating state of the UE. In the case of the FBE scheme, if the channel is occupied by another communication device, the base station and the UE can be configured not to send data within a fixed frame period (FFP). The fixed frame period may include a channel occupation time (COT) and an idle period. In this case, the channel occupation time may represent the time when the communication node is successful in channel access and can continue data transmission, and may correspond to a duration of 1ms to 10ms. The idle duration may be a time corresponding to at least 5% of the channel occupancy time. The CCA process of observing the channel may be performed during a CCA time slot (at least 20 μs) located at the end of the idle period. The communication node may perform CCA in units of fixed frames. For example, when the channel is not occupied, the communication node may perform data transmission during the channel occupation time, and when the channel is occupied, the communication node may maintain data transmission and wait for transmission until the CCA time slot of the next cycle. The communication node described in this specification is a communication device and may refer to a base station or a UE.

[0289] Fig.18 The FBE operation according to an embodiment of the present disclosure is shown.

[0290] refer to Fig.18 , the communication node can perform a CCA process during the CCA timeslot before performing data transmission on a single carrier channel. If the channel is in an idle state as a result of performing CCA, the communication node can perform data transmission. As a result of performing CCA, if the channel is in a busy state, the communication node can perform the CCA process again after waiting for the time obtained by subtracting the CCA timeslot from the fixed frame period. The communication node performs data transmission during the channel occupancy time, and when the data transmission is terminated, the communication node can wait for the time obtained by subtracting the CCA timeslot from the idle duration, and then perform the CCA process again. On the other hand, when the channel is in an idle state but the communication node has no data to send, the communication node can perform the CCA process again after waiting for the time obtained by subtracting the CCA timeslot from the fixed frame period.

[0291] In the case where the LBE node does not exist for a long time at a level determined by the regulatory level and a base station (eNB or gNB) capable of performing FBE is synchronized, the FBE scheme uses a frequency reuse factor of 1. Therefore, there is no need to perform random backoff, and the complexity of channel access can be reduced. The operations of LBE mode and FBE mode may be different in terms of channel access. In the scheme of the FBE mode, the communication node can obtain the channel occupancy time through the channel access of LBT category 2 just before the fixed frame period. If the gap is 16us or less in the channel occupancy time initiated and acquired by the base station, the base station and the UE can use the channel access scheme of category 1. When the gap in the channel occupancy time acquired by the base station exceeds 16us, the base station and the UE can use the channel access scheme of category 2. The channel access operation can be configured so that the relevant constraints match to correspond to the operation of FBE.

[0292] Fig.19 An LBE operation according to an embodiment of the present disclosure is shown.

[0293] refer to Fig.19 (a), the communication node can perform CCA for each CCA time slot within a predetermined duration in order to perform LBE operation.

[0294] refer to Fig.19 (b), the communication node can perform the CCA process in one CCA time slot. If the channel is in an unoccupied state in the first CCA time slot, the communication node can send data by ensuring the corresponding time length based on the maximum channel occupancy time. However, if the channel is in an occupied state in the first CCA time slot, the communication node can randomly select a value of N and store the selected value as the initial value of the counter value. N can have one of the values ​​of 1, 2... and q. When sensing the channel state in units of CCA time slots, the communication node can reduce the configured counter value by 1 when the channel is in an unoccupied state in a specific CCA time slot. When the counter value becomes 0, the communication node can send data for a time length equal to the maximum channel occupancy time.

[0295] In the case of LBT operation (i.e., semi-static channel access mode) using frame-based equipment (FBE) in an unlicensed band, the UE is allowed to send data within a channel occupancy duration initiated by the base station, and the channel access procedure for this is defined in the 3GPP standard and is shown in Table 5.

[0296] [Table 5]

[0297]

[0298]

[0299]

[0300] The base station may indicate to the UE through a higher layer parameter that the channel access mode is semi-static. For example, the base station may indicate that the channel access mode is semi-static by using a higher layer parameter called 'channelaccessmode-r16' via SIB1 or a dedicated RRC configuration. In this case, starting with the even-indexed radio frame at x*T_x with the maximum channel occupancy time (T_y), periodic channel occupancy may be initiated every T_x within every two consecutive radio frames, where T_y=0.95*T_x, T_x is the channel occupancy period in ms, and x is a value indicated by the base station through a higher layer parameter and may have values ​​of 0, 1, ..., 20 / T_x-1. The sensing slot duration (T_sl) described in this specification may be 9us. The dedicated RRC described in this specification may be a dedicated RRC for a specific UE, and the dedicated RRC configuration may be configuration information configured in the UE by the base station through a dedicated RRC for a specific UE.

[0301] The occupancy of a single channel initiated by the base station and shared with the UE should meet the following conditions:

[0302] i) The base station may send a DL transmission burst starting from the beginning of the channel occupancy time immediately after detecting that the channel is idle for at least the sensing slot duration (T_sl). If the channel is detected to be busy, the base station may not perform any transmission during the current channel occupancy time.

[0303] ii) If there is a gap of more than 16 us between a DL transmission burst and a previous transmission burst, the base station may send a DL transmission burst within the channel occupancy time immediately after detecting that the channel is in an idle state for at least T_sl.

[0304] iii) If the gap between the DL transmission burst and the UL transmission burst is at most 16 us, the base station can send a DL transmission burst within the channel occupancy time after the UL transmission burst without detecting the channel.

