KR20220139191A - Method, apparatus, and system for performing channel access in unlicensed spectrum - Google Patents

Abstract

A purpose of the present invention is to provide a channel access method for performing transmission in a base station and a terminal on an unlicensed band in a wireless communication system, particularly a cellular wireless communication system, a method for transmitting in a base station and receiving in a terminal and a device thereof, and a system thereof. In addition, provided are a method for efficiently transmitting a signal in a wireless communication system, particularly a cellular wireless communication system, and a device thereof. Another purpose of the present invention is to provide a method for efficiently sensing a channel in a specific frequency band (e.g., an unlicensed band) and transmitting a signal/channel, a method for receiving the signal/channel, and a device therefor.

Description

Channel access method and device in unlicensed band {METHOD, APPARATUS, AND SYSTEM FOR PERFORMING CHANNEL ACCESS IN UNLICENSED SPECTRUM}

The present invention relates to a method, apparatus, and system for channel access in a base station and a terminal when a frame structure and system based on NR are used in an unlicensed band.

After commercialization of 4G (4th generation) communication system, efforts are being made to develop a new 5G (5th generation) communication system in order to meet the increasing demand for wireless data traffic. 5G communication system is called a 4G network after (beyond 4G network) communication system, LTE system after (post LTE) system or NR (new radio) system. In order to achieve a high data rate, the 5G communication system includes a system operated using an ultra-high frequency (mmWave) band of 6 GHz or higher, and a communication system operated using a frequency band of 6 GHz or less in terms of securing coverage Implementation in the base station and the terminal, including

The 3rd generation partnership project (3GPP) NR system improves the spectral efficiency of the network, allowing carriers to provide more data and voice services in a given bandwidth. Therefore, the 3GPP NR system is designed to meet the demand for high-speed data and media transmission in addition to high-capacity voice support. The advantages of the NR system are that it can have low operating costs with high throughput, low latency, support for frequency division duplex (FDD) and time division duplex (TDD) on the same platform, improved end-user experience and simple architecture.

For more efficient data processing, dynamic TDD of the NR system may use a method of varying the number of orthogonal frequency division multiplexing (OFDM) symbols that can be used for uplink and downlink according to the data traffic direction of users of the cell. For example, when the downlink traffic of the cell is greater than the uplink traffic, the base station may allocate a plurality of downlink OFDM symbols to a slot (or subframe). Information on the slot configuration should be transmitted to the terminals.

In order to alleviate the path loss of radio waves and increase the propagation distance of radio waves in the ultra-high frequency band, in the 5G communication system, beamforming, massive MIMO, full dimensional MIMO, FD-MIMO ), an array antenna, analog beam-forming, hybrid beamforming that combines analog beamforming and digital beamforming, and large scale antenna technologies are being discussed. In addition, to improve the network of the system, in the 5G communication system, an evolved small cell, an advanced small cell, a cloud radio access network (cloud radio access network: cloud RAN), an ultra-dense network (ultra-dense network) , device to device communication (D2D), vehicle to everything communication (V2X), wireless backhaul, non-terrestrial network communication (NTN), mobile network (moving network), cooperative communication (cooperative communication), CoMP (coordinated multi-points), and technology development related to reception interference cancellation (interference cancellation) and the like are being made. In addition, in the 5G system, hybrid FSK and QAM modulation (FQAM) and sliding window superposition coding (SWSC), which are advanced coding modulation (ACM) methods, and filter bank multi-carrier (FBMC), which are advanced access technologies, Non-orthogonal multiple access (NOMA) and sparse code multiple access (SCMA) are being developed.

On the other hand, the Internet is evolving from a human-centered connection network where humans create and consume information to an Internet of Things (IoT) network that exchanges and processes information between distributed components such as objects. Internet of Everything (IoE) technology, which combines big data processing technology through connection with cloud servers, etc. with IoT technology, is also emerging. In order to implement IoT, technology elements such as sensing technology, wired and wireless communication and network infrastructure, service interface technology, and security technology are required, and recently, sensor networks for connection between objects, machine to machine (M2M), Technologies such as MTC (machine type communication) are being studied. In the IoT environment, an intelligent Internet technology (IT) service that creates new value in human life by collecting and analyzing data generated from connected objects can be provided. IoT is a field of smart home, smart building, smart city, smart car or connected car, smart grid, health care, smart home appliance, advanced medical service, etc. can be applied to

Accordingly, various attempts are being made to apply the 5G communication system to the IoT network. For example, technologies such as sensor network, machine to machine (M2M), and machine type communication (MTC) are being implemented by 5G communication technologies such as beamforming, MIMO, and array antenna. The application of a cloud radio access network (cloud RAN) as the big data processing technology described above can also be said to be an example of the convergence of 5G technology and IoT technology. In general, a mobile communication system has been developed to provide a voice service while ensuring user activity.

However, the mobile communication system is gradually expanding its scope not only to voice but also to data services, and has now developed to the extent that it can provide high-speed data services. However, in a mobile communication system in which a service is currently provided, a more advanced mobile communication system is required due to a shortage of resources and users' demand for high-speed service.

As mobile traffic increases due to the recent proliferation of smart devices, it is becoming difficult to cope with the increased data usage to provide cellular communication services using only the existing licensed frequency spectrum or licensed frequency band.

In such a situation, a method of using an unlicensed frequency spectrum or an unlicensed frequency band (eg, a 2.4 GHz band, a 5 GHz band, etc.) to provide a cellular communication service is being considered as a solution to the problem of a lack of spectrum.

However, unlike licensed bands, where telecommunication operators secure exclusive frequency use rights through auctions, etc., in unlicensed bands, multiple communication facilities can be used simultaneously without restrictions if only a certain level of adjacent band protection regulations are complied with. For this reason, when an unlicensed band is used for a cellular communication service, it is difficult to guarantee the level of communication quality provided in the licensed band, and an interference problem with a wireless communication device (eg, a wireless LAN device) using the previously unlicensed band may occur. can

Therefore, in order to establish LTE and NR technologies in unlicensed bands, research on a coexistence method with existing unlicensed band devices and a method for efficiently sharing radio channels should be conducted in advance. That is, a robust coexistence mechanism (RCM) must be developed so that devices using LTE and NR technologies in unlicensed bands do not affect existing unlicensed band devices.

An object of the present invention is to provide a channel access method in a case of performing multi-carrier transmission and wideband operation on an unlicensed band in a wireless communication system, particularly a cellular wireless communication system, a method and apparatus for transmission in a base station and a reception method in a terminal, and a system will provide Another object of the present invention is to provide a method and an apparatus for efficiently transmitting a signal in a wireless communication system, in particular, a cellular wireless communication system, and another object of the present invention is to efficiently sense a channel in a specific frequency band (eg, unlicensed band) and signal To provide a method for transmitting a /channel, a method for receiving a corresponding signal/channel, and an apparatus for the same.

The technical problems to be achieved in the present invention are not limited to the above technical problems, and other technical problems not mentioned will be clearly understood by those of ordinary skill in the art to which the present invention belongs from the following description.

In order to solve the above problems, a terminal and a wireless communication method of the following wireless communication system are provided.

According to an embodiment of the present invention, a channel access method in a case of performing multi-carrier transmission and wideband operation on an unlicensed band in a wireless communication system, in particular, a cellular wireless communication system, a transmission method in a base station, and a reception method and apparatus in a terminal is provided Also provided are a discovery reference signal (DRS) and a channel access method and apparatus for signals and channels multiplexed with the DRS. It also relates to a discovery reference signal (DRS) and a channel access method, apparatus and system for signals and channels multiplexed with DRS. In addition, a method for accessing a channel in a specific frequency band (eg, an unlicensed band) and efficiently transmitting a signal, and an apparatus therefor are provided.

The effects obtainable in the present invention are not limited to the above-mentioned effects, and other effects not mentioned may be clearly understood by those of ordinary skill in the art from the following description. will be.

1 shows an example of a radio frame structure used in a wireless communication system.
2 shows an example of a downlink (DL)/uplink (UL) slot structure in a wireless communication system.
3 is a diagram for explaining a physical channel used in a 3GPP system and a general signal transmission method using the corresponding physical channel.
4 shows an SS/PBCH block for initial cell access in a 3GPP NR system.
5 shows a procedure for transmitting control information and a control channel in a 3GPP NR system.
6 is a diagram illustrating a control resource set (CORESET) through which a physical downlink control channel (PDCCH) can be transmitted in a 3GPP NR system.
7 is a diagram illustrating a method of configuring a PDCCH search space in a 3GPP NR system.
8 is a conceptual diagram illustrating carrier aggregation.
9 is a diagram for explaining single-carrier communication and multi-carrier communication.
10 is a diagram illustrating an example to which a cross-carrier scheduling technique is applied.
11 illustrates a deployment scenario of a terminal and a base station in an LAA service environment.
12 illustrates a communication method that operates in an existing unlicensed band.
13 and 14 illustrate a Listen-Before-Talk (LBT) process for DL transmission.
15 illustrates DL transmission in an unlicensed band.
16 illustrates a method of adjusting CWS when accessing a channel in an unlicensed band.
17 is an example of a method of configuring a BWP having a bandwidth less than or equal to the bandwidth of a carrier (or cell) to terminals in a 3GPP NR system.
Referring to FIG. 18 , when the terminal is allocated a plurality of bandwidth parts, at least one CORESET is configured or allocated to the terminal for each bandwidth part.
19 relates to a base station transmission method and a terminal reception method when multiple LBT units are included in one activated BWP as an embodiment of the present invention.
20 is another embodiment of the present invention relates to a base station transmission method and a terminal reception method when multiple LBT units are included in one activated BWP.
21 is another embodiment of the present invention relates to a base station transmission method and a terminal reception method when multiple LBT units are included in one activated BWP.
22 is a block diagram showing the configurations of a terminal and a base station, respectively, according to an embodiment of the present invention.
23 shows symbol positions in one slot that can be occupied by 1 symbol PSS, 1 symbol SSS, and PBCH defined in NR, that is, an SSB composed of 20 RBs in 4 symbols.
24 shows the position of a slot that can be occupied by the SSB within 5 ms, which is a half radio frame.
25 shows that when one or more BWPs are configured on each carrier, each BWP#1 composed of one or more LBT units on each carrier #1 and carrier #2 is activated to downlink through two carriers in downlink. It is a diagram for a case in which it is set to perform transmission.
26 is a diagram related to a configuration in which intra-band carrier aggregation and inter-band carrier aggregation are performed with a BWP composed of one or more LBT sub-bands on each carrier in NR-U.
27 shows a scenario in which transmissions from the responding node are transmitted within the MCOT set by the initiating node when transmissions from the initiating node do not occupy the MCOT within the MCOT set by the initiating node.
28 is an embodiment of the present invention, when a base station is configured as an initiating node and a terminal is configured as a responding node, and when downlink transmission does not occupy the MCOT within the MCOT set by the base station, the terminal within the MCOT set by the base station It shows a scenario when the transmission is scheduled or configured.

The terms used in the present specification have been selected as widely used general terms as possible while considering their functions in the present invention, but these may vary depending on the intention of those skilled in the art, customs, or emergence of new technologies. In addition, in certain cases, there are also terms arbitrarily selected by the applicant, and in this case, the meaning will be described in the description of the relevant invention. Therefore, it is intended to clarify that the terms used in this specification should be interpreted based on the actual meaning of the terms and the contents of the entire specification, rather than the names of simple terms.

Throughout the specification, when a component is said to be "connected" with another component, this includes not only the case where it is "directly connected" but also the case where it is "electrically connected" with another component interposed therebetween. do. Also, when it is said that a certain component "includes" a specific component, this means that other components may be further included, rather than excluding other components, unless otherwise stated. In addition, the limitation of “greater than” or “less than” based on a specific threshold may be appropriately replaced with “greater than” or “less than”, respectively, depending on the embodiment.

The following technologies include code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), etc. It can be used in various wireless access systems. CDMA may be implemented with a radio technology such as universal terrestrial radio access (UTRA) or CDMA2000. TDMA may be implemented with a radio technology such as global system for mobile communications (GSM)/general packet radio service (GPRS)/enhanced data rates for GSM evolution (EDGE). OFDMA may be implemented with a radio technology such as IEEE 802.11 (ie, Wi-Fi), IEEE 802.16 (ie, WiMAX), IEEE 802-20, Evolved UTRA (E-UTRA), and the like. UTRA is part of the universal mobile telecommunications system (UMTS). 3GPP long term evolution (LTE) is a part of evolved UMTS (E-UMTS) using E-UTRA, and LTE-advanced (LTE-A) is an evolved version of 3GPP LTE. A system designed separately from 3GPP NR LTE/LTE-A to support eMBB (enhanced Mobile BroadBand), URLLC (Ultra-Reliable and Low Latency Communication), and mMTC (massive Machine Type Communication) services, which are the requirements of IMT-2020. is a system for For clarity of explanation, 3GPP NR is mainly described, but the technical spirit of the present invention is not limited thereto.

Unless otherwise specified herein, the base station may include a next generation node B (gNB) defined in 3GPP NR. Also, unless otherwise specified, a terminal may include user equipment (UE).

1 shows an example of a radio frame structure used in a wireless communication system. Referring to FIG. 1 , a radio frame (or radio frame) used in a 3GPP NR system may have a length of 10 ms (Δf _max N _f / 100) * T _c ). In addition, the radio frame consists of 10 equally sized subframes (subframes, SFs). Here, Δf _max N _f =480*10 ³ Hz, N _f =4096, T _c =1/(Δf _ref *N _f,ref ), Δf _ref =15*10 ³ Hz, N _f,ref =2048.

A number from 0 to 9 may be assigned to each of 10 subframes in one radio frame. Each subframe has a length of 1 ms, and may consist of one or a plurality of slots according to subcarrier spacing. More specifically, in the 3GPP NR system, the usable subcarrier spacing is 15*2 ^μ kHz. μ is a subcarrier spacing configuration factor, and may have a value of μ=0-4. That is, 15 kHz, 30 kHz, 60 kHz, 120 kHz, or 240 kHz may be used as the subcarrier spacing. A subframe of 1 ms length may consist of 2 ^μ slots. At this time, the length of each slot is 2 ^-μ ms. 2 ^μ slots in one subframe may be numbered from 0 to 2 ^μ - 1, respectively. Also, slots in one radio frame may be assigned a number from 0 to 10*2 ^μ - 1, respectively. The time resource may be divided by at least one of a radio frame number (or also referred to as a radio frame index), a subframe number (or referred to as a subframe index), and a slot number (or a slot index).

2 shows an example of a downlink (DL)/uplink (UL) slot structure in a wireless communication system. In particular, FIG. 2 shows the structure of a resource grid of a 3GPP NR system. There is one resource grid per antenna port. Referring to FIG. 2 , a slot includes a plurality of orthogonal frequency division multiplexing (OFDM) symbols in the time domain and a plurality of resource blocks (RBs) in the frequency domain. The OFDM symbol also means one symbol interval. Unless otherwise specified, an OFDM symbol may be simply referred to as a symbol. Referring to FIG. 2 , a signal transmitted in each slot is represented by a resource grid consisting of N ^{size, μ} _{grid, x} * N ^RB _sc subcarriers and N ^slot _symb OFDM symbols. have. Here, in the downlink resource grid, x=DL, and in the uplink resource grid, x=UL. N ^size,μ _grid,x represents the number of resource blocks (RBs) according to the subcarrier interval configuration factor μ (x is DL or UL), and N ^slot _symb represents the number of OFDM symbols in the slot. N ^RB _sc is the number of subcarriers constituting one RB, and N ^RB _sc =12. The OFDM symbol may be referred to as a cyclic prefix OFDM (CP-OFDM) symbol or a discrete Fourier transform spread OFDM (DFT-S-OFDM) symbol according to a multiple access scheme.

The number of OFDM symbols included in one slot may vary according to the length of a cyclic prefix (CP). For example, in the case of a normal CP, one slot may include 14 OFDM symbols, but in the case of an extended CP, one slot may include 12 OFDM symbols. In a specific embodiment, the extended CP may be used only at a 60 kHz subcarrier interval. 2 illustrates a case in which one slot consists of 14 OFDM symbols for convenience of description, embodiments of the present invention may be applied to slots having other numbers of OFDM symbols in the same manner. Referring to FIG. 2 , each OFDM symbol includes N ^{size, μ} _{grid, x} * N ^RB _sc subcarriers in the frequency domain. The type of subcarrier may be divided into a data subcarrier for data transmission, a reference signal subcarrier for transmission of a reference signal, and a guard band. The carrier frequency is also referred to as the center frequency (fc).

One RB may be defined as N ^RB _sc (eg, 12) consecutive subcarriers in the frequency domain. For reference, a resource composed of one OFDM symbol and one subcarrier may be referred to as a resource element (RE) or a tone. Accordingly, one RB may be composed of N ^slot _symb * N ^RB _sc resource elements. Each resource element in the resource grid may be uniquely defined by an index pair (k, l) in one slot. k is an index assigned from 0 to N ^size,μ _grid,x * N ^RB _sc - 1 in the frequency domain, and l may be an index assigned from 0 to N ^slot _symb - 1 in the time domain.

In order for the terminal to receive a signal from the base station or to transmit a signal to the base station, the time/frequency synchronization of the terminal may need to be aligned with the time/frequency synchronization of the base station. This is because, only when the base station and the terminal are synchronized, the terminal can determine the time and frequency parameters required to perform demodulation of the DL signal and transmission of the UL signal at an accurate time.

Each symbol of a radio frame operating in time division duplex (TDD) or unpaired spectrum is at least one of a downlink symbol (DL symbol), an uplink symbol (UL symbol), or a flexible symbol (flexible symbol). It may consist of either one. In frequency division duplex (FDD) or paired spectrum, a radio frame operating as a downlink carrier may consist of a downlink symbol or a flexible symbol, and a radio frame operating as an uplink carrier may include an uplink symbol or It may be composed of flexible symbols. In the downlink symbol, downlink transmission is possible but uplink transmission is impossible, and in the uplink symbol, uplink transmission is possible but downlink transmission is impossible. Whether the flexible symbol is used for downlink or uplink may be determined according to a signal.

Information on the type of each symbol, that is, information indicating any one of a downlink symbol, an uplink symbol, and a flexible symbol may be composed of a cell-specific (cell-specific or common) radio resource control (RRC) signal. have. In addition, information on the type of each symbol may be additionally configured as a UE-specific (or dedicated) RRC signal. The base station uses the cell-specific RRC signal to i) the period of the cell-specific slot configuration, ii) the number of slots with only downlink symbols from the beginning of the period of the cell-specific slot configuration, iii) the slot immediately following the slot with only downlink symbols. The number of downlink symbols from the first symbol, iv) the number of slots having only uplink symbols from the end of the cell-specific slot configuration period, v) the number of uplink symbols from the last symbol of the slot immediately preceding the slot having only uplink symbols let me know Here, a symbol that is not composed of either an uplink symbol or a downlink symbol is a flexible symbol.

When the information on the symbol type is configured as a UE-specific RRC signal, the base station may signal whether the flexible symbol is a downlink symbol or an uplink symbol with a cell-specific RRC signal. In this case, the UE-specific RRC signal cannot change the downlink symbol or the uplink symbol composed of the cell-specific RRC signal to another symbol type. The UE-specific RRC signal may signal the number of downlink symbols among N ^slot _symb symbols of the corresponding slot and the number of uplink symbols among N ^slot _symb symbols of the corresponding slot for each slot. In this case, the downlink symbol of the slot may be continuously configured from the first symbol of the slot to the i-th symbol. In addition, the uplink symbol of the slot may be continuously configured from the j-th symbol to the last symbol of the slot (here, i<j). A symbol that is not composed of either an uplink symbol or a downlink symbol in a slot is a flexible symbol.

A symbol type composed of the above RRC signal may be referred to as a semi-static DL/UL configuration. In the semi-static DL/UL configuration configured with the RRC signal above, the flexible symbol is a downlink symbol, an uplink symbol through dynamic slot format information (SFI) transmitted through a physical downlink control channel (PDCCH). , or a flexible symbol. In this case, the downlink symbol or the uplink symbol composed of the RRC signal is not changed to another symbol type. Table 1 illustrates the dynamic SFI that the base station can indicate to the terminal.

In Table 1, D denotes a downlink symbol, U denotes an uplink symbol, and X denotes a flexible symbol. As shown in Table 1, a maximum of two DL/UL switching can be allowed within one slot.

3 is a diagram for explaining a physical channel used in a 3GPP system (eg, NR) and a general signal transmission method using the corresponding physical channel. When the power of the terminal increases or the terminal enters a new cell, the terminal performs an initial cell search operation (S101). Specifically, the terminal may synchronize with the base station in the initial cell search. To this end, the terminal may receive a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) from the base station, synchronize with the base station, and obtain information such as a cell ID. Thereafter, the terminal may receive the physical broadcast channel from the base station to obtain broadcast information in the cell.

After completing the initial cell search, the UE receives a physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH) according to information carried on the PDCCH, thereby acquiring through initial cell search. It is possible to obtain more specific system information than one system information (S102).

When the terminal accesses the base station for the first time or there is no radio resource for signal transmission, the terminal may perform a random access procedure with respect to the base station (steps S103 to S106). First, the UE may transmit a preamble through a physical random access channel (PRACH) (S103), and receive a response message to the preamble from the base station through a PDCCH and a corresponding PDSCH (S104). When a valid random access response message is received from the terminal, the terminal transmits data including its identifier through a physical uplink shared channel (PUSCH) indicated by the uplink grant delivered through the PDCCH from the base station. It is transmitted to the base station (S105). Next, the terminal waits for the reception of the PDCCH as an indication of the base station for conflict resolution. When the terminal successfully receives the PDCCH through its identifier (S106), the random access process ends.

After the procedure described above, the UE receives PDCCH/PDSCH (S107) and a physical uplink shared channel (PUSCH)/physical uplink control channel (PUCCH) as a general uplink/downlink signal transmission procedure. may be transmitted ( S108 ). In particular, the UE may receive downlink control information (DCI) through the PDCCH. DCI may include control information such as resource allocation information for the terminal. Also, the format of the DCI may vary depending on the purpose of use. Uplink control information (UCI) transmitted by the UE to the base station through the uplink is a downlink/uplink ACK/NACK signal, a channel quality indicator (CQI), a precoding matrix index (PMI), and a rank indicator (RI). ) and the like. Here, CQI, PMI, and RI may be included in CSI (channel state information). In the case of the 3GPP NR system, the UE may transmit control information such as the above-described HARQ-ACK and CSI through PUSCH and/or PUCCH.

4 shows an SS/PBCH block for initial cell access in a 3GPP NR system. When the UE is powered on or wants to access a cell anew, the UE may acquire time and frequency synchronization with the cell and perform an initial cell search process. The UE may detect the physical cell identity N ^cell _ID of the cell in the cell search process. To this end, the terminal may receive a synchronization signal, for example, a main synchronization signal (PSS) and a secondary synchronization signal (SSS) from the base station to synchronize with the base station. In this case, the terminal may obtain information such as a cell identifier (identity, ID).

