Method and apparatus for transmitting an uplink channel in a wireless communication system

Abstract

To provide a method for transmitting an uplink channel in a wireless communication system, and an apparatus therefor.SOLUTION: A method for transmitting an uplink channel in a wireless communication system performed by a terminal comprises the steps of: receiving resource information related to transmission of an uplink channel from a base station (S2410); detecting a downlink channel transmitted from the base station (S2420); and transmitting an uplink channel to the base station based on the resource information according to a result of detecting the downlink channel (S2430), the uplink channel being transmitted within a channel occupancy time (COT) initiated by the base station or within a COT initiated by the terminal.SELECTED DRAWING: Figure 24

Description

[Technical Field]

[0001] This specification relates to a wireless communication system, specifically to a method for transmitting an uplink channel and an apparatus for doing so. [Background technology]

[0002] Following the commercialization of 4G (4th generation) communication systems, efforts are being made to develop new 5G (5th generation) communication systems to meet the increasing demand for wireless data traffic. 5G communication systems are also referred to as "beyond 4G network" systems, "post-LTE" systems, or "NR (new radio)" systems. To achieve high data transmission rates, 5G communication systems include systems operating in ultra-high frequency (mmWave) bands above 6 GHz, and also include systems operating in frequency bands below 6 GHz to ensure coverage. Implementation at base stations and terminals is being considered.

[0003] The 3GPP® (registered trademark, hereinafter the same) (3rd generation partnership project) NR system improves the efficiency of the network spectrum, enabling telecommunications carriers to provide more data and voice services within the given bandwidth. To this end, the 3GPP NR system is designed to meet the demands for high-speed data and media transmission, in addition to high-capacity voice support. The advantages of the NR system include high processing power, low latency, support for FDD (frequency division duplex) and TDD (time division duplex), an improved end-user environment, and low operating costs due to a simple architecture, all on the same platform.

[0004] For more efficient data processing, the NR system's dynamic TDD utilizes a method that varies the number of OFDM (orthogoal frequency division multiplexing) symbols available for uplink and downlink depending on the data traffic direction of the cell's users. For example, if a cell's downlink traffic is greater than its uplink traffic, the base station allocates multiple downlink OFDM symbols to a slot (or subframe). Information regarding the slot configuration needs to be transmitted to the terminal.

[0005] To mitigate path loss in the ultra-high frequency band and increase the transmission distance of radio waves, beamforming, massive MIMO, full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, hybrid beamforming (combining analog and digital beamforming), and large-scale antenna technologies are being discussed for 5G communication systems. Furthermore, in order to improve the system network, 5G communication systems are undergoing technological development related to advanced small cells, improved 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), moving networks, cooperative communication, CoMP (coordinated multi-points), and interference cancellation.In addition, 5G systems have seen the development of advanced coding modulation (ACM) methods such as FQAM (hybrid FSK and QAM modulation) and SWSC (sliding window superposition coding), as well as advanced access technologies such as FBMC (filter bank multi-carrier), NOMA (non-orthogonal multiple access), and SCMA (sparse code multiple access).

[0006] Meanwhile, the internet, a human-centered interconnected network where humans generate and consume information, is evolving into the Internet of Things (IoT) network, where distributed components such as objects exchange and process information. Internet of Everything (IoE) technology, which combines IoT technology with big data processing technologies via connections to cloud servers and other systems, is also emerging. To realize IoT, technological elements such as sensing technology, wired and wireless communication and network infrastructure, service interface technology, and security technology are required. Recently, technologies such as sensor networks for connecting objects, machine-to-machine (M2M), and machine-type communication (MTC) are being researched. In an IoT environment, intelligent IT services are provided that collect and analyze data generated from connected objects to create new value in human life. IoT, through the fusion and integration of conventional IT technologies with diverse industries, can be applied to fields such as smart homes, smart buildings, smart cities, smart cars or connected cars, smart grids, healthcare, smart home appliances, and advanced medical services.

[0007] Therefore, various attempts are being made to apply 5G communication systems to IoT networks. For example, technologies such as sensor networks, machine-to-machine communication, and MTC are being realized through 5G communication technologies such as beamforming, MIMO, and array antennas. As mentioned above, the application of cloud radio access networks (cloud RAN) as a big data processing technology can also be considered an example of the fusion of 5G technology and IoT technology. In general, mobile communication systems are developed to provide voice services while ensuring user activity.

[0008] However, mobile communication systems are gradually expanding their service scope beyond voice to include data services, and have now developed to the point where they can provide high-speed data services. However, due to resource shortages and user demand for high-speed services, there is a need for more advanced mobile communication systems in use today.

[0009] In recent years, the proliferation of smart devices has led to a massive increase in mobile traffic, making it difficult to keep up with the growing data usage required to provide cellular communication services using only the existing licensed frequency spectrum or licensed frequency bands.

[0010] In this context, the use of unlicensed frequency spectrum or unlicensed frequency bands (e.g., 2.4 GHz band, 5 GHz band, etc.) to provide cellular communication services is being discussed as a solution to the spectrum shortage problem.

[0011] Unlike licensed frequency bands, where telecommunications carriers secure exclusive frequency usage rights through procedures such as auctions, unlicensed frequency bands can be used simultaneously by multiple communication devices without restriction, provided that certain levels of adjacent band protection regulations are observed. Therefore, when using unlicensed frequency bands for cellular communication services, it is difficult to guarantee the same level of communication quality as that provided by licensed frequency bands, and interference problems may occur with wireless communication devices (e.g., wireless LAN devices) that previously used unlicensed frequency bands.

[0012] In order to use LTE and NR technologies in unlicensed bands, research should be conducted in advance on coexistence strategies with conventional unlicensed band equipment and strategies for efficiently sharing radio channels with other radio channels. In other words, a robust coexistence mechanism (RCM) needs to be developed so that equipment using LTE and NR technologies in unlicensed bands does not affect conventional unlicensed band equipment. [Overview of the Initiative] [Problems that the invention aims to solve]

[0013] The purpose of this specification is to provide a method for determining whether an uplink channel is transmitted based on a channel occupancy interval initiated by the base station or based on a channel occupancy interval initiated by the terminal, when fixed frame intervals are set for both the base station and the terminal in a wireless communication system. [Means for solving the problem]

[0014] This specification provides a method for transmitting an uplink channel in a wireless communication system.

[0015] Specifically, the method performed by the terminal includes the steps of: receiving resource information related to the 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 as a result of the downlink channel detection, wherein the uplink channel is transmitted based on a Channel Occupancy Time (COT) initiated and shared by the base station, or based on a COT initiated by the terminal.

[0016] Also, in the present invention, the method performed by the terminal further includes receiving dynamic signaling including scheduling information for the uplink channel transmission from the base station, where the resource information is included in the scheduling information, and when the scheduling information includes information regarding the COT in which the uplink channel is transmitted, the step of sensing the downlink channel is not performed, the uplink channel is transmitted based on the information regarding the COT, and when the scheduling information does not include information regarding the COT in which the uplink channel is transmitted, the uplink channel is transmitted based on the scheduling information according to the downlink channel sensing result, and the information regarding the COT is information indicating whether the uplink channel is transmitted based on the COT started and shared by the base station or based on the COT started by the terminal.

[0017] Also, in the present invention, a terminal that transmits an uplink channel in a wireless communication system includes a communication module; and a processor that controls the communication module, where the processor receives resource information related to the transmission of the uplink channel from the base station, senses the downlink channel transmitted from the base station, and transmits the uplink channel to the base station based on the resource information according to the downlink channel sensing result, and the uplink channel is transmitted based on the COT (Channel Occupancy Time) started and shared by the base station or based on the COT started by the terminal.

[0018] Also, in the present invention, the uplink channel is transmitted based on a configured grant.

[0019] In the present invention, when the terminal senses the downlink channel as a result of the downlink channel sensing, the uplink channel is transmitted based on the COT started and shared by the base station, and when the terminal does not sense the downlink channel, the uplink channel is transmitted based on the COT started by the terminal.

[0020] In the present invention, the COT started and shared by the base station is a section within the FFP (Fixed Frame Period) set for the base station, and the COT started by the terminal is a section within the FFP set for the terminal.

[0021] In the present invention, when the uplink channel is transmitted based on the COT started and shared by the base station, the uplink channel is transmitted in a section other than the idle section within the FFP set for the base station.

[0022] In the present invention, when the uplink channel is transmitted based on the COT started by the terminal, the uplink channel is transmitted in a section other than the idle section within the FFP set for the terminal.

[0023] In the present invention, the FFP set for the base station is different from the FFP set for the terminal.

[0024] In the present invention, when the uplink channel is transmitted based on the COT started by the terminal, the uplink channel is transmitted regardless of whether the transmission section of the uplink channel is included in the idle section within the FFP set for the base station.

[0025] Furthermore, in the present invention, when the uplink channel is transmitted based on a COT initiated and shared by the base station, the uplink channel is characterized in that the transmission section of the uplink channel is transmitted in a section other than an idle section within the FFP set up by the base station.

[0026] Furthermore, in the present invention, the FFP set in the terminal is characterized by being set in the terminal by dedicated RRC signaling information.

[0027] Furthermore, in the present invention, the information relating to the COT is included in the field for channel access constituting the dynamic signaling.

[0028] Furthermore, in the present invention, a method for receiving an uplink channel in a wireless communication system, performed by a base station, includes the steps of: transmitting resource information related to the transmission of an uplink channel to a terminal; and receiving an uplink channel from the terminal based on the resource information, wherein the uplink channel is transmitted based on whether or not the terminal has detected a downlink channel transmitted from the base station, and the uplink channel is transmitted within a Channel Occupancy Time (COT) initiated by the base station or within a COT initiated by the terminal. [Effects of the Invention]

[0029] This specification provides a method for determining whether an uplink channel is transmitted based on a channel occupancy interval initiated by the base station or a channel occupancy interval initiated by the terminal, when fixed frame intervals are set for both the base station and the terminal in a wireless communication system. This method has the effect of enabling efficient uplink channel transmission. [Brief explanation of the drawing]

[0030] [Figure 1]This figure shows an example of a wireless frame structure used in wireless communication systems. [Figure 2] This figure shows an example of a downlink (DL) / uplink (UL) slot structure in a wireless communication system. [Figure 3] This diagram illustrates the physical channels used in 3GPP systems and a common signal transmission method using those channels. [Figure 4] This figure shows the SS / PBCH block for initial cell access in a 3GPP NR system. [Figure 5] This diagram shows the procedure for transmitting control information and control channels in a 3GPP NR system. [Figure 6] This diagram shows the CORESET (control resource set) to which the PDCCH (physical downlink control channel) is transmitted in a 3GPP NR system. [Figure 7] This diagram shows how to configure the PDCCH search space in a 3GPP NR system. [Figure 8] This is a conceptual diagram explaining career aggregation. [Figure 9] This is a diagram illustrating single-carrier and multiple-carrier communication. [Figure 10] This figure shows an example where the cross-carrier scheduling technique is applied. [Figure 11] This figure shows the position of the OFDM symbol occupied by SSB within multiple slots of the licensed bandwidth in an NR system according to one embodiment of the present invention. [Figure 12] This figure shows the position of the slots occupied by SSB within a half-wireless frame, i.e., 5ms, of the licensed bandwidth in an NR system according to one embodiment of the present invention. [Figure 13] This figure shows the position of the OFDM symbols occupied by the SSB within a slot containing 16 OFDM symbols according to one embodiment of the present invention. [Figure 14] This is a block diagram showing the configuration of a terminal and a base station according to one embodiment of the present invention. [Figure 15] This figure shows a downlink channel access procedure according to one embodiment of the present invention. [Figure 16] This figure shows a scheduled uplink transmission according to one embodiment of the present invention. [Figure 17] This figure shows the LBT operation process based on FBE according to one embodiment of the present invention. [Figure 18] This figure shows the FBE operation according to one embodiment of the present invention. [Figure 19] This figure shows the LBE operation according to one embodiment of the present invention. [Figure 20] This figure shows a method for performing uplink transmission and downlink transmission when different FFPs are set on the base station and the terminal, according to one embodiment of the present invention. [Figure 21] This figure shows a method for performing uplink transmission and downlink transmission when different FFPs are set on the base station and the terminal, according to one embodiment of the present invention. [Figure 22] This figure shows a method for performing uplink transmission and downlink transmission when different FFPs are set on the base station and the terminal, according to one embodiment of the present invention. [Figure 23] This figure shows a method for performing uplink transmission and downlink transmission when different FFPs are set on the base station and the terminal, according to one embodiment of the present invention. [Figure 24] This figure shows a method for a terminal to transmit an uplink channel according to one embodiment of the present invention. [Modes for carrying out the invention]

[0031] The terminology used herein has been selected to be as widely used and general as possible, taking into account the function of the present invention; however, this may differ depending on the intentions, conventions, or emergence of new technologies of the articulate. In some cases, the applicant has arbitrarily selected certain terms, in which case their meaning will be described in the relevant section of the invention description. Therefore, it should be made clear that the terminology used herein should not be merely names of terms, but should be analyzed based on the substantive meaning of the terms and the overall content of this specification.

[0032] Throughout the specification, when one configuration is said to be “connected” to another, this includes not only cases where they are “directly connected,” but also cases where they are “electrically connected” through other intermediate components. Furthermore, when a configuration is said to “include” a particular component, this means, unless otherwise stated, that it includes other components rather than excluding them. In addition, the limitations of “greater than or equal to” or “less than” a particular critical point may be appropriately replaced by “greater than” or “less than” depending on the embodiment.

[0033] The following technologies are used in a variety of wireless connectivity systems, including CDMA (code division multiple access), FDMA (frequency division multiple access), TDMA (time division multiple access), OFDMA (orthogonal frequency division multiple access), and SC-FDMA (single carrier frequency division multiple access). CDMA is implemented using radio technology such as UTRA (Universal Terrestrial Radio Access) and CDMA2000. TDMA is implemented using radio technology such as GSM (Global System for Mobile communications) / GPRS (General Packet Radio Service) / EDGE (Enhanced Data Rates for GSM Evolution). OFDMA is implemented using radio technology such as IEEE802.11 (Wi-Fi), IEEE802.16 (WiMAX), IEEE802-20, and E-UTRA (Evolved UTRA). UTRA is part of UMTS (Universal Mobile Telecommunication System). 3GPP LTE (Long term evolution) is part of E-UMTS (Evolved UMTS) which uses E-UTRA, and LTE-A (Advanced) is an advanced version of 3GPP LTE. 3GPP NR is a system designed separately from LTE / LTE-A, and is intended to support eMBB (enhanced Mobile Broadband), URLLC (Ultra-Reliable and Low Latency Communication), and mMTC (massive Machine Type Communication) services, which are requirements of IMT-2020. While this explanation will focus on 3GPP NR for clarity, the technical concept of this invention is not limited to this.

[0034] Unless otherwise specified herein, a base station may include a gNB (next generation node B) as defined in 3GPP NR. Also, unless otherwise specified, a terminal may include a UE (user equipment). To facilitate understanding of the description below, each concept will be described separately in examples, but these examples can be combined and used in conjunction with each other. In this disclosure, terminal configuration may represent configuration by the base station. Specifically, the base station may transmit channels or signals to the terminal to configure the operation of the terminal or the values ​​of parameters used in the wireless communication system.

[0035] Figure 1 shows an example of a wireless frame structure used in a wireless communication system.

[0036] Referring to Figure 1, a radio frame (or radio frame) used in a 3GPP NR system has a length of 10 ms (ΔfmaxNf / 100) * Tc). A radio frame consists of 10 subframes (SF) of equal size, where Δfmax = 480 * 10³ Hz, Nf = 4096, Tc = 1 / (Δfref * Nf,ref), Δfref = 15 * 10³ Hz, and Nf,ref = 2048. Each of the 10 subframes within a single frame is assigned a number from 0 to 9. Each subframe has a length of 1 ms and consists of one or more slots depending on the subcarrier spacing. More specifically, the subcarrier spacing usable in a 3GPP NR system is 15 * 2 μkHz, where μ is the subcarrier spacing configuration, with values ​​from 0 to 4. In other words, 15kHz, 30kHz, 60kHz, 120kHz, or 240kHz are used as subcarrier intervals. A 1ms subframe consists of 2μm slots, each with a length of 2-μms. The 2μm slots within a subframe are each assigned numbers from 0 to 2μ-1. Similarly, the slots within a radio frame are each assigned numbers from 0 to 10*2μ-1. Time resources are segmented by at least one of the following: radio frame number (also called radio frame index), subframe number (also called subframe index), or slot number (or slot index).

[0037] Figure 2 shows an example of a downlink (DL) / uplink (UL) slot structure in a wireless communication system. In particular, Figure 2 shows the resource grid structure of a 3GPP NR system.

[0038] There is one resource grid per antenna port. Referring to Figure 2, a slot contains multiple orthogonal frequency division multiplexing (OFDM) symbols in the time domain and multiple resource blocks (RBs) in the frequency domain. An OFDM symbol also means a symbol section. Unless otherwise specified, an OFDM symbol is sometimes simply called a symbol. One RB contains 12 consecutive subcarriers in the frequency domain. Referring to Figure 2, a signal transmitted from each slot may be represented by a resource grid containing Nsize,μgrid,x*NRBsc subcarriers and Nslotsymb OFDM symbols, where x=DL when the signal is a DL signal and x=UL when the signal is a UL signal. Nsize,μgrid,x represents the number of resource blocks (RBs) according to the subcarrier spacing of μ (where x is DL or UL), and Nslotsymb represents the number of OFDM symbols in the slot. NRBsc is the number of subcarriers that make up one RB, and NRBsc=12. OFDM symbols are sometimes called cyclic shift OFDM (CP-OFDM) symbols or discrete Fourier transform spread OFDM (DFT-s-OFDM) symbols, depending on the multiple access scheme.

[0039] The number of OFDM symbols contained in a single slot may vary depending on the length of the cyclic prefix (CP). For example, with a normal CP, a single slot may contain 14 OFDM symbols, while with an extended CP, a single slot may contain 12 OFDM symbols. In certain embodiments, the extended CP may be used only at a 60 kHz subcarrier interval. In Figure 2, for illustrative purposes, a single slot is configured using 14 OFDM symbols as an example, but embodiments of this disclosure may similarly apply to slots with different numbers of OFDM symbols. Referring to Figure 2, each OFDM symbol has N in the frequency domain. size,μgrid,x *N RB sc It includes sub - carriers of the book. The types of sub - carriers can be divided into data sub - carriers for data transmission, reference signal sub - carriers for reference signal transmission, and guard bands. The carrier frequency is also called the center frequency (fc).

[0040] One RB can be defined by N RB sc (For example, 12) consecutive sub - carriers of the book. For reference, a resource composed of one OFDM symbol and one sub - carrier may be called a resource element (RE) or tone. Therefore, one RB is N slot symb *N RB sc resource elements can be used to construct. Each resource element in the resource grid can be uniquely defined by a pair of indices (k, l) within one slot. k can be an index allocated from 0 to N size,μ grid,x *N RB sc −1, and l can be an index allocated from 0 to N slot symb −1.

[0041] For the UE to receive signals from the base station or transmit signals to the base station, the time / frequency of the UE may be synchronized with the time / frequency of the base station. This is because when the base station and the UE are synchronized, the UE can determine the time and frequency parameters necessary to demodulate the DL signal and transmit the UL signal at an appropriate time.

[0042] Each symbol in a radio frame used in time-division duplexing (TDD), i.e., in an unpaired spectrum, may consist of at least one of DL symbols, UL symbols, and flexible symbols. A radio frame used as a DL carrier in frequency-division duplexing (FDD), i.e., in a paired spectrum, may consist of DL symbols or flexible symbols, and a radio frame used as a UL carrier may consist of UL symbols or flexible symbols. DL transmission is possible with DL symbols, but UL transmission is not. UL transmission is possible with UL symbols, but DL transmission is not. Flexible symbols may be determined to be used as DL or UL depending on the signal.