[0305] iv) The UE may send a UL transmission burst within the channel occupancy time after detecting a DL transmission burst as in the following cases iv-1 and iv-2.

[0306] iv-1) If the gap between the UL transmission burst and the DL transmission burst is at most 16 us, the UE can send the UL transmission burst within the channel occupancy time after the DL transmission burst without detecting the channel.

[0307] iv-2) If the gap between the UL transmission burst and the DL transmission burst exceeds 16us, the UE may send an UL transmission burst within the channel occupancy time after the DL transmission burst after detecting that the channel is in an idle state for at least one sensing slot duration (T_sl).

[0308] v) The base station and the UE may be configured to not send any transmission in a set of consecutive symbols for at least T_z duration before the start of the next channel occupancy time. Here, T_z is max(0.05T_x, 100us), where max(a,b) is a function that returns the larger value between a and b.

[0309] Conventionally, in an unlicensed band, when the channel access mode is semi-static, channel occupation is initiated by the UE, or the base station and the UE share the channel occupation time within the channel occupation initiated by the UE, so the UE and the base station can be configured not to perform data transmission. Hereinafter, a method in which channel occupation is initiated by the UE or the base station and the UE share the channel occupation time within the channel occupation initiated by the UE to perform data transmission will be described.

[0310] When the UE operates as a channel occupation initiating device, the signaling method for performing the FBE operation is as follows.

[0311] Similar to the case where the base station operates as a channel occupation initiating device, the base station can instruct the UE to operate as a channel occupation initiating device on the current network through higher layer signaling such as SIB1 or dedicated RRC configuration. The base station may know that the current network situation is in a controlled environment or in a single network environment mentioned in the regulations, or may know that the communication node operating as LBE does not exist for a long time at the level determined by the regulations. In addition, the base station may know that multiple base stations capable of performing FBE are synchronized. In other words, since the base station recognizes the scenario in which the UE can perform FBE operation, the base station can instruct the UE to operate as a channel occupation initiating device and send uplink bursts as FBE operation through RRC configuration or MAC CE.

[0312] Alternatively, when the base station instructs the UE to send an uplink channel or signal through scheduling, the base station can instruct the UE as a channel occupancy initiating device to initiate a channel occupancy time (COT) to perform transmission through dynamic L1 signaling, and share the corresponding COT with the base station for transmission of the UE and the base station. Specifically, the indication given by the base station to the UE through dynamic L1 signaling can be performed through an uplink (UL) grant or a downlink (DL) grant including scheduling information for sending an uplink channel or signal. Alternatively, the base station can provide indications to grouped UEs present in the network through group common signaling.

[0313] The base station can indicate through dynamic L1 signaling when the UE sends an uplink channel or signal whether the transmission is performed based on the COT initiated by the UE as the channel occupancy initiating device or based on the channel occupancy time shared after being initiated by the base station (shared gNB-initiated COT). In addition, when receiving a downlink channel or signal scheduled by the base station, the UE can determine through dynamic L1 signaling whether it is based on the COT reception shared after being initiated by the UE or based on the COT reception shared after being initiated by the base station. The indication given to the UE by the base station through dynamic L1 signaling can be performed through a UL grant or a DL grant including scheduling information for sending the uplink channel or signal. Alternatively, the base station can provide indications to grouped UEs present in the network through group common signaling.

[0314] On the other hand, there may be a case where the UE does not transmit / receive an uplink / downlink channel or signal according to a UL grant or a DL grant by scheduling using dynamic L1 signaling from the base station, that is, a case where the UE performs uplink transmission through a configured UL grant. In this case, through dynamic L1 signaling, the base station may be configured not to allow the UE to determine whether to perform transmission as an occupied initiating device according to a COT initiated by the UE or to perform transmission according to a COT initiated by the base station.

[0315] When the UE can receive downlink transmission through downlink detection and recognize the COT and FFP-g shared after being initiated by the base station, the UE can perform uplink transmission according to the configured UL grant in a duration that is not an idle duration within the FFP-g under the assumption of the COT shared after being initiated by the base station. In this case, the FFP-g may be a fixed frame period configured in the base station.

[0316] Since the UE fails to receive downlink transmission through downlink detection, the UE may not assume FFP-g and the COT shared after being initiated by the base station, or the UE may configure the UE-initiated COT in the FFP-u duration. In this case, if resources for uplink transmission by the configured UL grant are configured within the UE-initiated COT, the UE assumes that uplink transmission by the configured UL grant is performed within the UE-initiated COT. Therefore, the UE may perform uplink transmission according to the configured UL grant in the UE-initiated channel occupancy duration in a duration that is not an idle duration in FFP-u. In this case, FFP-u may correspond to a fixed frame period configured in the UE.