With reference to FIG. 4( a ), a synchronization signal (SS) will be described in more detail. The synchronization signal may be divided into PSS and SSS. PSS may be used to obtain time domain synchronization and/or frequency domain synchronization such as OFDM symbol synchronization, slot synchronization. SSS may be used to obtain frame synchronization and cell group ID. Referring to FIG. 4(a) and Table 2, the SS/PBCH block may be composed of 20 RBs (=240 subcarriers) contiguous in the frequency axis, and may be composed of 4 OFDM symbols contiguous in the time axis. At this time, in the SS/PBCH block, the PSS is transmitted through the 56th to 182th subcarriers in the first OFDM symbol and the SSS in the third OFDM symbol. Here, the lowest subcarrier index of the SS/PBCH block is numbered from 0. In the first OFDM symbol in which the PSS is transmitted, the base station does not transmit a signal through the remaining subcarriers, that is, the 0 to 55 and 183 to 239 subcarriers. In addition, the base station does not transmit a signal through the 48th to 55th and 183th to 191th subcarriers in the third OFDM symbol in which the SSS is transmitted. The base station transmits a physical broadcast channel (PBCH) through the remaining REs except for the above signal in the SS/PBCH block.

SS specifies a total of 1008 unique physical layer cell IDs through a combination of three PSSs and SSSs, and each physical layer cell ID is a part of only one physical-layer cell-identifier group. Preferably, each group may be grouped into 336 physical-layer cell-identifier groups containing three unique identifiers. Therefore, physical layer cell ID N ^cell _ID = 3N ⁽¹⁾ _ID + N ⁽²⁾ _ID is an index N ⁽¹⁾ _ID within the range from 0 to 335 indicating a physical-layer cell-identifier group and the physical-layer cell - Can be uniquely defined by the index N ⁽²⁾ _ID from 0 to 2 indicating the physical-layer identifier in the identifier group. The UE may identify one of three unique physical-layer identifiers by detecting the PSS. In addition, the UE may identify one of 336 physical layer cell IDs associated with the physical-layer identifier by detecting the SSS. At this time, the sequence d _PSS (n) of the PSS is as follows.

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In addition, the sequence d _SSS (n) of the SSS is as follows.

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A radio frame with a length of 10 ms can be divided into two half frames with a length of 5 ms. A slot in which an SS/PBCH block is transmitted in each half frame will be described with reference to FIG. 4(b). 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 interval is 15 kHz, and the start time of the SS/PBCH block is {2, 8} + 14*nth symbol. In this case, n=0, 1 may be at a carrier frequency of 3 GHz or less. In addition, n=0, 1, 2, 3 may be in a carrier frequency of more than 3 GHz and less than or equal to 6 GHz. In case B, the subcarrier interval is 30 kHz, and the start time of the SS/PBCH block is {4, 8, 16, 20} + 28*nth symbol. In this case, n = 0 at a carrier frequency of 3 GHz or less. In addition, n=0, 1 may be in a carrier frequency of more than 3 GHz and less than or equal to 6 GHz. In case C, the subcarrier interval is 30 kHz, and the start time of the SS/PBCH block is {2, 8} + 14*nth symbol. In this case, n=0, 1 may be at a carrier frequency of 3 GHz or less. In addition, n=0, 1, 2, 3 may be in a carrier frequency of more than 3 GHz and less than or equal to 6 GHz. In case D, the subcarrier interval is 120 kHz, and the start time of the SS/PBCH block is {4, 8, 16, 20} + 28*nth symbol. In this case, n=0, 1, 2, 3, 5, 6, 7, 8, 10, 11, 12, 13, 15, 16, 17, 18 at a carrier frequency of 6 GHz or higher. In case E, the subcarrier interval is 240 kHz, and the start time of the SS/PBCH block is {8, 12, 16, 20, 32, 36, 40, 44} + 56*nth symbol. In this case, n=0, 1, 2, 3, 5, 6, 7, 8 may be at a carrier frequency of 6 GHz or higher.

5 shows a procedure for transmitting control information and a control channel in a 3GPP NR system. Referring to FIG. 5A , the base station may add a cyclic redundancy check (CRC) masked (eg, XOR operation) with a radio network temporary identifier (RNTI) to control information (eg, downlink control information, DCI). (S202). The base station may scramble the CRC with an RNTI value determined according to the purpose/target of each control information. The common RNTI used by one or more terminals includes at least one of a system information RNTI (SI-RNTI), a paging RNTI (P-RNTI), a random access RNTI (RA-RNTI), and a transmit power control RNTI (TPC-RNTI). may include In addition, the UE-specific RNTI may include at least one of a cell temporary RNTI (C-RNTI) and a CS-RNTI. Thereafter, after performing channel encoding (eg, polar coding) (S204), the base station may perform rate-matching according to the amount of resource(s) used for PDCCH transmission (S206). Thereafter, the base station may multiplex DCI(s) based on a control channel element (CCE)-based PDCCH structure (S208). In addition, the base station may apply an additional process (S210) such as scrambling, modulation (eg, QPSK), interleaving, etc. to the multiplexed DCI(s), and then map the multiplexed DCI(s) to a resource to be transmitted. A CCE is a basic resource unit for a PDCCH, and one CCE may consist of a plurality (eg, six) of a resource element group (REG). One REG may consist of a plurality (eg, 12) of REs. The number of CCEs used for one PDCCH may be defined as an aggregation level. In the 3GPP NR system, aggregation levels of 1, 2, 4, 8 or 16 may be used. FIG. 5(b) is a diagram related to multiplexing of a CCE aggregation level and a PDCCH, and shows the types of CCE aggregation levels used for one PDCCH and CCE(s) transmitted in the control region accordingly.

6 is a diagram illustrating a control resource set (CORESET) through which a physical downlink control channel (PDCCH) can be transmitted in a 3GPP NR system. CORESET is a time-frequency resource through which PDCCH, which is a control signal for a terminal, is transmitted. Also, a search space, which will be described later, may be mapped to one CORESET. Accordingly, the UE may decode the PDCCH mapped to the CORESET by monitoring the time-frequency domain designated as CORESET, rather than monitoring all frequency bands for PDCCH reception. The base station may configure one or a plurality of CORESETs for each cell to the terminal. CORESET may consist of up to 3 consecutive symbols on the time axis. In addition, CORESET may be configured in units of 6 consecutive PRBs on the frequency axis. 5, CORESET#1 consists of continuous PRBs, and CORESET#2 and CORESET#3 consist of discontinuous PRBs. CORESET can be located in any symbol within the slot. For example, in the embodiment of Figure 5, CORESET#1 starts at the 1st symbol of the slot, CORESET#2 starts at the 5th symbol of the slot, and CORESET#9 starts at the 9th symbol of the slot.

7 is a diagram illustrating a method of configuring a PDCCH search space in a 3GPP NR system. In order to transmit the PDCCH to the UE, at least one search space may exist in each CORESET. In an embodiment of the present invention, the search space is a set of all time-frequency resources (hereinafter, PDCCH candidates) through which the PDCCH of the UE can be transmitted. The search space may include a common search space that a terminal of 3GPP NR searches for and a terminal-specific or UE-specific search space that a specific terminal searches for. In the common search space, it is possible to monitor a PDCCH configured to be commonly found by all terminals in a cell belonging to the same base station. In addition, the terminal-specific search space may be configured for each terminal so that the PDCCH allocated to each terminal can be monitored at different search space positions depending on the terminal. In the case of the UE-specific search space, the search space between terminals may be allocated partially overlapping due to a limited control region to which the PDCCH can be allocated. Monitoring the PDCCH includes blind decoding of PDCCH candidates in the search space. A case in which blind decoding is successful may be expressed as that the PDCCH has been detected/received (successfully), and a case in which blind decoding has failed may be expressed as non-detection/non-reception of the PDCCH, or it may be expressed as not successfully detected/received.

For convenience of explanation, a PDCCH scrambled with a group common (GC) RNTI that UEs already know in order to transmit downlink control information to one or more UEs is referred to as a group common (GC) PDCCH or a common PDCCH. refers to In addition, in order to transmit uplink scheduling information or downlink scheduling information to one specific UE, a PDCCH scrambled with a UE-specific RNTI that a specific UE already knows is referred to as a UE-specific PDCCH. The common PDCCH may be included in the common search space, and the UE-specific PDCCH may be included in the common search space or the UE-specific PDCCH.

The base station transmits information related to resource allocation of a paging channel (PCH) and a downlink-shared channel (DL-SCH) that are transport channels through the PDCCH (ie, DL Grant) or resource allocation of UL-SCH and hybrid automatic repeat request (HARQ). related information (ie, UL grant) may be informed to each UE or UE group. The base station may transmit the PCH transport block and the DL-SCH transport block through the PDSCH. The base station may transmit data excluding specific control information or specific service data through the PDSCH. In addition, the terminal may receive data excluding specific control information or specific service data through the PDSCH.

The base station may transmit information about which terminal (one or a plurality of terminals) the PDSCH data is transmitted to and how the corresponding terminal should receive and decode the PDSCH data by including it in the PDCCH. For example, the DCI transmitted to a specific PDCCH is CRC-masked with an RNTI of "A", and the DCI indicates that the PDSCH is allocated to a radio resource (eg, frequency location) of "B", and It is assumed that transmission format information (eg, transport block size, modulation scheme, coding information, etc.) is indicated. The UE monitors the PDCCH using its own RNTI information. In this case, if there is a terminal that blindly decodes the PDCCH with the "A" RNTI, the corresponding terminal receives the PDCCH, and receives the PDSCH indicated by "B" and "C" through the received PDCCH information.

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

The PUCCH may be used to transmit the following uplink control information (UCI).

- SR (scheduling request): information used to request uplink UL-SCH resources.

- HARQ-ACK: A response to a PDCCH (indicating DL SPS release) and/or a response to a downlink transport block (TB) on the PDSCH. HARQ-ACK indicates whether information transmitted through PDCCH or PDSCH is received. The HARQ-ACK response includes positive ACK (simply, ACK), negative ACK (hereinafter, NACK), discontinuous transmission (DTX) or NACK/DTX. Here, the term HARQ-ACK is used interchangeably with HARQ-ACK/NACK and ACK/NACK. In general, ACK may be expressed as a bit value of 1, and NACK may be expressed as a bit value of 0.

- CSI (channel state information): feedback information for a downlink channel. The terminal is generated based on a CSI-RS (reference signal) transmitted by the base station. Multiple input multiple output (MIMO)-related feedback information includes a rank indicator (RI) and a precoding matrix indicator (PMI). CSI may be divided into CSI part 1 and CSI part 2 according to information indicated by the CSI.

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

PUCCH format 0 is a format capable of transmitting 1-bit or 2-bit HARQ-ACK information or SR. PUCCH format 0 may 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 in two OFDM symbols, the same sequence in two symbols may be transmitted in different RBs. Through this, the terminal can obtain a frequency diversity gain. More specifically, the UE determines the value m _cs of the cyclic shift according to the M _bit UCI (M _bit = 1 or 2), and changes the length 12 base sequence to the predetermined value m _cs . The click-shifted sequence may be mapped to 12 REs of one OFDM symbol and one PRB and transmitted. When the number of cyclic shifts usable by the UE is 12 and M _bit = 1, 1-bit UCI 0 and 1 may be represented by a sequence corresponding to two cyclic shifts in which the difference between the cyclic shift values is 6. In addition, when M _bit = 2, 2-bit UCI 00, 01, 11, and 10 may be expressed as a sequence corresponding to four cyclic shifts having a difference of three cyclic shift values.

PUCCH format 1 may carry 1-bit or 2-bit HARQ-ACK information or SR. PUCCH format 1 may be transmitted through consecutive OFDM symbols on the time axis and one PRB on the frequency axis. Here, the number of OFDM symbols occupied by PUCCH format 1 may be one of 4 to 14. More specifically, UCI with M _bit = 1 may be modulated with BPSK. The UE may modulate UCI with M _bit = 2 by quadrature phase shift keying (QPSK). A signal is obtained by multiplying a modulated complex valued symbol d(0) by a sequence of length 12. The UE spreads the obtained signal as an orthogonal cover code (OCC) on the even-numbered OFDM symbol to which PUCCH format 1 is allocated and transmits it. In PUCCH format 1, the maximum number of different terminals multiplexed to the same RB is determined according to the length of the OCC used. A demodulation reference signal (DMRS) may be spread and mapped to odd-numbered OFDM symbols of PUCCH format 1 as OCC.

PUCCH format 2 may carry more than 2 bits of UCI. PUCCH format 2 may be transmitted through one or two OFDM symbols on a time axis and one or a plurality of RBs on a frequency axis. When PUCCH format 2 is transmitted with two OFDM symbols, the same sequence may be transmitted on different RBs through the two OFDM symbols. Through this, the terminal can obtain a frequency diversity gain. More specifically, M _bit bit UCI (M _bit >2) is bit-level scrambled, QPSK modulated and mapped to RB(s) of one or two OFDM symbol(s). Here, the number of RBs may be one of 1 to 16.

PUCCH format 3 or PUCCH format 4 may carry more than 2 bits of UCI. PUCCH format 3 or PUCCH format 4 may be transmitted through consecutive 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 modulates M _bit UCI (M _bit >2) with ð/2-BPSK (Binary Phase Shift Keying) or QPSK to generate complex symbols d(0) to d(M _symb -1). . Here, when ð/2-BPSK is used, M _symb = M _bit , and when QPSK is used, M _symb = M _bit /2. The UE may not apply block-unit spreading to PUCCH format 3. However, the UE uses a PreDFT-OCC of length-12 length so that the PUCCH format 4 can have 2 or 4 multiplexing capacity in 1 RB (ie, 12 subcarriers) block-unit spreading can be applied. The UE may transmit the spread signal by transmitting precoding (or DFT-precoding) and mapping the spread signal to each RE.

In this case, the number of RBs occupied by PUCCH format 2, PUCCH format 3, or PUCCH format 4 may be determined according to the length of the UCI transmitted by the UE and the maximum code rate. 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 available for PUCCH format 2, PUCCH format 3, or PUCCH format 4, the UE does not transmit some UCI information according to the priority of UCI information and does not transmit the remaining Only UCI information can be transmitted.

PUCCH format 1, PUCCH format 3, or PUCCH format 4 may be configured through an RRC signal to indicate frequency hopping in a slot. When frequency hopping is configured, an index of an RB to be frequency hopping may be configured as an RRC signal. When PUCCH format 1, PUCCH format 3, or PUCCH format 4 is transmitted over N OFDM symbols in the time axis, the first hop has floor (N/2) OFDM symbols and the second hop is ceil ( N/2) OFDM symbols.

PUCCH format 1, PUCCH format 3, or PUCCH format 4 may be configured to be repeatedly transmitted in a plurality of slots. In this case, the number K of slots in which the PUCCH is repeatedly transmitted may be configured by the RRC signal. The repeatedly transmitted PUCCH should start from the OFDM symbol at the same position in each slot and have the same length. If any one OFDM symbol among the OFDM symbols of the slot in which the UE should transmit the PUCCH is indicated as a DL symbol by the RRC signal, the UE may transmit the PUCCH by delaying it to the next slot without transmitting the PUCCH in the corresponding slot.

Meanwhile, in the 3GPP NR system, the UE may perform transmission/reception using a bandwidth equal to or smaller than the bandwidth of a carrier (or cell). To this end, the terminal may be configured with a bandwidth part (BWP) composed of a continuous bandwidth of a part of the bandwidth of the carrier. A UE operating according to TDD or operating in an unpaired spectrum may be configured with up to four DL/UL BWP pairs in one carrier (or cell). Also, the UE may activate one DL/UL BWP pair. A terminal operating according to FDD or operating in a paired spectrum may be configured with up to four DL BWPs on a downlink carrier (or cell) and up to four UL BWPs on an uplink carrier (or cell). can be configured. The UE may activate one DL BWP and one UL BWP for each carrier (or cell). The UE may not receive or transmit in time-frequency resources other than the activated BWP. The activated BWP may be referred to as an active BWP.

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

8 is a conceptual diagram illustrating carrier aggregation. In the carrier aggregation, in order for the wireless communication system to use a wider frequency band, a frequency block or (logical meaning) of a terminal consisting of an uplink resource (or component carrier) and/or a downlink resource (or component carrier) or a plurality of cells It means how to use it as one large logical frequency band. Hereinafter, for convenience of description, the term "component carrier" will be used.

Referring to FIG. 8 , as an example of a 3GPP NR system, the entire system band includes up to 16 component carriers, and each component carrier may have a bandwidth of up to 400 MHz. A component carrier may include one or more physically contiguous subcarriers. 8 shows that each component carrier has the same bandwidth, but this is only an example, and each component carrier may have a different bandwidth. In addition, although each component carrier is illustrated as being adjacent to each other on the frequency axis, the figure is illustrated in a logical concept, and each component carrier may be physically adjacent to each other or may be separated from each other.

A different center frequency may be used in each component carrier. Also, one center frequency common to physically adjacent component carriers may be used. Assuming that all component carriers are physically adjacent to each other in the embodiment of FIG. 8 , the center frequency A may be used in all component carriers. In addition, assuming that the respective component carriers are not physically adjacent to each other, the center frequency A and the center frequency B may be used in each of the component carriers.

When the entire system band is extended by carrier aggregation, a frequency band used for communication with each terminal may be defined in units of component carriers. Terminal A can use 100 MHz, which is the entire system band, and performs communication using all five component carriers. Terminals B ₁ to B ₅ can use only 20 MHz bandwidth and perform communication using one component carrier. Terminals C ₁ and C ₂ may use a 40 MHz bandwidth and perform communication using two component carriers, respectively. Two component carriers may or may not be logically/physically adjacent. In the embodiment of FIG. 8 , the terminal C ₁ uses two non-adjacent component carriers and the terminal C ₂ uses two adjacent component carriers.

9 is a diagram for explaining single carrier communication and multi-carrier communication. In particular, FIG. 9(a) shows a subframe structure of a single carrier, and FIG. 9(b) shows a subframe structure of a multi-carrier.

Referring to FIG. 9A , in the case of the FDD mode, a general wireless communication system may perform data transmission or reception through one DL band and one UL band corresponding thereto. In another specific embodiment, in the case of the TDD mode, the wireless communication system divides a radio frame into an uplink time unit and a downlink time unit in the time domain, and may transmit or receive data through the uplink/downlink time unit. . Referring to FIG. 9B , a bandwidth of 60 MHz may be supported by collecting three 20 MHz component carriers (CCs) in UL and DL, respectively. Each of the CCs may be adjacent to or non-adjacent to each other in the frequency domain. 9(b) shows a case in which both the bandwidth of the UL CC and the bandwidth of the DL CC are identical and symmetric for convenience, but the bandwidth of each CC may be independently determined. In addition, asymmetric carrier aggregation in which the number of UL CCs and the number of DL CCs are different is possible. A DL/UL CC allocated/configured to a specific UE through RRC may be referred to as a serving DL/UL CC of a specific UE.

The base station may communicate with the terminal by activating some or all of the serving CCs of the terminal or by deactivating some CCs. The base station may change activated/deactivated CCs and may change the number of activated/deactivated CCs. If the base station allocates the available CCs to the terminal in a cell-specific or terminal-specific manner, unless the CC allocation to the terminal is completely reconfigured or the terminal is handed over, at least one of the CCs once allocated is not deactivated. it may not be One CC that is not deactivated to the UE is referred to as a primary CC (PCC) or a primary cell (PCell), and a CC that the base station can freely activate/deactivate is a secondary CC (SCC) or a secondary cell (SCell). ) is called

Meanwhile, 3GPP NR uses the concept of a cell to manage radio resources. A cell is defined as a combination of downlink and uplink resources, that is, a combination of DL CC and UL CC. A cell may be configured with a DL resource alone or a combination of a DL resource and a UL resource. When carrier aggregation is supported, linkage between the carrier frequency of the DL resource (or DL CC) and the carrier frequency of the UL resource (or UL CC) may be indicated by system information. The carrier frequency means the center frequency of each cell or CC. A cell corresponding to the PCC is referred to as a PCell, and a cell corresponding to the SCC is referred to as an SCell. A carrier corresponding to the PCell in the downlink is a DL PCC, and a carrier corresponding to the PCell in the uplink is a UL PCC. Similarly, a carrier corresponding to the SCell in the downlink is a DL SCC, and a carrier corresponding to the SCell in the uplink is a UL SCC. According to the terminal capability (capability), the serving cell(s) may be composed of one PCell and zero or more SCells. For a UE that is in the RRC_CONNECTED state but has not configured carrier aggregation or does not support carrier aggregation, there is only one serving cell configured only with PCell.

As mentioned above, the term "cell" used in carrier aggregation is distinguished from the term "cell" that refers to a certain geographic area in which a communication service is provided by one base station or one antenna group. In order to distinguish a cell indicating a certain geographic area from a cell of carrier aggregation, in the present invention, a cell of carrier aggregation is referred to as a CC, and a cell of the geographic area is referred to as a cell.

10 is a diagram illustrating an example to which a cross-carrier scheduling technique is applied. When cross-carrier scheduling is configured, the control channel transmitted through the first CC may schedule the data channel transmitted through the first CC or the second CC using a carrier indicator field (CIF). CIF is contained within DCI. In other words, a scheduling cell is configured, and the DL grant/UL grant transmitted in the PDCCH region of the scheduling cell schedules the PDSCH/PUSCH of the scheduled cell. That is, a search region for a plurality of component carriers exists in the PDCCH region of the scheduling cell. A PCell is basically a scheduling cell, and a specific SCell may be designated as a scheduling cell by a higher layer.

In the embodiment of FIG. 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 carrier #1 and DL component carrier #2 are assumed to be DL SCC (or SCell). Also, it is assumed that the DL PCC is set as the PDCCH monitoring CC. If cross-carrier scheduling is not configured by UE-specific (or UE-group-specific or cell-specific) higher layer signaling, CIF is disabled, and each DL CC has its own without CIF according to the NR PDCCH rule. It is possible to transmit only the PDCCH scheduling the PDSCH of (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) higher layer signaling, CIF is enabled, and a specific CC (eg, DL PCC) uses CIF. Thus, not only the PDCCH scheduling the PDSCH of DL CC A but also the PDCCH scheduling the PDSCH of another CC can be transmitted (cross-carrier scheduling). On the other hand, the PDCCH is not transmitted in other DL CCs. Therefore, the UE receives a self-carrier scheduled PDSCH by monitoring a PDCCH not including a CIF depending on whether cross-carrier scheduling is configured for the UE, or monitors a PDCCH including a CIF to monitor a cross-carrier scheduled PDSCH receive

Meanwhile, although FIGS. 9 and 10 exemplify the subframe structure of the 3GPP LTE-A system, the same or similar configuration may be applied to the 3GPP NR system. However, in the 3GPP NR system, the subframes of FIGS. 9 and 10 may be replaced with slots.