[0043] Information about each symbol type, i.e., information representing any one of DL symbols, UL symbols, and flexible symbols, may be provided using cell-specific or common radio resource control (RRC) signals. In addition, information about each symbol type may be provided using UE-specific or dedicated RRC signals. The base station notifies the following using cell-specific RRC signals: i) the duration of the cell-specific slot configuration, ii) the number of slots with only DL symbols from the beginning of the cell-specific slot configuration period, iii) the number of DL symbols from the first symbol of the slot immediately following a slot with only DL symbols, iv) the number of slots with only UL symbols from the end of the cell-specific slot configuration period, and v) the number of UL symbols from the last symbol of the slot immediately preceding a slot with only UL symbols. Here, a flexible symbol is a symbol that is not configured using either a UL symbol or a DL symbol.

[0044] When information about symbol type is configured using UE-specific RRC signals, the base station may signal in the cell-specific RRC signal whether the flexible symbol is a DL symbol or a UL symbol. In this case, the UE-specific RRC signal cannot change a DL symbol or a UL symbol configured using the cell-specific RRC signal to another symbol type. The UE-specific RRC signal may signal the number of DL symbols among the Nslotsymb symbols of the corresponding slot for each slot, and the number of UL symbols among the Nslotsymb symbols of the corresponding slot. In this case, the DL symbols of the slot may be continuously configured using the first symbol to the i-th symbol of the slot. In addition, the UL symbols of the slot may be continuously configured using the j-th symbol to the last symbol of the slot (where i < j). Among the slots, a symbol that is not configured using either a UL symbol or a DL symbol is a flexible symbol.

[0045] The type of symbol consisting of the RRC signal as described above is referred to as a semi-static DL / UL configuration. In the semi-static DL / UL configuration consisting of the RRC signal described above, the flexible symbol is indicated as a downlink symbol, an uplink symbol, or a flexible symbol via the dynamic SFI (slot format information) transmitted on the physical downlink control channel (PDCCH). At this time, the downlink symbol or uplink symbol consisting of the RRC signal is not changed to another symbol type. Table 1 exemplifies the dynamic SFI indicated by the base station to the terminal.

[0046]

Table 1

[0047] In Table 1, D represents the downlink symbol, U represents the uplink symbol, and X represents the flexible symbol. As shown in Table 1, a maximum of two DL / UL switching operations are permitted in a single slot.

[0048] Figure 3 illustrates the physical channels used in 3GPP systems (e.g., NR) and a typical signal transmission method using those physical channels.

[0049] When the UE is powered on or camp-on to a new cell, the UE performs an initial cell discovery (S101). Specifically, the UE may synchronize with the base station during the initial cell discovery. To this end, the UE may receive primary synchronization signals (PSS) and secondary synchronization signals (SSS) from the base station to synchronize with the base station and obtain information such as the cell ID. Subsequently, the UE may receive physical broadcast channels from the base station and obtain broadcast information in the cell.

[0050] Upon completion of the initial cell discovery, the UE receives the physical downlink control channel (PDCCH) and the physical downlink shared channel (PDSCH) according to the information in the PDCCH. As a result, the UE can obtain more specific system information than the system information obtained through the initial cell discovery (S102). Here, the system information obtained by the UE is the cell-common system information necessary for the UE to operate correctly at the physical layer in the Radio Resource Control (RRC), and is also called remaining system information or system information block (SIB) 1.

[0051] When a UE first accesses a base station or does not have radio resources for signal transmission, the UE may perform a random access procedure to the base station (operations S103-S106). First, the UE can transmit a preamble through a physical random access channel (PRACH) (S103), and can receive a response message for the preamble from the base station through the PDCCH and the corresponding PDSCH (S104). Once the UE receives a valid random access response message, the UE transmits data, including the UE's identifier, to the base station through a physical uplink shared channel (PUSCH), indicated by a UL authorization transmitted from the base station via the PDCCH (S105). Next, the UE waits to receive the PDCCH as an indication from the base station for collision resolution. If the UE successfully receives the PDCCH with the UE's identifier (S106), the random access process is terminated. During the random access process, the UE can obtain UE-specific system information at the RRC layer that is necessary for the UE to operate correctly at the physical layer. When the UE obtains UE-specific system information at the RRC layer, the UE enters RRC_CONNECTED mode.

[0052] The RRC layer is used for message generation and management for control between terminals and the Radio Access Network (RAN). More specifically, base stations and terminals can perform storage management at the RRC layer, including broadcasting of cell system information required by all terminals in the cell, transmission management of paging messages, mobility management and handover, terminal measurement reporting and control therefor, terminal capability management and equipment management. In general, the update of signals transmitted at the RRC layer (hereinafter referred to as RRC signals) is longer than the transmission time interval (i.e., TTI) at the physical layer, so RRC signals can be maintained unchanged over long periods.

[0053] After the procedure described above, the UE receives the PDCCH / PDSCH (S107) and transmits the physical uplink shared channel (PUSCH) / physical uplink control channel (PUCCH) as a general UL / DL signal transmission procedure (S108). Specifically, the UE may receive downlink control information (DCI) through the PDCCH. The DCI may include control information such as resource allocation information for the UE. The format of the DCI may also vary depending on the intended use. The uplink control information (UCI) that the UE transmits to the base station through the UL includes DL / UL ACK / NACK signals, a channel quality indicator (CQI), a precoding matrix index (PMI), a rank indicator (RI), etc. Here, the CQI, PMI, and RI may be included in the channel state information (CSI). In a 3GPP NR system, the UE may transmit control information such as the HARQ-ACK and CSI described above via PUSCH and / or PUCCH.

[0054] Figure 4 shows the SS / PBCH block for initial cell access in a 3GPP NR system.

[0055] When powered on or when a new cell is desired, the UE can obtain time and frequency synchronization with the cell and execute the initial cell discovery procedure. During the cell discovery procedure, the UE can discover the cell's physical cell identification information, NcellID. To this end, the UE can receive synchronization signals from the base station, such as a primary synchronization signal (PSS) and a secondary synchronization signal (SSS), and synchronize with the base station. In this case, the UE can obtain information such as cell identification information (ID).

[0056] The synchronization signal (SS) is described in more detail with reference to Figure 4a. Synchronization signals 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 slot synchronization. SSS can be used to obtain frame synchronization and cell group ID. Referring to Figure 4a and Table 1, an SS / PBCH block can be constructed using 20 consecutive RBs (=240 subcarriers) in the frequency axis and 4 consecutive OFDM symbols in the time axis. In this case, within the SS / PBCH block, the PSS is transmitted in the first OFDM symbol, and the SSS is transmitted in the third OFDM symbol through subcarriers 56 to 182. Here, the smallest subcarrier index in the SS / PBCH block is numbered starting from 0. In the first OFDM symbol in which PSS is transmitted, the base station does not transmit signals through the remaining subcarriers, namely subcarriers 0-55 and 183-239. In addition, in the third OFDM symbol in which SSS is transmitted, the base station does not transmit signals through subcarriers 48-55 and 183-191. The base station transmits the physical broadcast channel (PBCH) through the remaining REs in the SS / PBCH block, excluding the signals mentioned above.

[0057] [Table 2]

[0058] The SS allows a total of 1008 unique physical layer cell IDs to be grouped into 336 physical layer cell identifier groups, each group containing three unique identifiers through a combination of three PSSs and SSSs such that each physical layer cell ID is part of only one physical layer cell identifier group. Thus, a physical layer cell ID NcellID = 3N(1)ID + N(2)ID can be uniquely defined by an index N(1)ID ranging from 0 to 335, representing a physical layer cell identifier group, and an index N(2)ID ranging from 0 to 2, representing a physical layer identifier within a physical layer cell identifier group. The UE can discover the PSS and identify one of the three unique physical layer identifiers. In addition, the UE can discover the SSS and identify one of the 336 physical layer cell IDs associated with a physical layer identifier. In this case, the PSS sequence dPSS(n) is as follows:

[0059]

number

[0060] Here,

number

number

[0061] Furthermore, the SSS sequence dSSS(n) is as follows:

[0062]

number

[0063] Here,

number

number

[0064] A radio frame with a length of 10 ms can be divided into two half-frames with a length of 5 ms. Referring to Figure 4b, the slot in which the SS / PBCH block is transmitted within each half-frame is described. The slot in which the SS / PBCH block is transmitted may be any one of cases A, B, C, D, and E. In case A, the subcarrier spacing is 15 kHz, and the start of the SS / PBCH block is the ({2,8}+14*n)th symbol. In this case, n=0 or 1 at carrier frequencies below 3 GHz. In addition, n may be 0, 1, 2, or 3 at carrier frequencies above 3 GHz and below 6 GHz. In case B, the subcarrier spacing is 30 kHz, and the start of the SS / PBCH block is {4,8,16,20}+28*n. In this case, n=0 at carrier frequencies below 3 GHz. In addition, n may be 0 or 1 at carrier frequencies above 3 GHz and below 6 GHz. In Example C, the subcarrier spacing is 30 kHz, and the start of the SS / PBCH block is the ({2,8}+14*n)th symbol. In this case, n=0 or 1 at carrier frequencies below 3 GHz. In addition, n may be 0, 1, 2, or 3 at carrier frequencies above 3 GHz and below 6 GHz. In Example D, the subcarrier spacing is 120 kHz, and the start of the SS / PBCH block is the ({4,8,16,20}+28*n)th symbol. In this case, n is 0, 1, 2, 3, 5, 6, 7, 8, 10, 11, 12, 13, 15, 16, 17, or 18 at carrier frequencies above 6 GHz. In Example E, the subcarrier spacing is 240 kHz, and the start of the SS / PBCH block is the ({8,12,16,20,32,36,40,44}+56*n)th symbol. In this case, for carrier frequencies above 6 GHz, n = 0, 1, 2, 3, 5, 6, 7, 8.

[0065] Figure 5 shows the procedure for transmitting control information and control channels in a 3GPP NR system. Referring to Figure 5a, a base station may add a cyclic redundancy check (CRC) masked (e.g., by XOR operation) using a radio network temporary identifier (RNTI) to the control information (e.g., downlink control information (DCI)) (S202). The base station may scramble the CRC using an RNTI value determined according to the purpose / target of each piece of control information. A common RNTI used by one or more UEs may include at least one of the following: system information RNTI (SI-RNTI), paging RNTI (P-RNTI), random access RNTI (RA-RNTI), and transmit power control RNTI (TPC-RNTI). In addition, UE-specific RNTIs may include at least one of the following: cell temporary RNTI (C-RNTI) and CS-RNTI. Subsequently, the base station may perform channel coding (e.g., polar coding) (S204) and then perform rate matching according to the amount of resources used for PDCCH transmission (S206). The base station may then multiplex the DCI based on a control channel element (CCE)-based PDCCH structure (S208). In addition, the base station may apply additional processes such as scrambling, modulation (e.g., QPSK), and interleaving to the multiplexed DCI (S210), and then map the DCI to the resources to be transmitted. A CCE is the basic resource unit for a PDCCH, and one CCE may contain multiple (e.g., six) resource element groups (REGs). One REG may consist of multiple (e.g., twelve) REs. The number of CCEs used for one PDCCH may be defined as the aggregation level.In 3GPP NR systems, aggregation levels 1, 2, 4, 8, or 16 may be used. Figure 5b is a diagram relating CCE aggregation levels and PDCCH multiplexing, showing the type of CCE aggregation level used for a single PDCCH and the CCE transmitted within the control area accordingly.

[0066] Figure 6 shows the control resource set (core set) that a physical downlink control channel (PDCCH) can transmit within in a 3GPP NR system.

[0067] A coreset is a time-frequency resource in which PDCCHs, i.e., control signals for the UE, are transmitted. In addition, a search space, which will be described later, may be mapped to a single coreset. Thus, a UE may monitor a time-frequency domain designated as a coreset, rather than monitoring all frequency bands for PDCCH reception, and can decode the PDCCH mapped to the coreset. A base station may configure one or more coresets per cell for the UE. A coreset may be configured using up to three consecutive symbols on the time axis. In addition, a coreset may be configured in units of six consecutive PRBs on the frequency axis. In the embodiment of Figure 6, coreset #1 is configured using consecutive PRBs, and coresets #2 and #3 are configured using non-contiguous PRBs. A coreset may be placed in any symbol within a slot. For example, in the embodiment of Figure 6, coreset #1 starts at the first symbol of the slot, coreset #2 starts at the fifth symbol of the slot, and coreset #9 starts at the ninth symbol of the slot.

[0068] Figure 7 shows a method for setting up the PDCCH search space in the 3GPP NR system.

[0069] To transmit a PDCCH to a UE, each core set may have at least one search space. In embodiments of this disclosure, the search space is a set of all time-frequency resources through which a UE's PDCCH can be transmitted (hereinafter, PDCCH candidates). The search space may include a common search space that all UEs of 3GPP NR are required to search in common, and terminal-specific or UE-specific search spaces that a particular UE is required to search. In the common search space, a UE may monitor a PDCCH that is set up to be searched in common by all UEs in a cell belonging to the same base station. In addition, UE-specific search spaces may be set up per UE so that a UE monitors a PDCCH allocated to each UE at different search space locations according to the UE. In the case of UE-specific search spaces, the search spaces between UEs may partially overlap or be allocated due to the limited control area through which a PDCCH is allocated. Monitoring a PDCCH involves blind decoding to find PDCCH candidates in the search space. When blind decoding is successful, it may be expressed that the PDCCH has been (successfully) detected / received, and when blind decoding fails, it may be expressed that the PDCCH has not been detected / received, or has not been successfully detected / received.

[0070] For the sake of explanation, a PDCCH scrambled using a group-common (GC) RNTI previously known to one or more UEs to send DL control information to one or more UEs is called a group-common (GC) PDCCH or common PDCCH. In addition, a PDCCH scrambled using a terminal-specific RNTI already known to a particular UE to send UL scheduling information or DL ​​scheduling information to a particular UE is called a UE-specific PDCCH. Common PDCCHs may be included in the common search space, and UE-specific PDCCHs may be included in the common search space or within UE-specific PDCCHs.

[0071] A base station may signal to each UE or UE group via the PDCCH about information relating to resource allocation for the transmission channels, namely the paging channel (PCH) and the downlink-shared channel (DL-SCH) (i.e., DL permission), or information relating to resource allocation for the uplink-shared channel (UL-SCH) and Hybrid Automatic Retransmission Request (HARQ) (i.e., UL permission). The base station may transmit PCH transport blocks and DL-SCH transport blocks via the PDSCH. The base station may transmit data, excluding certain control information or certain service data, via the PDSCH. In addition, UEs may receive data, excluding certain control information or certain service data, via the PDSCH.

[0072] A base station may include information within a PDCCH about where the UE(s) PDSCH data will be transmitted to and how the corresponding UE will receive and decode the PDSCH data, and may transmit such a PDCCH. For example, suppose a DCI transmitted on a particular PDCCH is CRC masked using an RNTI named "A", and the DCI indicates that the PDSCH is allocated to a radio resource (e.g., frequency location) named "B", and indicates transmission format information (e.g., transport block size, modulation scheme, coding information, etc.) named "C". A UE monitors the PDCCH using the RNTI information it possesses. In this case, if there is a UE performing blind decoding of the PDCCH using the RNTI of "A", that UE will receive the PDCCH and, through the received PDCCH information, receive the PDSCH indicated by "B" and "C".

[0073] Table 3 shows one embodiment of a physical uplink control channel (PUCCH) used in a wireless communication system.

[0074] [Table 3]

[0075] PUCCH can be used to transmit the following UL control information (UCI):

[0076] - Scheduling Request (SR): Information used to request UL-SCH resources.

[0077] - HARQ-ACK: A response to the PDCCH (indicating DL SPS release) and / or to the DL transport block (TB) on the PDSCH. HARQ-ACK indicates whether information transmitted on the PDCCH or PDSCH has been received. HARQ-ACK responses include positive ACK (simply ACK), negative ACK (hereinafter NACK), discontinuous transmission (DTX), or NACK / DTX. Here, the term HARQ-ACK is used in conjunction with HARQ-ACK / NACK and ACK / NACK. Generally, ACK may be represented by a bit value of 1, and NACK may be represented by a bit value of 0.

[0078] - Channel Status Information (CSI): Feedback information on the DL channel. The UE generates it based on the CSI reference signal (RS) transmitted by the base station. Multi-input multiple-output (MIMO) related feedback information includes a rank indicator (RI) and a 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.

[0079] The 3GPP NR system may use five PUCCH formats to support various service scenarios, channel environments, and frame structures.

[0080] PUCCH format 0 is a format capable of transmitting 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 RB on the frequency axis. When PUCCH format 0 is transmitted through two OFDM symbols, the same sequence on the two symbols may be transmitted through different RBs. In this case, the sequence may be a sequence that has been cyclically shifted (CS) from the base sequence used in PUCCH format 0. Through this, the UE can obtain frequency diversity gain. Specifically, the terminal can determine the cyclic shift (CS) value mcs by the Mbit bit UCI (Mbit=1 or 2). Alternatively, a base sequence of length 12 can be cyclically shifted based on a defined CS value mcs and transmitted by mapping the resulting sequence to 12 REs (Resonance Sequences) consisting of one OFDM symbol and one RB. If the terminal has 12 available cyclic shifts and Mbit=1, then 1-bit UCI 0 and 1 can be mapped to two cyclic shifted sequences, each with a cyclic shift value difference of 6. If Mbit=2, then 2-bit UCI 00, 01, 11, and 10 can be mapped to four cyclic shifted sequences, each with a cyclic shift value difference of 3.

[0081] PUCCH format 1 transmits 1-bit or 2-bit HARQ-ACK information or SR. PUCCH format 1 is transmitted via 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 is one of 4 to 14. More specifically, a UCI with Mbit=1 is modulated with BPSK. The terminal modulates a UCI with Mbit=2 with QPSK (quadrature phase shift keying). A signal is obtained by multiplying the modulated complex valued symbol d(0) by a sequence of length 12. The terminal transmits the obtained signal by spreading it with a time-axis OCC (orthogonal cover code) to the even-numbered OFDM symbols assigned to PUCCH format 1. The maximum number of different terminals that can be multiplexed with the same RB in PUCCH format 1 is determined by the length of the OCC used. For odd-numbered OFDM symbols in PUCCH format 1, the DMRS (demodulation reference signal) is spread across the OCC and mapped to them.

[0082] PUCCH format 2 can deliver UCIs of more than 2 bits. PUCCH format 2 can be transmitted through one or two OFDM symbols on the time axis and one or more RBs on the frequency axis. When PUCCH format 2 is transmitted through two OFDM symbols, the sequences transmitted through the two OFDM symbols in different RBs may be the same as each other. Here, the sequence is a plurality of modulated complex value symbols d(0),...,d(M symbol -1) is acceptable. Here, M symbol is M bit It may be / 2. Through this, the UE can obtain frequency diversity gain. More specifically, M bit Bit UCI(M bit>2) is bit-level scrambled, QPSK modulated, and mapped to one or two OFDM symbols as RBs, where the number of RBs can be one between 1 and 16.

[0083] PUCCH format 3 or PUCCH format 4 can deliver UCIs of more than 2 bits. PUCCH format 3 or PUCCH format 4 can be transmitted through a sequence of 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 may be one of 4 to 14. Specifically, the UE uses π / 2-2 phase shift keying (BPSK) or QPSK for M bit Modulate the bit UCI (Mbit>2) to obtain the complex value symbol d(0)~d(M symb -1) is generated. Here, when using π / 2-BPSK, M symb =M bit And when using QPSK, M symb =M bit The value is / 2. The UE does not have to apply block-based spread to PUCCH format 3. However, the UE may apply block-based spread to one RB (i.e., 12 subcarriers) using a PreDFT-OCC of length 12 such that PUCCH format 4 may have a multiplexing capacity of 2 or 4. The UE performs transmit precoding (or DFT precoding) on ​​the spread signal and maps it to each RE to transmit the spread signal.

[0084] 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 and maximum code rate of the UCI transmitted by the UE. When the UE uses PUCCH format 2, the UE may transmit HARQ-ACK information and CSI information together through PUCCH. If the number of RBs that the UE can transmit is greater than the maximum number of RBs that PUCCH format 2, PUCCH format 3, or PUCCH format 4 can use, the UE may transmit only the remaining UCI information without transmitting some of the UCI information, according to the priority of the UCI information.