[0317] The base station may schedule an uplink channel or signal for the UE through a UL grant or a DL grant. In this case, the base station may configure information about the channel access-related field included in the UL grant or the DL grant in the UE through RRC signaling. When the UE is configured with information about the channel access-related field through RRC signaling, the UE may provide an indication through the channel access-related field included in the UL grant or the DL grant to determine whether to perform transmission according to the COT shared after being initiated by the base station or according to the COT initiated by the UE. However, there may be a situation in which the UE does not receive a configuration of information about the channel access-related field included in the UL grant or the DL grant from the base station through RRC signaling, or in which the information about the channel access-related field is configured as 0 bits through RRC signaling, that is, the information about the channel access-related field is 0 bits. That is, the base station may be configured not to indicate whether the UE performs transmission according to the COT initiated by the UE or according to the COT shared after being initiated by the base station. In this case, the UE may perform uplink transmission in the same manner as performing uplink transmission through the configured uplink grant. That is, the UE can receive a downlink channel through downlink detection and recognize FFP-g and the COT shared after being initiated by the base station, and the UE can perform uplink transmission in a duration that is not an idle duration within the FFP-g duration. However, when the UE cannot assume FFP-g and the COT shared after being initiated by the base station because the downlink channel is not received through downlink detection, the UE can perform uplink transmission in a duration that is not an idle duration within the FFP-u duration configured in the UE by assuming the UE-initiated COT in the FFP-u duration.

[0318] When uplink channel transmission is scheduled for the UE and there is an uplink burst to be sent by the UE, the UE can send the uplink burst in the COT initiated by the UE. In addition, the UE can share the channel occupancy with the base station within the COT initiated by the UE, and the UE's uplink burst transmission and the base station's downlink burst transmission can be performed within the shared channel occupancy after being initiated by the UE. In this case, the channel occupancy shared with the base station within the COT shared after being initiated by the UE should meet the following conditions.

[0319] i) The UE may send an UL transmission burst starting from the beginning of the channel occupation time immediately after detecting that the channel is in an idle state for at least the sensing time slot duration (T_sl). If the channel is detected to be busy, the UE may not perform any transmission during the current channel occupation time. However, after the base station performs downlink transmission during the channel occupation time initiated by the base station and the UE detects a DL transmission burst during the channel occupation time, the UE may perform data transmission according to the following methods i-1) and i-2).

[0320] i-1) If the gap between a DL transmission burst and a UL transmission burst is at most 16 us, the UE may send a UL transmission burst within the channel occupancy time after a DL transmission burst without detecting the channel.

[0321] i-2) If the gap between the UL transmission burst and the DL transmission burst exceeds 16us, the UE may send an UL transmission burst within the channel occupancy time after the DL transmission burst after detecting that the channel is in an idle state for at least one sensing slot duration (T_sl) within a 25us interval ending immediately before the transmission.

[0322] ii) If there is a gap of more than 16 us between the UL transmission burst and the previous transmission, the base station may send the UL transmission burst within the channel occupancy time immediately after detecting that the channel is in an idle state for at least T_s1.

[0323] iii) If the gap between the DL transmission burst and the UL transmission burst is at most 16 us, the UE can send a UL transmission burst within the channel occupancy time after the DL transmission burst without detecting the channel.

[0324] iv) The base station may send a DL transmission burst within the channel occupancy time after detecting the UL transmission burst like in the following cases iv-1 and iv-2.

[0325] iv-1) If the gap between the UL transmission burst and the DL transmission burst is at most 16 us, the base station can send a DL transmission burst within the channel occupancy time after the UL transmission burst without detecting the channel.

[0326] iv-2) If the gap between the UL transmission burst and the DL transmission burst exceeds 16us, the base station may send a DL transmission burst within the channel occupancy time after the UL transmission burst after detecting that the channel is in an idle state for at least one sensing slot duration (T_sl) within a 25us interval ending immediately before the transmission.

[0327] v) The base station and the UE may not send any transmission in a set of consecutive symbols for at least T_z duration before the start of the next channel occupancy time. Here, T_z is max(0.05T_x, 100us).

[0328] When the base station operates as a channel occupancy initiating device, one base station is able to manage and schedule uplink transmissions for different UEs, and thus can flexibly perform multiplexing between different UEs within one channel occupancy. However, when the UE operates as a channel occupancy initiating device, conflicts may occur in transmissions between UEs due to channel occupancy times initiated at different time points or different lengths (number of symbols). Specifically, when the base station performs downlink transmission by sharing the COT initiated by the UE with the base station, there may be channel occupancy times initiated by multiple UEs at different times or with different lengths. In this case, depending on whether the base station has detected uplink transmissions performed by different UEs, ambiguity regarding channel access for downlink transmission by the base station may occur. Therefore, in this specification, a method for solving the conflict problem caused by channel occupancy times initiated by different UEs at different time points or with different lengths is proposed. In addition, when the base station performs downlink transmission by sharing the channel occupancy time between the UE and the base station, a method for solving the ambiguity regarding channel access for downlink transmission is proposed.

[0329] When the channel access mode operates in LBE mode instead of semi-static mode, there may be a situation where the UE performs autonomous transmission or configures licensed PUSCH transmission in an existing unlicensed band. In this case, the PUSCH sent by the UE may include UCI. The UCI may include HARQ-ID, new data indication (NDI), RV, CAPC, and channel occupancy time sharing (COT sharing) information. The base station can identify the channel occupancy time shared with the base station within the COT initiated by the UE based on the CAPC and COT sharing information included in the UCI sent by the UE. In addition, the base station can perform downlink transmission within the COT initiated by the UE.