In addition, unlike 3GPP LTE (-A) in the NR system, CBG-based transmission is used. Below is a related explanation.

In 3GPP LTE(-A), a TB (Transport Block), which is a unit transmitted to the PDSCH, is attached with a TB-CRC (Cyclic Redundancy Code) for detecting an error of the TB, and is divided into several CBs for the efficiency of the channel code. . Each CB is attached with a CB-CRC (Cyclic redundancy code) for detecting a CB error. When receiving the PDSCH, the UE transmits an ACK if no error is detected in the TB-CRC, and transmits a NACK if an error is detected in the TB-CRC. That is, one HARQ-ACK is transmitted per TB. When the NACK is received, the base station determines that an error has occurred in the previous TB, and performs HARQ retransmission of all CBs included in the TB. Accordingly, in the LTE system, if even one CB is received incorrectly, all CBs included in the TB are retransmitted, so that inefficient retransmission is highly likely to occur. To solve this problem, in the NR system, the CBs constituting the TB are bundled to form a CBG (Code block group), and HARQ-ACK in the CBG unit is configured to be transmitted, so that reception success for each CBG is determined by CBG level HARQ-ACK. In the case of downlink transmission as feedback, a method of retransmitting HARQ only CBGs that the base station has failed to receive by notifying the base station has been introduced. In the case of uplink, in addition to setting to transmit HARQ-ACK in TB unit for uplink transmission, CBs constituting TB as uplink transmission are bundled to form a CBG (Code block group), and HARQ in CBG unit -ACK is configured to be transmitted, so that reception success or failure for each CBG is informed to the UE as CBG level HARQ-ACK feedback, so that the UE retransmits HARQ only CBGs that have failed to receive may be configured.

11 illustrates a deployment scenario of a terminal and a base station in an LAA service environment. The frequency band targeted by the LAA service environment does not have a long wireless communication reach due to its high-frequency characteristics. Considering this, in an environment where the existing LTE-L service and the LAA service coexist, the deployment scenario of the terminal and the base station may be an overlay model or a co-located model.

In the overlay model, the macro base station may perform wireless communication with terminal X and terminal X' within the macro area 32 using a licensed band carrier, and may be connected to a plurality of RRHs (Radio Remote Heads) through an X2 interface. Each RRH may perform wireless communication with terminal X or terminal X' within a certain area 31 using an unlicensed band carrier. Although the frequency bands of the macro base station and the RRH are different from each other, there is no mutual interference. However, in order to use the LAA service as an auxiliary downlink channel of the LTE-L service through carrier aggregation, fast data exchange is performed between the macro base station and the RRH through the X2 interface. should be done

In the co-located model, the pico/femto base station may perform wireless communication with the Y terminal using a licensed band carrier and an unlicensed band carrier at the same time. However, the pico/femto base station may be limited to downlink transmission using the LTE-L service and the LAA service together. The coverage 33 of the LTE-L service and the coverage 34 of the LAA service may be different according to a frequency band, transmission power, and the like.

When LTE communication is performed in an unlicensed band, existing equipment (eg, wireless LAN (Wi-Fi) equipment) communicating in the unlicensed band cannot demodulate LAA messages or data. Therefore, existing equipments may determine an LAA message or data as a kind of energy and perform an interference avoidance operation using an energy detection (or detection) technique. That is, when the energy corresponding to the LAA message or data is less than -62 dBm or a specific ED (Energy Detection) threshold, the WLAN devices may ignore the message or data and communicate. For this reason, from the standpoint of a terminal performing LTE communication in an unlicensed band, it may be frequently interfered with by wireless LAN equipment.

Therefore, in order to effectively implement the LAA technology/service, it is necessary to allocate or reserve a specific frequency band for a specific time. However, since peripheral devices communicating through the unlicensed band attempt access based on the energy detection technique, there is a problem in that efficient LAA service is difficult. Therefore, in order to establish the LAA technology, research on a method for coexistence with existing unlicensed band devices and a method for efficiently sharing a radio channel should be preceded. That is, a strong coexistence mechanism that does not affect LAA devices to existing unlicensed band devices should be developed.

12 illustrates an existing communication method (eg, wireless LAN) operating in an unlicensed band. Since most devices operating in the unlicensed band operate based on Listen-Before-Talk (LBT), a Clear Channel Assessment (CCA) for sensing a channel before data transmission is performed.

Referring to FIG. 12 , a wireless LAN device (eg, AP, STA) checks whether a channel is busy by performing carrier sensing before data transmission. When a wireless signal of a predetermined strength or higher is detected in a channel to transmit data, the corresponding channel is determined to be in use, and the wireless LAN device delays access to the corresponding channel. This process is called clear channel evaluation, and the signal level that determines whether or not a signal is detected is called a CCA threshold. On the other hand, when no radio signal is detected in the corresponding channel or when a radio signal having an intensity smaller than the CCA threshold is detected, the channel is determined to be in an idle state.

If the channel is determined to be idle, the terminal having data to transmit performs a backoff procedure after a defer period (eg, Arbitration InterFrame Space (AIFS), PCF IFS (PIFS), etc.). The dipper period means the minimum time that the terminal must wait after the channel becomes idle. The backoff procedure causes the terminal to wait longer for an arbitrary amount of time after the dipper deadline. For example, the terminal waits while decreasing the slot time as much as a random number assigned to the terminal within the contention window (CW) while the channel is idle, and exhausts all the slot times. The terminal may attempt to access the corresponding channel.

Upon successful access to the channel, the terminal may transmit data through the channel. If data transmission is successful, the CW size (CWS) is reset to the initial value (CWmin). On the other hand, if data transmission fails, the CWS is doubled. Accordingly, the UE is assigned a new random number within a double range of the previous random number range and performs a backoff procedure in the next CW. In the wireless LAN, only ACK is defined as reception response information for data transmission. Accordingly, when an ACK is received for data transmission, the CWS is reset to an initial value, and when feedback information is not received for data transmission, the CWS is doubled.

As described above, since most communication in the existing unlicensed band operates based on LBT, LTE is also considering LBT in LAA for coexistence with existing devices. Specifically, the channel access method on the unlicensed band in LTE can be divided into the following four categories according to the presence / application of LBT.

● Category 1: No LBT

- Tx entity (entity) does not perform the LBT procedure for transmission.

● Category 2: LBT without random backoff

- The Tx entity senses whether the channel is idle during the first interval without random backoff to perform transmission. That is, the Tx entity may perform transmission through the corresponding channel immediately after the channel is sensed in the idle state during the first interval. The first interval is an interval of a preset length just before the Tx entity performs transmission. According to an embodiment, the first interval may be an interval of 25us length, but the present invention is not limited thereto.

● Category 3: LBT performing random backoff using a CW of a fixed size

- The Tx entity obtains a random number N within a CW of a fixed size, sets it as a backoff counter (or a backoff timer), and performs backoff using the set backoff counter N. That is, in the backoff procedure, the Tx entity decrements the backoff counter by 1 whenever a channel is sensed as idle for a preset slot period. Here, the preset slot period may be 9 us, but the present invention is not limited thereto. The backoff counter is decremented from the initial value N, and when the value of the backoff counter reaches 0, the Tx entity may perform transmission. Meanwhile, in order to perform the backoff, the Tx entity first senses whether the channel is idle during the second interval. The second interval may be set based on the channel access priority class of the Tx entity, and consists of a period of 16 us and consecutive m slot periods. Here, m is a value set according to the channel access priority class. The Tx entity performs channel sensing for decrementing the backoff counter when the channel is sensed in the idle state during the second interval. Meanwhile, if the channel is sensed as being occupied during the backoff procedure, the backoff procedure is stopped. After stopping the backoff procedure, the Tx entity may resume the backoff if the channel is sensed to be idle for the second interval. In this way, the Tx entity may perform transmission when the channel is idle during the slot period of the backoff counter N in addition to the second interval. In this case, the backoff counter N is obtained within a CW of a fixed size.

● Category 4: LBT performing random backoff using CW of variable size

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

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

13 to 14 illustrate a DL transmission process based on category 4 LBT. Category 4 LBT can be used to ensure fair channel access with Wi-Fi. 13 to 14, the LBT process includes ICCA (Initial CCA) and ECCA (Extended CCA). In ICCA, random back-off is not performed, and in ECCA, random back-off is performed using CW of a variable size. ICCA is applied when the channel is idle at the time signal transmission is required, and ECCA is applied when the channel is in use or there is DL transmission just before the time signal transmission is required. That is, it is determined whether the channel is in an idle state through ICCA, and data transmission is performed after the ICCA period. If the interference signal is recognized and data transmission is not possible, the data transmission time may be acquired through a defer period + backoff counter after a random backoff counter is set.

Referring to FIG. 13 , a signal transmission process may be performed as follows.

Initial CCA

- S302: The base station confirms that the channel is in an idle state.

- S304: The base station checks whether signal transmission is necessary. If signal transmission is not required, the process returns to S302, and if signal transmission is required, it proceeds to S306.

- S306: The base station checks whether the channel is idle during the ICCA dipper period (BCCA). The ICCA dipper period is configurable. As an implementation example, the ICCA dipper period may consist of a 16 μs interval and n consecutive CCA slots. Here, n is a positive integer, and one CCA slot period may be 9 μs. The number of CCA slots may be set differently according to QoS classes. The ICCA dipper period may be set to an appropriate value in consideration of the dipper period (eg, DIFS, AIFS) of Wi-Fi. For example, the ICCA dipper period may be 34 μs. If the channel is idle during the ICCA dipper period, the base station may perform a signal transmission process (S308). If it is determined that the channel is in use during the ICCA dipper period, the process proceeds to S312 (ECCA).

- S308: The base station may perform a signal transmission process. If there is no signal transmission, it proceeds to S302 (ICCA), and if there is signal transmission, it proceeds to S310. Even when the back-off counter N reaches 0 in S318 and S308 is performed, if there is no signal transmission, the process proceeds to S302 (ICCA), and if there is a signal transmission, the process proceeds to S310.

- S310: If additional signal transmission is not required, proceeds to S302 (ICCA), and if additional signal transmission is required, proceeds to S312 (ECCA).

Extended CCA

- S312: The base station generates a random number N in the CW. N is used as a counter in the back-off process, and is generated from [0, q-1]. The CW consists of q ECCA slots, and the ECCA slot size may be 9 μs or 10 μs. The CW size (CWS) is defined as q and may be changed in S314. Thereafter, the base station proceeds to S316.

- S314: The base station may update the CWS. CWS q can be updated with a value between X and Y. The X and Y values are configurable parameters. CWS update/adjustment may be performed every N generation (dynamic back-off), or semi-statically performed at regular time intervals (semi-static back-off). CWS may be updated/adjusted based on exponential back-off or binary back-off. That is, the CWS may be updated/adjusted in the form of a power of 2 or a multiple of 2. In relation to PDSCH transmission, the CWS may be updated/adjusted based on the feedback/report (eg, HARQ ACK/NACK) of the UE, or updated/adjusted based on the base station sensing.

- S316: The base station checks whether the channel is idle during the ECCA dipper period (DeCCA). The ECCA dipper period is configurable. As an implementation example, the ECCA dipper period may consist of a 16 μs interval and n consecutive CCA slots. Here, n is a positive integer, and one CCA slot period may be 9 μs. The number of CCA slots may be set differently according to QoS classes. The ECCA dipper period may be set to an appropriate value in consideration of the dipper period (eg, DIFS, AIFS) of Wi-Fi. For example, the ECCA dipper period may be 34 μs. If the channel is idle during the ECCA dipper period, the base station proceeds to S318. If it is determined that the channel is in use during the ECCA dipper period, the base station repeats S316.

- S318: The base station checks whether N is 0. If N is 0, the base station may perform a signal transmission process (S308). In this case (ie, N=0), the base station may continue the ECCA process by performing a CCA check for at least one slot without performing transmission immediately. If N is not 0 (that is, N>0), the process proceeds to S320.

- S320: The base station senses a channel during one ECCA slot period (T). The ECCA slot size may be 9 μs or 10 μs, and the actual sensing time may be at least 4 μs.

- S322: If it is determined that the channel is in an idle state, it proceeds to S324. If it is determined that the channel is in use, it returns to S316. That is, one ECCA dipper period is applied again after the channel is idle, and N is not counted down during the ECCA dipper period.

- S324: Decrease N by 1 (ECCA count down).

FIG. 14 is substantially the same as/similar to the transmission process of FIG. 13, and there is a difference according to an implementation method. Accordingly, for details, reference may be made to the contents of FIG. 13 .

Initial CCA

- S402: The base station checks whether signal transmission is necessary. If signal transmission is not required, S402 is repeated, and if signal transmission is required, it proceeds to S404.

- S404: The base station checks whether the slot is in an idle state. If the slot is idle, the process proceeds to S406, and if the slot is in use, proceeds to S412 (ECCA). The slot may correspond to the CCA slot in FIG. 13 .

- S406: The base station checks whether the channel is idle during the dipper period (D). D may correspond to the ICCA dipper period in FIG. 13 . If the channel is idle during the dipper period, the base station may perform a signal transmission process (S408). If it is determined that the channel is in use during the dipper period, the flow proceeds to S404.

- S408: The base station may perform a signal transmission process if necessary.

- S410: If there is no signal transmission, proceed to S402 (ICCA), if there is signal transmission, proceed to S412 (ECCA). Even when the back-off counter N reaches 0 in S418 and S408 is performed, if there is no signal transmission, the process proceeds to S402 (ICCA), and if there is a signal transmission, the process proceeds to S412 (ECCA).

Extended CCA

- S412: The base station generates a random number N in the CW. N is used as a counter in the back-off process, and is generated from [0, q-1]. The CW size (CWS) is defined as q and may be changed in S414. Thereafter, the base station proceeds to S416.

- S414: The base station may update the CWS. CWS q can be updated with a value between X and Y. The X and Y values are configurable parameters. CWS update/adjustment may be performed every N generation (dynamic back-off), or semi-statically performed at regular time intervals (semi-static back-off). CWS may be updated/adjusted based on exponential back-off or binary back-off. That is, the CWS may be updated/adjusted in the form of a power of 2 or a multiple of 2. In relation to PDSCH transmission, the CWS may be updated/adjusted based on the feedback/report (eg, HARQ ACK/NACK) of the UE, or updated/adjusted based on the base station sensing.

- S416: The base station checks whether the channel is idle during the dipper period (D). D may correspond to the ECCA dipper period of FIG. 13 . In S406 and S416, D may be the same. If the channel is idle during the dipper period, the base station proceeds to S418. If it is determined that the channel is in use during the dipper period, the base station repeats S416.

- S418: The base station checks whether N is 0. If N is 0, the base station may perform a signal transmission process (S408). In this case (N=0), the base station may continue the ECCA process by performing a CCA check for at least one slot without performing transmission immediately. If N is not 0 (that is, N>0), the process proceeds to S420.

- S420: The base station selects one of the operations of decreasing N by 1 (ECCA countdown) or not decreasing N (self-deferral). The self-differential operation may be performed according to the implementation/selection of the base station. In self-differential, the base station does not perform sensing for energy detection and does not perform ECCA countdown.

- S422: The base station may select one of an operation not performing sensing for energy detection and an energy detection operation. If sensing for energy detection is not performed, the process proceeds to S424. When the energy detection operation is performed, if the energy level is equal to or less than the energy detection threshold value (ie, idle), the process proceeds to S424. If the energy level exceeds the energy detection threshold (ie, busy), it returns to S416. That is, one dipper period is applied again after the channel is idle, during which N is not counted down.

- S424: Proceed to S418.

15 shows an example in which a base station performs DL transmission in an unlicensed band. A base station is a cell of one or more licensed bands (for convenience, it may be an LTE-L cell or an NR-Licensed cell) and one or more cells of one or more unlicensed bands (for convenience, an LTE-U cell or NR-Unlicensed cell, NR-U cell) can be assembled 15 assumes that one LTE-L cell and one LTE-U cell are aggregated for communication with the terminal. The LTE-L cell may be a PCell and the LTE-U cell may be a SCell. In the LTE-L cell, the base station exclusively uses the frequency resource and can perform an operation according to the existing LTE. Accordingly, all radio frames are composed of regular subframes (rSFs) having a length of 1 ms (see FIG. 2), and DL transmission (eg, PDCCH, PDSCH) may be performed in every subframe (see FIG. 1). . Meanwhile, in the LTE-U cell, DL transmission is performed based on LBT for coexistence with an existing device (eg, a Wi-Fi device). In addition, in order to effectively implement LTE-U technology/service, it is necessary to allocate or reserve a specific frequency band for a specific time. Therefore, in the LTE-U cell, DL transmission may be performed through one or more consecutive subframe sets after LBT (DL transmission burst). The DL transmission burst may start with a regular subframe (rSF) as shown in FIG. 15(a) or start with a partial subframe (pSF) as shown in FIG. 15(b) according to the LBT situation. The pSF is a part of a subframe and may include the second slot of the subframe. Also, a DL transmission burst may end in rSF or pSF.

Hereinafter, a method for adaptively adjusting CWS during channel access in an unlicensed band is proposed. CWS may be adjusted based on User Equipment (UE) feedback, and UE feedback used for CWS adjustment may include a HARQ-ACK response and CQI/PMI/RI. The present invention proposes a method for adaptively adjusting CWS based on the HARQ-ACK response. The HARQ-ACK response includes ACK, NACK, and DTX.

As described with reference to FIG. 12, even in Wi-Fi, CWS is adjusted based on ACK. When the ACK feedback is received, the CWS is reset to the minimum value (CWmin), and when the ACK feedback is not received, the CWS is increased. However, in a cellular system (eg, LTE), a CWS adjustment method considering multiple access is required.

First, terms are defined as follows for the description of the present invention.

- A set of HARQ-ACK feedback values (HARQ-ACK feedback set): means HARQ-ACK feedback value(s) used for CWS update/adjustment. The HARQ-ACK feedback set corresponds to HARQ-ACK feedback values that are decoded and available at the time the CWS is determined. The HARQ-ACK feedback set includes HARQ-ACK feedback value(s) for one or more DL (channel) transmissions (eg, PDSCH) on an unlicensed band (eg, LTE-U cell). The HARQ-ACK feedback set may include HARQ-ACK feedback value(s) for DL (channel) transmission (eg, PDSCH), for example, a plurality of HARQ-ACK feedback values fed back from a plurality of terminals. The HARQ-ACK feedback value indicates reception response information for a transport block or PDSCH, and may indicate ACK, NACK, DTX, and NACK/DTX. Depending on the context, the HARQ-ACK feedback value may be mixed with the HARQ-ACK value/bit/response/information.

- Reference window: refers to a time interval in which DL transmission (eg, PDSCH) corresponding to the HARQ-ACK feedback set is performed in an unlicensed band (eg, LTE-U cell). It can be defined in SF units. It will be explained/suggested in more detail later.

According to the HARQ-ACK feedback scheme or PUCCH format in LTE, the HARQ-ACK value may indicate only ACK and NACK or may further indicate DTX. For example, when PUCCH format 3 is configured as the HARQ-ACK feedback method, the HARQ-ACK value may indicate only ACK and NACK. On the other hand, when the channel selection method using the PUCCH format 1b is set as the HARQ-ACK feedback method, the HARQ-ACK value may indicate ACK, NACK, DTX, and NACK/DTX.

Referring to FIG. 16 , after the base station transmits the nth DL transmission burst in the unlicensed band (eg, LTE-U cell) (S502), when additional DL transmission is required, the (n+1)th DL transmission based on ECCA A burst may be transmitted (S512). Specifically, when the channel of the unlicensed band is in an empty state during the ECCA dipper period, the base station additionally performs a random back-off in the CW (S510). The base station may generate a random number N in the CW (eg, [0, q-1]) (S508), and may perform back-off by as many slots as the random number N (S510). In the present invention, the CWS is adjusted based on the HARQ-ACK feedback values from the terminals (S506). HARQ-ACK feedback values used for CWS adjustment include HARQ-ACK feedback values for the most recent DL transmission burst (n-th DL transmission burst). HARQ-ACK feedback values used for CWS adjustment include HARQ-ACK feedback values for DL transmission on a reference window within a DL transmission burst (S504).

In the description of the present invention so far, LTE-based LAA cell is defined as LTE-U cell, but in the same way, the terms NR licensed cell and LTE-L cell may be substituted for NR, and also NR Unlicensed cell and LTE- U cell may be applied to the present invention by replacing the term. However, if it is stated otherwise in the specific details of the present invention for other points using the NR unlicensed cell, it is applied to the corresponding NR-Unlicensed cell.

Referring to FIG. 17 , in the 3GPP NR system, terminals may perform transmission/reception using a bandwidth that is less than or equal to the bandwidth of a carrier (or cell). To this end, the terminal may be configured with a plurality of bandwidth parts from the base station. Bandwidth part consists of consecutive PRBs. Referring to FIG. 17-(a), bandwidth parts may be divided non-overlapping. One or a plurality of bandwidth parts of the non-overlapping bandwidth parts may be allocated and configured to terminals. The terminals can transmit and receive with the base station using allocated and configured bandwidth parts. Referring to FIG. 17-(b), Bandwidth parts may be divided by overlapping the bandwidth of the carrier. In this case, one Bandwidth part may be configured to be included in another Bandwidth part. One or a plurality of bandwidth parts of the overlapped bandwidth parts may be allocated and configured to terminals. The terminals can transmit and receive with the base station using one of the allocated and configured bandwidth parts.

Referring to FIG. 18 , when the terminal is allocated a plurality of bandwidth parts, at least one CORESET may be configured or allocated to the terminal for each bandwidth part. 18-(a) and 18-(b), when Bandwidth parts are configured not to overlap each other and when Bandwidth parts are configured to overlap, CORESET for each Bandwidth part is the time occupied by each Bandwidth part It may be located in the /frequency resource region. In other words, CORESET #1 for Bandwidth part #1 exists within the PRB in the time/frequency resource domain occupied by Bandwidth part #1, and CORESET #2 for Bandwidth part #2 is the time/frequency occupied by Bandwidth part #2. It may exist within the PRB in the resource area. Referring to FIG. 18-(b), when bandwidth parts are configured to overlap each other, the PRBs occupied by CORESET are within their own bandwidth part time/frequency resource region, but may be located in other bandwidth parts. In other words, CORESET #2 for Bandwidth part #2 may overlap with PRB in the time/frequency resource domain occupied by Bandwidth part #1.