[0085] PUCCH format 1, PUCCH format 3, or PUCCH format 4 may be configured through an RRC signal to indicate frequency hopping within a slot. When frequency hopping is configured, the index of the RB to be frequency-hopped may be configured using the RRC signal. When PUCCH format 1, PUCCH format 3, or PUCCH format 4 is transmitted through N OFDM symbols on the time axis, the first hop may have floor(N / 2) OFDM symbols, and the second hop may have ceil(N / 2) OFDM symbols.

[0086] PUCCH format 1, PUCCH format 3, or PUCCH format 4 may be configured to be transmitted repeatedly in multiple slots. In this case, the number K of slots in which the PUCCH is transmitted repeatedly may be determined by the RRC signal. The repeatedly transmitted PUCCH must begin at a fixed position OFDM symbol in each slot and must be of a constant length. When one of the OFDM symbols in a slot in which the UE is to transmit the PUCCH is indicated as a DL symbol by the RRC signal, the UE does not have to transmit the PUCCH in the corresponding slot and may delay the transmission of the PUCCH until the next slot in which it is to be transmitted.

[0087] On the other hand, in a 3GPP NR system, a terminal can transmit and receive using a bandwidth smaller than or equal to the carrier (or cell) bandwidth. To this end, a terminal may have a bandwidth part (BWP) consisting of a contiguous portion of the carrier bandwidth. A terminal operating by TDD or in an unpaired spectrum may have up to four DL / UL BWP pairs per carrier (or cell). A terminal can also activate one DL / UL BWP pair. A terminal operating by FDD or in a paired spectrum may have up to four DL BWPs per downlink carrier (or cell) and up to four UL BWPs per uplink carrier (or cell). A terminal can activate one DL BWP and one UL BWP for each carrier (or cell). A terminal does not need to receive or transmit using time-frequency resources other than the activated BWPs. Activated BWPs can be called active BWPs.

[0088] A base station can indicate to a terminal which of the configured BWPs (bandwidth points) are activated using downlink control information (DCI). The BWP indicated in the DCI is activated, and the other configured BWPs are deactivated. In a carrier (or cell) operating in TDD mode, the base station may include a bandwidth part indicator (BPI) indicating the activated BWP in the DCI that schedules a PDSCH or PUSCH to change the terminal's DL / UL BWP pair. The terminal can receive the DCI that schedules the PDSCH or PUSCH and identify the activated DL / UL BWP pair based on the BPI. In a downlink carrier (or cell) operating in FDD mode, the base station may include a BPI indicating the activated BWP in the DCI that schedules a PDSCH to change the terminal's DL BWP. In an uplink carrier (or cell) operating in FDD mode, the base station may include a BPI indicating the activated BWP in the DCI that schedules a PUSCH to change the terminal's UL BWP.

[0089] Figure 8 is a conceptual diagram illustrating career integration.

[0090] Carrier aggregation is a method by which a wireless communication system uses a wider frequency band by allowing a UE (Unified Element) to use multiple frequency blocks or cells (in a logical sense) composed of UL resources (or component carriers) and / or DL ​​resources (or component carriers) as one large logical frequency band. A single component carrier may also be referred to as a primary cell (PCell), secondary cell (SCell), or primary SCell (PScell). However, for the sake of explanation, the term "component carrier" will be used below.

[0091] Referring to Figure 8, as an example of a 3GPP NR system, the overall system bandwidth may include up to 16 component carriers, each component carrier may have a bandwidth of up to 400 MHz. A component carrier may include one or more physically continuous subcarriers. Although Figure 8 shows that each component carrier has the same bandwidth, this is just an example, and each component carrier may have a different bandwidth. Also, although each component carrier is shown as being adjacent to each other on the frequency axis, the diagram is shown in a logical concept, and each component carrier may be physically adjacent to each other or separated from each other.

[0092] A different center frequency may be used for each component carrier. Alternatively, a single common center frequency may be used for physically adjacent component carriers. In the embodiment shown in Figure 8, assuming that all component carriers are physically adjacent, center frequency A may be used for all component carriers. Furthermore, assuming that the component carriers are not physically adjacent to each other, center frequencies A and B may be used for each component carrier.

[0093] When the entire system bandwidth is extended by carrier aggregation, the frequency bandwidth used for communication with each UE can be defined in units of component carriers. UE A may use the entire system bandwidth of 100 MHz and communicate using all five component carriers. UEs B1-B5 may use only 20 MHz bandwidth and communicate using one component carrier. UEs C1 and C2 may use 40 MHz bandwidth and communicate using two component carriers each. The embodiment in Figure 8 shows UE C1 using two non-adjacent component carriers and UE C2 using two adjacent component carriers.

[0094] Figure 9 illustrates single-carrier and multi-carrier communication. Specifically, Figure 9(a) shows a single-carrier subframe structure, and Figure 9(b) shows a multi-carrier subframe structure.

[0095] Referring to Figure 9(a), in FDD mode, a typical wireless communication system may perform data transmission or data reception through one DL band and one UL band, respectively. In another specific embodiment, in TDD mode, the wireless communication system may divide a radio frame in the time domain into UL time units and DL time units, and perform data transmission or data reception through the UL / DL time units. Referring to Figure 9(b), three 20 MHz component carriers (CCs) may be aggregated into UL and DL so that a 60 MHz bandwidth can be supported. Each CC may or may not be adjacent to each other in the frequency domain. Figure 9(b) shows an example where the bandwidths of the UL CC and DL CC are the same and symmetric, but the bandwidth of each CC may be determined independently. In addition, asymmetric carrier aggregation with different numbers of UL CCs and DL CCs is possible. DL / UL CCs allocated / configured to a particular UE through RRC are sometimes called the serving DL / UL CCs of that particular UE.

[0096] A base station may communicate with a UE by activating some or all of the UE's serving CCs, or by deactivating some of the CCs. The base station may change which CCs are to be activated / deactivated, and may change the number of CCs to be activated / deactivated. If the base station allocates CCs available to a UE as cell-specific or UE-specific, at least one of the allocated CCs may be deactivated unless the CC allocation to the UE is completely reconfigured or the UE is handed over. The CC that is not deactivated by the UE is called the Primary CC (PCC) or Primary Cell (PCell), and the CCs that the base station can freely activate / deactivate are called Secondary CCs (SCC) or Secondary Cells (SCell).

[0097] On the other hand, 3GPP NR uses the concept that a cell manages radio resources. A cell is defined as a combination of DL resources and UL resources, i.e., a combination of DL CC and UL CC. A cell may consist of DL resources only, or a combination of DL resources and UL resources. When carrier aggregation is supported, the coordination between the carrier frequencies of DL resources (i.e., DL CC) and UL resources (i.e., UL CC) may be indicated by system information. The carrier frequency refers to the center frequency of each cell or CC. A cell corresponding to a PCC is called a PCell, and a cell corresponding to an SCC is called a SCell. The carrier corresponding to a PCell in DL is a DL PCC, and the carrier corresponding to a PCell in UL is a UL PCC. Similarly, the carrier corresponding to a SCell in DL is a DL SCC, and the carrier corresponding to a SCell in UL is a UL SCC. Depending on the UE capability, a serving cell may consist of one PCell and zero or more SCells. If a UE is in the RRC_CONNECTED state but is not configured for or does not support carrier aggregation, it will have only one serving cell configured using only PCells.

[0098] As described above, the term "cell" as used in carrier aggregation is distinct from the term "cell" which refers to several geographical areas where communication services are provided by a single base station or antenna group. That is, a single component carrier may also be called a scheduling cell, scheduled cell, primary cell (PCell), secondary cell (SCell), or primary SCell (PScell). However, in order to distinguish between cells referring to several geographical areas and cells in carrier aggregation, in this disclosure, cells in carrier aggregation are referred to as CCs, and cells in geographical areas are referred to as cells.

[0099] Figure 10 shows an example where the cross-carrier scheduling technique is applied. When cross-carrier scheduling is set up, a control channel transmitted through the first CC can schedule a data channel transmitted through the first or second CC using a carrier indicator field (CIF). The CIF is included in the DCI. In other words, a scheduling cell is set up, and DL / UL permissions transmitted within the PDCCH area of ​​the scheduling cell schedule the PDSCH / PUSCH of the scheduled cell. That is, a search area for multiple component carriers exists within the PDCCH area of ​​the scheduling cell. A PCell can essentially be a scheduling cell, and a particular SCell may be designated as a scheduling cell by a higher layer.

[0100] In the embodiment shown in Figure 10, it is assumed that three DL CCs are merged. Here, it is assumed that DL component carrier #0 is a DL PCC (or PCell), and DL component carriers #1 and #2 are DL SCCs (or SCells). In addition, it is assumed that the DL PCC is configured as a PDCCH that monitors CCs. When cross-carrier scheduling is not configured by UE-specific (or UE group-specific or cell-specific) upper-layer signaling, CIF is disabled, and each DL CC can send only a PDCCH to schedule its PDSCH without using CIF, according to the NR PDCCH rule (non-cross-carrier scheduling, self-carrier scheduling). On the other hand, when cross-carrier scheduling is configured by UE-specific (or UE group-specific or cell-specific) upper-layer signaling, CIF is enabled, and a particular CC (e.g., DL PCC) may send not only a PDCCH to schedule the PDSCH of DL CC A using CIF, but also a PDCCH to schedule the PDSCH of another CC (cross-carrier scheduling). On the other hand, PDCCH is not transmitted within another DL CC. Therefore, depending on whether cross-carrier scheduling is configured for the UE, the UE will either monitor a PDCCH without a CIF to receive a self-carrier scheduled PDSCH, or monitor a PDCCH with a CIF to receive a cross-carrier scheduled PDSCH.

[0101] On the other hand, Figures 9 and 10 show the subframe structure of a 3GPP LTE-A system, and the same or a similar configuration may be applied to a 3GPP NR system. However, in a 3GPP NR system, the subframes in Figures 9 and 10 may be replaced with slots.

[0102] Since most communications in conventional unlicensed bandwidths operate on an LBT (Low-Band Test) basis, channel access in NR-U systems also utilizes LBT to coexist with conventional equipment. Specifically, channel access methods on unlicensed bandwidths in NR are categorized into the following four categories depending on the presence / absence and application method of LBT.

[0103] ● Category 1: No LBT

[0104] -Tx entities do not perform LBT procedures for transmission.

[0105] ● Category 2: LBT without random backoff

[0106] - The Tx entity senses whether the channel is idle during the first interval without random backoff in order to perform a transmission. That is, immediately after the Tx entity senses that the channel is idle during the first interval, it performs a transmission through that channel. The first interval is a preset interval of length immediately before the Tx entity performs a transmission. In one embodiment, the first interval may be an interval of length 25us, but the present invention is not limited thereto.

[0107] ● Category 3: LBT that uses a fixed-size CW to perform random backoff

[0108] - The Tx entity obtains a random number within a fixed-size CW and sets it as the initial value of the backoff counter (or backoff timer) N, and performs backoff using the set backoff counter N. In other words, in the backoff procedure, the Tx entity decrements the backoff counter by 1 each time the channel is sensed to be idle during a preset slot period. Here, the preset slot period may be 9us, but the present invention is not limited to this. The backoff counter N is decremented by 1 from its initial value, and when the value of the backoff counter N reaches 0, the Tx entity transmits. On the other hand, in order to perform backoff, the Tx entity uses a second interval (i.e., a differ period T) d The Tx entity first senses whether the channel is idle during the second interval. According to an embodiment of the present invention, the Tx entity senses (or determines) whether the channel is idle during the second interval, depending on whether the channel is idle during at least a portion of the second interval (e.g., one slot period). The second interval is set based on the channel access priority class of the Tx entity and consists of a period of 16us and m consecutive slot periods, where m is a value set by the channel access priority class. If the Tx entity senses that the channel is idle during the second interval, it performs channel sensing to decrement the backoff counter. On the other hand, if the channel is sensed to be occupied during the backoff procedure, the backoff procedure is interrupted. After interrupting the backoff procedure, the Tx entity resumes backoff if the channel is sensed to be idle during an additional second interval. In this way, the Tx entity transmits if the channel is idle during the second interval plus the slot periods of the backoff counter N. In this case, the initial value of the backoff counter N is obtained within a fixed-size CW (Continuous Wave) transmission.

[0109] ● Category 4: LBT that uses variable-size CW to perform random backoff

[0110] - The Tx entity obtains a random number within the variable-size CW and sets it as the initial value of the backoff counter (or backoff timer) N, and then uses the set backoff counter N to perform backoff. More specifically, the Tx entity adjusts the size of the CW based on HARQ-ACK information for previous transmissions, but the initial value of the backoff counter N is obtained within the adjusted-size CW. The detailed process by which the Tx entity performs backoff is as described in Category 3. The Tx entity transmits if the channel is idle for the second interval plus the slot period of the backoff counter N. In this case, the initial value of the backoff counter N is obtained within the variable-size CW.

[0111] In categories 1 to 4, the Tx entity is a base station or a terminal. In the embodiments of the present invention, the first type of channel access refers to a category 4 channel access, and the second type of channel access refers to a category 2 channel access.

[0112] Figure 11 shows the position of the OFDM symbol occupied by SSB within multiple slots of the licensed bandwidth in an NR system according to an embodiment of the present invention.

[0113] SSB can contain four OFDM symbols and 20 RBs. Specifically, PSS occupies one OFDM symbol, SSS occupies one OFDM symbol, and PBCH can occupy two OFDM symbols and one OFDM symbol multiplexed with SSS and FDM. The position of the OFDM symbols within the slot occupied by SSB may change depending on the subcarrier spacing (SCS). Figure 11(a) shows the SSB pattern when the subcarrier spacing for SSB transmission is 15 kHz and 30 kHz, respectively. Figure 11(b) shows the SSB pattern when the subcarrier spacing for SSB transmission is 120 kHz and 240 kHz, respectively. When the subcarrier spacing is 30 kHz, either the SSB pattern for eMBB transmission or the SSB pattern considering URLLC may be used. In Figure 11, the hatched OFDM symbols indicate the position of the OFDM symbols within the slot occupied by SSB. Furthermore, different hatching patterns indicate that they correspond to different SSB indices.

[0114] Figure 12 shows the position of the slots occupied by SSB within a half-wireless frame of the licensed bandwidth, i.e., within 5ms, in an NR system according to an embodiment of the present invention.

[0115] In Figure 12, the hatched slots indicate the location of slots containing SSBs within a half-radio frame. One slot can contain two SSBs. Two SSBs within a single slot may have different SSB indices. Similarly, SSBs located in different slots may have different SSB indices. SSB indices will be discussed further later. In Figure 12, L indicates the maximum number of SSBs that a base station can transmit in a half-radio frame.

[0116] The NR system specifies that one subcarrier spacing should be defined for each frequency band, reducing the complexity for terminals to search for SSB for initial cell access. Specifically, if a frequency band below 6 GHz is used, the NR system specifies that either a 15 kHz or 30 kHz subcarrier spacing should be used for SSB. If a frequency band above 6 GHz is used, the NR system specifies that either a 120 kHz or 240 kHz subcarrier spacing should be used for SSB.

[0117] In unlicensed bands, the LBT procedure is used when a radio communication device accesses a channel. Therefore, if the channel is not idle, the radio communication device may fail to access the channel. Similarly, when a base station accesses a channel to transmit SSB, it may fail to access the channel, meaning that SSB transmission may not occur at the location set by the base station. Ultimately, even if the base station configures the terminal to assume the location where SSB is transmitted, the terminal may still not receive the SSB. Since SSB is transmitted periodically, even if the terminal fails to receive the SSB at any given time, it can receive it one cycle later. However, if the terminal receives the SSB in this way, a delay occurs in RRM measurement and measurement to neighboring cells. Ultimately, this increases latency across the entire system.

[0118] Furthermore, SSB is used for beamlink configuration and beam operation. Specifically, the base station transmits multiple SSBs corresponding to different SSB indices in different time domains. The terminal uses multiple SSBs to configure multiple beamlinks. The base station performs beam sweeping. The terminal configures the beamlinks depending on whether it received SSBs transmitted in different time domains and on different beams. If the base station fails to access the channel and cannot transmit the SSB, a problem occurs where the beamlink cannot be configured. Ultimately, the latency for beamlinks increases due to the failure of channel access. Therefore, a method is needed to reduce SSB transmission failures and increase the opportunities for SSB transmission.

[0119] If an NR system is used in an unlicensed band, 60kHz subcarrier spacing is used to transmit SSB in order to increase channel access opportunities. In licensed bands below 6GHz, 15kHz or 30kHz subcarrier spacing is used to transmit SSB. Also in licensed bands below 6GHz, 15kHz, 30kHz, or 60kHz subcarrier spacing is used to transmit data. In licensed bands above 6GHz, 120kHz or 240kHz subcarrier spacing is used to transmit SSB. Also in licensed bands above 6GHz, 60kHz or 120kHz subcarrier spacing is used to transmit data. If an NR system is used in an unlicensed band below 7GHz (e.g., below 7.125GHz), 15kHz or 30kHz subcarrier spacing may be considered, similar to the subcarrier spacing used in licensed bands below 6GHz. However, if 60kHz subcarrier spacing is used to transmit SSB in an unlicensed band, the spacing between OFDM symbols is reduced to one-quarter of that when 15kHz subcarrier spacing is used. Therefore, if 60kHz subcarrier spacing is used in an NR system in an unlicensed band, the transmission opportunities at the symbol level after channel access can be increased for SSB and data channels. If 15kHz and 30kHz subcarrier spacing are used, when a base station successfully accesses a channel within a single OFDM symbol, the time required to transmit the reservation signal is reduced when using 60kHz subcarrier spacing to allow time for transmission of the reservation signal. The following describes SSB transmission methods usable in an unlicensed band, particularly when 60kHz subcarrier spacing is used.

[0120] NR-U DRS (or DRS) configuration

[0121] In the unlicensed band of an NR system, a base station may transmit a signal that includes at least one SSB or at least one SSB burst set transmission. An SSB burst set is a series of SSB transmissions within a given time interval. In this case, the signal may be a discovery signal burst (DRS burst). A base station may transmit a DRS burst in accordance with the following principles: A base station may transmit a DRS burst in such a way that there is no gap in the time interval during which the DRS burst is transmitted within the beam. A base station may transmit a DRS burst in such a way that it satisfies the occupied channel bandwidth (OCB) requirement. However, in some cases, a base station may transmit a DRS burst in such a way that it does not satisfy the occupied channel bandwidth requirement. Furthermore, a base station may consider methods to minimize the channel occupancy time of the DRS burst and to enable rapid channel access. For convenience of explanation, a DRS burst is referred to as DRS.

[0122] DRS transmitted in an unlicensed band may include a PDSCH containing RMSI (remaining system information), i.e., SIB1 (System Information Block 1), related to SSB. Furthermore, the DRS may include an RMSI-CORESET, which is the time and frequency resource area for control channel transmissions to transmit scheduling information for RMSI. That is, it may include a CORESET, which is the time and frequency resource area for transmitting a PDCCH that schedules the PDSCH containing SIB1. Furthermore, the DRS may include CSI-RS. Furthermore, the DRS may include other types of signals. Specifically, the DRS may include other system information (OSI) or paging. Therefore, when a base station transmits DRS in an unlicensed band, the base station can multiplex the DRS with physical channels or signals. At this point, the method by which the base station accesses the channels becomes important. In particular, the method by which the base station uses one of the various channel access methods described above and sets the parameters used for channel access becomes important. Furthermore, the DRS may include SSB or SSB burst set transmissions.

[0123] In one embodiment of the present invention, when a base station multiplexes DRS with unicast data, the base station can perform random backoff using a variable-size CW for the transmission of the multiplexed DRS and unicast data, and the size of the CW can be determined by the channel access priority class. In this case, the terminal can perform channel access according to the channel access priority class of the unicast data being multiplexed. Specifically, the channel access method may be the first type of channel access described above.