[0330] When the channel access mode is in semi-static mode, the UE can send a configuration grant PUSCH by sharing the UE-initiated COT with the base station. In this case, the UCI included in the PUSCH may include channel occupancy time sharing information. The base station can identify the UE-initiated COT based on the COT sharing information included in the UCI sent by the UE. In addition, the base station can send a downlink burst by performing channel access within the UE-initiated COT. In this case, channel access can be performed according to the gap length. For example,

[0331] i) When the transmission of the downlink burst should start and end within the UE-initiated COT, the base station may perform channel access and transmit the downlink burst according to each gap length. As another example, in the case where the transmission of the downlink burst starts within the UE-initiated COT, but the end time of the downlink burst is not included in the UE-initiated COT, the base station may stop the downlink burst transmission in units of slots or symbols outside the UE-initiated COT. This is to ensure that the downlink burst is transmitted only within the UE-initiated COT.

[0332] ii) In the case where the transmission of a downlink burst starts within the COT initiated by the UE, but the end time of the downlink burst is not included in the COT initiated by the UE, the base station may perform channel sensing again in order to transmit the downlink burst not included in the COT initiated by the UE. Specifically, for the transmission of a downlink burst not included in the COT initiated by the UE, the base station may perform channel sensing within a radio frame of x*T_x duration after the COT initiated by the UE and configure channel occupancy in order to transmit the downlink burst.

[0333] iii) There may be a case where the transmission of a downlink burst starts within the UE-initiated COT, but the end time of the downlink burst is not included in the UE-initiated COT. Here, if the length of the downlink burst not included in the UE-initiated COT is included in the x*T_x duration of the FBE operation in which there is a UE-initiated channel occupancy time, the base station can sense the channel within one sensing slot duration (T_sl), and when the sensed channel is in an idle state, the downlink burst can be sent.

[0334] Unlike the configuration grant PUSCH, the UE that sends the channels and signals configured by scheduling from the base station and the channels used for the random access procedure can operate as a channel occupancy initiating device, and in this case, the COT initiated by the UE can be shared with the base station. Regarding the channels and signals configured by scheduling and the channels used for the random access procedure, there is no mechanism for the UE to provide COT sharing information to the base station through PUSCH. Therefore, the base station can be configured to be unaware of the information related to the channel occupancy shared after being initiated by the UE operating as a device for initiating channel occupancy. In this case, ambiguity may occur in the channel access method performed by the base station to send downlink bursts. Hereinafter, a method for resolving ambiguity in the channel access method will be described.

[0335] Channels and signals configured by scheduling from the base station and channels for the random access process can be sent on resources scheduled based on resource allocation information about time resources and frequency resources sent by the base station. Specifically, when the base station sends downlink control information through the PDCCH and the UE successfully receives the PDCCH, the base station can send resource allocation information to the UE, and the UE can perform uplink transmission based on the resource allocation information. In this case, the channel used for the random access process can be a PRACH for contention-free random access and a PRACH for a 2-step random access process, except for the PRACH for a contention-based random access process. Therefore, the UE can send channels and signals scheduled from the base station to the base station, and the base station can detect the channels and signals sent from the UE. In this case, the base station can determine the length of the COT shared after being initiated by the UE based on the resource allocation information configured for the UE. In this case, the resource allocation information may be time domain resource allocation (TDRA) information.

[0336] When the UE and the base station are synchronized in the FBE mode, the base station may transmit a downlink burst within the T_y duration by considering the length of the COT shared after being initiated by the UE and the T_x duration. T_y may be a duration excluding a duration during which the base station performs channel sensing within the T_x duration, and may correspond to 0.95*T_x [ms]. In this case, if there is a gap of more than 16us, the base station may transmit a downlink burst while the channel is in an idle state for a sensing slot duration (T_sl) after sensing the channel.

[0337] In order to perform LBT during operation in LBE mode, a channel access priority level may be configured in channels and signals through scheduling and channels used in a random access procedure. The base station and the UE may determine the length of the UE-initiated COT based on the maximum channel occupancy time corresponding to the channel access priority level used by each channel and signal. With respect to channels and signals through scheduling and channels used in a random access procedure, the length of the channel occupancy time assumed by the base station and the UE is as follows.

[0338] i) When only PUSCH is transmitted without PUCCH or UL-SCH, the LBT priority level or channel access priority may be 1. In this case, the length of the channel occupancy time that can be used may be configured to be 2 ms, which is the MCOT value, as shown in Table 6.

[0339] ii) The priority level of the PUSCH associated with the random access procedure without PRACH and user plane data or the channel access priority level may correspond to 1. In this case, the length of the UE-initiated COT may be configured to be 2 ms, which is the MCOT value, as shown in Table 6.

[0340] iii) SRS excluding PUSCH may have an LBT priority level or a channel access priority level of 1. In this case, the length of the UE-initiated COT may be configured to be 2 ms, which is the MCOT value, as shown in Table 6.

[0341] iv) For PUSCH excluding i) to iii), the length of the channel occupancy time may be configured based on the service sent by the UE or based on the channel access priority level indicated by the base station to the UE. Specifically, the MCOT value disclosed in Table 6 may be configured as the length of the channel occupancy time.

[0342] v) When various types of uplink channels and signals are mixed to configure one uplink burst, the length of the channel occupation time can be configured as the longest MCOT length among the MCOT lengths that can be configured for each channel and signal. Alternatively, the length of the channel occupation time can be configured as the MCOT with the longest length in time based on the resources configured to send the mixed uplink burst.

[0343] Table 6 shows values ​​of parameters for channel access for each channel access priority level for uplink transmission used in the LTE LAA system.