A maximum of 4 DL BWPs and a maximum of 4 UL BWPs may be configured in a time division duplex (TDD) cell per cell. The UE may simultaneously activate one DL BWP and one UL BWP in one cell. Up to 4 DL/UL BWP pairs per cell can be configured in a frequency division duplex (FDD) cell. The UE may have one DL/UL BWP active in one cell at the same time. The UE does not expect to receive any signal in the PRB other than the activated DL BWP, and does not expect to transmit any signal in the PRB other than the activated UL BWP. It instructs the UE to move from one BWP to another, that is, deactivate the currently used BWP and activate a new BWP using downlink control information (DCI). In more detail, in order to change the DL BWP of the UE in the TDD cell, a Bandwidth part indicator (BPI) indicating the activated BWP is included in the DCI scheduling PDSCH. That is, when the UE receives the DCI scheduling the PDSCH, it can know which BWP the PDSCH is transmitted through the BPI, and which PRBs of the BWP are transmitted through the resource allocation (RA) of the DCI. . Similarly, in order to change the UL BWP of the UE in the TDD cell, a Bandwidth part indicator (BPI) indicating the activated BWP is included in DCI scheduling PUSCH. That is, when the UE receives the DCI scheduling the PUSCH, it can know through which BWP the PUSCH should be transmitted through the BPI, and which PRBs of the BWP indicated through the resource allocation (RA) of the DCI should be transmitted. Able to know. In the case of an FDD cell, a BWP value of a DCI for scheduling a PDSCH and a PUSCH may indicate one of a DL/UL BWP pair.

In the present invention, when the NR system operates on the unlicensed band based on the NR frame structure and transmission method, unlike the existing LAA, methods for a channel access procedure that can be newly applied on the NR-Unlicensed band are proposed. As described in the above description of the present invention, in the NR system utilizing the Licensed band, CBG-based transmission is performed for fast data decoding. CBG-based transmission may be highly useful in NR-Unlicensed systems. Depending on the success or failure of channel access, only downlink or uplink transmission in some time domain units can be allowed. -It may be advantageous to increase the frequency efficiency of an unlicensed system. Therefore, in the present invention, when CBG-based transmission used in the NR system is performed on the unlicensed band, it needs to be applied differently from the channel access procedure used in the existing LAA. In particular, in the case of downlink, a method different from the method used in LAA needs to be applied when the base station performs contention window size (CWS) adaptation in the process of performing the channel access procedure. When performing contention window size (CWS) adaptation in the process of performing the procedure, a method different from the method used in LAA needs to be applied. The NR unlicensed band system also needs to consider coexistence with Wi-Fi. In the case of A-MPDU used in Wi-Fi, CWS adaptation can be performed only with some HARQ-ACK responses, so even in the NR-Unlicensed system, Wi-Fi It may be necessary to modify the channel access procedure compared to LAA so as not to be inferior in performing the channel access procedure compared to Fi.

When the base station configures CBG-based transmission to the terminal and the terminal transmits a CBG-based HARQ-ACK response, the following method may be considered as the CWS update method of the base station. In the cell managed by the base station, there may be terminals configured for CBG-based transmission depending on the capability of the terminal, and there may be terminals for which CBG-based transmission is not configured. In case of receiving it from , CBG-based HARQ-ACK feedback will be transmitted, and terminals for which CBG-based transmission is not configured will maintain TB-based transmission and transmit TB-based HARQ-ACK feedback. In LTE-LAA, since the UE transmits only TB-based A/N to the base station, the base station can determine whether to increase the CWS to the next preset level based on the HARQ-ACK ratio of 80% or to reset the CWS to CW_min without specific ambiguity. have. However, in the NR-Unlicensed system, since the HARQ-ACK feedback transmitted by the UE may be TB-based or CBG-based, a method for solving this is required.

First, when TB-based HARQ-ACK feedback and CBG-based HARQ-ACK feedback are mixed and received by the base station, the base station may perform CWS adaptation during channel access according to the following methods.

As an embodiment of the present invention, the TB-based A/N is calculated as it is when calculating the NACK ratio, and when the CBG-based A/N is fed back, at least one of the CBG A/Ns based on one TB If there is an ACK of , it may be determined as an ACK based on the corresponding TB and included in the calculation of the NACK ratio for CWS update. First, even for CBG-based transmission, the calculation of the NACK ratio is calculated based on the TB rather than based on the number of CBG ACKs. Even if only one ACK among the CBGs indicating that at least one of the CBGs has been received is fed back, it can be determined that the UE gave feedback as ACK because the base station successfully sent the CBG-based transmission to the UE and successfully channeled access to the UE. , the TB can be calculated as ACK and reflected when calculating the NACK ratio. Therefore, based on the calculated NACK ratio, in the same manner as used in LAA, the base station increases the CWS to the next preset level based on the channel access priority class based on the HARQ-ACK ratio of 80% or resets the CWS to CW_min. can be decided Alternatively, based on the calculated NACK ratio, the base station may determine whether to increase the CWS to the next preset level based on the channel access priority class based on the HARQ-ACK ratio Z% or to reset the CWS to CW_min. Here, Z may be a natural number having a range of 0<=Z<=100, and more specifically, it may have one of {30, 50, 70, 80, 100} or the same method used in LAA. In general, the base station may set the HARQ-ACK ratio to 80%.

In addition, when receiving CBG-based transmission from the base station or CBG-based transmission from the terminal, some CBGs are successfully decoded, and decoding of other CBGs fails, so the base station transmits a CBG-based NACK to the base station. When receiving the corresponding information, the base station performs partial CBG retransmission. At this time, when the terminal according to CBG retransmission performs CBG based HARQ-ACK feedback, CBG based HARQ- CBG based HARQ- for CBG that has been successfully decoded before ACK feedback is ACK feedback for the CBG that the terminal feedbacks as ACK and generates a CBG based A/N based on the success of decoding in the terminal for the CBG on which retransmission is performed from the base station, and together with the ACK feedback for the CBG that has been successfully decoded before the base station send. Therefore, when CBG-based retransmission occurs, the base station indicates that the terminal has well received at least one of the CBGs retransmitted from the base station based on the CBG-based HARQ-ACK from the terminal for the CBG-based retransmission transmitted by the base station. Even if only one of the ACKs is feedback, it can be determined that the terminal gave feedback as ACK because the base station successfully sent the CBG-based retransmission to the terminal as an ACK. It may be reflected in calculating the NACK ratio, otherwise, that is, in the case of not at least one ACK, it may be regarded as a NACK and reflected in the calculation of the NACK ratio. Therefore, based on the calculated NACK ratio, the base station can determine whether to increase the CWS to the next preset level based on the channel access priority class based on the HARQ-ACK ratio Z% or to reset the CWS to CW_min. Here, Z may be a natural number having a range of 0<=Z<=100, and more specifically, it may have one of {30, 50, 70, 80, 100} or the same method used in LAA. In general, the base station may set the HARQ-ACK ratio to 80%.

As another embodiment of the present invention, TB-based A/N is calculated as it is when calculating the NACK ratio, and when CBG-based A/N is fed back, all CBG-based A/N of CBGs based on one TB If N is fed back as ACK, TB based CRC is also checked and TB is also determined as ACK, it is judged as ACK based on the corresponding TB. can be included. First, even for CBG-based transmission, the calculation of the NACK ratio is calculated based on the TB rather than based on the number of CBG ACKs. Only when it indicates that all of them have been well received, it can be determined that the terminal gave feedback as ACK because the base station successfully transmitted the CBG-based transmission to the terminal by successfully accessing the channel, and also from the reception point of the terminal In response to the interference environment, it can be determined that the reception is successful because the channel access is made well, so the transmission through the channel from the base station is considered as channel access success, and the TB is calculated as an ACK and reflected when calculating the NACK ratio. can Therefore, based on the calculated NACK ratio, the base station can determine whether to increase the CWS to the next preset level based on the channel access priority class based on the HARQ-ACK ratio Z% or to reset the CWS to CW_min. Here, Z may be a natural number having a range of 0<=Z<=100, and more specifically, it may have one of {30, 50, 70, 80, 100} or the same method used in LAA. In general, the base station may set the HARQ-ACK ratio to 80%.

In addition, when receiving CBG-based transmission from the base station or CBG-based transmission from the terminal, some CBGs are successfully decoded, and decoding of other CBGs fails, so the base station transmits a CBG-based NACK to the base station. When receiving the corresponding information, the base station performs partial CBG retransmission. At this time, when the terminal according to CBG retransmission performs CBG based HARQ-ACK feedback, CBG based HARQ- CBG based HARQ- for CBG that has been successfully decoded before ACK feedback is ACK feedback for the CBG that the terminal feedbacks as ACK and generates a CBG based A/N based on the success of decoding in the terminal for the CBG on which retransmission is performed from the base station, and together with the ACK feedback for the CBG that has been successfully decoded before the base station send. Therefore, when CBG-based retransmission occurs, the base station considers it as ACK when calculating the NACK ratio if all ACKs are ACKs based on the CBG-based HARQ-ACK from the terminal for the CBG-based retransmission transmitted by the base station. That is, all cases other than ACK may be regarded as NACK and reflected when calculating the NACK ratio. Therefore, based on the calculated NACK ratio, the base station can determine whether to increase the CWS to the next preset level based on the channel access priority class based on the HARQ-ACK ratio Z% or to reset the CWS to CW_min. Here, Z may be a natural number having a range of 0<=Z<=100, and more specifically, it may have one of {30, 50, 70, 80, 100} or the same method used in LAA. In general, the base station may set the HARQ-ACK ratio to 80%.

In another embodiment of the present invention, when CBG-based transmission is made to a terminal and CBG-based HARQ-ACK feedback is transmitted from the terminal, the base station calculates the NACK ratio by calculating the HARQ-ACK feedback from the terminal. It is possible to determine A/N of TB based on /N. This is because there are cases in which the TB CRC check is determined to be a failure when the TB-based ACK is determined even though all CBG-based ACKs have occurred in a case where the CBG-based transmission is well received and the TB NACK is transmitted. This is the channel for the base station to access the medium Since it may be separate from the access procedure, this is intended to be excluded.

In another embodiment of the present invention, when CBG-based transmission is made to the terminal and CBG-based HARQ-ACK feedback is transmitted from the terminal, the base station calculates the NACK ratio by calculating the HARQ-ACK feedback from the corresponding terminal. It is possible to determine A/N of TB based on /N. This means that if the CBG-based transmission is well received, all CBGs have been successfully received for the CBG-based transmission, and if the check is successful until the CRC of the TB configured with the CBG is successful, all CBG-based A/ N is ACK, which the terminal generates and transmits to the base station. Therefore, the base station determines the A/N of the TB based on the CBG-based A/N, and if all of the CBG-based A/Ns are ACKs, the TB is regarded as ACK and reflected when calculating the NACK ratio. However, even though the reception of all CBG-based transmissions has been successful, the TB CRC check is determined to be a failure when the TB-based ACK is determined. As a meaning of TB NACK, the UE generates all CBG-based A/N with NACK and performs retransmission for the TB. There may be times when you may be asked to. Therefore, the base station determines the A/N of the TB based on the CBG-based A/N, and if all of the CBG-based A/Ns are NACK, the TB is considered as NACK and reflected when calculating the NACK ratio.

In another embodiment of the present invention, when receiving CBG-based transmission from a base station or CBG-based transmission from a terminal, some CBGs are successfully decoded, and decoding of other CBGs fails, so CBG-based NACK to the base station and the base station receives the corresponding information, the base station performs partial CBG retransmission. CBG based HARQ-ACK feedback for CBG is ACK, which generates CBG based A/N based on the success of decoding in the terminal for CBG that the terminal feedbacks and retransmission is performed from the base station, and is decoded successfully before the base station. It is transmitted with ACK feedback for CBG. In this case, if the reception of the retransmitted CBG-based transmission is successfully received, and the check is successful up to the CRC of the TB configured with the CBG, and the reception of the TB is successful, all CBG-based A/Ns are ACKed, and the UE generates generation In this case, the base station can determine the success of TB reception based on the CBG-based A/N and reflect it as an ACK when calculating the NACK ration. However, even though the reception of all CBG-based retransmissions has been successful, the TB CRC check is determined to fail when the TB-based ACK is determined. There may be cases in which the UE generates all of the CBG based A/N with NACK to request retransmission for the corresponding TB. Therefore, in this case, the base station received all the CBGs successfully, but the TB CRC check failed because the A/N information on the CBG that the base station had previously received was received as NACK after being flipped instead of received as ACK. Since it can be determined that all A/N of A/N are fed back NACK, in this case, even if all CBG-based A/N are fed back NACK, for CWS update, TB is considered as ACK and reflected when calculating NACK ratio. can do it This is intended to reflect this more accurately when calculating the NACK ratio since it may be separate from the channel access procedure for the base station to access the medium.

In another embodiment of the present invention, when receiving CBG-based transmission from a base station or CBG-based transmission from a terminal, some CBGs are successfully decoded, and decoding of other CBGs fails, so CBG-based NACK to the base station and the base station receives the corresponding information, the base station performs partial CBG retransmission. CBG based HARQ-ACK feedback for CBG is ACK, which generates CBG based A/N based on the success of decoding in the terminal for CBG that the terminal feedbacks and retransmission is performed from the base station, and is decoded successfully before the base station. It is transmitted with ACK feedback for CBG. In this case, if the reception of the retransmitted CBG-based transmission is successfully received, and the check is successful up to the CRC of the TB configured with the CBG, and the reception of the TB is successful, all CBG-based A/Ns are ACKed, and the UE generates generation In this case, the base station can determine the success of TB reception based on the CBG-based A/N and reflect it as an ACK when calculating the NACK ration. However, even though the reception of all CBG-based retransmissions has been successful, the TB CRC check is determined to fail when the TB-based ACK is determined. There may be cases in which the UE generates all of the CBG based A/N with NACK to request retransmission for the corresponding TB. Therefore, in this case, the base station received all the CBGs successfully, but the TB CRC check failed because the A/N information on the CBG that the base station had previously received was received as NACK after being flipped instead of received as ACK. It can be determined that all A/N of A/N are fed back as NACK. Nevertheless, for CWS update, if all CBG-based A/Ns are fed back with NACK using a single rule in order to take both the method for initial transmission and the method for retransmission in the same way, whether it is initial transmission or retransmission Regardless, for CWS update, TB can be regarded as NACK and reflected when calculating NACK ratio.

As another embodiment of the present invention, the maximum number of CBGs in one TB may be determined by the RRC configuration. Therefore, since the transmission of the first CBG transmitted by the base station to the terminal can reflect the channel condition of the channel access in the base station well, when calculating the NACK ratio by calculating the CBG-based A/N for the first transmission of the CBG constituting the TB A method to reflect it may be considered.

As another embodiment of the present invention, when TB-based HARQ-ACK feedback and CBG-based HARQ-ACK feedback are mixed and received by the base station, CBG-based transmission is configured for at least one serving cell. The maximum number of CBGs is set for each. Therefore, for the A/N of the TB received by the base station, the NACK ratio is calculated by integrating the total CBG-based A/N and the TB-based A/N by giving a weight to the maximum number of CBGs configured for CBG-based transmission. It can be used for CWS update.

In addition, the NR system can allow the base station to flexibly designate the HARQ-ACK timing for each terminal. The base station may indicate different HARQ-ACK timing according to the terminal capability for each terminal through RRC and dynamic scheduling. In determining the CWS for performing DL transmission in the base station, the HARQ-ACK feedback set so that the base station expects to receive HARQ-ACK based on the DL time point at which the base station wants to transmit is used to determine the CWS for the corresponding DL transmission. You can calculate the ratio and use it for CWS update accordingly. Considering all cases where there is no transmission of HARQ-ACK feedback from the terminal or the base station does not receive the corresponding HARQ-ACK at the time when the base station expects the reception of the HARQ-ACK feedback, it is determined that the case is DTX and the corresponding DTX is NACK can be judged as However, in the case of the corresponding DTX, for the DTX corresponding to cross-carrier scheduling from the licensed carrier, the corresponding DTX should be ignored, that is, set not to be included in the total number of A/Ns. Contrary to this, when cross-carrier scheduling in unlicensed carrier is used, the corresponding DTX can be regarded as NACK and included in the calculation of the NACK ratio.

In the case of downlink described in the present invention, a reference slot as a reference in calculating the NACK ratio among HARQ-ACKs for TB-based HARQ-ACK or CBG-based HARQ-ACK feedback corresponding to PDSCH is TB-based. The HARQ-ACK or CBG-based HARQ-ACK feedback may be the earliest starting slot among the most recent transmissions performed by a base station that is expected to be available. This is to set the starting slot from the point of view that the most advanced starting slot can best reflect the state of the channel when it is transmitted through DL by configuring multiple slots. However, when multiple slot transmissions are performed continuously without a gap before the reference slot when setting the reference slot, the most advanced slot among the multiple slot transmissions may be set as the reference slot.

In addition, regardless of the reference slot of PDSCH Type A/B, the base station selects the earliest starting slot among the most recent transmissions performed by the base station so that TB-based HARQ-ACK or CBG-based HARQ-ACK feedback is available. One can be set as a reference slot, or if the reference slot is transmitted in PUSCH Type A, it can be considered as slot-based transmission, so one slot is set as a reference slot, and when transmitted in PUSCH Type B, PUSCH type B transmission It is possible to set the reference slot and the next slot as the reference slot. This is a non-slot based transmission (mini-slot based transmission), that is, considering that the slot is transmitted with a shorter time length than the maximum number of symbols that the slot can contain, even though the base station successfully accesses the channel and transmits the PDSCH, the non-slot This is to compensate for the NACK occurring due to slot-based transmission, which affects CW increase.

In addition, when the base station transmits the PDSCH having two codewords to the terminal, TBs are allocated for each codeword, and CBG-based transmission according to the maximum number of CBGs for each TB is performed from the base station, and the terminal performs CBG-based transmission for each TB. Since HARQ-ACK feedback is transmitted, it may be possible to extend and apply the embodiments described in the present invention described based on one TB. That is, it can be applied based on individual TBs, and the number of HARQ-ACKs can be counted for different codewords, respectively.

PDSCH transmission criteria in reference slot

In the following invention, in performing CWS update of the base station, the terminal transmits HARQ-ACK feedback TB-based A/N in response to the transmission of the PDSCH transmitted by the base station in the reference slot, and the CBG-based A It relates to a method of performing CWS update by calculating a NACK ratio when /N is transmitted. In particular, when CBG-based A/N transmission is performed, the base station in the reference slot may be reflected in calculating the NACK ratio based on the A/N from the UE corresponding to the PDSCH transmission.

As an embodiment of the present invention, as HARQ-feedback transmitted by the terminal for PDSCH transmission performed by the base station in the reference slot, the NACK ratio is calculated for TB-based A/N as it is, and CBG-based When the A/N is fed back, if there is at least one ACK among the A/Ns of the CBG based on the transmission of the PDSCH transmitted by the base station in the reference slot, it is determined as an ACK based on the corresponding PDSCH transmission and CWS update It can be included in the calculation of the NACK ratio for First, even for CBG-based transmission, the calculation of the NACK ratio is not calculated based on the number of CBG ACKs but based on the transmission standard of the PDSCH. Even if only one ACK among CBGs indicating that the UE has received at least one of the CBGs is fed back, it is determined that the UE gave feedback as ACK because the base station successfully transmitted the CBG-based PDSCH transmission to the UE after successful channel access. Therefore, it can be regarded as channel access success, and the corresponding PDSCH can be calculated as ACK and reflected when calculating the NACK ratio. Therefore, based on the calculated NACK ratio, in the same manner as used in LAA, the base station increases the CWS to the next preset level based on the channel access priority class based on the HARQ-ACK ratio of 80% or resets the CWS to CW_min. can be decided Alternatively, based on the calculated NACK ratio, the base station may determine whether to increase the CWS to the next preset level based on the channel access priority class based on the HARQ-ACK ratio Z% or to reset the CWS to CW_min. Here, Z may be a natural number having a range of 0<=Z<=100, and more specifically, it may have one of {30, 50, 70, 80, 100} or the same method used in LAA. In general, the base station may set the HARQ-ACK ratio to 80%.

In addition, when receiving CBG-based transmission from the base station or CBG-based transmission from the terminal, some CBGs are successfully decoded, and decoding of other CBGs fails, so the base station transmits a CBG-based NACK to the base station. When receiving the corresponding information, the base station performs partial CBG retransmission. At this time, when the terminal according to CBG retransmission performs CBG based HARQ-ACK feedback, CBG based HARQ- CBG based HARQ- for CBG that has been successfully decoded before ACK feedback is ACK feedback for the CBG that the terminal feedbacks as ACK and generates a CBG based A/N based on the success of decoding in the terminal for the CBG on which retransmission is performed from the base station, and together with the ACK feedback for the CBG that has been successfully decoded before the base station send. Therefore, when CBG-based retransmission occurs, the base station receives the CBG based on the CBG-based HARQ-ACK from the terminal for the transmission of the CBG-based PDSCH in the reference slot transmitted by the base station. Even if only one ACK among the CBGs indicating that at least one has been received is fed back, it can be determined that the terminal gave feedback as ACK because the base station successfully sent the CBG-based retransmission to the terminal by successfully accessing the channel. Considering that, the corresponding transmission may be calculated as ACK and reflected when calculating the NACK ratio. Otherwise, it may be regarded as NACK and reflected when calculating the NACK ratio if it is not at least one ACK. Therefore, based on the calculated NACK ratio, the base station can determine whether to increase the CWS to the next preset level based on the channel access priority class based on the HARQ-ACK ratio Z% or to reset the CWS to CW_min. Here, Z may be a natural number having a range of 0<=Z<=100, and more specifically, it may have one of {30, 50, 70, 80, 100} or the same method used in LAA. In general, the base station may set the HARQ-ACK ratio to 80%.

As another embodiment of the present invention, the TB-based A/N is calculated as it is when calculating the NACK ratio, and when the CBG-based A/N is fed back , the transmission of the PDSCH transmitted by the base station in the reference slot is performed. If all CBG-based A/Ns of CBGs are fed back as ACK, it is determined as ACK based on the corresponding PDSCH transmission. can do it First, even for CBG-based transmission, the calculation of the NACK ratio is not calculated based on the number of CBG ACKs, but based on the transmission of the PDSCH transmitted in the reference slot . only when the UE indicates that it has received all CBGs for the corresponding PDSCH, it can be determined that the UE has given feedback as ACK because the eNB successfully transmits the CBG-based transmission to the UE through channel access. Also, from the reception point of the terminal, it can be determined that the reception is successful because the channel access is well made in response to the interference environment of the corresponding channel, so transmission through the corresponding channel in the base station is regarded as channel access success, and the corresponding PDSCH is ACK can be calculated and reflected when calculating the NACK ratio. Therefore, based on the calculated NACK ratio, the base station can determine whether to increase the CWS to the next preset level based on the channel access priority class based on the HARQ-ACK ratio Z% or to reset the CWS to CW_min. Here, Z may be a natural number having a range of 0<=Z<=100, and more specifically, it may have one of {30, 50, 70, 80, 100} or the same method used in LAA. In general, the base station may set the HARQ-ACK ratio to 80%.