[0124] These embodiments describe cases where a base station multiplexes DRS with signals or information other than unicast data. Non-unicast data signals or information may represent signals or channels that are not data traffic and cannot establish a channel access priority class. Non-unicast data signals or information may include control messages related to initial connection, random access, mobility, or paging. Furthermore, non-unicast data signals or information may include transmissions containing only reference signals. Furthermore, non-unicast data signals or information may include transmissions containing only PDCCHs. A transmission containing only PDCCHs may include at least one of the following under the random access procedure: RACH message-4, handover command, group common PDCCH, short paging message, OSI (other system information), paging, and RAR (random access response). Non-unicast data signals or information may also be transmitted via PDCCHs and PDSCHs. For convenience of explanation, non-unicast data signals or information are referred to as non-unicast data. Furthermore, the multiplexing of DRS and non-unicast data as described herein can be interpreted as indicating that the corresponding transmission does not contain unicast data. In certain embodiments, when a base station multiplexes DRS with non-unicast data, the base station can perform channel access where only single-time interval (LBT) based LBT is performed for the transmission of the DRS and non-unicast data multiplexed together. Channel access where only single-time interval based LBT is performed may be the second type of channel access described above. In this case, the duration of the single-time interval may be 25us or 34us.

[0125] In yet another specific embodiment, when a base station multiplexes DRS with non-unicast data, the base station can perform random backoff using a variable-size CW for the multiplexed transmission of DRS and non-unicast data, and perform channel access where the size of the CW is determined by the channel access priority class. Such embodiments take into account that single-time interval-based LBT can be performed only if the total duration of the transmission containing only DRS is 1 ms or less and the duty cycle of the DRS transmission is 1 / 20 or less. In such embodiments, the base station can use the channel access priority class with the highest priority (e.g., channel access priority class #1). This allows the base station to assign a higher priority to non-unicast data than to channel access compared to unicast data. Furthermore, while using the channel access priority class with the highest priority, the base station can use the smallest size of CW among the sizes of CW allowed in the corresponding channel access priority class. In yet another specific embodiment, the base station can use the largest size of CW among the sizes of CW allowed in the corresponding channel access priority class while using the channel access priority class with the highest priority.

[0126] In yet another specific embodiment, when a base station multiplexes DRS with non-unicast data, the base station can perform channel access using a fixed-size CW to perform random backoff for the multiplexed transmission of DRS and non-unicast data. In this case, the channel access method may be a Category 3 channel access as described above. In such an embodiment, the base station can use the channel access priority class with the highest priority (e.g., channel access priority class #1). This allows the base station to assign a higher priority to non-unicast data than to channel access compared to unicast data. Furthermore, while using the channel access priority class with the highest priority, the base station can use the smallest CW size among the CW sizes allowed in the corresponding channel access priority class. In yet another specific embodiment, the base station can use the largest CW size among the CW sizes allowed in the corresponding channel access priority class while using the channel access priority class with the highest priority.

[0127] When a base station transmits non-unicast data that is not multiplexed with the DRS, the base station can use the channel access method used when multiplexing non-unicast data with the DRS to access the channel for transmitting the non-unicast data. Specifically, when a base station transmits non-unicast data that is not multiplexed with the DRS, the base station can use the channel access type and channel access parameters used when multiplexing non-unicast data with the DRS.

[0128] In yet another specific embodiment, when a base station transmits non-unicast data that is not multiplexed with DRS, the base station can perform channel access for the transmission of non-unicast data using a variable-size CW with random backoff, where the CW size is determined by the channel access priority class. Specifically, the channel access method may be the first type channel access described above. In such an embodiment, the base station can use the channel access priority class with the highest priority (e.g., channel access priority class #1). This allows the base station to give non-unicast data a higher priority than channel access compared to unicast data. Furthermore, while using the channel access priority class with the highest priority, the base station can use the smallest CW size among the CW sizes allowed in that channel access priority class. In yet another specific embodiment, while using the channel access priority class with the highest priority, the base station can use the largest CW size among the CW sizes allowed in that channel access priority class.

[0129] In yet another specific embodiment, when a base station transmits non-unicast data that is not multiplexed with DRS, the base station can perform channel access with random backoff using a fixed-size CW for transmitting the non-unicast data. In this case, the channel access method may be the Category 3 channel access described above. In such an embodiment, the base station can use the channel access priority class with the highest priority (e.g., channel access priority class #1). This allows the base station to give non-unicast data a higher priority than channel access compared to unicast data. Furthermore, while using the channel access priority class with the highest priority, the base station can use the smallest CW size among the CW sizes allowed in that channel access priority class. In yet another specific embodiment, while using the channel access priority class with the highest priority, the base station can use the largest CW size among the CW sizes allowed in that channel access priority class.

[0130] In the embodiment described above, the base station determined the channel access method for a transmission multiplexed with DRS and non-unicast data or unicast data, regardless of the duration of the transmission multiplexed with 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, it can treat a transmission containing only DRS and a transmission multiplexed with DRS and non-unicast data the same. Specifically, the base station can determine the channel access method for a transmission multiplexed with DRS and non-unicast data or unicast data based on the duration of the transmission multiplexed with DRS and non-unicast data or unicast data and the duty cycle of the DRS transmission. The base station can determine the channel access method for a transmission multiplexed with DRS and non-unicast data or unicast data based on whether the duration of the transmission multiplexed with DRS and non-unicast data or unicast data is 1 ms or less, and whether the duty cycle of the DRS transmission is 1 / 20 or less.

[0131] When a base station performs a multiplexed transmission of DRS and non-unicast data, the base station can select one of two channel access types depending on whether it satisfies both of the following two conditions: the duration of the multiplexed transmission of DRS and non-unicast data is 1 ms or less, and the duty cycle of the DRS transmission is 1 / 20 or less. In this case, one of the two channel access types is a channel access in which only single-time-interval-based LBT is performed, and the other is a channel access in which random backoff is performed using variable-size CW, and the size of the CW is determined by the channel access priority class. In a specific embodiment, if the duration of the multiplexed transmission of DRS and non-unicast data is 1 ms or less, and the duty cycle of the DRS transmission is 1 / 20 or less, the base station can perform a channel access in which only single-time-interval-based LBT is performed for the multiplexed transmission of DRS and non-unicast data. In this case, the duration of the single-time-interval may be 25 u. Furthermore, the single-time-interval-based LBT may be the second type of channel access described above. Furthermore, if the duration of a transmission with multiplexed DRS and non-unicast data is greater than 1 ms, or if the duty cycle of the DRS transmission is greater than 1 / 20, the base station can perform channel access for the multiplexed DRS and non-unicast data transmission using variable-size CW with random backoff, where the CW size is determined by the channel access priority class. The base station can also select any channel access priority class. In this case, the base station can arbitrarily select one of the channel access priority classes that satisfies the MCOT length condition based on the duration of the multiplexed DRS and non-unicast data transmission. The base station can use the selected channel access priority class for channel access for the multiplexed DRS and non-unicast data transmission.In other words, a base station can use the size of the CW (Continuous Wave) for channel access based on the selected channel access priority class. For example, a base station can use the channel access priority class with the highest priority (e.g., channel access priority class #1). This allows the base station to give non-unicast data a higher priority than channel access compared to unicast data. Furthermore, while using the channel access priority class with the highest priority, the base station can use the smallest CW size among the CW sizes allowed in that channel access priority class. In yet another specific embodiment, while using the channel access priority class with the highest priority, the base station can use the largest CW size among the CW sizes allowed in that channel access priority class.

[0132] In such embodiments, if the base station can determine whether a terminal has received non-unicast data and whether the reception was successful, the base station can adjust the size of the CW based on the ratio of ACK to NACK. Specifically, the base station can convert feedback information for non-unicast data received by the terminal into ACK and NACK, and adjust the size of the CW based on the ratio of ACK to NACK. A channel access method in which random backoff is performed using a variable-size CW and the size of the CW is determined by the channel access priority class may be a first-type channel access.

[0133] As mentioned above, base stations and terminals can adjust the size of the CW based on HARQ feedback when using CW for channel access. However, base stations and terminals may not be able to expect HARQ feedback for all or part of the non-unicast data. Also, base stations and terminals may not be able to determine whether they have received all or part of the non-unicast data, respectively. Furthermore, when base stations and terminals perform an initial connection procedure, they may not be able to determine HARQ-ACK feedback for some of the downlink signals and channels and uplink signals and channels used during the initial connection procedure. In addition, base stations and terminals may not transmit to a specific channel access priority class and may not be able to determine the HARQ-ACK feedback corresponding to the transmission to that channel access priority class. In such cases, a method for determining the CW to use for channel access when base stations and terminals transmit channels and signals that include all or part of the non-unicast data for which HARQ feedback cannot be expected will be described. For the sake of explanation, the explanation will mainly focus on the base station, but the following embodiments may also be applied to terminals.

[0134] When a base station cannot determine the HARQ-ACK feedback for a transmission associated with a channel access priority class that determines the size of the CW, the base station may perform channel access with random backoff within the CW corresponding to the channel access priority class. In this case, the base station can use the smallest CW size among the CW sizes allowed in that channel access priority class. In yet another specific embodiment, the base station may use the channel access priority class with the highest priority while using the largest CW size among the CW sizes allowed in that channel access priority class.

[0135] Furthermore, if the base station cannot determine whether the terminal has received all or part of the non-unicast data for which HARQ feedback cannot be expected, the base station may perform channel access with random backoff within a fixed CW size for transmission in which the non-unicast data and DRS are multiplexed. Specifically, the base station may use CW corresponding to any one of the channel access priority classes in the first type channel access described above. In a specific embodiment, the base station may use any one of the channel access priority classes that satisfy the MCOT length condition, depending on the duration of the transmission in which the non-unicast data and DRS are multiplexed in the first type channel access. The base station may use the channel access priority class with the highest priority. In a specific embodiment, the base station may use the channel access priority class with the highest priority among the channel access priority classes that satisfy the MCOT length condition, depending on the duration of the transmission in which the non-unicast data and DRS are multiplexed in the first type channel access. In addition, the base station may use the smallest CW size among the CW sizes allowed in the channel access priority class while using the channel access priority class with the highest priority. In yet another specific embodiment, the base station may use the channel access priority class with the highest priority, and use the largest CW size among the CW sizes allowed in that channel access priority class.

[0136] In further specific embodiments, if a base station cannot determine whether a terminal has received all or part of non-unicast data for which HARQ feedback cannot be expected, the base station may perform the aforementioned Category 3 channel access for a transmission in which the non-unicast data and DRS are multiplexed. The base station may use the channel access priority class with the highest priority. Depending on the duration of the transmission in which the non-unicast data and DRS are multiplexed, the base station may use the channel access priority class with the highest priority that satisfies the MCOT length requirements. Furthermore, while using the channel access priority class with the highest priority, the base station may use the smallest CW size among the CW sizes allowed in that channel access priority class. In yet another specific embodiment, while using the channel access priority class with the highest priority, the base station may use the largest CW size among the CW sizes allowed in that channel access priority class.

[0137] A base station may be unable to transmit an SSB due to a failure in the channel access procedure (e.g., LBT). An SSB transmit window may be defined so that if the base station cannot transmit an SSB at a configured location, it can transmit it at another location. The SSB transmit window is a time interval in which the base station can transmit an SSB, and includes multiple candidate SSB transmit locations. If the base station is unable to initiate an SSB transmit at any one candidate SSB transmit location, it can attempt to transmit an SSB at a later SSB transmit location within the SSB transmit window. An SSB transmit location is a point in time when the base station can initiate an SSB transmit. If a terminal is unable to receive an SSB at any one candidate SSB transmit location within the SSB transmit window, the terminal can receive an SSB at a later SSB transmit location within the SSB transmit window. At this point, the terminal can determine whether the base station was unable to initiate an SSB transmit at the candidate SSB transmit location or whether the base station failed to transmit the SSB. In a specific embodiment, if a terminal fails to receive an SSB at any of the SSB transmission candidate positions within the SSB transmission window, the terminal may attempt to receive an SSB at the next SSB transmission candidate position within the same SSB transmission window. After the terminal starts and completes SSB reception at any of the SSB transmission candidate positions, the terminal does not need to expect to receive any further SSBs within that SSB transmission window. Specifically, after the terminal starts and completes SSB reception at any of the SSB transmission candidate positions, the terminal does not need to attempt to receive any further SSBs within that SSB transmission window.

[0138] In further specific embodiments, if a terminal fails to receive a specific SSB at any of the SSB transmission candidate positions within the SSB transmission window, the terminal may attempt to receive the specific SSB at the next SSB transmission candidate position within that SSB transmission window. After the terminal starts receiving a specific SSB at any of the SSB transmission candidate positions and completes the reception of the specific SSB, the terminal does not need to attempt to receive the specific SSB again within that SSB transmission window. Specifically, after the terminal receives a specific SSB at any of the SSB transmission candidate positions, the terminal does not need to attempt to receive the specific SSB again within that SSB transmission window.

[0139] In yet another specific embodiment, even after a terminal has completed receiving a specific SSB at any of the SSB transmission candidate locations, the terminal can attempt to receive the specific SSB within that SSB transmission window. This is because the terminal can receive the specific SSB again and obtain a combining gain from the further received SSB. Such embodiments may apply not only when multiple SSBs corresponding to different beam indices are transmitted for beam operation, but also when an omni-TX transmission method is used. Specifically, it may also apply when the same SSB is transmitted repeatedly.

[0140] DRS LBT method

[0141] Figure 13 shows the position of the OFDM symbols occupied by the SSB according to an embodiment of the present invention within a slot containing 14 OFDM symbols.

[0142] The following describes a channel access method for a DRS containing one or more SSBs, with reference to Figure 13. Specifically, it describes a channel access method that a base station performs before transmitting a DRS, depending on the number of SSBs included in the DRS transmitted by the base station, and how to configure it so that different LBTs can be performed.

[0143] Figure 13 shows the position of OFDM symbols occupied by SSBs within a slot composed of 14 OFDM symbols. SSB pattern A is identical to the position of OFDM symbols occupied by SSBs in NR systems as defined in 3GPP Rel.15. In SSB pattern B, the OFDM symbols occupied by SSBs in the second half slot within a single slot are positioned one symbol later than in SSB pattern A. Therefore, in SSB pattern B, the positions of OFDM symbols occupied by SSBs within a single slot are set to be symmetrical on a half-slot basis.

[0144] A base station can perform multiple transmissions and determine a channel access method for each of the multiple DRS transmissions if the total duration of the transmissions, including DRS, is 1 ms or more.

[0145] When an unlicensed band in the 5GHz or 6GHz range is used, the base station can transmit up to n SSBs to the DRS. In this case, the value of n may be 2, 4, or 8. The subcarrier spacing used for DRS transmission may be 15KHz or 30KHz. When the subcarrier spacing is 15KHz, the duration of one slot is 1ms, and the number of SSBs that can be included in a 1ms interval may be 2. When the subcarrier spacing is 30KHz, the duration of one slot is 0.5ms, and the number of SSBs that can be included in a 1ms interval may be 4. Depending on the DRS transmission period setting, the total duration of DRS transmission with a duty cycle of 1 / 20 may change.

[0146] As mentioned above, the total duration of a transmission including DRS may be 1 ms or less, and the duty cycle of the DRS transmission may be 1 / 20 or less. In this case, when the base station performs a transmission including only DRS, or a transmission with DRS and non-unicast data multiplexed together, the base station may perform channel access where only single-time interval-based LBT is performed for the transmission. Channel access where only single-time interval-based LBT is performed may be the second type channel access described above. The total duration of a transmission including DRS may be greater than 1 ms, or the duty cycle of the DRS transmission may be greater than 1 / 20. In this case, when the base station performs a transmission including only DRS, or a transmission with DRS and non-unicast data multiplexed together, the base station may perform channel access where random backoff is performed using a variable-size CW, and the size of the CW is determined by the channel access priority class. In this case, the channel access method in which random backoff is performed using a variable-size CW, and the size of the CW is determined by the channel access priority class, may be the first type channel access.

[0147] In one embodiment of the present invention, a method may be used in which the base station performs single-time interval-based LBT, taking into account the characteristics of the transmission including DRS. When the total duration of the transmission including DRS is greater than 1 ms, the base station can determine the channel access method in 1 ms duration units. Specifically, when the total duration of the transmission including DRS is greater than 1 ms, the base station can perform multiple transmissions, each with a duration of 1 ms or less, and perform channel access including only single-time interval-based LBT for each of the multiple transmissions. The base station can apply this embodiment only when the duty cycle of the DRS transmission is 1 / 20 or less. This is because there is an ETSI provision that in the case of transmissions without LBT, the short control signal must not exceed 5% of the transmission. With this embodiment, the base station and the terminal can quickly perform initial connection and RRM measurement using the SSB included in the DRS transmitted from the base station. For example, if the DRS transmission period is set to 40ms or more, and the base station transmits DRS within a 5ms DRS transmission window set at a minimum of 40ms period units, the total duration of transmissions including DRS that satisfy the condition of a duty cycle of 1 / 20 or less may be 2ms or less. The base station can perform multiple DRS transmissions, each with a duration of 1ms or less, under the constraint of a total transmission duration of 2ms or less including DRS. In this case, the base station can perform a second-type channel access before performing each of the multiple transmissions. With such an embodiment, the base station can quickly transmit DRS to the terminal. Also, if the DRS transmission period is set to 80ms or more, and the base station transmits DRS within a 5ms DRS transmission window set at a minimum of 80ms period units, the total duration of transmissions including DRS that satisfy the condition of a duty cycle of 1 / 20 or less including DRS may be 4ms or less. The base station can perform multiple DRS transmissions, each with a duration of 1ms or less, under the constraint of a total transmission duration of 4ms or less including DRS.In this case, the base station can perform a second-type channel access before each of the multiple transmissions.

[0148] Furthermore, if the total duration of the transmission including DRS is greater than 1 ms and the duty cycle of the DRS transmission is greater than 1 / 20, the base station may perform channel access for the transmission including DRS using variable-size CW with random backoff, where the size of the CW is determined by the channel access priority class. In this case, the channel access method may be a first-type channel access.

[0149] In other specific embodiments, a portion of a transmission including DRS may have a transmission duty cycle of 1 / 20 or less. In this case, the base station can perform channel access with only single-time-interval-based LBT for a portion of the transmission portion of the transmission including DRS that has a duty cycle of 1 / 20 or less. In such embodiments, the base station can perform multiple transmissions, each with a duration of 1 ms or less, and perform channel access with only single-time-interval-based LBT for each of the multiple transmissions. In this case, channel access with only single-time-interval-based LBT may be a second-type channel access. Furthermore, the base station can perform channel access with random backoff using variable-size CW for the remaining transmission portion of the transmission including DRS, where the size of the CW is determined by the channel access priority class. In this case, channel access with random backoff using variable-size CW and where the size of the CW is determined by the channel access priority class may be a first-type channel access. For example, the period of the DRS transmission may be a multiple of 20 ms. Specifically, when the DRS transmission period is 20ms, the duration of the transmission section where the DRS transmission duty cycle is 1 / 20 or less is 1ms. When the DRS transmission period is 40ms, the duration of the transmission section where the DRS transmission duty cycle is 1 / 20 or less is 2ms. When the DRS transmission period is 60ms, the duration of the transmission section where the DRS transmission duty cycle is 1 / 20 or less is 3ms. When the DRS transmission period is 80ms, the duration of the transmission section where the DRS transmission duty cycle is 1 / 20 or less is 4ms. In this case, the base station can perform Type 2 channel access for a portion of the transmission section of the transmission containing DRS with a duty cycle of 1 / 20, and Type 1 channel access for the remaining transmission section of the transmission containing DRS.

[0150] The maximum number of SSBs that can be included in a DRS may be 8. In the following explanation, we will assume that the number of SSBs included in the DRS is 8. When the period of DRS transmission is 20ms, the duration of a transmission section in which the duty cycle of the DRS transmission is 1 / 20 or less is 1ms. Therefore, when the subcarrier spacing is 15KHz, a transmission section in which the duty cycle of the DRS transmission is 1 / 20 or less may contain 2 SSBs. In this case, the base station can perform a second-type channel access before the first transmission, and if the channel access is successful, it can transmit 2 SSBs. Also, the base station can perform a first-type channel access before the second transmission, and if the channel access is successful, it can transmit 6 SSBs. Furthermore, when the period of DRS transmission is 20ms, the duration of a transmission section in which the duty cycle of the DRS transmission is 1 / 20 or less is 1ms. Therefore, when the subcarrier spacing is 30KHz, a transmission section in which the duty cycle of the DRS transmission is 1 / 20 or less may contain 4 SSBs. In this case, the base station can perform a Type 2 channel access before the first transmission, and if the channel access is successful, it can transmit four SSBs. Furthermore, the base station can perform a Type 1 channel access before the second transmission, and if the channel access is successful, it can transmit four SSBs.