[0344] [Table 6]

[0345]

[0346]

[0347] Referring to Table 6, when one or more gaps are included in the transmission, the value of the MCOT of 6 ms may be increased to 8 ms. A gap refers to the time from the interruption of transmission via the carrier to the resumption of transmission. In this case, the minimum value of the duration of the gap may be 100 us. In addition, the maximum value of the duration of the transmission performed before the gap is included may be 6 ms. The duration of the gap may not be included in the channel occupation time.

[0348] In the case where the value of the channel access priority level is 3 or 4 and it is guaranteed that other radio access technologies are not used in the carrier via which the channel access is performed, the value of MCOT may be 10 ms. In this case, the other radio access technologies may include Wi-Fi. In other cases, the MCOT value may be determined as in Note 1 of Table 6.

[0349] MCOT represents the time during which the initiating node can continuously occupy the channel of one carrier on the unlicensed band as much as possible. A gap as a duration during which no transmission is performed may be included between multiple transmissions, and when the gap is included, the value of MCOT may be applied differently.

[0350] Hereinafter, in this specification, when the base station and the UE operate as FBE, that is, when the channel access mode is semi-static, a method in which the base station and the UE perform transmission within a COT initiated by the base station, which is shared between the base station and the UE, will be described.

[0351] First, a signaling method for performing FBE operation when the UE operates as a channel occupation initiating device will be described. The base station can indicate to the UE through higher layer signaling such as SIB1 or dedicated RRC configuration that the UE is capable of operating as a channel occupation initiating device. In addition, the base station can provide the UE with information about FFP through higher layer signaling such as SIB1 or dedicated RRC configuration, and the UE that has received the information can configure FFP.

[0352] However, there may be a case where the base station does not receive a configuration of signaling that notifies information about the semi-static channel access mode or information about the FFP through SIB1 that the UE can receive before performing the RRC connection, and where the base station receives a configuration of signaling that notifies information about the semi-static channel access mode or information about the FFP through SIB1 that the UE can receive after the RRC connection. In this case, the UE needs to assume the PRACH preamble and the FFP configured in the UE for Msg3 transmission, which is sent during the random access process in which the UE needs to perform transmission before the RRC connection. This is because the PRACH preamble and Msg3 should be sent before the RRC connection. That is, during operation in FBE mode, transmission is not allowed during the idle duration, and transmission is allowed in the duration excluding the idle duration in the FFP duration. Therefore, when information about the channel access mode or information about the FFP is not received from the base station, the UE can assume the FFP configured in the base station as the UE's FFP to perform uplink transmission. In this case, the UE can perform uplink transmission in the duration excluding the idle duration of the FFP duration configured in the base station. The base station may perform downlink transmission in a duration excluding the idle duration in the FFP configured in the base station. If the FFP assumed by the UE is different from the FFP configured in the base station, downlink transmission may not be performed in a duration excluding the idle duration in the FFP configured in the base station. However, the FFP assumed by the UE is the same as the FFP configured in the base station, so the base station may perform downlink transmission in a duration excluding the idle duration in the FFP configured in the base station. In other words, if the base station and the UE have different FFPs, the duration during which the base station performs downlink transmission may correspond to the duration excluding the idle duration in the FFP configured in the base station, and may correspond to the idle duration in the FFP configured in the UE.

[0353] Even before the RRC connection, the UE can receive a PRACH opportunity capable of transmitting the PRACH from the base station. The base station can configure the PRACH opportunity in the UE for a duration excluding the idle duration in the FFP configured in the base station. When the UE does not receive information about the channel access mode or information about the FFP from the base station, the UE can perform uplink transmission by assuming the FFP configured in the base station as the FFP of the UE. In this case, when the UE performs uplink transmission, it is necessary to define whether to perform transmission without channel sensing or after channel sensing.

[0354] The base station may configure the PRACH opportunity in the UE regardless of the idle duration in the FFP configured in the base station. In other words, part / all of the PRACH opportunity may be included in the idle duration in the FFP configured in the base station. In this case, the UE may send PRACH on the PRACH opportunity configured in the duration excluding the idle duration in the FFP configured in the base station. The UE may not receive a downlink transmission from the base station, and may perform an uplink transmission in the duration excluding the idle duration in the FFP. The method for performing uplink transmission by the UE is as follows. The uplink / downlink burst in this specification may include uplink / downlink channels and signals.

[0355] i) The UE may send an UL burst starting from the beginning of the channel occupation time immediately after detecting that the channel is in an idle state for at least the sensing slot duration (T_sl), and includes channels or signals sent via the uplink before the RRC connection. As a result of channel sensing, if the channel is detected to be busy, the UE station may not perform any transmission during the current channel occupation time. However, when the UE detects a DL burst sent during the channel occupation time initiated by the base station, the UE may send an uplink burst according to the i-1 and i-2 methods during the channel occupation time initiated by the base station.

[0356] i-1) If the gap between a DL burst and a UL burst is at most 16 us before the RRC connection, the UE may send a UL burst after a DL burst without sensing the channel.

[0357] i-2) If the gap between the DL burst and the UL burst before the RRC connection exceeds 16us, the UE may send a UL burst within the channel occupancy time after the DL burst after detecting that the channel is in an idle state for at least one sensing slot duration (T_sl) within a 25us interval ending immediately before the UL burst transmission.