In addition, when receiving CBG-based transmission from the base station or CBG-based transmission from the terminal, some CBGs are successfully decoded, and decoding of other CBGs fails, so the base station transmits a CBG-based NACK to the base station. When receiving the corresponding information, the base station performs partial CBG retransmission. At this time, when the terminal according to CBG retransmission performs CBG based HARQ-ACK feedback, CBG based HARQ- CBG based HARQ- for CBG that has been successfully decoded before ACK feedback is an ACK that the UE feeds back and generates a CBG based A/N based on the decoding success in the UE based on the PDSCH transmission for the CBG on which retransmission has been performed from the base station, and the CBG that has been successfully decoded before the base station It is transmitted with ACK feedback for Therefore, when CBG-based retransmission occurs, the base station determines the NACK ratio if all ACKs are based on the CBG-based HARQ-ACK from the terminal for the transmission of the CBG-based PDSCH in the reference slot transmitted by the base station. It may be regarded as ACK, otherwise, all cases other than ACK may be regarded as NACK and reflected when calculating the NACK ratio. Therefore, based on the calculated NACK ratio, the base station can determine whether to increase the CWS to the next preset level based on the channel access priority class based on the HARQ-ACK ratio Z% or to reset the CWS to CW_min. Here, Z may be a natural number having a range of 0<=Z<=100, and more specifically, it may have one of {30, 50, 70, 80, 100} or the same method used in LAA. In general, the base station may set the HARQ-ACK ratio to 80%.

In another embodiment of the present invention, when CBG-based transmission is made to the terminal and CBG-based HARQ-ACK feedback is transmitted from the terminal, the base station calculates the NACK ratio by calculating the HARQ-ACK feedback from the corresponding terminal. Based on /N , the base station in the reference slot may determine A/N of PDSCH transmission that has been transmitted . This means that when the CBG-based transmission is well received through the transmission of the PDSCH transmitted by the base station in the reference slot, all CBGs are successfully received for the CBG-based transmission, and the check is performed until the CRC of the TB configured with the CBG. When the reception of the TB is successful, all CBG-based A/Ns are generated by the terminal as ACK and transmitted to the base station. Therefore, the base station determines the A/N of the PDSCH transmission performed by the base station in the reference slot based on the CBG-based A/N, and if all CBG-based A/Ns are ACK, the corresponding PDSCH transmission is ACK It can be considered to be reflected when calculating the NACK ratio. However, even though the reception of all CBG-based transmissions through the PDSCH was successful, when the UE determines the TB-based ACK, the TB CRC check is determined to be a failure. There may be a case where a request for retransmission for the TB is requested. Therefore, the base station determines the A/N of the corresponding PDSCH transmission based on the CBG-based A/N, and if all CBG-based A/Ns are NACK, the corresponding PDSCH transmission is considered as NACK and reflected when calculating the NACK ratio. can do.

In another embodiment of the present invention, when receiving CBG-based transmission from a base station or CBG-based transmission from a terminal, some CBGs are successfully decoded, and decoding of other CBGs fails, so CBG-based NACK to the base station and the base station receives the corresponding information, the base station performs partial CBG retransmission. CBG based HARQ-ACK feedback for CBG is ACK feedback from the UE and based on the PDSCH transmission for the CBG retransmitted from the base station, CBG based A/N is generated and sent to the base station based on the decoding success in the UE. It is transmitted together with the ACK feedback for the CBG that has been successfully decoded previously. In this case, if the reception of the retransmitted CBG-based transmission is successfully received, and the check is successful up to the CRC of the TB configured with the CBG, and the reception of the TB is successful, all CBG-based A/Ns are ACKed, and the UE generates generation In this case, the base station may determine the reception success of the corresponding PDSCH transmission based on the corresponding CBG-based A/N and reflect it as an ACK when calculating the NACK ratio. However, even though the reception of all CBG-based retransmissions has been successful, the TB CRC check is determined to fail when the TB-based ACK is determined. There may be cases in which the UE generates all of the CBG based A/N with NACK to request retransmission for the corresponding TB. Therefore, in this case, the base station received all the CBGs successfully, but the TB CRC check failed because the A/N information on the CBG that the base station had previously received was received as NACK after being flipped instead of received as ACK. Since it can be determined that all A/N of A/N are fed back with NACK, in this case, even if all CBG-based A/N are fed back with NACK based on the corresponding PDSCH transmission, for CWS update, the corresponding PDSCH transmission is ACK. It can be considered to be reflected when calculating the NACK ratio. This is intended to reflect this more accurately when calculating the NACK ratio since it may be separate from the channel access procedure for the base station to access the medium.

In another embodiment of the present invention, when receiving CBG-based transmission from a base station or CBG-based transmission from a terminal, some CBGs are successfully decoded, and decoding of other CBGs fails, so CBG-based NACK to the base station and the base station receives the corresponding information, the base station performs partial CBG retransmission. CBG based HARQ-ACK feedback for CBG is ACK feedback from the UE and based on the PDSCH transmission for the CBG retransmitted from the base station, CBG based A/N is generated and sent to the base station based on the decoding success in the UE. It is transmitted together with the ACK feedback for the CBG that has been successfully decoded previously. In this case, if the reception of the retransmitted CBG-based transmission is successfully received, and the check is successful up to the CRC of the TB configured with the CBG, and the reception of the TB is successful, all CBG-based A/Ns are ACKed, and the UE generates generation In this case, the base station determines the reception success of the corresponding PDSCH transmission based on the corresponding CBG-based A/N and reflects it as an ACK when calculating the NACK ration. However, even though the reception of all CBG-based retransmissions has been successful, the TB CRC check is determined to fail when the TB-based ACK is determined. There may be cases in which the UE generates all of the CBG based A/N with NACK to request retransmission for the corresponding TB. Therefore, in this case, the base station received all the CBGs successfully, but the TB CRC check failed because the A/N information on the CBG that the base station had previously received was received as NACK after being flipped instead of received as ACK. It can be determined that all A/N of A/N are fed back as NACK. Nevertheless, for CWS update, all CBG-based A/N are fed back with NACK based on the PDSCH transmission using a single rule in order to take both the method for initial transmission and the method for retransmission in the same way. For CWS update, regardless of initial transmission or retransmission, the corresponding PDSCH transmission may be considered as NACK and reflected when calculating the NACK ratio.

In the case of downlink described in the present invention, a reference slot as a reference in calculating the NACK ratio among HARQ-ACKs for TB-based HARQ-ACK or CBG-based HARQ-ACK feedback corresponding to PDSCH is TB-based. The HARQ-ACK or CBG-based HARQ-ACK feedback may be the earliest starting slot among the most recent PDSCH transmissions performed by a base station that is expected to be available. This is to set the starting slot from the point of view that the most advanced starting slot can best reflect the state of the channel when it is transmitted through DL by configuring multiple slots. However, when multiple slot transmissions are performed continuously without a gap before the reference slot when setting the reference slot, the most advanced slot among the multiple slot transmissions may be set as the reference slot.

In addition, regardless of the reference slot of PDSCH Type A/B, the base station is expected to use TB-based HARQ-ACK or CBG-based HARQ-ACK feedback corresponding to PDSCH among the most recent PDSCH transmissions performed by the base station. One of the preceding starting slots can be set as a reference slot, or if the reference slot is transmitted with PUSCH Type A, it can be considered as slot-based transmission. The transmitted reference slot and the next slot of PUSCH type B may be set as the reference slot. This is a non-slot based transmission (mini-slot based transmission), that is, considering that the slot is transmitted with a shorter time length than the maximum number of symbols that the slot can contain, even though the base station successfully accesses the channel and transmits the PDSCH, the non-slot This is to compensate for the NACK occurring due to slot-based transmission, which affects CW increase.

In addition, when the base station transmits the PDSCH having two codewords to the terminal, TBs are allocated for each codeword, and CBG-based transmission according to the maximum number of CBGs for each TB is performed from the base station, and the terminal performs CBG-based transmission for each TB. Since HARQ-ACK feedback is transmitted, it may be possible to extend and apply the embodiments described in the present invention described based on one TB. That is, it can be applied based on individual TBs, and the number of HARQ-ACKs can be counted for different codewords, respectively.

Uplink CWS update procedure

Below, in the case of uplink, when the UE performs contention window size (CWS) adaptation in the process of performing a channel access procedure, a method different from the CWS update method used in LTE-LAA needs to be applied. In the case of the existing LTE-LAA, if NDI is toggling depending on whether to toggling the NDI associated with the HARQ-process-ID reference for the reference subframe based on the TB-based transmission, reset the CWS for all priority classes. If not, the CWS is preset for each priority class and then increased to a higher allowed value.

The present invention relates to a method for performing uplink CWS update when CBG-based transmission for NR uplink transmission is configured. The CWS update procedure may be performed in consideration of both the CBGTI field and the New Data Indicator (NDI) included in the DCI format.

In the NR system, CBG-based transmission is basically configured to the UE to transmit PUSCH. It can be expected to indicate, and the terminal includes all CBGs of the TB and transmits them to the base station. In addition, in the case of retransmission of one TB indicated by the NDI of the scheduling DCI, the terminal includes only the CBG indicated by the CBGTI field of the scheduling DCI and transmits it to the base station. Here, when the bit value of the CBGTI field is 0, it indicates that the corresponding CBG is not transmitted, and when the bit value of the CBGTI field is 1, it indicates that the corresponding CBG is transmitted. In the CBGTI field, the bit size is determined according to the maximum number of CBGs per TB for PUSCH signaled as a high layer parameter (RRC parameter).

In the case of receiving DCI format 0-0 in the UL fallback DCI format regardless of CBG-based transmission to the UE in the NR-Unlicensed system, the UL grant is received from the base station to perform TB-based transmission, so the existing LTE-LAA CWS can be updated based on only NDI in the same way as used in . However, the NR system may allow the base station to flexibly designate the PUSCH scheduling timing for each terminal. Therefore, if the NDI is toggling according to whether the NDI associated with the HARQ-process_ID for the transmission of the PUSCH transmitted in the reference slot is toggling by defining the reference slot, the CWS is reset for all priority classes. Otherwise, the CWS is reset. is preset for each priority class and then increases to a higher allowed value. Here, in defining the reference slot, the following method may be considered.

- First, a reference slot may be set based on PUSCH scheduling timing in NR. Before PUSCH scheduling timing, Type-1 channel access, which is an LBT procedure with random backoff, may be performed to set the most recent slot in which the PUSCH is transmitted as a reference slot. In more detail, when the subcarrier spacing of the PUSCH and the PDCCH scheduling the PUSCH is set to be the same and the UL grant is received through the PDCCH in the nth slot, the slot is determined based on the previous slot (n - K2 + 1). You can set it as a reference slot. Here, K2 is a slot offset value for PUSCH scheduling through the PDCCH set based on subcarrier spacing for PUSCH transmission. When the PDCCH and the PUSCH use the same subcarrier spacing, it means an offset value from the slot in which the PDCCH scheduling the PUSCH is received to the slot in which the PUSCH is transmitted. Contrary to this, since the subcarrier spacing of the PDCCH scheduling the PUSCH and the PUSCH may be set differently and transmitted, taking this into consideration, the subcarrier spacing of the PDCCH scheduling the PUSCH and the PUSCH is set differently, and the UL grant is provided through the PDCCH in the nth slot. In the case of reception, the corresponding slot may be set as a reference slot based on the slot before the value according to Equation X below.

<Equation X>

However, when multiple slot transmissions are performed continuously without a gap before the reference slot when setting the reference slot, the most advanced slot among the multiple slot transmissions may be set as the reference slot. In addition, one slot can be configured as a reference slot regardless of PUSCH Type A/B, or if the reference slot is transmitted in PUSCH Type A, one slot is configured as a reference slot and transmitted in PUSCH Type B If so, the transmitted reference slot of PUSCH type B and the next slot may be set as the reference slot. This is in consideration of non-slot-based transmission (mini-slot based transmission), that is, transmission with a shorter time length than the maximum number of symbols that a slot can contain, even though the UE succeeds in channel access and transmits the PUSCH despite the non-slot transmission. This is to compensate for the influence on the UE to unnecessarily increase the CW due to the occurrence of NACK due to slot-based transmission.

- Next, the reference slot is set in consideration of the PUSCH scheduling timing in LTE, but is set according to the NR that performs transmission in slot units. have. Similar to the method used in LTE-LAA, this is to consider the scheduling timing of the UL grant and the PUSCH by configuring the slot unit instead of the subframe unit.

- Next, the reference slot sets the default scheduling delay and considers the corresponding timing, but is set according to the NR for performing transmission in slot units. It can be set as a slot. This is similar to the method used in LTE-LAA, except that the minimum value is set for the timing between PUSCH and UL grant by setting the slot unit instead of the subframe unit. It is to set not to apply to CWS throttling. Here, the default scheduling delay may be configured for each terminal or fixed to a specific value according to the capability of the terminal. In LTE-LAA, the subframe is set as the reference subframe before the n-3th time using 3 as its value in subframe unit. Considering that transmission in units of multiple symbols may occur, since the capability of each terminal may be different, it may have one of the values of {0, 1, 2, 3}.

In addition, in the present invention, when CBG-based transmission is configured to the UE in the NR-Unlicensed system to transmit PUSCH, the UE receives DCI format 0-1, which is a UL non-fallback format, from the base station to perform CBG-based transmission. In this case, unlike in LTE-LAA, the UE adjusts the CWS according to the value of the NDI toggling or CBGTI field associated with the HARQ-process_ID for the transmission of the PUSCH transmitted in the reference slot.

When the NDI associated with the HARQ-process-ID for the transmission of the PUSCH transmitted in the reference slot is toggling and received from the UL grant, in this case, the CWS is reset for all priority classes regardless of the value of the CBGTI. This means NDI toggling and means transmission of new data rather than retransmission of previous transmission. Therefore, it is determined that the previous transmission of the associated HARQ-process-ID has been successful, and the UE can reset the CWS. However, if NDI is not toggling and thus means retransmission of a previous transmission, the following methods of adjusting CWS according to the value of CBGTI may be used. As an embodiment of the present invention, when at least one bit field of the CBGTI field is indicated by 0 from the base station, the terminal determines that the base station has received at least one CBG from the previous CBG-based transmission and therefore has not requested retransmission. Therefore, from the viewpoint of uplink channel access of the terminal, it is determined as success and CWS is reset for all priority classes. Otherwise, the CWS is preset for each priority class and then increased to a higher allowed value. As another embodiment of the present invention, when 0% or more of bit fields in the CBGTI field are indicated by the base station, the terminal does not request retransmission because the base station has received at least Y% of CBG during the previous CBG-based transmission. In view of the UE's uplink channel access, it is determined to be successful and the CWS is reset for all priority classes. Here, as the value of Y, {1/X, 2/X, ... You can configure one of (X-1)/X} or set it by fixing one of them to a fixed value.

In addition, when the UE transmits the PUSCH having two codewords to the base station, TBs are allocated for each codeword, CBG-based transmission according to the maximum number of CBGs for each TB is performed from the UE, and the base station provides NDI and CBGTI to the UL grant. Since the UE will request TB retransmission or CBG retransmission for each TB through , it may be possible to extend and apply the embodiments described in the present invention described based on one TB. However, when receiving an NDI or CBGTI corresponding to a PUSCH performing transmission of at least one TB or codewords among the two TBs or codewords transmitted by the UE, at least one TB or codeword-related NDI or CBGTI resets the CWS through the CBGTI. If the condition is satisfied, it is determined as success from the viewpoint of the UE's uplink channel access and CWS is reset for all priority classes.

RACH enhancement for NR-Unlicensed

In NR-U, channel access is performed based on a transmission unit of a 20 MHz unit, and whether or not transmission is performed by a base station and a terminal in a corresponding 20 MHz basic unit is determined according to a channel sensing result. In the case of the terminal, a random access process is required to match uplink synchronization with the base station. This is not only when the NR-U is set to operate as a standalone, but also in an indoor environment or an outdoor environment where the coverage is not large, in which the NR-U is introduced. In a deployment environment using dual connectivity of , uplink synchronization between the terminal and the base station is essential, so a random access process between the terminal and the base station is required.

Due to the nature of NR-U, which requires LBT to be performed based on a 20 MHz transmission unit, when using multiple of 20 MHz wide-BW of 20 MHz or more, if only one random access preamble is transmitted in a specific 20 MHz unit, the channel at the 20 MHz If the channel sensing result becomes busy due to this channel access, even if the other 20 MHz channels are idle, transmission cannot be performed on the entire wideband, and spectral efficiency may decrease. Therefore, it is necessary for a random access preamble transmission method in wideband operation for this purpose. First, in NR-U, the basic unit of channel access is set to a unit of 20 MHz for both downlink and uplink for coexistence with other RATs (eg, Wi-Fi) using unlicensed bands. In NR-U, by setting one BWP (Bandwidth Part) to one 20 MHz, uplink/downlink transmission in BWP unit can be made. In the case of performing wideband operation, multiple of 20 MHz may exist, and multiple BWPs may be configured in the terminal. Since the base station can synchronize uplink between the terminal and the base station when the random access process is successful in at least one BWP, the base station can configure an occasion for PRACH transmission for each BWP. Therefore, in this case, if the channel access is successful in at least one BWP among the multiple BWPs and PRACH transmission is performed, the first step for synchronizing uplink between the terminal and the base station can be performed as well as PRACH transmission to one specific BWP. In the case of performing , there may be an advantage in comparison to the result that transmission cannot be performed on all widebands. However, from the UE's point of view, when channel access is successful in each of the multiple BWPs, if the PRACH transmission is transmitted in each BWP, multiple UEs succeed in channel access for each BWP through the multiple BWPs and perform PRACH transmission. A lot of collisions between UEs on the PRACH occasion may increase latency for performing contention resolution, and in spite of performing uplink synchronization through transmission in one BWP among multiple BWPs, multiple BWPs By performing PRACH transmission in , the capacity for PRACH in each cell according to the PRACH occasion can be reduced. Therefore, in the present invention, when a terminal is configured with multiple BWPs to perform a wideband operation, each terminal performs channel access in each BWP, but PRACH transmission is not performed on all BWPs that have succeeded in channel access, but between the terminal and the base station. We propose a method to perform PRACH transmission on PRACH occasion only in one BWP under the promise of That is, the priority of the BWP transmitted after LBT success between the terminal and the base station is set, and the terminal transmits the PRACH to the base station according to the corresponding priority, and the base station performs PRACH detection according to the corresponding priority to perform PRACH detection in the BWP according to the priority. When detection is finished, the base station operation for PRACH detection in the additional BWP is not performed. The method of setting the priority according to the lowest or highest serving cell index based on the serving cell index can be considered. By operating as multiple BWPs, the lowest or highest BWP index is prioritized based on the index of the BWP. Thus, the terminal and the base station can assume PRACH transmission. The following method may be considered.

In NR-U, LBT is basically performed for uplink/downlink transmission, and transmission is performed when idle in the channel according to the procedure. However, in the case of a random access procedure for matching RRC connection and uplink synchronization, the random access procedure can be completed after at least a 4-step procedure is performed between the UE and the base station. From the standpoint of the terminal and the base station, the uplink LBT for PRACH transmission transmitted by the terminal, the LBT for downlink transmission for transmitting the RAR from the base station, and PUSCH transmission as a response to the RAR, that is, uplink for message-3 transmission LBT procedure is required, and downlink LBT in the base station for message-4 transmission from the base station performing final contention resolution is required. In particular, it can be said that all 4-step procedures are important, but if the PRACH transmission from the UE is not performed from the start due to LBT, the procedures for the remaining 3 steps may be meaningless. Therefore, as a method of increasing the opportunity for PRACH transmission due to LBT failure, a PRACH opportunity window in which PRACH transmission is possible is set, and even if LBT fails on the PRACH occasion set by the base station within the window, PRACH transmission is not stopped. , a method that can give multiple opportunities for PRACH transmission within the PRACH opportunity window through the continuous LBT procedure may be considered. For the setting of the corresponding PRACH opportunity window, it may be configured from the base station through RRC configuration, and before RRC connection, the RMSI may indicate information of the corresponding PRACH opportunity window. Alternatively, when the corresponding information is not received, a method of using the terminal by default setting a specific fixed value based on the PRACH configuration information set in the RMSI from the base station may be considered.

In NR-U, channel access is performed based on a transmission unit of a 20 MHz unit, and whether or not transmission is performed by a base station and a terminal in a corresponding 20 MHz basic unit can be determined according to a channel sensing result.

Due to the nature of NR-U, which requires LBT to be performed based on a 20 MHz transmission unit, a method for performing channel access needs to be defined when using multiple of 20 MHz wide-BW of 20 MHz or more, and one having a BW of 20 MHz or more When one or more bandwidth parts (hereinafter, BWP) are configured and used in a carrier of , it is necessary to newly define a channel access method according to the configuration of the BWP. If a channel at 20 MHz, which is the basic transmission unit for performing LBT, becomes busy as a result of channel sensing due to channel access, even if other channels at 20 MHz are idle, transmission cannot be performed on the entire wideband, resulting in lower spectral efficiency. Also, when one or more BWPs having a BW of 20 MHz or more are configured under one carrier having a wideband of 20 MHz or more, at least one 20 MHz channel, which is an LBT performing unit, becomes busy as a result of channel sensing by channel access. If this occurs, even if another 20MHz channel within the same BWP is idle, it may result in that transmission cannot be performed on the entire BWP, and spectral efficiency may decrease. Therefore, there is a need for a method for performing channel access in a wideband operation.

First, in NR-U, the basic unit of channel access is set to a unit of 20 MHz for both downlink and uplink for coexistence with other RATs (eg, Wi-Fi) using unlicensed bands. In NR-U, by setting one BWP (Bandwidth Part) to one 20 MHz, uplink/downlink transmission in BWP unit can be made. When BWP configures one 20 MHz, NR- according to the channel access method (reference. 3GPP TS 36.213 V14.8.0 (2018-09) section 15 in the multiple carrier operation used in LTE-LAA) It is possible to enable simultaneous transmission for one or more BWPs configured in U.

In addition, by setting one BWP to multiple of 20 MHz, uplink/downlink transmission of 20 MHz or more can be made within at least one BWP. At this time, depending on the channel sensing result of 20 MHz, which is the LBT unit, within one BWP, full transmission of the BWP and partial transmission within the BWP may be considered. It is necessary to further consider the operation method of the terminal and the base station for the case of successful channel access in one or more BWPs.

The following four methods can be considered as a method for performing a channel access in downlink to perform a BWP-based operation in one carrier for NR-U, and the operation method of a related base station and a terminal will be described. .

1. Configure multiple BWPs in the UE, activate multiple BWPs, and when channel access is successful in at least one BWP, PDSCH is transmitted in one or more BWPs that have succeeded in channel access.