[0151] When the DRS transmission period is 40ms, the duration of a transmission segment where the DRS transmission duty cycle is 1 / 20 or less is 2ms. Therefore, when the subcarrier spacing is 15KHz, a transmission segment where the DRS transmission duty cycle is 1 / 20 or less may contain 4 SSBs. In this case, the base station can perform two transmissions with a duration of 1ms, transmitting 2 SSBs with each transmission. The base station can perform a Type 2 channel access before the first transmission, and if the channel access is successful, transmit 2 SSBs. Furthermore, the base station can perform a Type 2 channel access before the second transmission, and if the channel access is successful, transmit 2 SSBs. Finally, the base station can perform a Type 1 channel access before the third transmission, and if the channel access is successful, transmit the remaining 4 SSBs. Furthermore, when the DRS transmission period is 40ms, the duration of a transmission section where the DRS transmission duty cycle is 1 / 20 or less is 2ms. Therefore, when the subcarrier spacing is 30KHz, a transmission section where the DRS transmission duty cycle is 1 / 20 or less may contain 8 SSBs. In this case, the base station can perform a second-type channel access before the first transmission, and if the channel access is successful, it can transmit 4 SSBs. Also, the base station can perform a second-type channel access before the second transmission, and if the channel access is successful, it can transmit 4 SSBs.

[0152] In further specific embodiments, a portion of the transmission including DRS may have a duration of 1 ms or less, and the DRS transmission duty cycle may be 1 / 20 or less. In this case, the base station can perform channel access where only single-time-interval-based LBT is performed for a portion of the transmission including DRS having a duty cycle of 1 / 20 or less and a duration of 1 ms or less. In this case, channel access where only single-time-interval-based LBT is performed may be a second-type channel access. The base station can also perform channel access where random backoff is performed using variable-size CW for the remaining transmission portion, and the size of the CW is determined by the channel access priority class. In this case, channel access where random backoff is performed using variable-size CW and the size of the CW is determined by the channel access priority class may be a first-type channel access.

[0153] The maximum number of SSBs that can be included in a DRS may be 8. The following explanation assumes that the number of SSBs included in the DRS is 8.

[0154] When the DRS transmission period is 20ms, the duration of a transmission segment where the DRS transmission duty cycle is 1 / 20 or less is 1ms. Therefore, when the subcarrier spacing is 15KHz, a transmission segment where the DRS transmission duty cycle is 1 / 20 or less may contain 2 SSBs. In this case, the base station can perform a Type 2 channel access before the first transmission, and if the channel access is successful, it can transmit 2 SSBs. Also, the base station can perform a Type 1 channel access before the second transmission, and if the channel access is successful, it can transmit 6 SSBs. Furthermore, when the DRS transmission period is 20ms, the duration of a transmission segment where the DRS transmission duty cycle is 1 / 20 or less is 1ms. Therefore, when the subcarrier spacing is 30KHz, a transmission segment where the DRS transmission duty cycle is 1 / 20 or less may contain 4 SSBs. In this case, the base station can perform a Type 2 channel access before the first transmission, and if the channel access is successful, it can transmit 4 SSBs. Furthermore, the base station can perform a first-type channel access before the second transmission, and if the channel access is successful, it can transmit four SSBs.

[0155] When the DRS transmission period is 40ms, the duration of a transmission segment where the DRS transmission duty cycle is 1 / 20 or less is 2ms. When the subcarrier spacing is 15KHz, a transmission segment with a duration of 1ms and a DRS transmission duty cycle of 1 / 20 or less may contain 2 SSBs. The base station can perform a second-type channel access before the first transmission, and if the channel access is successful, it can transmit 2 SSBs. The base station can also perform a first-type channel access before the second transmission, and if the channel access is successful, it can transmit the remaining 6 SSBs. Furthermore, when the DRS transmission period is 40ms, the duration of a transmission segment where the DRS transmission duty cycle is 1 / 20 or less is 2ms. When the subcarrier spacing is 30KHz, a transmission segment with a duration of 1ms and a DRS transmission duty cycle of 1 / 20 or less may contain 4 SSBs. In this case, the base station can perform a Type 2 channel access before the first transmission, and if the channel access is successful, it can transmit four SSBs. Furthermore, the base station can perform a Type 1 channel access before the second transmission, and if the channel access is successful, it can transmit four SSBs.

[0156] Furthermore, the DRS transmission window duration may be set to Tms. In this case, T may be a natural number greater than or equal to 1. T may be 5 or 6. Alternatively, T may be set to a multiple of the smallest time interval in which the maximum possible number of SSBs included in the DRS can be included. When the duration of the DRS transmission window is 1ms or more, the base station may perform channel access with only single-time interval-based LBT in the last 1ms of the DRS transmission window. In this case, when the DRS transmission duty cycle in the last 1ms of the DRS transmission window is 1 / 20 or less, the base station may perform channel access with only single-time interval-based LBT in the last 1ms of the DRS transmission window. Channel access with only single-time interval-based LBT may be the second type channel access described above. Furthermore, the base station may perform either the first type channel access or the second type channel access in the last 1ms of the DRS transmission window. With such an embodiment, the terminal can quickly perform initial connection and RRM measurement.

[0157] Figure 14 is a block diagram showing the configurations of a terminal and a base station according to one embodiment of the present invention.

[0158] In one embodiment of the present invention, the terminal is embodied in various types of wireless communication devices or computing devices that ensure portability and mobility. The terminal is referred to as UE, STA (Station), MS (Mobile Subscriber), etc. In another embodiment of the present invention, the base station controls and manages the cells (e.g., macrocells, femtocells, picocells, etc.) in the service area and performs functions such as signal transmission, channel assignment, channel monitoring, self-diagnosis, and relaying. The base station is referred to as gNB (next Generation NodeB) or AP (Access Point), etc.

[0159] As shown in the figure, a terminal 100 according to one embodiment of the present invention includes a processor 110, a communication module 120, a memory 130, a user interface unit 140, and a display unit 150.

[0160] First, the processor 110 executes various instructions or programs to process data inside the terminal 100. The processor 110 also controls the overall operation of the terminal 100, including each unit, and controls the transmission and reception of data between units. Here, the processor 110 is configured to perform the operations described in the embodiment of the present invention. For example, the processor 110 may receive slot configuration information, determine the slot configuration based on that information, and perform communication according to the determined slot configuration.

[0161] Next, the communication module 120 is an integrated module that performs wireless communication using a wireless communication network and wireless LAN access using a wireless LAN. For this purpose, the communication module 120 incorporates multiple network interface cards (NICs), such as cellular communication interface cards 121 and 122 and an unlicensed band communication interface card 123, either internally or externally. In the drawing, the communication module 120 is shown as an integrated module, but each network interface card may be arranged independently depending on the circuit configuration or application, contrary to the drawing.

[0162] The cellular communication interface card 121 transmits and receives radio signals to and from at least one of the base station 200, an external device, and a server via a mobile communication network, and provides cellular communication services in a first frequency band based on instructions from the processor 110. According to one embodiment, the cellular communication interface card 121 includes at least one NIC module that utilizes a frequency band of less than 6 GHz. At least one NIC module of the cellular communication interface card 121 independently performs cellular communication with at least one of the base station 200, an external device, and a server, according to the cellular communication standard or protocol of the sub-6 GHz frequency band supported by the NIC module.

[0163] The cellular communication interface card 122 uses a mobile communication network to send and receive radio signals with at least one of the base station 200, an external device, or a server, and provides cellular communication services in the second frequency band based on instructions from the processor 110. In one embodiment, the cellular communication interface card 122 includes at least one NIC module that utilizes a frequency band of 6 GHz or higher. At least one NIC module of the cellular communication interface card 122 independently performs cellular communication with at least one of the base station 200, an external device, or a server, according to the cellular communication standard or protocol of the 6 GHz or higher frequency band supported by the NIC module.

[0164] The unlicensed band communication interface card 123 transmits and receives radio signals to and from at least one of the base station 200, an external device, or a server via the third frequency band, which is an unlicensed band, and provides communication services in the unlicensed band based on instructions from the processor 110. The unlicensed band communication interface card 123 includes at least one NIC module that utilizes the unlicensed band. For example, the unlicensed band may be a band of 2.4GHz, 5GHz, 6GHz, 7GHz, or 52.6GHz or higher. At least one NIC module of the unlicensed band communication interface card 123 independently or dependently performs cellular communication with at least one of the base station 200, an external device, or a server, depending on the unlicensed band communication standard or protocol of the frequency band supported by the NIC module.

[0165] Next, the memory 130 stores control programs used by the terminal 100 and various data associated with them. Such control programs include predetermined programs necessary for the terminal 100 to communicate wirelessly with at least one of the following: a base station 200, an external device, or a server.

[0166] Next, the user interface 140 includes various forms of input / output means provided in the terminal 100. In other words, the user interface unit 140 receives user input using various input means, and the processor 110 controls the terminal 100 based on the received user input. The user interface 140 also outputs based on instructions from the processor 110 using various output means.

[0167] Next, the display unit 150 outputs various images to the display screen. The display unit 150 outputs various display objects, such as content generated by the processor 110 or user interfaces based on control instructions from the processor 110.

[0168] Furthermore, the base station 200 according to the embodiment of the present invention includes a processor 210, a communication module 220, and a memory 230.

[0169] First, the processor 210 executes various instructions or programs to process data within the base station 200. The processor 210 also controls the overall operation of the base station 200, including each unit, and controls the transmission and reception of data between units. Here, the processor 210 is configured to perform the operations described in the embodiment of the present invention. For example, the processor 210 may signal slot configuration information and perform communication according to the signaled slot configuration.

[0170] Next, the communication module 220 is an integrated module that performs wireless communication using a wireless communication network and wireless LAN access using a wireless LAN. To this end, the communication module 220 incorporates multiple network interface cards, such as cellular communication interface cards 221 and 222, and an unlicensed band communication interface card 223, either internally or externally. In the drawing, the communication module 220 is shown as an integrated module, but each network interface card may be arranged independently depending on the circuit configuration or application, contrary to the drawing.

[0171] The cellular communication interface card 221 transmits and receives wireless signals to and from at least one of the terminal 100, external devices, and servers described above using a mobile communication network, and provides cellular communication services in the first frequency band based on instructions from the processor 210. According to one embodiment, the cellular communication interface card 221 includes at least one NIC module that utilizes a frequency band of less than 6 GHz. At least one NIC module of the cellular communication interface card 221 independently performs cellular communication with at least one of the terminal 100, external devices, and servers, according to the cellular communication standard or protocol of the frequency band of less than 6 GHz supported by the NIC module.

[0172] The cellular communication interface card 222 transmits and receives wireless signals to and from at least one of the terminal 100, an external device, and a server using a mobile communication network, and provides cellular communication services in the second frequency band based on instructions from the processor 210. According to one embodiment, the cellular communication interface card 222 includes at least one NIC module that utilizes a frequency band of 6 GHz or higher. At least one NIC module of the cellular communication interface card 222 independently performs cellular communication with at least one of the terminal 100, an external device, and a server, according to the cellular communication standard or protocol of the 6 GHz or higher frequency band supported by the NIC module.

[0173] The unlicensed band communication interface card 223 uses the third frequency band, which is an unlicensed band, to send and receive wireless signals with at least one of the terminal 100, an external device, or a server, and provides unlicensed band communication services based on instructions from the processor 210. The unlicensed band communication interface card 223 includes at least one NIC module that utilizes the unlicensed band. For example, the unlicensed band may be 2.4GHz, 5GHz, 6GHz, 7GHz, or a band of 52.6GHz or higher. At least one NIC module of the unlicensed band communication interface card 223 independently or dependently performs cellular communication with at least one of the terminal 100, an external device, or a server, depending on the unlicensed band communication standard or protocol of the frequency band supported by the NIC module.

[0174] The terminal 100 and base station 200 shown in Figure 14 are block diagrams according to one embodiment of the present invention, and the separately shown blocks represent logically distinguished elements of the device. Therefore, the above-mentioned elements of the device are mounted on one or more chips depending on the device design. Furthermore, some components of the terminal 100, such as the user interface unit 150 and the display unit 150, may be selectively provided in the terminal 100. In addition, the user interface 140 and the display unit 150 may be additionally provided in the base station 200 as needed.

[0175] This specification describes the channel access methods that a base station performs before transmitting a downlink channel in a wireless communication system on an unlicensed band. More specifically, it describes what Channel Access Priority Class (CAPC) a base station must use when performing channel access to transmit a downlink control channel (e.g., PDCCH).

[0176] When a base station performs channel access before transmitting a downlink control channel, different channel access priority classes must be applied depending on the various information transmitted via the downlink control channel and the timing of the downlink control channel's transmission. Typically, when a PDSCH containing unicast data scheduled via a PDCCH is transmitted on the same slot of the same carrier as the PDCCH, the base station can set a CAPC based on the type of traffic of the unicast data contained in the PDSCH. Based on the set CAPC, the base station can then perform channel access to transmit the PDCCH and PDSCH on the same slot of the same carrier. However, for transmissions of other PDCCHs, excluding the PDCCH used for scheduling PDSCHs containing unicast data transmitted on the same slot of the same carrier as the PDCCH, it can be ambiguous which CAPC the base station must select when performing channel access. Therefore, the present invention explains which CAPC a base station should select to access the channel for PDCCH transmission, depending on the information transmitted via PDCCH, the scheduling timing of PDCCH and PDSCH, and whether the PDSCH scheduled by PDCCH is transmitted on the same carrier as PDCCH or on a different carrier.

[0177] When a base station transmits a downlink control channel (e.g., PDCCH) to a terminal, the information transmitted via the PDCCH may be various types of information, as described below. In this case, the base station can transmit a separate PDCCH containing each of these various types of information individually, or it can transmit multiple PDCCHs containing each type of information within a single control resource set (CORESET). The CORESET can represent the resource area from which the PDCCH is transmitted.

[0178] This document describes the various types of information transmitted via PDCCH, specifically the various DCI formats that can be transmitted via PDCCH.

[0179] 1. DCI format for Downlink Shared Channel (PDSCH) transmissions sent via PDCCH

[0180] 1-A. DCI format for scheduling a PDSCH containing unicast data to be transmitted on one or more slots, including the same slot as the PDCCH transmission time on the same carrier as the PDCCH.

[0181] 1-B. DCI format for scheduling PDSCH containing unicast data, transmitted on a different slot than the PDCCH on the same carrier as the PDCCH.

[0182] 1-C. DCI format for scheduling PDSCH containing unicast data transmitted on a slot different from the PDCCH and on a different carrier.

[0183] 1-D. Semi-Persistent Scheduling (SPS) DCI format for instructing PDSCH reception.

[0184] 1-E. DCI format to indicate the release of SPS PDSCH reception

[0185] 2. DCI format for uplink shared channel (PUSCH) transmissions sent via PDCCH

[0186] 2-A. DCI format for scheduling PUSCHs containing unicast data transmitted by a terminal on one or more slots, including the same slot as the PDCCH transmission time of the PDCCH on the same carrier.

[0187] 2-B. DCI format for scheduling PUSCHs containing unicast data, which are transmitted by a terminal on a different slot than the PDCCH transmitted on the same carrier as the PDCCH.

[0188] 2-C. DCI format for scheduling PUSCHs containing unicast data transmitted by a terminal on a slot of a different carrier than PDCCH.

[0189] 2-D. DCI format instructing the activation of a configured grant PUSCH.

[0190] 2-E. DCI format instructing the release of a configured grant push.

[0191] 2-F. DCI format indicating downlink feedback information for configured grant pusher

[0192] 3. DCI format for other purposes transmitted via PDCCH (excluding purposes for transmission via Uplink / Downlink Shared Channel (PUSCH / PDSCH))

[0193] 3-A. DCI format that informs a group of UEs of the slot format, available RB sets, channel occupancy time (COT) interval (duration), and search space set group switching.

[0194] 3-B. DCI format that informs the terminal of PRB and OFDM symbols so that it can assume that no intended transmission occurred.

[0195] 3-C. DCI format for notifying a group of UEs of the transmission of TPC (Transmit Power Control) commands for PUCCH and PUSCH.

[0196] 3-D. DCI format to notify one or more UEs of a TPC group command transmission for SRS (Sounding Reference Signal) transmission.

[0197] When the DCI format transmitted via the PDCCH described in 1-3 above is multiplexed with a PDSCH containing unicast data, the base station can select the CAPC based on the traffic type of the unicast data contained in the PDSCH.

[0198] However, as described above in 1-B to 1-E, 2-A to 2-F, and 3-A to 3-D, when the DCI format is not multiplexed with a PDSCH containing unicast data transmitted in a slot different from the slot in which the PDCCH is transmitted, and is transmitted independently on a single slot via the PDCCH, or when the DCI format scheduling a PUSCH containing unicast data is transmitted on a single slot via the PDCCH (for example, 2-A to 2-F above), it is necessary to define which CAPC the base station should select when accessing the channel for PDCCH transmission.

[0199] If the DCI format is not multiplexed with a PDSCH containing unicast data transmitted in a slot different from the slot in which the PDCCH is transmitted, the base station can select the highest priority CAPC to obtain channel access for the transmission of the PDCCH. When the base station obtains channel access using the highest priority CAPC, it has the effect of increasing the channel access priority for the transmission of the control channel (i.e., the PDCCH).

[0200] If the DCI format is not multiplexed with a PDSCH containing unicast data transmitted in a slot different from the slot in which the PDCCH is transmitted, the base station can select the lowest priority CAPC to access the channel for PDCCH transmission. When the base station accesses the channel using the lowest priority CAPC, it can access the channel using the longest MCOT (Maximum Channel Occupancy Time) among the CAPCs, because the longest MCOT is set for the lowest priority CAPC. Therefore, control channels and data channels having the same CAPC as the lowest priority CAPC and higher priority CAPCs within the MCOT set by the lowest priority CAPC can be multiplexed and transmitted in slots after the channel access.

[0201] There are possible methods by which the base station can select the CAPC for each of the three DCI formats mentioned above. Specifically, when a DCI format transmitted via a PDCCH is multiplexed with a PDSCH containing unicast data, the base station can select the CAPC based on the traffic type of the unicast data contained in the PDSCH. For example, if the two DCI formats mentioned above transmitted via a PDCCH schedule a PUSCH containing unicast data, the base station can select the CAPC based on the traffic type of the unicast data contained in the PUSCH.

[0202] In the three DCI formats described above, transmitted via PDCCH for specific purposes, the base station can use the highest priority CAPC to access the channel in order to increase its channel access priority. This is because information for specific purposes must be transmitted in the DCI. On the other hand, when the three DCI formats described above are transmitted via PDCCH for specific purposes, the base station can use the lowest priority CAPC when accessing the channel. When the base station accesses the channel using the lowest priority CAPC, it can use the longest MCOT (Maximum Channel Occupancy Time) among the CAPCs. This is because the longest MCOT is set for the lowest priority CAPC. Therefore, within the MCOT set by the lowest priority CAPC, control channels and data channels having the same CAPC as the lowest priority CAPC and higher priority CAPCs can be multiplexed and transmitted in slots after channel access. In other words, the three DCI formats described above can be considered DCI formats that do not include information for scheduling uplink / downlink channels (e.g., PUSCH, PDSCH).

[0203] When each of the DCI formats 1-3 described above is transmitted via PDCCH, the base station can select a CAPC for channel access based on the respective DCI format. The specific CAPC selection method is shown in Table 4.

[0204] [Table 4-1] [Table 4-2] [Table 4-3]

[0205] Each of the DCI formats 1-3 described above may be transmitted via a single PDCCH, and one or more PDCCHs may be multiplexed within a CORESET and transmitted from the base station to the terminal. Therefore, when there is one or more multiplexed PDCCHs within a CORESET, the base station must select which CAPC to select when accessing a channel to transmit one or more PDCCHs in the time and frequency domain that contains one or more PDCCHs.