[0358] ii) If there is a gap of more than 16us between the UL transmission and the previous transmission, the UE may send a UL burst within the channel occupancy time after detecting that the channel is in an idle state for at least one sensing slot duration (T_sl).

[0359] iii) If the gap between the DL burst and the UL burst is at most 16 us, the UE can send a UL burst within the channel occupancy time after the DL burst without sensing the channel.

[0360] iv) The base station may send a DL burst after detecting a UL burst sent within the channel occupancy time before the RRC connection.

[0361] iv-1) If the gap between the UL burst and the DL burst is at most 16 us, the base station can send a DL burst after the UL burst sent within the channel occupancy time before the RRC connection without sensing the channel.

[0362] iv-2) If the interval between the UL burst and the DL burst exceeds 16us, the base station can detect that the channel is in an idle state for at least one sensing slot duration (T_sl) within the 25us interval ending immediately before the DL burst transmission. Thereafter, the base station can send a DL burst after the UL burst sent during the channel occupancy time before the RRC connection.

[0363] v) The base station and UE may not send any transmission in a set of consecutive symbols for at least T_z duration before the next channel occupancy time starts. T_z may be max(0.05T_x, 100us).

[0364] There may be a case where different FFPs are configured between the UE and the base station to perform uplink transmission and downlink transmission. Hereinafter, a method in which the UE performs uplink transmission and a method in which the base station performs downlink transmission will be described.

[0365] Figure 20 to Figure 23 A method for performing uplink transmission and downlink transmission when different FFPs are configured in a base station and a UE according to an embodiment of the present disclosure is illustrated. Figure 20 to Figure 23 FFP-u is the FFP configured for the UE, and FFP-g is the FFP configured for the base station. Idle-u is the idle duration configured for the UE, and idle-g is the idle duration configured for the base station.

[0366] refer to Fig. 20 , different FFPs may be configured in the base station and the UE. In this case, the base station may be configured not to perform downlink transmission in the idle duration of the FFP configured in the base station, but to perform downlink transmission in the idle duration of the FFP configured in the UE. In other words, the UE may receive downlink transmission performed by the base station in the idle duration of the FFP configured in the UE. Similarly, the UE may be configured not to perform uplink transmission in the idle duration of the FFP configured in the UE, but to perform uplink transmission in the idle duration of the FFP configured in the base station. In other words, the base station may receive uplink transmission performed by the UE in the idle duration of the FFP configured in the base station.

[0367] refer to Fig.21, different FFPs may be configured in the base station and the UE. In this case, the base station and the UE may assume that no uplink transmission and no downlink transmission are performed in all idle durations. In other words, the base station and the UE may assume that no uplink transmission and no downlink transmission are performed in the idle duration of the FFP configured in the base station and the idle duration of the FFP configured in the UE. That is, it may be assumed that in the idle duration of the FFP configured in the base station, there is no downlink transmission performed by the base station and there is no uplink transmission performed by the UE. Similarly, it may be assumed that in the idle duration of the FFP configured in the UE, there is no downlink transmission performed by the UE and there is no uplink transmission performed by the base station.

[0368] refer to Fig. 22 , different FFPs may be configured for the base station and the UE. In this case, the base station may be configured not to perform downlink transmission only in the idle duration of the FFP configured in the base station, but to perform downlink transmission in the idle duration of the FFP configured in the UE. In other words, the UE may receive downlink transmission performed by the base station in the idle duration of the FFP configured in the UE. The UE may perform uplink transmission in the idle duration of the FFP configured in the base station, but not perform uplink transmission in the idle duration of the FFP configured in the UE. In other words, the base station may receive uplink transmission performed by the UE in the idle duration of the FFP configured in the base station.

[0369] refer to Fig.23, different FFPs may be configured in the base station and the UE. In this case, the base station and the UE may assume that uplink transmission and downlink transmission are not performed in all idle durations. In other words, the base station and the UE may assume that uplink transmission and downlink transmission are not performed in the idle duration of the FFP configured in the base station and the idle duration of the FFP configured in the UE. That is, it may be assumed that in the idle duration of the FFP configured in the base station, there is no downlink transmission by the base station and there is no uplink transmission performed by the UE. Similarly, it may be assumed that in the idle duration of the FFP configured in the UE, there is no downlink transmission by the UE and there is no uplink transmission performed by the base station. The uplink transmission performed by the UE to the base station may be scheduled from the base station. In addition, the duration for performing downlink transmission or uplink transmission may be configured in the duration excluding the idle duration within the FFP configured in the base station and the FFP configured in the UE. Therefore, in the duration excluding the idle duration within the FFP configured in the base station, the duration for downlink transmission and the duration for uplink transmission may be configured. The base station may perform downlink transmission in a duration during which downlink transmission is configured, excluding an idle duration in an FFP configured in the base station, and may receive uplink transmission performed by the UE in a duration during which uplink transmission is configured. Similarly, the UE may perform uplink transmission when uplink transmission is configured in a duration excluding an idle duration in an FFP configured in the UE, and may receive downlink transmission performed by the base station when downlink transmission is configured.