As the terminal behavior, from the viewpoint of the terminal, it is impossible to determine which BWP the base station will succeed in channel access from the activated multiple BWPs, so the PDCCH is monitored in the CORESET configured for the multiple BWPs activated by the terminal. The UE attempts PDCCH monitoring and reception in the CORESET configured in each BWP, and performs reception of the PDSCH in each BWP using scheduling information in the received PDCCH. From the UE's point of view, since monitoring of the PDCCH must be performed in the CORESET configured in all multiple BWPs activated by the UE, UE complexity and UL power consumption due to blind decoding of the PDCCH may greatly occur.

In the case of the BWP configured by the base station for the terminal, different BWPs may be configured to be located in different BWs, or different BWPs may be configured to partially overlap BW, and BWP having a large BW is small. It may be configured in the terminal including the BWP having the BW. Therefore, when multiple BWPs are activated for the terminal, from the viewpoint of the base station, the priority of the BWP that the base station can send is set according to the BW configured in the BWP, and the terminal sets the PDCCH in the CORESET of the corresponding BWP according to the predetermined priority with the base station. Monitoring and reception are attempted, and reception of the PDSCH in each BWP is performed using scheduling information in the received PDCCH.

If the BWP having a larger BW among the BWPs configured in the terminal includes a BWP having a smaller BW, PDCCH monitoring and reception are first attempted in the CORESET of the BWP having a larger BW, and scheduling information in the received PDCCH is used. The reception of the PDSCH in the corresponding BWP is performed, and in this case, the PDCCH monitoring may be skipped in the CORESET of the BWP having a smaller BW. Therefore, by skipping PDCCH monitoring in some activated BWPs, UE complexity and UL power consumption according to blind decoding of PDCCH can be reduced.

On the contrary, if the BWP having a larger BW among the BWPs configured in the terminal includes a BWP having a smaller BW, PDCCH monitoring and reception are first attempted in the CORESET of the BWP having a smaller BW, and scheduling information in the received PDCCH is attempted. is used to perform the reception of the PDSCH in the corresponding BWP, and in this case, the PDCCH monitoring may be skipped in the CORESET of the BWP having a larger BW. This is because the channel access success probability of the BWP having a smaller BW may be high from the viewpoint of performing channel access in the base station, because the number of basic units of the LBT of 20 MHz will be small for a smaller BW. Therefore, by skipping PDCCH monitoring in some activated BWPs, UE complexity and UL power consumption according to blind decoding of PDCCH can be reduced.

2. Configure multiple BWPs in the UE, activate multiple BWPs, and when channel access is successful in at least one BWP, PDSCH is transmitted from one BWP that has succeeded in channel access.

When the base station has two or more BWPs that have succeeded in channel access among multiple BWPs for which activation is performed to the terminal, it is necessary to determine which BWP the base station will transmit the PDCCH or PDSCH through. From the viewpoint of the UE, since it is impossible to determine which BWP the base station will succeed in channel access to from the activated multiple BWPs, the PDCCH is monitored in the CORESET configured in the multiple BWPs activated for the UE. Although the base station will transmit the PDCCH or PDSCH in one BWP, the UE has to perform monitoring of the PDCCH in the CORESET configured in all multiple BWPs activated by the terminal, so the UE following blind decoding of the PDCCH There is a disadvantage in that complexity and UL power consumption may occur significantly. Therefore, when the base station succeeds in channel access in at least one BWP, by setting a method of preferentially selecting one BWP that has succeeded in channel access with the terminal, the terminal sets the BWP to monitor the PDCCH preferentially, and selects the PDCCH from the corresponding BWP. In the case of reception, it can be set to reduce UE complexity and UL power consumption by not performing blind decoding of PDCCH configured in another BWP. In the case of the corresponding priority, the lowest or highest BWP index may be set to the priority based on the index of the configured BWP in the terminal. Alternatively, the BWP composed of the largest BW among the BWPs configured in the terminal may be set as a priority, and in the same BW size, the lowest or highest BWP index may be set as the priority based on the BWP index.

In the case of the BWP configured by the base station for the terminal, different BWPs may be configured to be located in different BWs, or different BWPs may be configured to partially overlap BW, and BWP having a large BW is small. It may be configured in the terminal including the BWP having the BW. Therefore, when multiple BWPs are activated for the terminal, from the viewpoint of the base station, the priority of the BWP that the base station can send is set according to the BW configured in the BWP, and the terminal sets the PDCCH in the CORESET of the corresponding BWP according to the predetermined priority with the base station. Monitoring and reception are attempted, and reception of the PDSCH in each BWP is performed using scheduling information in the received PDCCH.

If the BWP having a larger BW among the BWPs configured in the terminal includes a BWP having a smaller BW, PDCCH monitoring and reception are first attempted in the CORESET of the BWP having a larger BW, and scheduling information in the received PDCCH is used. The reception of the PDSCH in the corresponding BWP is performed, and in this case, the PDCCH monitoring may be skipped in the CORESET of the BWP having a smaller BW. Therefore, by skipping PDCCH monitoring in some activated BWPs, UE complexity and UL power consumption following blind decoding of PDCCH can be reduced.

On the contrary, if the BWP having a larger BW among the BWPs configured in the terminal includes a BWP having a smaller BW, PDCCH monitoring and reception are first attempted in the CORESET of the BWP having a smaller BW, and scheduling information in the received PDCCH is attempted. is used to perform the reception of the PDSCH in the corresponding BWP, and in this case, the PDCCH monitoring may be skipped in the CORESET of the BWP having a larger BW. This is because the channel access success probability of the BWP having a smaller BW may be high from the viewpoint of performing channel access in the base station, because the number of basic units of the LBT of 20 MHz will be small for a smaller BW. Therefore, by skipping PDCCH monitoring in some activated BWPs, UE complexity and UL power consumption according to blind decoding of PDCCH can be reduced.

3. Configure multiple BWPs for the terminal and activate one BWP. The base station transmits the PDSCH in the corresponding BWP when channel access is successful for all activated BWPs.

When the single BWP has a BW size larger than 20 MHz, which is the basic unit for performing LBT, the success of channel access in activated BWP is judged to be successful when CCA (Clear Channel Assessment) for all BWPs is all successful. . The UE performs only monitoring of the PDCCH in the CORESET configured in the activated BWP among multiple BWPs configured in the UE. Therefore, UE complexity and UL power consumption according to PDCCH monitoring in the terminal do not increase compared to the method used in the existing NR system. However, although channel access in the LBT unit, which is a part of activated BWP, is successful and the channel is idle, the transmission of the entire activated BWP becomes impossible due to channel access failure in other parts of the BWP, so spectral efficiency may be reduced. In addition, when the size of the BWP in the frequency unit is gradually increased, the success probability of channel access in the corresponding activated BWP decreases as more success in accessing the channel in the 20 MHz unit is required, and thus the transmission probability of the activated BWP may be reduced.

4. Configure multiple BWPs for the terminal and activate one BWP. The base station transmits the PDSCH in all or part of the activated BWP when channel access in the LBT unit of all or part of the activated BWP is successful.

When the single BWP has a BW size larger than 20 MHz, which is the basic unit for performing LBT, the success of channel access in activated BWP is not only judged to be successful when CCA (Clear Channel Assessment) for all BWPs is successful. Rather, based on 20 MHz, which is a part of the LBT unit constituting the activated BWP, even if the CCA is successful in the corresponding LBT unit, it is determined that the channel access is successful in the part of the activated BW, and the PDCCH or the PDSCH can be transmitted. The UE performs only monitoring of the PDCCH in the CORESET configured in the activated BWP among multiple BWPs configured in the UE. Therefore, UE complexity and UL power consumption according to PDCCH monitoring in the terminal do not increase compared to the method used in the existing NR system. This is to increase spectral efficiency by enabling transmission in a part of the total activated BWP due to successful channel access in the LBT unit, which is a part of the activated BWP, and the channel is idle, and channel access failure in other parts of the activated BWP. can However, since channel access in the LBT unit, which is a part of activated BWP, is successful, and the base station can transmit in some activated BWP, the base station asks the terminal to configure CORESET in LBT unit, and the terminal sends transmission from the base station in LBT unit. It may be necessary to perform PDCCH monitoring on the assumption that this is possible. In this case, when the size of the BWP in frequency unit gradually increases, the number of LBT units for which the UE needs to perform PDCCH monitoring increases. There is a disadvantage that UE complexity and UL power consumption according to decoding may increase. Accordingly, the following method for reducing PDCCH monitoring in the terminal may be considered.

Method A. FIG. 19 relates to a base station transmission method and a terminal reception method when multiple LBT units are included in one activated BWP as an embodiment of the present invention. This divides one BWP into multiple LBT units, sets the primary LBT unit, and combines it with the LBT result in another LBT unit depending on the LBT result in the corresponding primary LBT unit, so that the base station performs transmission of multiple LBT units in one BWP. let it do That is, when LBT is successful in the primary LBT unit, the base station can make the PDCCH to be transmitted preferentially from the primary LBT unit to the terminal, but the PDSCH scheduled by the PDCCH transmitted by the base station to the terminal in the primary LBT unit can be occupied. The frequency position in the BWP may allow the base station to perform PDSCH scheduling through the corresponding PDCCH according to the LBT result of another LBT unit. In Fig. 19-(a), case 1) is a case in which LBT is successful only in the primary LBT unit, case 2) is a case in which LBT is successful in an LBT unit continuous with the primary LBT unit, case 3) is a case of two consecutive LBT units A case in which LBT is successful in the LBT unit, and case 4) is about a case in which LBT is successful in N consecutive LBT units with the primary LBT unit. When LBT fails in the primary LBT unit, the frequency position within the BWP that the PDSCH scheduled by the PDCCH transmitted by the base station to the terminal can be occupied by the method performed by the primary LBT unit by setting the next LBT unit is that of another LBT unit. According to the LBT result, the base station may perform PDSCH scheduling through the corresponding PDCCH. 19-(a), case 5) is when LBT is successful only in the secondary LBT unit, case 6) is when LBT is successful in the LBT unit continuous with the secondary LBT unit, case 7) is the secondary LBT unit and two consecutive LBT units It is about the BW in which the transmission of the PDSCH is possible when the LBT is successful in the LBT unit. In the case of LBT failure in the secondary LBT unit, a similar operation method in the same thirdly LBT unit may be continuously used. 19-(a) is an example of PDSCH transmission with the setting of BW as many as multiples of the LBT unit (eg 20MHz * M, M = {1, 2, 3, 4, ... , N}) of the PDSCH It is about the case where transmission is possible, and in Fig. 19-(b), the BW of the power of 2 is set in the LBT unit by the transmission of the PDSCH under the same concept as Fig. 19-(a) (eg 20MHz * 2 ^L , L = {0, 1, 2, 3, ... , X} ) is for a case in which PDSCH transmission is possible.

From the terminal's point of view, the terminal preferentially performs PDCCH monitoring in the primary LBT unit in one BWP. When the reception of the corresponding PDCCH occurs in the primary LBT unit, it is set to skip monitoring of the PDCCH in the LBT unit except for the remaining primary LBT unit by using the scheduling information in the PDCCH. The UE performs reception of the PDSCH through scheduling information in the PDCCH. This can reduce UE complexity and UL power consumption according to blind decoding of PDCCH, which may occur by performing PDCCH monitoring for each LBT unit within one BWP each time. However, when the reception of the PDCCH in the primary LBT unit cannot be performed, the PDCCH monitoring is performed in the secondary LBT unit with the following priority. When the reception of the corresponding PDCCH occurs in the secondary LBT unit, it is set to skip monitoring of the PDCCH in the LBT unit except for the remaining primary and secondary LBT units by using the scheduling information in the PDCCH. However, when the terminal fails to perform reception of the PDCCH in the secondary LBT unit, a similar operation method may be continuously used in the thirdly LBT unit.

The PDSCH scheduling information can be configured based on activated BWP, and the UE determines that resource allocation is performed based on activated BWP in the field for resource allocation (RA) in DCI in the PDCCH scheduling PDSCH. Interpret RA related fields. However, the base station may have to allocate differently the value of the RA field of the DCI in the PDCCH because the allocation of the resources occupied by the PDSCH may vary according to the LBT result of the LBT unit, and the size of the PDSCH may be allocated differently according to the LBT result. In this case, the base station scheduling complexity may occur in which the base station must prepare a PDCCH for transmitting DCI having different information and prepare a PDSCH of different sizes. Separately, by setting a resource allocation field in a unit through a combination with one LBT unit or multiple LBT units, the terminal reads the RA field to determine which LBT unit(s) the PDSCH is allocated to. This can be. In the case of scheduling by separately setting the resource allocation field for each LBT unit, there may be a method of designating the index of the LBT unit to the corresponding RA field, 1 ^st , 2 ^nd , 3 ^rd in FIG. 19-(a), . There may be a method to specify RA field in the corresponding RA field. That is, when the DCI is detected by monitoring the PDCCH in the primary LBT unit, the resource allocation field in the unit through combination with the LBT unit is set to one of case 1), case 2), case 3), and case 4). The UE can determine that the allocation is made to perform the reception of the PDSCH, and when the DCI is detected by monitoring the PDCCH in the secondary LBT unit, the resource allocation field in the unit through the combination with the LBT unit is case 5) , case 6), case 7) that the resource allocation of the PDSCH is made by the UE to determine that the reception of the PDSCH can be performed, similarly can be applied by extending the same to the N-th LBT unit.

Method B. FIG. 20 relates to a method for transmitting a base station and a method for receiving a terminal when multiple LBT units are included in one activated BWP as another embodiment of the present invention. This divides one BWP into multiple LBT units and sets multiple priority LBT units for the terminal to monitor, the base station transmits the PDCCH only from the corresponding priority LBT unit, and the terminal transmits the PDCCH only from the corresponding priority LBT unit. How to enable monitoring. 20 is an example of two LBT units by setting the primary LBT unit and the secondary LBT unit, depending on the LBT results in the primary LBT unit and the secondary LBT unit, in combination with the LBT results in other LBT units, the base station is multiple in one BWP A method for performing transmission of the LBT unit will be described. 20 is a method of performing transmission of the PDSCH in multiple LBT units by setting the priority and setting the primary LBT unit and the secondary LBT unit when setting multiple LBT units. 20-(a) is an example of PDSCH transmission with the setting of BW as much as a multiple of the LBT unit (eg 20MHz * M, M = {1, 2, 3, 4, ..., N}) of the PDSCH It is about a case where transmission is possible, and in FIG. 20-(b), setting of BW to the power of 2 in the LBT unit by transmission of PDSCH under the same concept as FIG. 20-(a) (eg 20MHz * 2 ^L , L = {0, 1, 2, 3, ..., X} ) is for a case in which PDSCH transmission is possible.

From the standpoint of the terminal, the terminal preferentially performs PDCCH monitoring in multiple priority LBT units in one BWP. When the priority is set, when the reception of the corresponding PDCCH occurs in the primary LBT unit, it is set to skip monitoring of the PDCCH in the LBT unit except for the remaining primary LBT unit by using the scheduling information in the PDCCH. The UE performs reception of the PDSCH through scheduling information in the PDCCH. This can reduce UE complexity and UL power consumption according to blind decoding of PDCCH, which may occur by performing PDCCH monitoring for each LBT unit within one BWP each time. However, when the reception of the PDCCH in the primary LBT unit cannot be performed, the PDCCH monitoring is performed in the secondary LBT unit with the following priority. When the reception of the corresponding PDCCH occurs in the secondary LBT unit, it is set to skip monitoring of the PDCCH in the LBT unit except for the remaining primary and secondary LBT units by using the scheduling information in the PDCCH. However, the terminal performs monitoring of the PDCCH only in multiple priority LBT units configured for the terminal, and does not additionally perform monitoring of the PDCCH when the PDCCH cannot be performed in the multiple priority LBT units.

The PDSCH scheduling information can be configured based on activated BWP, and the UE determines that resource allocation is performed based on activated BWP in the field for resource allocation (RA) in DCI in the PDCCH scheduling PDSCH. Interpret RA related fields. However, the base station may have to allocate differently the value of the RA field of the DCI in the PDCCH because the allocation of the resources occupied by the PDSCH may vary according to the LBT result of the LBT unit, and the size of the PDSCH may be allocated differently according to the LBT result. In this case, the base station scheduling complexity may occur in which the base station must prepare a PDCCH for transmitting DCI having different information and prepare a PDSCH of different sizes. Separately, by setting a resource allocation field in a unit through a combination with one LBT unit or multiple LBT units, the terminal reads the RA field to determine which LBT unit(s) the PDSCH is allocated to. This can be. In the case of scheduling through a combination of a single LBT unit and multiple LBT units as a method for enabling the allocation of wide BW, there may be a method of designating each case in the corresponding RA field in FIG. 20-(a). That is, when the DCI is detected by monitoring the PDCCH in the primary LBT unit, the resource allocation field in the unit through combination with the LBT unit is set to one of case 1), case 2), case 3), and case 4). The UE can determine that the allocation is made to perform the reception of the PDSCH, and when the DCI is detected by monitoring the PDCCH in the secondary LBT unit, the resource allocation field in the unit through the combination with the LBT unit is case 5) , case 6), case 7) that the UE determines that the resource allocation of the PDSCH is made, so that the reception of the PDSCH can be performed. can be applied.

Method C. FIG. 21 relates to a method of transmitting a base station and a receiving method of a terminal when multiple LBT units are included in one activated BWP as another embodiment of the present invention. This divides one BWP into multiple LBT units and sets multiple priority LBT units for the terminal to monitor, the base station transmits the PDCCH only from the corresponding priority LBT unit, and the terminal transmits the PDCCH only from the corresponding priority LBT unit. This is a method to enable monitoring, but it is a method to set the same priority when setting multiple LBT units of priority, and to set multiple LBT units managed by one priority LBT units to be disjoint from each other. The example in FIG. 21 is the transmission of the PDSCH so that the transmission of the PDSCH is possible with the setting of BW as much as a multiple of the LBT unit (eg 20MHz * M, M = {1, 2, 3, 4, ... , N} ). It is for the case of setting, but the setting of BW of the power of 2 in the LBT unit by transmission of PDSCH under the same concept as in FIGS. 19-(b) and 20-(b) (eg 20MHz * 2 ^L , L = { 0, 1, 2, 3, ... , X} ) may be a case in which PDSCH transmission is possible.

From the viewpoint of the terminal, the terminal always preferentially performs PDCCH monitoring in multiple priority LBT units in one BWP. When the reception of the corresponding PDCCH occurs in multiple LBT units of the same priority in which the priority is set, it is set to skip monitoring of the PDCCH in the LBT unit except for the LBT unit that monitors the PDCCH using the scheduling information in the PDCCH. The UE performs reception of the PDSCH through scheduling information in the PDCCH. This can reduce UE complexity and UL power consumption according to blind decoding of PDCCH, which may occur by performing PDCCH monitoring for each LBT unit within one BWP each time. However, the terminal performs monitoring of the PDCCH only in multiple priority LBT units configured for the terminal, and does not additionally perform monitoring of the PDCCH when the PDCCH cannot be performed in the multiple priority LBT units.

<Wideband operation method in case of having BWP for each carrier in multiple carriers>

In LTE-LAA, two types of multi-carrier transmission methods are used. A multi-carrier transmission scheme in LTE-LAA will be briefly described below.

First, the multicarrier transmission Type A scheme is a scheme in which channel access is independently performed for each carrier to be transmitted, and when channel access is successful for each carrier, transmission is performed individually by each carrier. Therefore, each carrier can have a counter value for performing backoff, and the corresponding counter value is maintained and managed according to whether a channel is busy or idle on an individual carrier. In addition, the contention window is maintained and managed independently for each carrier.

As a more detailed method of Type A, Type-A1 and Type-A2 methods exist. The Type-A1 method is a method that allows the backoff counter to be managed and determined independently for each carrier, and one node (base station, or terminal, When an AP or STA (which may be an AP or an STA) stops transmission on a specific carrier, if idle slots are detected for a specific interval (e.g. after reinitialization of 4 sensing slot intervals or a backoff counter), one node It is a method that enables the resume of reducing the independently managed and determined backoff counter. The Type-A2 method is a method in which a backoff counter is set to have one backoff counter common to all carriers that a node intends to transmit, and the common backoff counter is the current Based on the value (CWp), the backoff counter of the carrier with the largest CWp is set as a common backoff counter. However, the procedure for reducing the backoff counter is individually reduced according to the channel condition of each carrier, and is managed and determined independently for each carrier. When one node stops transmitting on a specific carrier, one node re-initializes the backoff counter on all carriers.

Next, it is a multicarrier transmission Type B method, and one node uniformly randomly selects one carrier from the set of carriers to be transmitted before transmission, prevents a specific carrier from being selected for more than every 1 second, and selects Category 4 LBT from the selected carrier. If the channel access is successful, the remaining carriers sense the channel for at least 25us sensing period immediately before transmission, and then, if the channel is idle, it is transmitted along with the transmission in the preselected carrier.

As a more detailed method of Type B, Type-B1 and Type-B2 methods exist. The Type-B1 method is a method that maintains only one CWp value in a set of carriers to be transmitted. One CWp is managed by increasing and resetting the size of CW based on the HARQ-ACK coming up as feedback. The Type-B2 method is a method in which each CWp value is maintained for each carrier in a set of carriers to be transmitted, and selected based on the CWp in the carrier having the largest CWp among the CWp values managed for each carrier. It is a method to select the initial value of the backoff counter for performing Category 4 LBT in the carrier.

In NR-U, unlike in LTE-LAA, which has 20 MHz on one carrier, one carrier may be greater than 20 MHz as in FIG. Accordingly, a multi-carrier transmission scheme for other NR-U operations is required.

25 shows that when one or more BWPs are configured on each carrier, each BWP#1 composed of one or more LBT units on each carrier #1 and carrier #2 is activated to downlink through two carriers in downlink. It is a diagram for a case in which it is set to perform transmission.

A method of operating a base station and a terminal as a method for performing downlink and uplink channel access to perform BWP-based operation on two or more carriers for NR-U will be described.

First, a method for performing downlink channel access will be described. A method of performing downlink channel access when configuring one or more BWPs for each carrier and transmitting downlink through two or more carriers will be described. For ease of explanation of the present invention, two carriers will be described as an example as shown in FIG. 25, but the same method presented in the present invention may be applied to two or more carriers.

<NR-U multicarrier/BWP Type-A method>

To perform Category 4 LBT for each LBT unit of 20 MHz regardless of the number of carriers to be transmitted and the carrier to which the LBT unit belongs during NR-U operation based on the 20 MHz unit (or LBT sub-band, or LBT unit) method can be considered. That is, this may be a method to apply the Type A method in LTE-LAA to the LBT unit of 20MHz unit in the active BWP belonging to the multi-carrier and each carrier.