[0206] When there is one or more multiplexed PDCCHs within a CORESET, the base station can access the channel using the CAPC with the lowest priority among the CAPCs set for each PDCCH. When the base station accesses the channel using the lowest priority CAPC, it can access the channel using the longest MCOT (Maximum Channel Occupancy Time) among the CAPCs. This is because the longest MCOT is set for the lowest priority CAPC. Therefore, control channels and data channels with the same CAPC as the lowest priority CAPC and higher priority CAPCs within the MCOT set by the lowest priority CAPC can be multiplexed and transmitted in slots after channel access.

[0207] On the other hand, if there is one or more PDCCHs multiplexed within the CORESET, the base station can access the channel using the CAPC set when a particular PDCCH schedules a PDSCH or PUSCH containing unicast data, or using the CAPC set when the PDCCH and PDSCH are multiplexed.

[0208] The highest-priority CAPC and the lowest-priority CAPC mentioned above can refer to the CAPC with the highest priority (e.g., p=1) and the lowest priority (e.g., p=4) among the multiple CAPCs that have already been set (see Table 4).

[0209] Figure 15 shows a downlink channel access procedure according to one embodiment of the present invention.

[0210] Figure 15 shows the downlink channel access procedure used when a terminal initiates Channel Occupancy Time (COT) sharing (UE-initiated COT sharing). Figure 15(a) shows an example of the downlink channel access procedure when the gap is less than 16us, Figure 15(b) shows an example of the downlink channel access procedure when the gap is 16us, and Figure 15(c) shows an example of the downlink channel access procedure when the gap is 25us.

[0211] To perform an uplink (e.g., push) transmission on a scheduled or configured resource, a terminal can use a Category 4 channel access procedure to obtain its own initiated channel occupancy. The terminal can then share the channel occupancy with the base station for base station transmission.

[0212] If information regarding the Energy Detection (ED) threshold is set

[0213] The terminal can receive an Energy Detection (ED) threshold applied when acquiring channel access from the base station. For example, the base station can configure the ED threshold by sending the terminal 'ULtoDL-CO-SharingED-Threshold-r16' as an RRC parameter for the ED threshold. When the terminal shares channel access with the base station, the base station can transmit a specific channel or a specific signal. In this case, the uplink transmission may be a configured grant (CG)-PUSCH or a scheduled uplink transmission (e.g., a scheduled grant-PUSCH). The base station may perform a downlink transmission after the terminal's uplink transmission. In this specification, a CG uplink transmission (e.g., CG-PUSCH) may be an uplink transmission (e.g., CG-PUSCH) performed by the terminal on a semi-statically configured resource for uplink transmission provided by the base station.

[0214] When an uplink transmission performed by a terminal is CG-PUSCH, the terminal can receive a table from the base station for sharing channel occupancy. Specifically, the terminal may receive a table from the base station for sharing information related to channel occupancy between the base station and the terminal (e.g., channel occupancy time (COT)), which may be configured by the RRC parameter 'COT-SharingList-r16'. The terminal can also 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 may be provided by the RRC parameter 'cg-COT-Sharing-r16'. In this case, one of the rows of the table may be configured to indicate that channel occupancy is not shared. When a terminal shares its initiated channel occupancy with the base station in order to perform a CG-PUSCH transmission, the terminal can indicate a row index corresponding to a single row in a table set up by the base station using the 'COT sharing information' included in the CG-UCI (Uplink control information) of the CG-PUSCH. That is, when the terminal indicates an index corresponding to a single row providing channel occupancy information, the base station can perform a downlink transmission by assuming one or more values ​​corresponding to the channel occupancy information indicated by the row in the table indicated by the index. Specifically, the channel occupancy information may include duration, offset, CAPC, etc. Duration can mean the number of slots available (assumed) for downlink transmission within the channel occupancy time initiated by the terminal. Offset means the time interval (difference) from the end of the slot in which the base station detected the CG-UCI to the slot in which the base station's downlink transmission begins. CAPC means the CAPC assumed when the terminal shares its initiated channel occupancy with the base station.

[0215] If information regarding the Energy Detection (ED) threshold is not set.

[0216] There may be cases where the base station does not set the ED threshold for the terminal. In other words, there may be cases where the terminal does not receive the ED threshold from the base station. That is, the base station does not need to configure the terminal to set the ED threshold by not configuring 'ULtoDL-CO-SharingED-Threshold-r16' as an RRC parameter for the ED threshold. In this case, if the uplink transmission performed by the terminal is CG-PUSCH, the CG-UCI of CG-PUSCH may include 'COT sharing information' indicating whether or not channel occupancy is shared. If the terminal indicates that channel occupancy is shared using the CG-UCI (for example, if the value of COT sharing information is 1), the terminal may accept X symbols set by the base station as for the downlink transmission performed by the base station. Specifically, the terminal may receive the RRC parameter 'cg-COT-SharingOffset-r16' from the base station indicating X symbols for downlink transmission, and the base station may accept X symbols as shared channel occupancy initiated by the terminal for downlink transmission. In this case, X symbols represent the last X symbols of slot n (slot #n) where the base station detected the CG-UCI.

[0217] In this case, the base station may transmit downlink after the terminal's uplink, but the length of the downlink transmission may be limited to a maximum of 2 symbols, 4 symbols, or 8 symbols, depending on the subcarrier interval. For example, if the subcarrier interval is 15 kHz, the downlink transmission may be limited to a maximum of 2 symbols; if the subcarrier interval is 30 kHz, the downlink transmission may be limited to a maximum of 4 symbols; and if the subcarrier interval is 60 kHz, the downlink transmission may be limited to a maximum of 8 symbols.

[0218] The following describes the downlink transmission performed by the base station after the uplink transmission by the terminal. In this case, the downlink transmission performed by the base station may be applicable whether or not the base station has transmitted (configured) RRC parameters for the ED threshold to the terminal.

[0219] i) When the base station configures the ED threshold on a terminal by configuring 'ULtoDL-CO-SharingED-Threshold-r16' as the RRC parameter for the ED threshold, the base station may perform a downlink transmission consisting only of DRS after the terminal has performed an uplink transmission (e.g., PUSCH) on a scheduled or configured resource. The DRS in this specification may include at least one SSB comprising a PSS (Primary synchronization signal), an SSS (Secondary synchronization signal), a PBCH (Physical broadcast channel), and a DM-RS for the PBCH. The DRS may also include a CORESET for a PDSCH that transmits a SIB1 (System information block 1) and a PDCCH that schedules it. The DRS may also include non-zero power CSI reference signals.

[0220] On the other hand, if the base station does not configure 'ULtoDL-CO-SharingED-Threshold-r16' as an RRC parameter for the ED threshold on the terminal, and therefore the ED threshold is not configured, downlink transmission including only DRS may be performed only if the subcarrier spacing is 30 kHz or more. This is because the minimum number of symbols occupied by SSB included in DRS is 4.

[0221] ii) After a terminal has made an uplink transmission (e.g., a push) on a scheduled or configured resource, the base station may make a downlink transmission including a DRS. In this case, the base station's downlink transmission may be multiplexed with non-unicast transmissions for any terminal.

[0222] iii) After a terminal has made an uplink (e.g., push) transmission on a scheduled or configured resource, the base station may make a downlink transmission. The downlink transmission made by the base station may include a reference signal for the terminal that initiated channel occupancy (e.g., CSI-RS, Tracking RS, etc.) and a non-unicast transmission for any terminal.

[0223] iv) After a terminal has made an uplink (e.g., push) transmission on a scheduled or configured resource, the base station may make a downlink transmission. In this case, the downlink transmission made by the base station may not include user plane data for the terminal that initiated channel occupancy, but may include a unicast transmission containing control plane data (e.g., data for RRC configuration) and a non-unicast transmission for any terminal.

[0224] When the channel occupancy initiated by the terminal is shared with the base station, after the terminal's uplink transmission, the base station can perform channel access using a gap smaller than or based on a specific gap, and then perform the downlink transmissions described in i) to iv) above. The base station's channel access procedure is described below.

[0225] If the gap is less than 16us, the base station can perform a Type 2C downlink channel access procedure before transmitting downlink. The Type 2C downlink channel access procedure means that the base station transmits downlink without performing channel sensing beforehand. The duration for downlink transmission may be limited to a maximum of 584us. (See 3GPP TS 37.213)

[0226] [Table 5]

[0227] If the gap is 16us, the base station can perform a Type 2B downlink channel access procedure before performing a downlink transmit. The Type 2B downlink channel access procedure means that the base station senses whether the channel is idle within a 16us (T_f) interval before immediately performing a downlink transmit. The 16us (T_f) interval may include one sensing slot within the last 9us. If the channel is sensed to be idle during the entire interval (e.g., at least 5us) including the interval in which sensing takes place in the sensing slot (e.g., at least 4us), the channel may be considered idle. (See 3GPP TS 37.213)

[0228] [Table 6]

[0229] If the gap is 25us, the base station can perform a Type 2A downlink channel access procedure before performing a downlink transmit. The Type 2A downlink channel access procedure means that the base station senses whether the channel is idle during a 25us (T_short_dl) sensing interval before immediately performing a downlink transmit. The 25us (T_short_dl) sensing interval may consist of a 16us (T_f) interval and one sensing slot (9us) immediately following the 16us (T_f) interval. The 16us (T_f) interval may contain one sensing slot (9us). If the 25us (T_short_dl) sensing interval (i.e., all sensing slots) is sensed to be idle, the channel may be considered idle during the 25us (T_short_dl) interval. (See 3GPP TS 37.213)

[0230] [Table 7]

[0231] Figure 16 shows a scheduling uplink transmission according to one embodiment of the present invention.

[0232] Specifically, Figure 16 illustrates the scheduled uplink transmission performed by a terminal when it is scheduled to perform consecutive, gap-free uplink transmissions after a resource configured for autonomous transmission or CG-PUSCH from the base station.

[0233] When a terminal is configured to perform the scheduled uplink transmission, the terminal may perform the scheduled uplink transmission without channel access if the following conditions are met: Uplink transmissions on resources configured for autonomous transmission or CG-PUSCH may be dropped at the last symbol of a slot prior to the start of the scheduled uplink transmission slot (e.g., the nth slot) (e.g., the (n-1)th slot).

[0234] The following describes the conditions under which a terminal can perform scheduled uplink transmissions without channel access.

[0235] a) The terminal must perform Category 4 channel access (e.g., Type 1 uplink channel access) for uplink transmission on a resource configured for autonomous transmission or CG-PUSCH. The terminal must perform uplink transmission on a resource configured for autonomous transmission or CG-PUSCH before the start of the scheduled uplink transmission slot.

[0236] b) The frequency domain resources for scheduled uplink transmission must be scheduled to occupy all resource blocks (RBs) of the LBT bandwidth (e.g., 20 MHz) that the first scheduled slot can occupy from the time domain resources set up for scheduled uplink transmission. Alternatively, all RBs of the uplink bandwidth part (BWP) set up on the terminal must be scheduled. In this case, the start symbol index of the first scheduled slot from the time domain resources set up for CG-PUSCH may be 0. Alternatively, there may be multiple LBT bandwidths within a single BWP. In this case, if resources for autonomous transmission or resources set up for CG-PUSCH are allocated to one or more LBT bandwidths within a single BWP, the frequency domain resources for scheduled uplink transmission may occupy all RBs of one subset of the one or more LBT bandwidths, or all RBs of all LBT bandwidths that include resources for autonomous transmission or resources set up for CG-PUSCH.

[0237] c) When a terminal makes Category 4 channel access (e.g., Type 1 uplink channel access) for uplink transmission on a resource configured for autonomous transmission or CG-PUSCH, the CAPC used must be greater than or equal to the CAPC instructed by the base station for scheduled uplink transmission.

[0238] d) The sum of the length of uplink transmissions on resources configured for autonomous transmission or CG-PUSCH and the length of scheduled uplink transmissions shall not exceed the Maximum Channel Occupancy Time (MCOT). In this case, the MCOT is the MCOT set when the terminal performs Category 4 channel access (e.g., Type 1 uplink channel access) for uplink transmissions on resources configured for autonomous transmission or CG-PUSCH.

[0239] If all of the above conditions a) to d) are not met, the terminal may interrupt an uplink transmission on a resource configured for autonomous transmission or CG-PUSCH at the last symbol of a slot prior to the start of a scheduled uplink transmission slot (e.g., the nth slot) (e.g., the (n-1)th slot). Alternatively, the terminal may interrupt an uplink transmission on a resource configured for autonomous transmission or CG-PUSCH at least one slot prior to the start of a scheduled uplink transmission slot (e.g., the nth slot) (e.g., the (n-1)th slot). On the other hand, if the time during which uplink transmission can be interrupted (the time during which cancellation is guaranteed) has not elapsed, the terminal may interrupt an uplink transmission on a resource configured for autonomous transmission or CG-PUSCH at least one slot prior to the start of a scheduled uplink transmission slot (e.g., the nth slot) (e.g., the (n-1)th slot). However, if the interruption period for uplink transmission has elapsed, the terminal may perform the scheduled uplink transmission in the next slot (e.g., the (n+1)th slot) after the start of the scheduled uplink transmission slot (e.g., the nth slot). In this case, the channel access procedure for performing the scheduled uplink transmission in the next slot (e.g., the (n+1)th slot) may be a Category 4 channel access (e.g., a Type 1 uplink channel access). Alternatively, if the resources for the scheduled uplink transmission are included in the MCOT configured when the terminal performs a Category 4 channel access (e.g., a Type 1 uplink channel access) for an uplink transmission using resources configured for autonomous transmission or CG-PUSCH, the terminal may perform the scheduled uplink transmission based on a Category 2 channel access (e.g., a Type 2A uplink channel access) procedure.

[0240] When an uplink transmission is scheduled from the base station without a gap following a resource configured for autonomous transmission or CG-PUSCH on the terminal, the terminal can perform the scheduled uplink transmission without channel access, depending on the type of scheduled uplink transmission. Possible types of scheduled uplink transmissions include PUSCH with UL-SCH (uplink-shared channel), PUSCH without UL-SCH, PUCCH which transmits uplink control information, uplink transmission associated with random access procedures (e.g., PRACH preamble, Msg3), and SRS (Sounding reference signal). In this case, PUCCH may include HARQ-ACK, SR (Scheduling Request), BFR (Beam-failure recovery request), or Channel State Information (CSI).

[0241] If the conditions a) to d) described above are met, the terminal can perform scheduled uplink transmissions without channel access (e.g., LBT), regardless of the type of scheduled uplink transmission.

[0242] If the scheduled uplink transmission is an uplink transmission other than a PUSCH transmission and satisfies the conditions a), c), and d) described above, the terminal can perform the scheduled uplink transmission without channel access.

[0243] If the scheduled uplink transmission is an uplink transmission other than PUSCH, including UL-SCH, and satisfies the conditions a), c), and d) described above, the terminal can perform the scheduled uplink transmission without channel access.

[0244] A scheduled uplink transmission may be a PUCCH containing at least one of HARQ-ACK, SR, or BFR. In this case, if the RRC configures interlaced-PUCCH transmission for PUCCH transmission and the PUCCH transmission is scheduled spread across the LBT bandwidth, and the conditions a), c), and d) described above are met, the terminal can perform the scheduled PUCCH transmission without channel access. A PUCCH containing at least one of HARQ-ACK, SR, or BFR is used to ensure transmission on the scheduled resource as much as possible, because failure of the channel access procedure can reduce the data transmission rate of uplink / downlink transmissions or significantly increase latency due to link failure. In addition, the CAPC used for PUCCH transmission may generally be set to 1. Therefore, the CAPC used for PUCCH transmission can always be smaller than or the same as the CAPC used when the terminal performs Category 4 channel access for uplink transmission on a resource configured for autonomous transmission or CG-PUSCH (e.g., Type 1 uplink channel access), thus satisfying condition c) above.

[0245] If the scheduled uplink transmission is an SRS transmission without PUSCH, a PUCCH transmission without UL-SCH, and a transmission associated with a random access procedure (e.g., PRACH preamble, Msg3), then the terminal can perform the scheduled uplink transmission without performing a channel access procedure if the conditions a), c), and d) described above are met. In this case, a Category 4 channel access procedure (e.g., Type 1 uplink channel access) may be performed for an SRS transmission without PUSCH, a PUCCH transmission without UL-SCH, and a transmission associated with a random access procedure (e.g., PRACH preamble, Msg3), in which case CAPC may be set to 1.

[0246] For the FBE (Frame based equipment)-based LBT operation in the unlicensed band, that is, when semi-static is used as the channel access mode, a channel access method and procedure for semi-static channel occupancy will be described. Specifically, the base station and the terminal can use the UE initiated channel occupancy that the terminal starts to perform the FBE operation. Using the UE initiated channel occupancy, a method for the base station and the terminal to transmit and receive channels will be described.

[0247] Devices operating in unlicensed bands mostly operate based on LBT (Listen-Before-Talk), so they perform Clear Channel Assessment (CCA) to sense the channel before data transmission. Communication devices (e.g., AP, STA) perform carrier sensing before transmitting data to check whether the channel is in use (busy). When a wireless signal with a certain intensity or above is sensed on the channel where data is to be transmitted, the channel is determined to be in use, and the communication device delays access to the channel. Such a process is called Clear Channel Assessment, and the signal level for determining the presence or absence of signal sensing is called the CCA threshold (CCA threshold). On the other hand, when no wireless signal is sensed on the channel or a wireless signal with an intensity lower than the CCA threshold is sensed, the channel is determined to be in an idle state. When the channel is determined to be in an idle state, the terminal having the data to transmit performs a backoff procedure after a deferral period (e.g., AIFS (Arbitration InterFrame Space), PIFS (PCF IFS), etc.). The deferral period means the minimum time that the terminal should wait after the channel becomes idle. The backoff procedure allows the terminal to wait for an arbitrary additional time after the deferral deadline. For example, the terminal waits while decreasing the slot time by the random number assigned to the terminal within the contention window (Contention Window, CW) during the period when the channel is idle, and the terminal whose slot time has expired can attempt to access the channel.

[0248] FIG. 17 shows the LBT operation process based on FBE according to an embodiment of the present invention.

[0249] LBT can be distinguished into FBE-type LBT and LBE (Load Based Equipment)-type LBT depending on the operating state of the terminal (see ETSI). In the FBE method, the base station and terminal cannot transmit data during the Fixed Frame Period (FFP) if the channel is occupied by other communication equipment. The Fixed Frame Period may consist of Channel Occupancy Time (COT) and Idle Period. In this case, Channel Occupancy Time means the time during which a communication node can sustain data transmission if it successfully accesses the channel, and may be in the range of 1ms to 10ms. The Idle Period may be a range of 5% or more of the Channel Occupancy Time. A Channel Control Assessment (CCA) process to observe the channel may be performed in a CCA slot (at least 20μs) located at the end of the Idle Period. A communication node can perform CCA on a fixed frame basis. For example, when a channel is unoccupied, a communication node can transmit data during the channel occupancy time; when a channel is occupied, the communication node can postpone data transmission and wait until the next cycle's CCA slot. In this specification, a communication node refers to a communication device and can mean a base station or a terminal.

[0250] Figure 18 shows the FBE operation according to one embodiment of the present invention.

[0251] Referring to Figure 18, a communication node can perform a Carrier Cancellation (CCA) process in a Carrier Cancellation (CCA) slot before transmitting data on a single carrier channel. If the CCA results in a idle state, the communication node can transmit data. If the CCA results in a busy state, the communication node waits for a time equal to the fixed frame period minus the CCA slot before performing the CCA process again. The communication node transmits data during the channel occupancy time, and once data transmission is complete, it waits for a time equal to the idle period minus the CCA slot before performing the CCA process again. On the other hand, if the channel is idle but the communication node has no data to transmit, the communication node waits for a time equal to the fixed frame period minus the CCA slot before performing the CCA process again.