[0370] The reference may be applied when the base station and the UE recognize the FFP configured in each of the base station and the UE. Figure 20 to Figure 23 The method described. However, the FFP configured in the base station can be notified to the UE by the base station through SIB1 or dedicated signaling. Therefore, no ambiguity regarding the FFP configured in the base station occurs between the base station and the UE. However, if the COT initiated by the UE is shared with the base station in the FFP configured in the UE, the base station may not be able to recognize the COT initiated by the UE. If the base station detects an uplink transmission performed by the UE in the FFP configured in the UE, the base station can determine the channel occupancy time in the FFP configured in the UE. In addition, the base station can perform downlink transmission before the idle duration within the determined channel occupancy time. In this case, the conditions for the base station to perform downlink transmission and the channel sensing method will be described.

[0371] If there is a gap of more than 16us between a DL transmission burst and a previous transmission, the base station may detect a channel in an idle state for a sensing time slot duration (T_sl), and may send a DL burst within the channel occupancy time immediately after the detection. If the gap between a DL burst and an uplink burst is at most 16us, the base station may send a downlink transmission burst within the channel occupancy time after an uplink transmission burst without sensing the channel.

[0372] However, if the base station fails to detect uplink transmission in the FFP configured in the UE, the base station may not recognize the COT initiated by the UE. Therefore, the base station may perform downlink transmission only in the duration excluding the idle duration of the FFP configured in the base station. The base station may perform channel sensing within at least one sensing slot duration (T_sl) to detect that the channel is in an idle state, and may send a downlink burst from the beginning of the channel occupancy time immediately after the detection. If the channel is detected to be busy as a result of the channel sensing, the base station may not perform any transmission during the FFP duration configured in the base station. If there is a gap of more than 16us between the downlink burst and the previous transmission, the base station may perform channel sensing within at least one sensing slot duration to detect a channel in an idle state, and may send a downlink burst in the FFP configured in the base station immediately after the detection.

[0373] A method in which different FFPs are configured in a plurality of UEs and the UEs perform uplink transmission will be described.

[0374] When the base station configures different FFPs in multiple different UEs through UE-specific dedicated signaling, one UE may be configured not to identify whether different UEs are configured with the same FFP or different FFPs. In this case, one UE may perform uplink transmission during the duration of the idle duration excluding the configured FFP, and not perform uplink transmission during the idle duration. In addition, when the UE shares the COT initiated by the base station within the FFP configured in the base station, the UE may be configured not to perform uplink transmission during the idle duration within the shared channel occupancy time.

[0375] Fig.24 A method in which a UE transmits an uplink channel according to an embodiment of the present disclosure is illustrated.

[0376] Will refer to Fig.24 Description by Figures 1 to 23 The method of sending the above uplink channel (signal) is described.

[0377] The UE may receive resource information related to transmission of an uplink channel from a base station in operation S2410.

[0378] The UE may detect a downlink channel transmitted from the base station in operation S2420.

[0379] According to the result of detecting the downlink channel, the UE may transmit an uplink channel to the base station based on the resource information in operation S2430.

[0380] In this case, the uplink channel may be transmitted based on the COT shared after being initiated by the base station or may be transmitted based on the COT initiated by the UE.

[0381] The uplink channel sent by the UE may be sent based on the configuration permission. When the UE has detected the downlink channel as a result of downlink channel detection performed by the UE in operation S2420, the uplink channel may be sent based on the COT shared after being initiated by the base station. Meanwhile, when the UE fails to detect the downlink channel, the uplink channel may be sent based on the COT initiated by the UE. In this case, the COT shared after being initiated by the base station may correspond to the duration within the fixed frame period (FFP) configured in the base station, and the COT initiated by the UE may correspond to the duration within the FFP configured in the UE. The FFP configured in the base station and the FFP configured in the UE may be different from each other. When the uplink channel is sent based on the COT shared after being initiated by the base station, the uplink channel may be sent in the duration excluding the idle duration within the FFP configured in the base station. On the other hand, when the uplink channel is sent based on the COT initiated by the UE, the uplink channel may be sent in the duration excluding the idle duration within the FFP configured in the UE. When an uplink channel is transmitted based on a COT initiated by the UE, the uplink channel may be transmitted regardless of whether the duration during which the uplink channel is transmitted is included in the idle duration within the FFP configured in the base station. On the other hand, when an uplink channel is transmitted based on a COT shared after being initiated by the base station, transmission of the uplink channel may occur in the duration during which the uplink channel is transmitted excluding the idle duration in the FFP configured in the base station. In this case, the FFP configured in the UE may be configured in the UE through dedicated RRC signaling information.

[0382] At the same time, the uplink channel can be scheduled by dynamic signaling from the base station. In this case, the UE can receive dynamic signaling including scheduling information for the transmission of the uplink channel from the base station. Resource information can be included in the scheduling information. When the scheduling information includes COT information about sending the uplink channel during it, the operation of detecting the downlink channel is not performed, and the uplink channel can be sent based on the information about the COT. However, when the scheduling information does not include information about the COT during which the uplink channel is sent, the uplink channel can be sent based on the scheduling information according to the result of the downlink channel detection. The information about the COT can be information indicating whether the uplink channel is sent based on the COT shared after being initiated by the base station or based on the COT initiated by the UE. The information about the COT can be included in the channel access related field of the configuration dynamic signaling.

[0383] Execution Reference Fig.24 The UE of the method for transmitting an uplink channel described may correspond to reference Fig.14 Specifically, the UE may include: a communication module, the communication module being configured to send or receive a wireless signal; and a processor, the processor being configured to control the communication module. In this case, the reference Fig.24 Similarly, here, the base station may correspond to the reference Fig.14 In addition, the base station may include: a communication module configured to send or receive a wireless signal; and a processor configured to control the communication module. That is, the base station may receive a reference signal from the UE. Fig.24 Here, a method of receiving an uplink channel (signal) by a processor of a base station may be performed.