<NR-U multicarrier/BWP Type-A1 method>

First, CW can be individually maintained for each LBT unit regardless of the number of carriers and the carrier to which the LBT unit belongs, and an independent backoff counter can be maintained for each LBT unit as in LTE-LAA Type A1. can do. However, in the operation for the base station to decrease the backoff counter, two methods can be considered for the self-deferral operation of the base station not performing the counter reduction operation when the counter is 1 or more in a specific LBT unit unit.

The first may be a method of using a self-deferral method that allows the base station to perform a counter reduction operation when the counter is 1 or more in a specific LBT unit unit regardless of the carrier to which the LBT unit belongs. Considering that channel sensing may be affected by RF leakage in several carriers adjacent to the self-deferral operation, this is a method to enable the self-deferral operation in the base station considering all the adjacent carriers. can Since this method performs self-deferral in consideration of simultaneous transmission in all LBT units, transmission of multiple LBT sub-bands may be easy, but when the base station considers simultaneous transmission in all LBT units, self-deferral There may be a disadvantage that transmission delay may occur greatly due to deferral operation.

Second, there may be a method of using a self-deferral method that allows the base station to perform a counter reduction operation when the counter is 1 or more in a specific LBT unit unit only for each carrier. Considering that channel sensing can be affected only by RF leakage in a BWP having multiple LBT units transmitted within a specific frequency band or one carrier, or within one carrier, only for each carrier. A method for enabling self-deferral operation in the base station may be used. Since this method performs self-deferral in consideration of simultaneous transmission in LBT units only in one carrier, it can be easy to transmit multiple LBT sub-bands in one carrier, and the base station intends to transmit When all self-deferrals of LBT sub-bands in different carriers are considered, simultaneous transmission in all LBT units can be performed, and the base station only considers simultaneous transmission of multiple LBT sub-bands in only one carry. In this case, transmission delay may not occur significantly due to self-deferral operation within one carrier.

<NR-U multicarrier/BWP Type-A2 method>

Next, CW can be individually maintained for each LBT unit regardless of the number of carriers and the carrier to which the LBT unit belongs, and a common backoff counter can be maintained and managed as in LTE-LAA Type A2. can However, two methods may be considered in the process of the base station picking a common backoff counter.

The first is common to each LBT unit regardless of the number of carriers by selecting a common backoff counter based on the largest CWp among all CWp managed by individual LBT unit regardless of the number of carriers and the carrier to which the LBT unit belongs. A method of performing category 4 LBT according to the backoff counter of . Considering that channel sensing may be affected by RF leakage in several adjacent carriers, this is a method for enabling self-deferral operation in the base station in all adjacent carriers. In this way, the transmission of multiple LBT sub-bands can be facilitated by performing self-defferal by selecting a common counter from the largest CWp in consideration of simultaneous transmission in all LBT units, but among all LBT units, it is the most By selecting a large CWp, there may be a disadvantage that a transmission delay as long as the length of the largest CWp may occur for every transmission.

Second, one common backoff counter for each carrier is drawn based on the largest CWp among all CWp managed by LBT units belonging to each carrier and stored in one common backoff counter for each LBT unit belonging to each carrier. Accordingly, a method to perform category 4 LBT may be used. This is a base station only for each carrier, considering that channel sensing may be affected by RF leakage in a BWP having multiple LBT units transmitted within a specific frequency band or one carrier or within one carrier. It can be said to be a method to enable self-deferral operation based on the common back-off counter in . This method considers simultaneous transmission in LBT units in only one carrier and performs self-deferral by selecting a common counter for each carrier from the largest CWp, so multiple LBT sub-bands in one carry may be easy to transmit, and if the base station considers all the self-deferrals of the LBT sub-band in different carriers intended to transmit, it may be possible to perform simultaneous transmission in all LBT units, and the base station If only one carry considers simultaneous transmission of multiple LBT sub-bands, transmission delay may not occur significantly due to self-deferral operation within one carrier.

The following NR-U multicareir/BWP Type-B schemes are schemes that can be applied to both the terminal and the base station for transmission.

<NR-U multicarrier/BWP Type-B method>

Category 4 LBT among LBT units of 20 MHz regardless of the number of carriers to be transmitted and the carrier to which the LBT unit belongs during NR-U operation based on the 20 MHz unit (or LBT sub-band, or LBT unit). A method of configuring one LBT sub-band and a method of configuring one LBT sub-band for performing category 4 LBT among 20 MHz LBT units for each carrier may be considered. If channel access is successful in one LBT sub-band to perform the corresponding category 4 LBT, the remaining LBT sub-band senses the channel for at least 25us sensing period immediately before transmission and if the channel is idle, the pre-selected category 4 LBT It is a method to transmit together with transmission in one LBT sub-band to perform. That is, this may be a method to apply the Type B method in LTE-LAA to the LBT unit of 20 MHz unit in the active BWP belonging to the multi-carrier and each carrier.

<NR-U multicarrier/BWP Type-B1 method>

First, in a method to set one LBT sub-band to perform category 4 LBT among LBT units of 20 MHz regardless of the number of carriers and carriers to which the LBT unit belongs, perform category 4 LBT regardless of the number of carriers One contention window (CW) is maintained for Therefore, one CWp can be managed by increasing and resetting the CW size according to the ratio of NACK based on the HARQ-ACK that comes up as feedback for transmission in all carriers regardless of the number of carriers and the carrier to which the LBT unit belongs. can

<NR-U multicarrier/BWP Type-B2 method>

Second, among the 20 MHz LBT units for each carrier, a method of setting one LBT sub-band to perform category 4 LBT may include a method of maintaining one contention window for each carrier, and 20 MHz LBT for each carrier One CWp can be managed by increasing and resetting the CW size according to the ratio of NACK based on the HARQ-ACK that comes up as feedback for the transmission transmitted from the units.

On the other hand, thirdly, it can be set so that the CW is independently maintained for each LBT sub-band in the BWP belonging to each carrier. However, it is possible to draw one backoff counter for each carrier. At this time, as a method of selecting one backoff counter, the initial value of the backoff counter may be selected based on the largest CWp among the current CWp independently managed for each LBT sub-band in the BWP belonging to each carrier. In the method of maintaining and managing CW, CW size increase and reset are performed according to the ratio of NACK based on HARQ-ACK, which comes up as feedback for transmission transmitted from each 20 MHz LBT unit for each carrier, and reset is performed to each LBT unit. CWp can be managed.

Fourth, each carrier based on the largest CWp among CWs managed by different carriers in order to enable simultaneous transmission between different carriers when one independent CW is maintained and managed in different carriers A method in which an independent backoff counter can be drawn may be considered. This may be a method of setting the largest CWp between different carriers to a length that can wait for the maximum self-deferral for simultaneous transmission on different carriers.

Next, in the NR-U multicarrier/BWP Type-B scheme, when one node selects one LBT subband before transmission from a set of carriers or LBT sub-bands to be transmitted, it relates to a uniformly random selection method. . Unlike in LTE-LAA, where one carrier is regarded as an LBT unit and configured with the same 20 MHz, in NR-U, the LBT subband included in the BWP for each carrier between different carriers may be different, so in the LTE-LAA method In the case of selecting a carrier randomly between carriers, the LBT sub-band for performing Category-4 LBT may not be uniformly and randomly selected. Therefore, first, in the method of setting one LBT sub-band to perform category 4 LBT among LBT units of 20 MHz, regardless of the number of carriers and the carrier to which the LBT unit belongs, all of the BWPs in the carrier to be transmitted are all A method of uniformly and randomly selecting one LBT sub-band to perform category-4 LBT based on the LBT unit may be considered. Next, in the method of setting one LBT sub-band for performing category 4 LBT among 20 MHz LBT units for each carrier, one LBT sub-band for performing category 4 LBT within each carrier is uniformly and randomly A way to select may be considered.

Next, a method for performing uplink channel access will be described. A method of performing uplink channel access when configuring one or more BWPs for each carrier and transmitting uplink through two or more carriers will be described. For ease of explanation of the present invention, two carriers will be described as an example as shown in FIG. 25, but the same method presented in the present invention may be applied to two or more carriers.

<NR-U multicarrier/BWP Type-A method>

To perform Category 4 LBT for each LBT unit of 20 MHz regardless of the number of carriers to be transmitted and the carrier to which the LBT unit belongs during NR-U operation based on the 20 MHz unit (or LBT sub-band, or LBT unit) method can be considered. That is, this may be a method to apply the Type A method in LTE-LAA to the LBT unit of 20MHz unit in the active BWP belonging to the multi-carrier and each carrier. However, in the case of uplink transmission in which the transmission is performed by scheduling, the base station provides the terminal with an LBT type (eg, Cat-4 LBT, Cat-2 LBT (eg, 16us Cat-2 LBT) by an uplink grant. Or 25us Cat-2 LBT), or Cat-1 LBT (No LBT, immediate transmission without channel sensing) may be indicated. -4 The description will be made on the assumption that the LBT is instructed by the uplink grant, and also methods for uplink multicarrier transmission based on the LBT unit to which the UE belongs the scheduled resource or the LBT unit to which the RRC configured resource belongs . Explain.

<NR-U multicarrier/BWP Type-A1 method>

First, CW can be individually maintained for each LBT unit regardless of the number of carriers and the carrier to which the LBT unit belongs, and an independent backoff counter can be maintained for each LBT unit as in LTE-LAA Type A1. can do. However, two methods can be considered for the self-deferral operation in which the terminal does not perform the counter reduction operation when the counter is 1 or more in a specific LBT unit in the operation for the terminal to decrease the backoff counter.

The first may be a method of using a self-deferral method that allows the terminal to perform a counter reduction operation when the counter is 1 or more in a specific LBT unit regardless of the carrier to which the LBT unit belongs. Considering that channel sensing may be affected by RF leakage in several carriers adjacent to the self-deferral operation, this is a method to enable the self-deferral operation in the terminal considering all the adjacent carriers. can Since this method performs self-deferral in consideration of simultaneous transmission in all LBT units, transmission of multiple LBT sub-bands may be easy, but when the terminal considers simultaneous transmission in all LBT units, self-deferral There may be a disadvantage that transmission delay may occur greatly due to deferral operation.

Second, there may be a method of using a self-deferral method that allows the terminal to perform a counter reduction operation when the counter is 1 or more in a specific LBT unit only for each carrier. Considering that channel sensing can be affected only by RF leakage in a BWP having multiple LBT units transmitted within a specific frequency band or one carrier, or within one carrier, only for each carrier. A method for enabling self-deferral operation in the terminal may be used. Since this method performs self-deferral in consideration of simultaneous transmission in LBT units in only one carrier, transmission of multiple LBT sub-bands in one carrier can be easy, and each other that the terminal intends to transmit In the case of considering all the self-deferral of the LBT sub-band in other carriers, simultaneous transmission in all LBT units may be performed, and the terminal considers only simultaneous transmission of multiple LBT sub-bands in only one carrier. In this case, transmission delay may not occur significantly due to self-deferral operation within one carrier.

<NR-U multicarrier/BWP Type-A2 method>

Next, CW can be individually maintained for each LBT unit regardless of the number of carriers and the carrier to which the LBT unit belongs, and a common backoff counter can be maintained and managed as in LTE-LAA Type A2. can However, two methods may be considered in the process of the UE pulling a common backoff counter.

The first is common for each LBT unit regardless of the number of carriers by selecting a common backoff counter based on the largest CWp among all CWp managed by individual LBT unit regardless of the number of carriers and the carrier to which the LBT unit belongs. A method of performing category 4 LBT according to the backoff counter of . Considering that channel sensing may be affected by RF leakage in several adjacent carriers, this is a method for enabling self-deferral operation in a terminal in all adjacent carriers. In this method, it is easy to transmit multiple LBT sub-bands by performing self-deferral by selecting a common counter from the largest CWp in consideration of simultaneous transmission in all LBT units, but among all LBT units, it is the most By selecting a large CWp, there may be a disadvantage that a transmission delay as long as the length of the largest CWp may occur for every transmission.

Second, one common backoff counter for each carrier is drawn based on the largest CWp among all CWp managed by LBT units belonging to each carrier and stored in one common backoff counter for each LBT unit belonging to each carrier. Accordingly, a method to perform category 4 LBT may be used. Considering that channel sensing may be affected by RF leakage within a BWP having multiple LBT units transmitted within a specific frequency band or one carrier or within one carrier, the terminal only for each carrier It can be said to be a method to enable self-deferral operation based on the common back-off counter in . This method considers simultaneous transmission in LBT units in only one carrier and performs self-deferral by selecting a common counter for each carrier from the largest CWp, so multiple LBT sub-bands in one carry may be easy to transmit, and when all self-deferrals of LBT sub-bands in different carriers intended to be transmitted by the terminal are considered, simultaneous transmission in all LBT units may be performed, and the terminal may If only one carrier considers simultaneous transmission of multiple LBT sub-bands, transmission delay may not occur significantly due to self-deferral operation within one carrier.

As NR-U multicarrier/BWP Type-B schemes, a method for performing uplink channel access for transmission in a UE will be described below. A method of performing uplink channel access when configuring one or more BWPs for each carrier and transmitting uplink through two or more carriers will be described. However, in the case of uplink transmission in which the transmission is performed by scheduling, the base station provides the terminal with an LBT type (eg, Cat-4 LBT, Cat-2 LBT (eg, 16us Cat-2 LBT) by an uplink grant. Or 25us Cat-2 LBT), or Cat-1 LBT (No LBT, immediate transmission without channel sensing) may be indicated. -4 The description will be made on the assumption that the LBT is instructed from the uplink grant, and also methods for uplink multicarrier transmission based on the LBT unit to which the UE belongs the scheduled resource or the LBT unit to which the RRC configured resource belongs . Explain.

<NR-U multicarrier/BWP Type-B method>

1) The number of carriers to be transmitted during NR-U operation based on the 20 MHz unit (or LBT sub-band, or LBT unit) to which the UE belongs the scheduled resource from the base station and the LBT unit to which the scheduled resource belongs A method of setting one LBT sub-band to perform category 4 LBT among all LBT units of 20 MHz to which a scheduled resource belongs regardless of a carrier may be considered. In addition , 2) from the base station, a method of setting one LBT sub-band for performing category 4 LBT among 20 MHz LBT units for each carrier to which the UE belongs to the scheduled resource may be considered. If channel access is successful in one LBT sub-band to perform the corresponding category 4 LBT, the remaining LBT sub-band senses the channel for at least 25us sensing period immediately before transmission and if the channel is idle, the pre-selected category 4 LBT It is a method to transmit together with transmission in one LBT sub-band to perform. That is, this may be a method to apply the Type B method in LTE-LAA to the LBT unit of 20 MHz unit to which the scheduled resource in the active BWP belonging to the multi-carrier and each carrier belongs.

<NR-U multicarrier/BWP Type-B1 method>

First, in the method of setting one LBT sub-band to perform category 4 LBT among LBT units of 20 MHz, regardless of the carrier to which the number of carriers and the LBT unit to which the scheduled resource belongs as the method 1) above, set the carrier One contention window (CW) for performing category 4 LBT is maintained regardless of the number of Therefore, regardless of the number of carriers and the carrier to which the LBT unit belongs, the terminal performs Cat-4 LBT to perform uplink transmission, and as feedback corresponding to uplink transmission in the LBT unit(s), the NDI (New When the corresponding NDI is toggled based on the data indication) to indicate the transmission of new data, the current CW value for all priority classes (CWp, p is the priority class) is CWmin,p (the minimum CW value for each priority class) to reset to , otherwise, the current CW value (CWp, where p is the priority class) for all priority classes can be increased to the next largest allowed CW value. However, if the current CWp is CWmax,p (the maximum CW value for each priority class), the next largest allowed CW value is CWmax,p. NDI (New Data indication) given down from the base station as feedback corresponding to uplink transmission in the LBT unit(s) in which the terminal performs uplink transmission by performing Cat-4 LBT is at least associated with HARQ-ID-ref. It may be NDI for one HARQ-process-ID, and for the setting method of HARQ-ID-ref, the methods exemplified in the embodiment in the <Uplink CWS update procedure> of the present invention may be used in the same manner.

<NR-U multicarrier/BWP Type-B2 method>

Second, in the method 2) above, in the method of setting one LBT sub-band to perform category 4 LBT among 20 MHz LBT units to which the resource scheduled for each carrier belongs , there is one contention window (CW) for each carrier. There may be a way to maintain it. In the 20 MHz LBT units to which the scheduled resource for each carrier belongs , the UE performs Cat-4 LBT to provide feedback corresponding to the uplink transmission in which the uplink transmission is performed, based on NDI (New Data indication) given down from the base station. When the NDI is toggled to indicate transmission of new data, the current CW values for all priority classes (CWp, p is the priority class) are reset to CWmin,p (the minimum CW value for each priority class), otherwise In this case, it is possible to increase the current CW value (CWp, where p is the priority class) to the next largest allowed CW value for all priority classes. However, if the current CWp is CWmax,p (the maximum CW value for each priority class), the next largest allowed CW value is CWmax,p. NDI (New Data indication) given down from the base station as feedback corresponding to uplink transmission in the LBT unit(s) in which the terminal performs uplink transmission by performing Cat-4 LBT is at least associated with HARQ-ID-ref. It may be NDI for one HARQ-process-ID, and for the setting method of HARQ-ID-ref, the methods exemplified in the embodiment in the <Uplink CWS update procedure> of the present invention may be used in the same manner.

On the other hand, thirdly, it can be set so that the CW is independently maintained for each LBT sub-band in the BWP belonging to each carrier. However, it is possible to draw one backoff counter for each carrier. At this time, as a method of selecting one backoff counter, the initial value of the backoff counter may be selected based on the largest CWp among the current CWp independently managed for each LBT sub-band in the BWP belonging to each carrier. Independent CW maintenance method for each LBT sub-band is feedback corresponding to uplink transmission in which the UE performs Cat-4 LBT in 20 MHz LBT units to which the scheduled resource for each carrier belongs and performs uplink transmission. When the corresponding NDI is toggled based on the NDI (New Data indication) given from the to indicate transmission of new data, the current CW value for all priority classes (CWp, p is the priority class) is set to CWmin,p (each priority Minimum CW value for each class), otherwise, the current CW value for all priority classes (CWp, where p is the priority class) can be increased to the next largest allowed CW value. However, if the current CWp is CWmax,p (the maximum CW value for each priority class), the next largest allowed CW value is CWmax,p. NDI (New Data indication) given down from the base station as feedback corresponding to uplink transmission in the LBT unit(s) in which the terminal performs uplink transmission by performing Cat-4 LBT is at least associated with HARQ-ID-ref. It may be NDI for one HARQ-process-ID, and for the setting method of HARQ-ID-ref, the methods exemplified in the embodiment in the <Uplink CWS update procedure> of the present invention may be used in the same manner.

Fourth, each carrier based on the largest CWp among CWs managed by different carriers in order to enable simultaneous transmission between different carriers when one independent CW is maintained and managed in different carriers A method in which an independent backoff counter can be drawn may be considered. This may be a method of setting the largest CWp between different carriers to a length that can wait for the maximum self-deferral for simultaneous transmission on different carriers. The method of maintaining and managing one independent CW on different carriers corresponds to uplink transmission in which the UE performs Cat-4 LBT in 20 MHz LBT units to which the scheduled resource for each carrier belongs , and performs uplink transmission. When the corresponding NDI is toggled based on the NDI (New Data indication) given down from the base station as feedback to indicate the transmission of new data, the current CW value for all priority classes (CWp, p is the priority class) is CWmin, Reset to p (minimum CW value for each priority class). have. However, if the current CWp is CWmax,p (the maximum CW value for each priority class), the next largest allowed CW value is CWmax,p. NDI (New Data indication) given down from the base station as feedback corresponding to uplink transmission in the LBT unit(s) in which the terminal performs uplink transmission by performing Cat-4 LBT is at least associated with HARQ-ID-ref. It may be NDI for one HARQ-process-ID, and for the setting method of HARQ-ID-ref, the methods exemplified in the embodiment in the <Uplink CWS update procedure> of the present invention may be used in the same manner.

Next, in the NR-U multi-carrier/BWP Type-B method for uplink transmission, one node is scheduled for uplink and transmits one before transmission in the set of carriers or LBT sub-bands to which the scheduled resource belongs . It relates to a method of uniformly randomly selecting the LBT sub-band of . Unlike in LTE-LAA, where one carrier is regarded as an LBT unit and configured at 20 MHz, in NR-U, the LBT sub-band included in the BWP for each carrier between different carriers may be different. In the case of selecting a carrier randomly between carriers as in the scheme, the LBT sub-band for performing the category-4 LBT may not be uniformly and randomly selected. Therefore, as a method to allow the LBT sub-band to perform category-4 LBT to be uniformly and randomly selected, the first is one of the LBT units of 20 MHz to perform category 4 LBT regardless of the number of carriers and the carrier to which the LBT unit belongs. A method of uniformly and randomly selecting one LBT sub-band for performing Category-4 LBT based on all LBT units belonging to the BWP in the carrier to be transmitted in a manner to set the LBT sub-band is considered can be Second, one LBT sub-band for performing category-4 LBT in each carrier is uniformly and randomly in a manner to set one LBT sub-band for performing category 4 LBT among 20 MHz LBT units for each carrier. A way to make a choice can be considered.

<CW update method in case of having BWP for each carrier in multiple carriers>

Figure 26 has a BWP consisting of one or more LBT sub-bands on each carrier in NR-U, intra-band CA, which is carrier aggregation (CA) within the same band, and inter-band, which is CA between different bands. It is a diagram regarding the case of a configuration to perform CA. 26 is an example of the same band and different bands. The same band may be in a 5 GHz band, a 6 GHz band, or an unlicensed band in a band of 52.6 GHz or more, and different bands are a 5 GHz band, a 6 GHz band, and 52.6 GHz. The inter-band CA that is CA between different bands may be a combination of a 5 GHz band, a 6 GHz band, and a CA between 52.6 GHz or more bands.

The present invention relates to a CW adjustment procedure in a scenario set to have a BWP composed of multiple carriers and at least one LBT sub-band and transmission in multiple carriers including the same band and different bands, respectively.

First, a CW adjustment procedure will be described when the BWP configured to have at least one LBT sub-band in each one of intra-band CA (CA) or multi-carrier within the same band is configured. Among the same bands, when transmission is performed with a BWP configured to have multiple carriers in intra-band and at least one LBT-sub-band. All HARQ-ACK values corresponding to the data channel transmitted by the control channel transmitted on carrier-1 may be included in the calculation of the NACK ratio used in CW adjustment based on HARQ-ACK feedback. When HARQ-ACK feedback for data channel transmission is not detected by the base station or feedback that can mean 'discontinuous transmission (DTX)' is detected by the base station from the terminal, the corresponding information is counted as NACK and may be included in the calculation.