[0252] In a scenario where LBE nodes are absent for an extended period at a level defined by the regulation level, and base stations (eNB or gNB) capable of FBE are synchronized, the FBE scheme can utilize frequency reuse factor 1. Therefore, random backoff is not required, reducing complexity for channel connectivity. The operation of LBE mode and FBE mode may differ in terms of channel access. In the FBE mode scheme, a communication node can acquire channel occupancy time by LBT category 2 channel access immediately before the fixed frame period. If the gap within the channel occupancy time initiated and acquired by the base station is 16us or less, the base station and terminals can use the category 1 channel access scheme. If the gap within the channel occupancy time acquired by the base station exceeds 16us, the base station and terminals can use the category 2 channel access scheme. Channel access operation may be configured so that the relevant constraints match those for FBE operation.

[0253] Figure 19 shows the operation of an LBE according to one embodiment of the present invention.

[0254] Referring to Figure 19(a), the communication node can perform CCA on each of the CCA slots at regular intervals in order to perform LBE operation.

[0255] Referring to Figure 19(b), the communication node can perform a CCA process in a CCA slot. If the channel in the first CCA slot is unoccupied, the communication node can transmit data for a time based on the maximum channel occupancy time. However, if the channel in the first CCA slot is occupied, the communication node can arbitrarily select a value of N and save it as the initial value of the counter. N can be any one of the values ​​1, 2, ..., q. The communication node senses the channel status on a per-CCA slot basis and, if the channel in a specific CCA slot is unoccupied, it can decrease the set counter value by 1. When the counter value reaches 0, the communication node can transmit data for a time length equal to the maximum channel occupancy time.

[0256] In Frame-Based Equipment (FBE) based LBT operation in unlicensed bands, i.e., when semi-static is used in channel access mode, terminals may be allowed to transmit data within a single channel occupancy period initiated by the base station, and the channel access procedure for this is defined in the 3GPP standard, as shown in Table 5.

[0257] [Table 8]

[0258] A base station can instruct a terminal that the channel access mode is semi-static using a higher-layer parameter. For example, a base station can use SIB1 or a dedicated RRC configuration to instruct a terminal that the channel access mode is semi-static with the higher-layer parameter "channelaccessmode-r16". In this case, the periodic channel occupancy is the maximum channel occupancy time (T_y), and may be initialized every two consecutive radio frames, starting with an even-indexed radio frame in x*T_x. In this case, T_y is 0.95*T_x, T_x is the channel occupancy period in ms, and x is a value indicated by the base station in the higher-layer parameter (semiStaticChannelAccessConfig-r16), which can be 0, 1, ..., 20 / T_x-1. The sensing slot interval (T_sl) described herein may be 9us. The dedicated RRC described herein is a dedicated RRC for a specific terminal, and the dedicated RRC setting may be the setting information that the base station sets on the terminal using the dedicated RRC for that specific terminal.

[0259] A single channel occupancy initiated by a base station and shared with a terminal must satisfy the following conditions:

[0260] i) Immediately after the base station detects that the channel is idle for at least the sensing slot interval (T_sl), it may transmit a downlink transmit burst that begins at the point where the channel occupancy time starts. If the channel is detected as being in use, the base station does not need to transmit any signals during the current channel occupancy time.

[0261] ii) If there is a gap of more than 16us between the downlink burst and the previous transmission, the base station may transmit a downlink transmit burst within the channel occupancy time immediately after detecting that the channel is idle, at least by T_sl.

[0262] iii) If the interval between the downlink transmit burst and the uplink transmit burst is a maximum of 16us, the base station can transmit a downlink transmit burst after the uplink transmit burst during the channel occupancy time without sensing the channel.

[0263] iv) The terminal can transmit an uplink transmit burst after detecting a downlink transmit burst within the channel occupancy time, as in iv-1 and iv-2.

[0264] iv-1) If the gap between the uplink transmit burst and the downlink transmit burst is a maximum of 16us, the terminal can transmit an uplink transmit burst after the downlink transmit burst during the channel occupancy time without sensing the channel.

[0265] iv-2) If the gap between the uplink transmit burst and the downlink transmit burst exceeds 16us, the terminal can detect that the channel is idle in at least one sensing slot interval (T_sl) within a 25us interval ending immediately before transmission, and then transmit an uplink transmit burst after the downlink transmit burst during the channel occupancy time.

[0266] v) Neither the base station nor the terminal can transmit any consecutive symbol sets for at least a T_z interval before the next channel occupancy time begins. In this case, T_z is max(0.05T_x, 100us), and max(a, b) is a function that returns the larger of a and b.

[0267] Conventionally, in unlicensed bandwidth, when the channel access mode is semi-static, a terminal initiates channel occupancy, or within the channel occupancy initiated by the terminal, the base station and the terminal share channel occupancy time, and neither the terminal nor the base station can transmit data. The following describes a method in which a terminal initiates channel occupancy, or a method in which the base station and the terminal share channel occupancy time within the channel occupancy initiated by the terminal and transmit data.

[0268] When the terminal operates as an initiating device, the signaling method for performing FBE operation is as follows.

[0269] Similar to when the base station operates as an initiating device, the base station can use upper layer signaling such as SIB1 or dedicated RRC configuration to instruct the terminal to operate as an initiating device on the current network. The base station knows that the current network situation is a controlled environment, or it is a single network environment mentioned in the regulation, or it knows that communication nodes operating in LBE do not exist for a long time at a level determined by the regulation level. Also, the base station knows that multiple base stations capable of FBE are synchronized. In other words, since the base station knows the scenario in which the terminal can perform FBE operation, the base station can instruct the terminal, through RRC configuration or MAC CE, to become an initiating device and transmit an uplink burst in FBE operation.

[0270] Or, when the base station instructs the terminal to perform transmission on the uplink channel or signal through scheduling, the base station can use dynamic L1 signaling to instruct the terminal to start the channel occupancy time (COT) as an initiating device and perform transmission, and share the COT with the base station for use in terminal and base station transmissions. Specifically, the base station's instruction to the terminal through dynamic L1 signaling may be by means of an uplink (UL) grant or a downlink (DL) grant that includes scheduling information for transmitting an uplink channel or signal. Or, the base station can use group common signaling to instruct the grouped terminals existing in the network.

[0271] A base station can use dynamic L1 signaling to instruct a terminal to decide whether to transmit an uplink channel or signal based on channel occupancy time initiated by the terminal as a channel occupancy initiator (UE-initiated COT) or based on channel occupancy time initiated and shared by the base station (shared gNB-initiated COT). Similarly, a terminal can decide whether to receive a downlink channel or signal scheduled by the base station based on channel occupancy time initiated and shared by the terminal via dynamic L1 signaling, or based on channel occupancy time initiated by the base station. The instructions given by the base station to a terminal via dynamic L1 signaling may be in the form of an uplink grant or downlink grant containing scheduling information for transmitting an uplink channel or signal. Alternatively, the base station can use group common signaling to instruct grouped terminals present in the network.

[0272] On the other hand, if a terminal does not transmit / receive an uplink / downlink channel or signal on an uplink grant or downlink grant scheduled by the base station using dynamic L1 signaling, that is, if the terminal transmits on the uplink due to a configured uplink grant, then the base station cannot instruct the terminal to decide whether to transmit based on the channel occupancy time initiated by the terminal as the occupancy initiator, or based on the channel occupancy time initiated by the base station, using dynamic L1 signaling.

[0273] When a terminal receives a downlink transmission through downlink detection and can recognize the channel occupancy time initiated and shared by the base station and FFP-g, it can perform an uplink transmission using the configured uplink grant in a section of FFP-g other than the idle section, assuming the channel occupancy time initiated and shared by the base station. In this case, FFP-g may be a fixed frame period set by the base station.

[0274] The terminal may be unable to receive downlink transmissions due to downlink detection, and therefore may not be able to assume the channel occupancy time and FFP-g initiated and shared by the base station, or the terminal may have set a channel occupancy time initiated by the terminal in the FFP-u section. In this case, if resources for uplink transmission are set by an uplink grant set within the channel occupancy time initiated by the terminal, the terminal can consider that the uplink transmission by the set uplink grant will be performed within the channel occupancy time initiated by the terminal. Therefore, the terminal can perform uplink transmission by the set uplink grant in the channel occupancy section initiated by the terminal in a section other than the idle section in FFP-u. In this case, FFP-u may be a fixed frame period set in the UE.

[0275] A base station may schedule an uplink channel or signal to a terminal via an uplink grant or downlink grant. In this case, the base station may configure the terminal with information about the channel access-related fields included in the uplink grant or downlink grant via RRC signaling. When the terminal has configured information about the channel access-related fields via RRC signaling, it can instruct the base station to decide whether to transmit based on the channel occupancy time initiated and shared by the base station or based on the channel occupancy time initiated by the terminal, using the channel access-related fields included in the uplink grant or downlink grant. However, there may be cases where the base station does not configure information about the channel access-related fields included in the uplink grant or downlink grant via RRC signaling, or where the information about the channel access-related fields is set to 0 bits via RRC signaling, i.e., the information about the channel access-related fields is 0 bits. In this case, the base station cannot instruct the terminal whether to transmit based on the channel occupancy time initiated by the terminal or based on the channel occupancy time initiated and shared by the base station. In this case, the terminal can perform uplink transmission in the same way as if it were performing uplink transmission with the configured uplink grant. That is, the terminal receives a downlink channel by downlink sensing, recognizes the channel occupancy time initiated and shared by the base station and FFP-g, and can perform uplink transmission in sections other than idle sections within the FFP-g section. However, if the terminal cannot receive a downlink channel by downlink sensing, and therefore cannot assume the channel occupancy time initiated and shared by the base station and FFP-g, the terminal can assume the channel occupancy time initiated by the terminal in the FFP-u section and can perform uplink transmission in sections other than idle sections within the FFP-u section configured for the terminal.

[0276] A terminal can transmit an uplink burst during a channel occupancy time initiated by the terminal, provided that an uplink channel transmission is scheduled and an uplink burst to be transmitted by the terminal exists. Furthermore, within the channel occupancy time initiated by the terminal, the terminal can share channel occupancy with the base station, and both the terminal's uplink burst transmission and the base station's downlink burst transmission may occur within the channel occupancy time initiated and shared by the terminal. In this case, the channel occupancy shared with the base station within the channel occupancy time initiated and shared by the terminal must satisfy the following conditions:

[0277] i) The terminal can transmit an uplink transmit burst that starts at the point where the channel occupancy time begins, immediately after sensing that the channel is idle for at least the sensing slot interval (T_sl). If the channel is sensed to be in use, the terminal does not need to transmit anything during the current channel occupancy time. However, if the base station transmits downlink data within the channel occupancy time initiated by the base station, and the terminal senses a downlink transmit burst during the channel occupancy time, the terminal can transmit data using the following methods i-1 and i-2.

[0278] i-1) If the gap between the uplink transmit burst and the downlink transmit burst is a maximum of 16us, the terminal may not detect the channel and can transmit an uplink transmit burst after the downlink transmit burst within the channel occupancy time.

[0279] i-2) If the gap between the uplink transmit burst and the downlink transmit burst exceeds 16us, the terminal can detect that the channel is idle in at least one sensing slot interval (T_sl) within a 25us interval ending immediately before transmission, and then transmit an uplink transmit burst after the downlink transmit burst within the channel occupancy time.

[0280] ii) If there is a gap of more than 16us between the uplink transmit burst and the previous transmit, the base station may transmit the uplink transmit burst within the channel occupancy time immediately after detecting that the channel is idle, at least by T_sl.

[0281] iii) If the interval between the uplink transmit burst and the downlink transmit burst is a maximum of 16us, the terminal may not detect the channel and may transmit an uplink transmit burst after the downlink transmit burst within the channel occupancy time.

[0282] iv) The base station can transmit a DL transmit burst after detecting an uplink transmit burst within the channel occupancy time, as in iv-1 and iv-2.

[0283] iv-1) When the gap between the uplink transmit burst and the downlink transmit burst is a maximum of 16us, the base station can transmit a downlink transmit burst after the uplink transmit burst within the channel occupancy time without sensing the channel.

[0284] iv-2) If the gap between the uplink transmit burst and the downlink transmit burst exceeds 16us, the base station may, after sensing that the channel is idle in at least one sensing slot section (T_sl) within a 25us interval ending immediately before transmission, transmit the downlink transmit burst after the uplink transmit burst within the channel occupancy time.

[0285] v) Neither the base station nor the terminal can transmit any consecutive symbol sets for at least a T_z interval before the next channel occupancy time begins. In this case, T_z is max(0.05T_x, 100us).

[0286] When a base station acts as a channel occupancy initiator, it can manage and schedule uplink transmissions to individual terminals, which has the effect of allowing flexible multiplexing between different terminals in a single channel occupancy. However, when a terminal acts as a channel occupancy initiator, collisions can occur in inter-terminal transmissions due to channel occupancy times that start at different times or with different lengths (number of symbols). Specifically, when terminals share channel occupancy time initiated by the base station and the base station performs downlink transmissions, there may be channel occupancy times initiated by multiple terminals at different times or with different lengths. In this case, ambiguity may arise in the base station's channel access for downlink transmissions depending on whether or not it has detected the uplink transmissions performed by each different terminal. Therefore, this specification proposes a method to solve the collision problem caused by channel occupancy times initiated by different terminals at different times or with different lengths. Furthermore, it proposes a method to solve the ambiguity in channel access for downlink transmissions when the base station performs downlink transmissions while sharing channel occupancy time between terminals and the base station.

[0287] When the channel access mode is operating in LBE mode rather than semi-static, a terminal may transmit an autonomous transmission or a configured grant push on an existing unlicensed band. In this case, the push transmitted by the terminal may include a UCI. The UCI may include HARQ-ID, NDI (New Data Indication), RV, (CAPC), and channel occupancy time sharing (COT sharing) information. Based on the CAPC and channel occupancy time sharing information included in the UCI transmitted by the terminal, the base station can determine the channel occupancy time with the base station within the channel occupancy time initiated by the terminal. The base station can then perform downlink transmission within the channel occupancy time initiated by the terminal.

[0288] The terminal can share the channel occupancy time initiated by the terminal with the base station in semi-static channel access mode and transmit a configured grant PUSCH. At this time, the UCI included in the PUSCH may include channel occupancy time sharing information. The base station can confirm the channel occupancy time initiated by the terminal based on the channel occupancy time sharing information included in the UCI transmitted by the terminal. The base station can then perform channel access within the channel occupancy time initiated by the terminal and transmit a downlink burst. At this time, channel access may be performed by the gap length. For example,

[0289] i) If the transmission of a downlink burst must begin and end within the channel occupancy time initiated by the terminal, the base station can access the channel and transmit the downlink burst according to the respective gap lengths. As another example, if the transmission of a downlink burst begins within the channel occupancy time initiated by the terminal, but the end of the downlink burst does not fall within that time, the base station can interrupt the transmission of the downlink burst outside of the terminal's channel occupancy time on a slot or symbol basis. This is to ensure that downlink bursts are transmitted only within the channel occupancy time initiated by the terminal.

[0290] ii) If a downlink burst transmission begins within the channel occupancy time initiated by the terminal, but the end of the downlink burst does not fall within that time, the base station can perform channel sensing again for the transmission of the downlink burst that does not fall within the channel occupancy time initiated by the terminal. Specifically, for the transmission of a downlink burst that does not fall within the channel occupancy time initiated by the terminal, the base station can perform channel sensing within the x*T_x section of the radio frame after the channel occupancy time initiated by the terminal, set up channel occupancy, and transmit the downlink burst.

[0291] iii) The transmission of a downlink burst may begin within the channel occupancy time initiated by the terminal, but the end of the downlink burst may not fall within the channel occupancy time initiated by the terminal. In this case, if the length of the downlink burst that does not fall within the channel occupancy time initiated by the terminal falls within the x*T_x interval of the FBE operation in which the channel occupancy time initiated by the terminal exists, the base station can sense the channel in one sensing slot interval (T_sl) and, if it is idle, can transmit a downlink burst.

[0292] Unlike a configured Grant PUSCH, a terminal that transmits channels and signals set by scheduling from the base station and channels used in random access procedures may become a channel occupancy initiator. In this case, the channel occupancy time initiated by the terminal may be shared with the base station. For channels and signals set by scheduling and channels used in random access procedures, there is no mechanism for the terminal to provide channel occupancy time sharing information to the base station via PUSCH. Therefore, the base station does not know the information related to the channel occupancy initiated and shared by the terminal as a channel occupancy initiator. In this case, ambiguity may arise in the channel access method used by the base station to transmit downlink bursts. The following describes how to resolve the ambiguity regarding the channel access method.

[0293] The channels and signals set by scheduling from the base station and the channels used for random access procedures may be transmitted on resources scheduled based on resource allocation information regarding time and frequency resources transmitted by the base station. Specifically, when the base station transmits downlink control information via PDCCH and the terminal successfully receives the PDCCH, the base station can transmit resource allocation information to the terminal, and the terminal can perform uplink transmission based on the resource allocation information. In this case, the channels used for random access procedures may be PRACH for non-conflict-based random access and PRACH for 2-step random access procedures, other than PRACH for conflict-based random access procedures. Therefore, the terminal can transmit the channels and signals scheduled from the base station to the base station, and the base station can sense the channels and signals transmitted from the terminal. In this case, the base station can determine the length of channel occupancy time initiated and shared by the terminal based on the resource allocation information set on the terminal. In this case, the resource allocation information may be time-domain resource allocation (TDRA) information.

[0294] When a terminal and a base station are synchronized in FBE mode, the base station can transmit a downlink burst within the T_y interval, taking into account the length of the channel occupancy time initiated and shared by the terminal and the T_x interval. T_y is an interval within the T_x interval other than the interval in which the base station performs channel sensing, and may be 0.95*T_x[0ms]. In this case, if a gap of more than 16us exists, the base station can sense the channel in one sensing slot interval (T_sl), and if the channel is idle, it can transmit a downlink burst.

[0295] In order for LBT to be performed when operating in LBE mode, channel access priority classes may be set for scheduled channels and signals and channels used during random access procedures. Based on the maximum channel occupancy time corresponding to the channel access priority class used by each channel and signal, the base station and the terminal can determine the length of the channel occupancy time that the terminal will start. The length of channel occupancy time that the base station and the terminal assume for scheduled channels and signals and channels used during random access procedures is as follows:

[0296] i) When only PUSCH is transmitted without PUCCH or UL-SCH, the LBT priority class or channel access priority may be 1. The length of the available channel occupancy time in this case may be set to the MCOT value of 2ms, as disclosed in Table 6.

[0297] ii) The priority class or channel access priority class of a PUSCH associated with a random access procedure that does not have PRACH and user plane data may be 1. In this case, the length of the channel occupancy time initiated by the terminal may be set to 2ms, which is the MCOT value, as disclosed in Table 6.

[0298] iii) An SRS that does not include a PUSCH may have an LBT priority class or channel access priority class of 1. In this case, the length of the channel occupancy time initiated by the terminal may be set to 2ms, which is the MCOT value, as disclosed in Table 6.

[0299] iv) For PUSCH operations other than those described in i) to iii), the length of channel occupancy may be set based on the traffic transmitted by the terminal or the channel access priority class instructed by the base station to the terminal. Specifically, the MCOT value disclosed in Table 6 may be set as the length of channel occupancy.

[0300] v) When various types of uplink channels and signals are mixed to form a single uplink burst, the channel occupancy time may be set to the longest MCOT length that can be set for each channel and signal. Alternatively, the channel occupancy time may be set to the longest length in time relative to the resources configured to transmit the mixed uplink burst.

[0301] Table 6 shows the parameter values ​​used for channel access by channel access priority class for uplink transmission in the LTE LAA system.

[0302] [Table 9]

[0303] Referring to Table 6, the MCOT value of 6ms may increase to 8ms if the transmission contains one or more gaps. A gap refers to the time between the interruption and restart of transmission on a carrier. In this case, the minimum duration of the gap may be 100us. The maximum duration of transmissions performed before the gap may be 6ms. The duration of the gap does not need to be included in the channel occupancy time.