[0384] The method and system of the present invention are described with reference to specific embodiments, but some or all of the components or operations may be implemented using a computer system having a general hardware architecture.

[0385] The above description of the present invention is merely illustrative, and it will be readily understood that those skilled in the art can easily make modifications without departing from the technical concept of the present invention or changing the essential features. Therefore, the above embodiments should be considered illustrative and should not be interpreted as restrictive. For example, each component described as a single type may be distributed, and similarly, the components described as distributed may be implemented as a combination.

[0386] The scope of the present invention is indicated by the following claims rather than the detailed description, and it should be interpreted that all changes or modifications derived from the meaning and scope of the claims and their equivalents are included in the scope of the present invention.

Claims

1. A user equipment (UE) configured to operate in a wireless communication system, the UE comprising: Communication module; as well as a processor configured to control the communication module, Wherein, the processor is configured to receiving configuration information associated with a base station (BS) fixed frame period (FFP) including a first idle duration, and dedicated configuration information associated with a UE FFP including a second idle duration, and performing an uplink (UL) transmission based on whether the UL transmission is associated with a BS-initiated channel occupation (CO) or a UE-initiated CO, wherein when the UE has initiated a CO within a UE FFP duration and the UL transmission occurs through a configuration grant (CG) within the UE FFP duration, the UL transmission is determined to be associated with a CO initiated by the UE, and When the UL transmission is scheduled by downlink control information (DCI), the UL transmission is determined to be associated with the CO initiated by the BS or the CO initiated by the UE based on information of a channel access related field in the DCI.

2. The UE according to claim 1, wherein: When the UE has not initiated the CO within the UE FFP duration and the UL transmission occurs through the CG, whether the UL transmission is determined to be associated with the CO initiated by the BS is based on whether the UE detects a downlink (DL) channel.

3. The UE according to claim 2, wherein: When the UE has not initiated the CO within the UE FFP duration and the UL transmission occurs through the CG, when the UE detects the DL channel, the UL transmission is determined to be associated with the CO initiated by the BS.

4. The UE according to claim 1, wherein: The DCI includes DL grant information or UL grant information.

5. The UE according to claim 1, wherein: The UL transmission is performed as follows: - when the UL transmission is associated with a CO initiated by the BS, performing the UL transmission in a duration other than the first idle duration in the BS FFP, and - When the UL transmission is associated with a CO initiated by the UE, performing the UL transmission in a duration other than the second idle duration in the UE FFP.

6. The UE according to claim 1, wherein: When the UL transmission is performed based on the CO initiated by the UE, the UL transmission is performed regardless of whether a duration for performing the UL transmission is included in a first idle duration in the BS FFP.

7. The UE according to claim 1, wherein: The dedicated configuration information related to the UE FFP is received via Radio Resource Control (RRC) signaling.

8. The UE according to claim 1, wherein: The BS FFP and the UE FFP are independently configured.

9. The UE according to claim 1, wherein: The BS FFP and the UE FFP have different starting times.

10. A method performed by a user equipment (UE) configured to operate in a wireless communication system, the method comprising: receiving configuration information associated with a base station (BS) fixed frame period (FFP) including a first idle duration, and dedicated configuration information associated with a UE FFP including a second idle duration, and performing an uplink (UL) transmission based on whether the UL transmission is associated with a BS-initiated channel occupation (CO) or a UE-initiated CO, wherein when the UE has initiated a CO within a UE FFP duration and the UL transmission occurs through a configuration grant (CG) within the UE FFP duration, the UL transmission is determined to be associated with a CO initiated by the UE, and When the UL transmission is scheduled by downlink control information (DCI), the UL transmission is determined to be associated with the CO initiated by the BS or the CO initiated by the UE based on information of a channel access related field in the DCI.

11. The method according to claim 10, wherein: When the UE has not initiated the CO within the UE FFP duration and the UL transmission occurs through the CG, whether the UL transmission is determined to be associated with the CO initiated by the BS is based on whether the UE detects a downlink (DL) channel.

12. The method according to claim 11, wherein: When the UE has not initiated the CO within the UE FFP duration and the UL transmission occurs through the CG, when the UE detects the DL channel, the UL transmission is determined to be associated with the CO initiated by the BS.

13. The method according to claim 10, wherein: The DCI includes DL grant information or UL grant information.

14. The method according to claim 10, wherein: The UL transmission is performed as follows: - when the UL transmission is associated with a CO initiated by the BS, performing the UL transmission in a duration other than the first idle duration in the BS FFP, and - When the UL transmission is associated with a CO initiated by the UE, performing the UL transmission in a duration other than the second idle duration in the UE FFP.

15. The method according to claim 10, wherein: When the UL transmission is performed based on the CO initiated by the UE, the UL transmission is performed regardless of whether a duration for performing the UL transmission is included in a first idle duration in the BS FFP.

16. The method according to claim 10, wherein: The dedicated configuration information related to the UE FFP is received via Radio Resource Control (RRC) signaling.

17. The method according to claim 10, wherein: The BS FFP and the UE FFP are independently configured.

18. The method according to claim 10, wherein: The BS FFP and the UE FFP have different starting times.

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