[0304] The MCOT value may be 10ms if the channel access priority class value is 3 or 4 and it is guaranteed that no other wireless connectivity technology is used by the carrier on which the channel access is performed. In this case, the other wireless connectivity technology may include Wi-Fi. Otherwise, the MCOT value may be determined as shown in NOTE 1 of Table 6.

[0305] MCOT refers to the maximum amount of time that a starting node can continuously occupy a channel of any one carrier in the unlicensed bandwidth. Gaps, which are periods in which no transmissions occur, may be included between multiple transmissions, and if gaps are included, the value of MCOT may be applied differently.

[0306] Hereafter, this specification describes how a base station and a terminal transmit within a channel occupancy time initiated by the base station, which is shared between the base station and the terminal, when the base station and the terminal are operating in FBE mode, that is, when the channel access mode is semi-static.

[0307] First, we will explain the signaling method for FBE operation when a terminal is operating as a channel occupancy initiator. The base station can instruct the terminal that it is capable of operating as a channel occupancy initiator through higher-layer signaling such as SIB1 or dedicated RRC settings. The base station can also provide the terminal with FFP information through higher-layer signaling such as SIB1 or dedicated RRC settings, and the terminal that receives this information can configure FFP.

[0308] However, the signaling configuration for semi-static channel access mode information or FFP information may not be set by SIB1, which the base station can receive before the terminal establishes RRC connection, and the signaling configuration for semi-static channel access mode information or FFP information may be set by dedicated RRC configuration information that the terminal can receive after RRC connection. In this case, the terminal needs to assume the FFP set on the terminal for sending the PRACH preamble and Msg3, which should be sent during the random access procedure that the terminal should transmit before RRC connection. This is because the PRACH preamble and Msg3 must be sent before RRC connection. That is, when operating in FBE mode, transmission is not permitted in idle sections, but transmission is permitted in sections other than idle sections within the FFP section. Therefore, if the terminal cannot receive channel access mode information or FFP information from the base station, it may assume the FFP set on the base station is the terminal's FFP and perform uplink transmission. In this case, the terminal can perform uplink transmission in sections of the FFP (Frequency Frequency Plan) set for the base station that are not idle sections. The base station can perform downlink transmission in sections of the FFP set for the base station that are not idle sections. If the FFP assumed by the terminal is different from the FFP set for the base station, downlink transmission does not need to be performed in sections of the FFP set for the base station that are not idle sections. However, since the FFP assumed by the terminal is the same as the FFP set for the base station, the base station can perform downlink transmission in sections of the FFP set for the base station that are not idle sections. In other words, if the FFPs are different between the base station and the terminal, the section in which the base station performs downlink transmission is a section of the FFP set for the base station that is not idle sections, but it may be an idle section of the FFP set for the terminal.

[0309] Even before RRC connection is established, a terminal can receive a PRACH opportunity from the base station in which it can send a PRACH. The base station can set a PRACH opportunity for the terminal within a section of the FFP configured on the base station that is not idle. If the terminal cannot receive information about the channel access mode or FFP from the base station, the terminal can perform uplink transmission assuming that the FFP configured on the base station is the terminal's FFP. In this case, it is necessary to define whether the terminal will transmit without channel sensing or after channel sensing when performing uplink transmission.

[0310] A base station can set up a PRACH opportunity for a terminal regardless of idle sections within the FFP configured for the base station. In other words, some or all of a PRACH opportunity may be included in the idle sections within the FFP configured for the base station. In this case, the terminal can transmit a PRACH on a PRACH opportunity set up in a section of the FFP other than the idle section configured for the base station. The terminal cannot receive downlink transmissions from the base station and can perform uplink transmissions in sections of the FFP other than the idle sections. The method by which the terminal performs uplink transmissions is as follows. In this specification, uplink / downlink bursts may include uplink / downlink channels and signals.

[0311] i) Immediately after sensing that a channel is idle for at least the sensing slot interval (T_sl), the terminal may transmit an uplink burst containing a channel or signal to be transmitted on the uplink before the RRC connection begins at the start of the channel occupancy time. If channel sensing results in the channel being sensed as in use, the terminal does not need to transmit anything during the current channel occupancy time. However, if the terminal senses a downlink burst transmitted within a channel occupancy initiated by the base station, the terminal may transmit an uplink burst within the channel occupancy time initiated by the base station using the i-1 or i-2 method.

[0312] i-1) If the gap between the uplink burst and the downlink burst before RRC coupling is a maximum of 16us, the terminal may transmit the uplink burst after the downlink burst without sensing the channel.

[0313] i-2) If the gap between the uplink burst and the downlink burst exceeds 16us before RRC coupling, the terminal may, after sensing that the channel is idle in at least one sensing slot section (T_sl) within a 25us interval ending immediately before transmitting the uplink burst, transmit an uplink burst after the downlink burst within the channel occupancy time.

[0314] ii) If there is a gap of more than 16us between the uplink burst and the previous transmission before RRC coupling, the terminal may transmit the uplink burst within the channel occupancy time immediately after sensing that the channel is idle in at least one sensing slot interval (T_sl).

[0315] iii) If the gap between the uplink burst and the downlink burst is a maximum of 16us, the terminal can transmit an uplink transmit burst after a downlink transmit burst within the channel occupancy time without sensing the channel.

[0316] iv) The base station may transmit a downlink burst after detecting an uplink burst transmitted within the channel occupancy time before RRC connection.

[0317] iv-1) If the gap between the uplink burst and the downlink burst is a maximum of 16us, the base station can transmit the downlink burst after the uplink burst, which is transmitted within the channel occupancy time before RRC coupling, without sensing the channel.

[0318] iv-2) If the gap between the uplink burst and the downlink burst exceeds 16us, the base station can sense that the channel is idle for at least one sensing slot interval (T_sl) within a 25us interval ending immediately before the transmission of the downlink burst. The base station can then transmit the downlink burst after the uplink burst, which is transmitted within the channel occupancy time before RRC coupling.

[0319] v) Neither the base station nor the terminal may transmit on a continuous set of symbols for at least a T_z interval before the next channel occupancy time begins. T_z may be max(0.05T_x, 100us).

[0320] It is possible that different FFPs (First Frequency Programs) may be configured between the terminal and the base station, resulting in uplink and downlink transmissions. The following describes how the terminal performs uplink transmissions and how the base station performs downlink transmissions.

[0321] Figures 20 to 23 show a method for performing uplink transmission and downlink transmission when different FFPs are set for the base station and terminal according to one embodiment of the present invention. In Figures 20 to 23, FFP-u is the FFP set for the terminal, and FFP-g is the FFP set for the base station. idle-u is the idle interval set for the terminal, and idle-g is the idle interval set for the base station.

[0322] Referring to Figure 20, different FFPs may be configured for the base station and the terminal. In this case, the base station can refrain from downlink transmissions in idle sections of the FFP configured for the base station, and perform downlink transmissions in idle sections of the FFP configured for the terminal. In other words, the terminal can receive downlink transmissions performed by the base station in idle sections of the FFP configured for the terminal. Similarly, the terminal can refrain from uplink transmissions in idle sections of the FFP configured for the terminal, and perform uplink transmissions in idle sections of the FFP configured for the base station. In other words, the base station can receive uplink transmissions performed by the terminal in idle sections of the FFP configured for the base station.

[0323] Referring to Figure 21, different FFPs may be configured for the base station and the terminal. In this case, the base station and the terminal can assume that no uplink transmissions or downlink transmissions occur within any idle intervals. In other words, the base station and the terminal can assume that no uplink transmissions or downlink transmissions occur within the idle intervals of the FFP configured for the base station and the FFP configured for the terminal. That is, the base station can assume that it cannot perform downlink transmissions within the idle intervals of the FFP configured for the base station, and that there are no uplink transmissions from the terminal. Similarly, the terminal can assume that it cannot perform downlink transmissions within the idle intervals of the FFP configured for the terminal, and that there are no uplink transmissions from the base station.

[0324] Referring to Figure 22, different FFPs may be configured for the base station and the terminal. In this case, the base station may refrain from downlink transmission only in idle segments of the FFP configured for the base station, and may perform downlink transmission in idle segments of the FFP configured for the terminal. In other words, the terminal can receive downlink transmissions performed by the base station in idle segments of the FFP configured for the terminal. The terminal may refrain from uplink transmissions in idle segments of the FFP configured for the terminal, and may perform uplink transmissions in idle segments of the FFP configured for the base station. In other words, the base station can receive uplink transmissions performed by the terminal in idle segments of the FFP configured for the base station.

[0325] Referring to Figure 23, different FFPs may be configured for the base station and the terminal. In this case, the base station and the terminal can assume that no uplink transmissions or downlink transmissions occur within any idle sections. In other words, the base station and the terminal can assume that no uplink transmissions or downlink transmissions occur within the idle sections of the FFP configured for the base station and the FFP configured for the terminal. That is, the base station can assume that it cannot perform downlink transmissions within the idle sections of the FFP configured for the base station, and that there are no uplink transmissions to be performed by the terminal. Similarly, the terminal can assume that it cannot perform downlink transmissions within the idle sections of the FFP configured for the terminal, and that there are no uplink transmissions to be performed by the base station. Uplink transmissions performed by the terminal to the base station may be scheduled by the base station. In addition, sections other than the idle sections within the FFP configured for the base station and the FFP configured for the terminal may be configured for downlink transmissions or uplink transmissions. Therefore, sections other than the idle sections within the FFP configured for the base station may be configured for downlink transmissions and uplink receptions. A base station can perform downlink transmissions in sections of its FFP (Frequently Used Frequency Plan) other than idle sections where downlink transmission is configured, and can receive uplink transmissions made by terminals in sections where uplink transmission is configured. Similarly, a terminal can perform uplink transmissions in sections of its FFP other than idle sections where uplink transmission is configured, and can receive downlink transmissions sent by base stations when downlink transmission is configured.

[0326] The method described in Figures 20 to 23 may be applied when the base station and terminal are aware of the FFP set on each. However, the FFP set on the base station can be communicated to the terminal by the base station via SIB1 or dedicated signaling. Therefore, there is no ambiguity regarding the FFP set on the base station between the base station and the terminal. However, when the channel occupancy time initiated by the terminal is shared with the base station in the FFP set on the terminal, the base station may not be able to determine the channel occupancy time initiated by the terminal. When the base station detects an uplink transmission performed by the terminal within the FFP set on the terminal, the base station can determine the channel occupancy time within the FFP set on the terminal. Then, the base station can perform a downlink transmission before the idle period within the determined channel occupancy time. At this time, the conditions for the base station to perform a downlink transmission and the channel sensing method will be described.

[0327] If there is a gap of more than 16us between a downlink transmit burst and a previous transmit, the base station can detect an idle channel in one sensing slot interval (T_sl) and transmit a downlink burst immediately after detection within the channel occupancy time. If the gap between a downlink burst and an uplink burst is a maximum of 16us, the base station can not sense the channel and transmit a downlink transmit burst after an uplink transmit burst within the channel occupancy time.

[0328] However, if the base station cannot detect an uplink transmission within the FFP configured on the terminal, the base station cannot recognize the channel occupancy time initiated by the terminal. Therefore, the base station can only perform downlink transmissions in sections of the FFP configured on the base station that are not idle. The base station can perform channel sensing in at least one sensing slot section (T_sl) to detect that the channel is idle, and immediately after detection, can transmit a downlink burst starting from the beginning of the channel occupancy time. If the channel sensing results in the channel being detected as in use, the base station does not need to perform any transmissions in the FFP section configured on the base station. If there is a gap of more than 16us between the downlink burst and the previous transmission, the base station can perform channel sensing in at least one sensing slot section to detect an idle channel, and immediately after detection, can transmit a downlink burst within the FFP configured on the base station.

[0329] This document explains how multiple devices can be configured with different First File Processors (FFPs) and how each device can perform uplink transmission.

[0330] When a base station configures different FFPs (First Frequency Processors) for multiple different terminals using UE-specific dedicated signaling, one terminal cannot determine whether the other terminals are configured with the same FFP or a different FFP. In this case, one terminal can choose not to perform uplink transmissions within the idle intervals of the configured FFP, and instead perform uplink transmissions within the intervals other than the idle intervals. Furthermore, when a terminal shares channel occupancy time initiated by a base station within the FFP configured on the base station, the terminal does not need to perform uplink transmissions within the idle intervals of the shared channel occupancy time.

[0331] Figure 24 shows a method by which a terminal according to one embodiment of the present invention transmits an uplink channel.

[0332] Referring to Figure 24, the method for transmitting the uplink channel (signal) described in Figures 1 to 23 will be explained.

[0333] The terminal can receive resource information from the base station related to the transmission of the uplink channel (S2410).

[0334] The terminal can detect the downlink channel transmitted from the base station (S2420).

[0335] The base station can transmit an uplink channel based on the resource information obtained from the downlink channel sensing result (S2430).

[0336] In this case, the uplink channel may be transmitted based on a COT initiated and shared by the base station, or based on a COT initiated by the terminal.

[0337] The uplink channel transmitted by the terminal may be transmitted based on a configured grant. If the terminal detects a downlink channel as a result of the downlink channel detection performed by the terminal at the S2420 stage, the uplink channel may be transmitted based on a COT initiated and shared by the base station. On the other hand, if the terminal does not detect a downlink channel, the uplink channel may be transmitted based on a COT initiated by the terminal. In this case, the COT initiated and shared by the base station may be a section within the FFP (Fixed Frame Period) set up in the base station, and the COT initiated by the terminal may be a section within the FFP set up in the terminal. The FFP set up in the base station and the FFP set up in the terminal may be different from each other. When the uplink channel is transmitted based on a COT initiated and shared by the base station, the uplink channel may be transmitted in a section other than the idle section within the FFP set up in the base station. On the other hand, when the uplink channel is transmitted based on a COT initiated by the terminal, the uplink channel may be transmitted in a section other than the idle section within the FFP set up for the terminal. When the uplink channel is transmitted based on a COT initiated by the terminal, the uplink channel may be transmitted regardless of whether the section in which the uplink channel is transmitted is included in the idle section within the FFP set up for the base station. On the other hand, when the uplink channel is transmitted based on a COT initiated and shared by the base station, the uplink channel may be transmitted in a section other than the idle section within the FFP set up for the base station. In this case, the FFP set up for the terminal may be set up for the terminal by dedicated RRC signaling information.

[0338] On the other hand, the uplink channel may be scheduled by dynamic signaling from the base station. In this case, the terminal can receive dynamic signaling from the base station that includes scheduling information for transmitting the uplink channel. The resource information may be included in the scheduling information. If the scheduling information includes information about the COT on which the uplink channel is transmitted, the step of sensing the downlink channel is not performed, and the uplink channel may be transmitted based on the information about the COT. However, if the scheduling information does not include information about the COT on which the uplink channel is transmitted, the uplink channel may be transmitted based on the scheduling information based on the downlink channel sensing result. The information about the COT may be information indicating whether the uplink channel is transmitted based on a COT initiated and shared by the base station or based on a COT initiated by the terminal. The information about the COT may be included in the field for channel access that constitutes the dynamic signaling.

[0339] The terminal that performs the uplink channel transmission method described in Figure 24 may be the terminal described in Figure 14. Specifically, the terminal may be configured to include a communication module for sending and receiving radio signals and a processor for controlling the communication module. In this case, the processor may perform the uplink channel (signal) transmission method described in Figure 24. Similarly, the base station may be the base station described in Figure 14. The base station may also be configured to include a communication module for sending and receiving radio signals and a processor for controlling the communication module. That is, the base station can receive the uplink channel (signal) described in Figure 24 from the terminal. In this case, the base station's processor may perform the uplink channel (signal) reception method.

[0340] Although the methods and systems of the present invention have been described in relation to specific embodiments, some or all of their components or operations may be embodied using a computer system having a general-purpose hardware architecture.

[0341] The above description of the present invention is illustrative, and a person with ordinary skill in the art to which the present invention belongs will understand that it can be easily modified into other specific forms without altering the technical idea or essential features of the present invention. Accordingly, the embodiments described above should be understood to be illustrative and not limiting in any respect. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

[0342] The scope of the present invention is defined by the claims, which are set forth below rather than by the above detailed description, and any modifications or alterations derived from the meaning and scope of the claims and the concept of equivalents thereof should be interpreted as being included within the scope of the present invention.

Claims

1. User equipment (UE) configured to operate in a wireless communication system, Communication module; and Includes a processor configured to control the aforementioned communication module, The aforementioned processor, The system receives configuration information related to a base station (BS) fixed frame period (FFP) including a first idle period, and dedicated configuration information related to a UE FFP including a second idle period. The uplink (UL) transmission is performed based on whether the uplink transmission is related to a channel occupancy (CO) initiated by the BS or a CO initiated by the UE. It is configured in such a way, If the aforementioned UE has already initiated a CO within the UE FFP section, and the UL transmission occurs due to a configured grant (CG) set within the UE FFP section, then the UL transmission is determined to be related to the CO initiated by the aforementioned UE. If the UL transmission is scheduled by downlink control information (DCI), the UE determines, based on the information in the fields related to channel access within the DCI, that the UL transmission is related to a CO initiated by the BS or a CO initiated by the UE.

2. The UE according to claim 1, wherein, if the UE has not yet initiated the CO within the UE FFP section and the CG causes the UL transmission, whether the UL transmission is determined to be related to the CO initiated by the BS depends on whether a downlink (DL) channel is detected by the UE.

3. The UE according to claim 2, wherein the UE has not yet started the CO within the UE FFP section, and the CG causes the UL transmission, and the UE detects the DL channel, the UL transmission is determined to be related to the CO started by the BS.

4. The UE according to claim 1, wherein the DCI includes a DL grant or an UL grant.

5. The UL transmission is performed as follows, namely, - If the UL transmission is related to a CO initiated by the BS, the UL transmission is performed in a section other than the first idle section within the BS FFP. - The UE according to claim 1, wherein if the UL transmission is related to a CO initiated by the UE, the UL transmission is performed in a section of the UE FFP other than the second idle section.

6. The UE according to claim 1, wherein when the UL transmission is performed based on a CO initiated by the UE, the UL transmission is performed regardless of whether the section in which the UL transmission is performed is included in the first idle section within the BS FFP.

7. The UE according to claim 1, wherein the dedicated configuration information related to the UE FFP is received by radio resource control (RRC) signaling.

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

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

10. A method performed by a user device (UE) configured to operate in a wireless communication system, The steps include receiving configuration information related to a base station (BS) fixed frame period (FFP) including a first idle period, and dedicated configuration information related to a UE FFP including a second idle period, The steps include performing the uplink (UL) transmission based on whether the uplink (UL) transmission is related to a channel occupancy (CO) initiated by the BS or a CO initiated by the UE, and Includes, If the aforementioned UE has already initiated a CO within the UE FFP section, and the UL transmission occurs due to a configured grant (CG) set within the UE FFP section, then the UL transmission is determined to be related to the CO initiated by the aforementioned UE. A method in which, when the UL transmission is scheduled by downlink control information (DCI), it is determined, based on information in the fields related to channel access within the DCI, that the UL transmission is related to a CO initiated by the BS or a CO initiated by the UE.

11. The method of claim 10, wherein, if the UE has not yet initiated the CO within the UE FFP section and the CG causes the UL transmission, whether the UL transmission is determined to be related to the CO initiated by the BS depends on whether a downlink (DL) channel is detected by the UE.

12. The method according to claim 11, wherein the UE has not yet started the CO within the UE FFP section, and the CG causes the UL transmission, and the UE detects the DL channel, the UL transmission is determined to be related to the CO started by the BS.

13. The method according to claim 10, wherein the DCI includes a DL grant or an UL grant.

14. The UL transmission is performed as follows, namely, - If the UL transmission is related to a CO initiated by the BS, the UL transmission is performed in a section other than the first idle section within the BS FFP. - The method according to claim 10, wherein if the UL transmission is related to a CO initiated by the UE, the UL transmission is performed in a section of the UE FFP other than the second idle section.

15. The method according to claim 10, wherein when the UL transmission is performed based on a CO initiated by the UE, the UL transmission is performed regardless of whether the section in which the UL transmission is performed is included in the first idle section within the BS FFP.

16. The method according to claim 10, wherein the dedicated configuration information related to the UE FFP is received by radio resource control (RRC) signaling.

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

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

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