When it is set to perform cross-carrier scheduling with intra-band CA, in one embodiment, it is transmitted to carrier-2 as a scheduled carrier by a control channel transmitted from carrier-1 performing cross-carrier scheduling in FIG. 26. All HARQ-ACK values corresponding to the data channel may be included in the calculation of the NACK ratio used in CW adjustment based on HARQ-ACK feedback. Because information on channel state and congestion in the same band can be similar, in intra-band, it is applied to all HARQ-ACK values transmitted from the terminal to the base station without distinction between self-carrier scheduling and cross-carrier scheduling. It is intended to be included in the calculation of the NACK ratio used in CW adjustment based on HARQ-ACK feedback.

However, in the description of the present invention for the channel access method in the multi-carrier, when CW is managed for each carrier or is managed in LBT subband units within each carrier, the following method is additionally considered for cross-carrier scheduling. can be

First, if the control channel and data channel are transmitted separately on different carriers, and if Cat-4 is performed as a channel access procedure on each carrier for transmission of each control channel and data channel, CW managed for each carrier For all HARQ-ACK values transmitted from the terminal to the base station, it may be included in the calculation of the NACK ratio used in CW adjustment based on HARQ-ACK feedback.

Second, even when the control channel and the data channel are transmitted separately in different carriers, when Cat-4 is performed as a channel access procedure in the scheduled carrier through which the data channel is transmitted, only the CW update in the scheduled carrier is transmitted from the terminal. The HARQ-ACK value of the corresponding data channel transmitted to the base station may be included in the calculation of the NACK ratio used in CW adjustment based on HARQ-ACK feedback.

Third, when the control channel and the data channel are transmitted separately on different carriers, and when Cat-4 is performed as a channel access procedure in each carrier for transmission of each control channel and data channel, the CW managed by each carrier can be included in the calculation of the NACK ratio used in CW adjustment based on HARQ-ACK feedback only for the HARQ-ACK value transmitted from the terminal to the base station for the control channel or data channel transmitted in each carrier. . That is, when HARQ-ACK feedback for transmission of a data channel scheduled through the control channel for CW update in the carrier that transmitted the control channel is not detected by the base station, it is determined that DTX has occurred due to inability to receive the control channel. Therefore, the corresponding DTX can be included in the calculation of the NACK ratio used in CW adjustment based on HARQ-ACK feedback in the carrier through which the control channel is transmitted. In addition, since it may be considered that the data channel reception failure or the terminal received the control channel well and performed HARQ-ACK transmission, but the base station failed to detect the corresponding A/N and DTX occurred, the HARQ- It can be included in the calculation of the NACK ratio used in CW adjustment based on ACK feedback. Alternatively, the base station may select only one of the two and include it in the calculation of the NACK ratio used in CW adjustment.

When it is set to perform cross-carrier scheduling with inter-band CA, as a scheduled carrier by a control channel transmitted from carrier-1 performing cross-carrier scheduling in FIG. 26 in one embodiment, carrier-3 (or vice versa) It is necessary to determine how to use the HARQ-ACK value corresponding to the data channel transmitted from carrier 3 to carrier 1 (carrier 1 can be scheduled) when adjusting the CW and how to use it when calculating the NACK ratio. This is because information on the channel state and congestion in the channels between different bands may not be similar. Therefore, during cross-carrier scheduling between inter-bands, HARQ-ACK feedback is provided for the HARQ-ACK value transmitted from the terminal to the base station. The CW adjustment method based on it should be further considered.

First, in the case of considering inter-band CA, in the description of the present invention for the channel access method in the multi-carrier, a method in which CW is managed for each carrier or LBT sub-band unit within each carrier is used. should be This is because information on channel state and congestion in channels between different bands may not be similar.

First, if the control channel and data channel are transmitted separately on different carriers, and if Cat-4 is performed as a channel access procedure on each carrier for transmission of each control channel and data channel, CW managed for each carrier For all HARQ-ACK values transmitted from the terminal to the base station, it may be included in the calculation of the NACK ratio used in CW adjustment based on HARQ-ACK feedback.

Second, even when the control channel and the data channel are transmitted separately in different carriers, when Cat-4 is performed as a channel access procedure in the scheduled carrier through which the data channel is transmitted, only the CW update in the scheduled carrier is transmitted from the terminal. The HARQ-ACK value of the corresponding data channel transmitted to the base station may be included in the calculation of the NACK ratio used in CW adjustment based on HARQ-ACK feedback.

Third, when the control channel and the data channel are transmitted separately on different carriers, and when Cat-4 is performed as a channel access procedure in each carrier for transmission of each control channel and data channel, the CW managed by each carrier can be included in the calculation of the NACK ratio used in CW adjustment based on HARQ-ACK feedback only for the HARQ-ACK value transmitted from the terminal to the base station for the control channel or data channel transmitted on each carrier. . That is, when HARQ-ACK feedback for transmission of a data channel scheduled through the control channel for CW update in the carrier that transmitted the control channel is not detected by the base station, it is determined that DTX has occurred due to inability to receive the control channel. Therefore, the corresponding DTX can be included in the calculation of the NACK ratio used in CW adjustment based on HARQ-ACK feedback in the carrier through which the control channel is transmitted. In addition, since it may be considered that the data channel reception failure or the terminal received the control channel well and performed HARQ-ACK transmission, but the base station failed to detect the corresponding A/N and DTX occurred, the HARQ- It can be included in the calculation of the NACK ratio used in CW adjustment based on ACK feedback. Alternatively, the base station may select only one of the two and include it in the calculation of the NACK ratio used in CW adjustment.

With respect to the scheduling information of the PDSCH, the RA field can be configured depending on the size of multiple LBT units grouped into a preset group, not the activated BWP as a reference, and the UE allocates resource allocation (RA) to DCI in the PDCCH scheduling the PDSCH. ), it is determined that resource allocation is made based on the size of multiple LBT units grouped into groups, and the RA-related field is interpreted. However, since the base station may vary the allocation of resources occupied by the PDSCH according to the LBT result of each LBT unit under the multiple LBT units grouped into a group, the value of the RA field of the DCI in the PDCCH may need to be allocated differently according to the LBT result. If the size of the PDSCH is also allocated differently according to the LBT result, the base station scheduling complexity may occur in which the base station must prepare the PDCCH for delivering the DCI having different information and prepare the PDSCH of different sizes. Separately, by setting a resource allocation field in a unit through a combination with one LBT unit or multiple LBT units, the terminal reads the RA field to determine which LBT unit(s) the PDSCH is allocated to. This can be. In the case of scheduling through a combination of a single LBT unit and multiple LBT units as a method for enabling the allocation of wide BW, there may be a method of designating each case in the corresponding RA field in FIG. That is, when the DCI is detected by monitoring the PDCCH in the ^1st LBT unit for PDSCH transmission in the ^{1st LBT} unit and ^2nd LBT unit grouped according to the LBT result, the resource in the unit through the combination with the LBT unit In the allocation field, one of case 1) and case 2) is indicated by the base station and the terminal determines that the resource allocation of the PDSCH is made according to the indicated value, so that the reception of the PDSCH can be performed. In the case of detecting the DCI by monitoring the PDCCH in the ^3rd LBT unit for PDSCH transmission in the N-th LBT unit in the ^3rd LBT unit grouped with the same priority as the ^st LBT unit and the ^2nd LBT unit, the LBT The base station indicates one of case 3) and case 4) of the resource allocation field in the unit through combination with the unit, and the terminal determines that the PDSCH resource allocation is made according to the indicated value, so that the PDSCH is received , and similarly, it can be extended and applied in the same way even in the case of configuring M groups.

As another embodiment of the present invention, in the case of BWP switching in which a PDCCH is transmitted in one BWP and a PDSCH is scheduled in a BWP different from the BWP in which the PDCCH is transmitted, a timing for learning to ensure a retuning time for switching of different BWPs gap is needed. A time gap in the unit of several hundred us may be necessary due to various conditions, such as when the center frequency changes, when the band changes, when the size of BW changes, etc. In the case of the licensed band, the base station can guarantee the gap, so that the base station can transmit the PDSCH due to BWP switching, and the terminal can receive the PDSCH after the corresponding time gap. However, considering that the basic unit for performing CCA used in LTE-LAA and Wi-Fi for unlicensed band is 9us, before performing BWP switching, the base station or terminal performs channel sensing before the time gap, and then the channel is idle. Therefore, even though the channel has already been secured, there may be cases in which the corresponding channel may be stolen by a terminal and a base station or Wi-Fi nodes that perform transmission using other unlicensed bands in a timing gap of several hundred us. Therefore, in the present invention, when performing the corresponding BWP switching, the reservation signal is transmitted in the time gap before transmission of the PDCCH or the PDSCH, so that the corresponding channel can be continuously secured.

SS/PBCH block composition in NR

In NR, the UE transmits the PSS and SSS from the base station to perform initial cell access, RRM measurement, and mobility management, that is, the Synchronization signal (SS) and PBCH (hereafter referred to as SS/PBCH block or SSB by combining SS and PBCH) receive

23 shows symbol positions in one slot that can be occupied by 1 symbol PSS, 1 symbol SSS, and PBCH defined in NR, that is, an SSB composed of 20 RBs in 4 symbols. Depending on the spacing of each subcarrier, the symbol positions in one slot that can be occupied by the SSB may be different from each other, and in the case of 30 kHz, a pattern for transmission for general eMBB and a pattern for URLLC transmission, that is, two types of SSB allocation pattern can be used.

24 shows the position of a slot that can be occupied by the SSB within 5 ms, which is a half radio frame. Depending on each subcarrier spacing, slot positions in the half radio frame that the SSB can occupy may be different.

In addition, in NR, one subcarrier spacing is defined for each band for SSB transmission, thereby reducing the complexity of finding an SSB in a UE for initial cell access. In particular, for the band below 6 GHz, either 15 kHz or 30 kHz subcarrier spacing is used for SSB, and for the band above 6 GHz, one of 120 kHz or 240 kHz subcarrier spacing is used for SSB.

In NR Unlicensed, if channel access fails due to Listen before talk (LBT) by the base station, SSB transmission may not be performed at the location set by the base station, and accordingly, the terminal may assume that the SSB is transmitted at a specific location. When the configuration information of the SSB is configured in the terminal, it may not be possible to receive the SSB in the corresponding terminal. Since the SSB is transmitted periodically with a specific period, if the terminal fails to receive the SSB at a specific location, the SSB can be received at a time point after one period has elapsed, which causes delay for RRM measurement and neighbor cell measurement and causes system It can increase latency overall. In addition, in order to perform a beam operation, different beams are transmitted using SSB indexes transmitted in different time domains to establish a beam link connecting the terminal and the corresponding beam to perform beam management. However, in this case, if the SSB transmission cannot be performed due to the failure of the LBT in the base station, the latency for establishing a beam link between the base station and the terminal through beam sweeping is further increased, which may cause significant deterioration in system performance. .

Also, in NR-U, subcarrier spacing of 60 kHz may be used to increase the opportunity for channel access. This means that when using the NR system in the licensed band, subcarrier spacing of 15 kHz or 30 kHz for SSB below 6 GHz, subcarrier spacing of 15 kHz, 30 kHz or 60 kHz for data transmission can be used, and 120 kHz or 240 kHz for SSB above 6 GHz. 60 kHz or 120 kHz subcarrier spacing can be used for data transmission, but when NR-U is used in a band below 7 GHz (7.125 GHz or less), 15 kHz or 30 kHz can be considered as the corresponding subcarrier spacing, but time In the case of using 60 kHz, where the interval between OFDM symbols in the domain can be reduced to 1/4 compared to 15 KHz, as the interval between OFDM symbols is reduced, the opportunity for transmission in symbol units after channel access can be increased, When channel access is successful within one symbol when 15 kHz and 30 kHz subcarrier spacing is used, the time for transmitting the reservation signal can be increased compared to when 60 kHz subcarrier spacing is used. can

Configuration of NR-U DRS (or DRS)

In NR-U, at least one signal including SSB or SSB burst set transmission is defined, and the corresponding signal is designed to have the following properties characterized for operation in unlicensed band.

- There is no gap within the time interval in which the signal is transmitted at least within the beam

- Must meet occupied channel bandwidth (OCB), although this may not be a requirement

- Minimize the channel occupancy time of the corresponding signal

- Characteristics that can facilitate quick channel access

Also, when one signal is called NR-U DRS (or DRS), NR-U DRS is associated with SS/PBCH block(s) in addition to the SSB or SSB burst set included at least in one continuous burst. PDSCH carrying RMSI (Remaining System Information) and RMSI-CORESET(s), that is, a region of control channel transmission for transmitting scheduling information for RMSI may be included, and CSI-RS may also be included in NR-U DRS. .

In addition, transmission of additional signals such as OSI (Other system information or On-demand system information) and paging may be included in the NR-U DRS.

When the base station transmits the NR-U DRS on the unlicensed band, the transmission should be performed when the channel is idle after performing the LBT. When different signals and channels are multiplexed in DRS, it is necessary to define what kind of LBT the base station should perform.

The present invention relates to an LBT method of transmission when signals and channels different from NR-U DRS used in NR-U are multiplexed, and more particularly, at least SS/PBCH block or SS/PBCH block burst set. When different signals and channels are multiplexed into the included NR-U DRS, various transmission burst types including NR-U DRS may exist, and accordingly, different LBT types and LBT parameters are applied to various transmission burst types. It's about the plan.

First, in the case of DRS multiplexed with unicast data, Cat-4 LBT is performed by setting a channel access priority class according to the multiplexed data. However, multiplexing with DRS for initial access, random access, mobility, and paging related control message or reference signals only, and PDCCH only transmission, that is, RACH message-4, handover command, group-common PDCCH or short message paging. What type of LBT is used for transmission in consideration of both the case where it is transmitted and the case where it is transmitted alone should be additionally defined, and the following method may be considered.

First, the following method may be considered as a method for multiplexing simultaneously with DRS.

- As an embodiment, when multiplexing with DRS for signals and channels that cannot set the channel access priority class due to non-data traffic, when multiplexed and transmitted, DRS transmission should be prioritized. A method of performing single interval LBT of 25us or 34us using Cat-2 LBT may be used.

- As another embodiment, considering that cat-2 LBT can be performed only when the total duration is 1 ms or less and the duty cycle of DRS is 1/20 or less even for DRS only transmission, it is not data traffic. For signals and channels that cannot set the channel access priority class due to this, when multiplexed with DRS and transmitted, channel access with the highest channel access priority (e.g. channel access priority class #1) with Cat-4 LBT is used. can This is a method of increasing the priority of channel access compared to other unicast data, and it can be said that it is a method of increasing the priority by considering it as a signal and a channel to perform a function specific to a specific function.

- As another embodiment, considering that cat-2 LBT can be performed only when the total duration is 1 ms or less and the duty cycle of DRS is 1/20 or less even for DRS only transmission, it is not data traffic. For signals and channels for which the channel access priority class cannot be set due to this, when multiplexed with DRS and transmitted, use the channel access with the highest channel access priority (e.g. channel access priority class #1) with Cat-4 LBT. For the contention window size, channel access can be performed by setting the smallest or largest value among allowable CW sizes that can be in the channel access priority class. This is a method of increasing the priority of channel access compared to other unicast data, and it can be said that it is a method of increasing the priority by considering it as a signal and a channel to perform a function specific to a specific function.

- As another embodiment, considering that cat-2 LBT can be performed only when the total duration is 1 ms or less and the duty cycle of DRS is 1/20 or less even for DRS only transmission, it is not data traffic. For signals and channels that cannot set the channel access priority class due to this, when multiplexed with DRS and transmitted, the LBT method of performing random back-off with a contention window having a fixed size is Cat-3 LBT. can be made to use As one example of a method of setting a fixed contention window, the smallest or largest value among allowable CW sizes that can have the highest channel access priority (e.g. channel access priority class #1) in the channel access priority class can be set to perform channel access. This is a method of increasing the priority of channel access compared to other unicast data, and it can be said that it is a method of increasing the priority by considering it as a signal and a channel to perform a function specific to a specific function.

Next, in the case of being independently transmitted without being multiplexed with DRS, the same LBT type and channel access are used for the same type of signal and channel regardless of whether DRS is used, using the same method as the DRS and multiplexed transmission method. can be made to use

On the other hand, since Cat-4 LBT is set to be used for both PDCCH or PDSCH in the case of not being multiplexed with DRS, Cat-4 LBT is the same as the method applied to PDCCH or PDSCH for signals and channels that are not multiplexed with DRS. can be set to be used.

For non-unicast data, for example, OSI (Other system information, On-demand system information), paging, and RAR (Random access response), when multiplexing with DRS, the total duration is 1 ms or less and the duty cycle of DRS is 1/ In the case of 20 or less, Cat-2 LBT of 25us may be performed similarly to the method in LTE-LAA. However, when OSI, Paging, or RAR is multiplexed with DRS, Cat-4 LBT can be performed if the total duration is greater than 1ms or the duty cycle of DRS is greater than 1/20. At this time, when setting the LBT parameter for performing Cat-4 LBT, the channel access can be performed by selecting the highest priority channel access priority class. If the base station can determine whether the terminal has received and whether the reception of non-unicast data is successful, the information of the feedback according to the reception success from the terminals is converted into ACK/NACK, and LTE- Channel access can be performed by adaptation of the contention window according to the ratio of NACK, which is a method used in LAA.

However, as non-unicast data, all or part of the channel(s) and signal(s) for which HARQ feedback is not expected may be multiplexed with DRS, or the base station cannot determine whether the base station receives the transmission from the base station. The (s) and signal(s) may be multiplexed with the DRS. In this case, CWS adaptation for applying a variable contention window size based on the feedback of HARQ-ACK, which is a characteristic of Cat-4 LBT, may not be possible. Therefore, as non-unicast data, all or part of the channel(s) and signal(s) for which HARQ feedback is not expected may be multiplexed with DRS, or the base station cannot determine whether the terminal receives the transmission of the base station. When (s) and signal (s) are multiplexed with DRS, a method of performing random back-off with a fixed CW size may be used. For the setting method of the LBT parameter, the channel access with the highest channel access priority (e.g. channel access priority class #1) is used as Cat-4 LBT, but the contention window size is also allowable within the channel access priority class. Channel access can be performed by setting the smallest or largest value among CW sizes. This is a method of increasing the priority of channel access compared to other unicast data, and it can be said that it is a method of increasing the priority by considering it as a signal and a channel to perform a function specific to a specific function. As another LBT parameter setting method, it is possible to use the LBT method of channel access that performs random back-off with a contention window having a fixed size as Cat-3 LBT. As one example of a method of setting a fixed contention window, the smallest or largest value among allowable CW sizes that can have the highest channel access priority (e.g. channel access priority class #1) in the channel access priority class can be set to perform channel access. This is a method of increasing the priority of channel access compared to other unicast data, and it can be said that it is a method of increasing the priority by considering it as a signal and a channel to perform a function specific to a specific function.

In the present invention, when the wireless communication node(s) performs transmission on the unlicensed band, the wireless communication node(s) LBT of the wireless communication node(s) for determining whether the channel is used or not before performing the transmission method, or a channel access procedure. In more detail, the channel access procedure in the case where the LBT method that allows the wireless communication node(s) to sense the channel during the 16us section on the unlicensed band is set or signaled, and the operation method of the wireless communication nodes in the case where the channel access fails it's about

In more detail, when an initiating node (eg, may be a base station or a terminal) for wireless communication intends to transmit data, the channel for performing Cat-4 LBT according to the type of data to be transmitted by the initiating node The access priority class is set, and the MCOT capable of maximum transmission is set according to the corresponding channel access priority class. To perform Cat-4 LBT, the initiating node sets LBT parameter values (eg, m_p, the minimum and maximum values of the contention window, the maximum available channel occupancy time (T_mcot)) according to the corresponding channel access priority class. do.

Table 4 below shows LBT parameter values for each channel access priority class for downlink transmission used in the LTE-LAA system.

Table 4 below shows that when the wireless communication node(s) performs transmission, when data traffic is included in a downlink channel to be transmitted, the dipper period is set according to the channel access priority class of the traffic included in the downlink channel. can In addition, the dipper period may be composed of 16us (T_f) and m_p slot periods. In this case, each slot section T_sl may be 9 us. T_f includes one idle slot period (T_sl). In addition, the m_p value may be set according to the channel access priority class as shown in Table 4 below.

Also, the wireless communication device may set the range of the CW value according to the channel access priority class. Specifically, the wireless communication device may set the range of the CW value to satisfy CW _min,p <= CW _min,p <= CW _max,p . In this case, the value of CW _min,p and the value of CW _max,p may be determined according to the channel access priority class as shown in Table 4 described above. In addition, the wireless communication device may set the value of CW _min,p and the value of CW _max,p in the step of the counter value setting procedure. During channel access, the base station may adjust the CW value as described above. In addition, the maximum transmission duration (T_mcot,p, maximum channel occupancy time (MCOT)) that can be used in one transmission through a channel to be transmitted on the unlicensed band may be determined according to the channel access priority of the transmitted data. Specifically, it may be determined as shown in Table 4 above. Accordingly, the wireless communication device must not continuously transmit for a time exceeding T_mcot,p. This is because, in the case of the unlicensed band, since it is a frequency band accessed by several wireless communication devices through a contention procedure, it is not desirable for any one wireless communication device to continuously use it for a predetermined time or more. In Table 4, when the value of the channel access priority class is p=3 or p=4, a long term unlicensed band is used according to regulations, and there is no wireless communication device using another technology. , the wireless communication device may set T_mcot,p=10ms. Otherwise, the wireless communication device may set T_mcot,p=8ms.

Table 5 below shows LBT parameter values for each channel access priority class for uplink transmission used in the LTE-LAA system.

Here, the 6ms MCOT can be increased up to 8ms by adding one or more gaps, and the minimum duration of the section stopped due to the gaps must be 100us. And the length of the maximum interval must be 6ms before including the gap. And the gap duration itself is not included in the channel occupancy time. Here, in the values 3 and 4 of the priority class, if the absence of another RAT (eg, Wi-Fi) on the same carrier is guaranteed, the MCOT can be up to 10 ms, otherwise the MCOT is from note 1 It is the same as determining

According to Tables 4 and 5, LBT parameters are set according to the type of the initiating node for wireless communication and the type of data traffic to be transmitted in order to perform Cat-4 LBT. In particular, in the case of MCOT (Maximum channel occupancy time), it means the time that the initiating node for wireless communication can occupy the maximum.

27 shows a scenario in which transmission from the responding node is transmitted within the MCOT set by the initiating node when transmission from the initiating node does not occupy the MCOT within the MCOT set by the initiating node.

If the transmission from the initiating node does not occupy the MCOT within the MCOT set by the initiating node, the transmission of the responding node may be transmitted within the MCOT set by the initiating node as shown in FIG. A channel access method performed prior to transmission may have various methods as follows.

Method 1) First, when the gap between transmissions of the responding node after the transmission of the initiating node is not greater than 16 us (microsecond), the responding node applies the Cat-1 LBT method to the corresponding gap without sensing the channel. Thereafter, immediate transmission may be performed. In this case, with respect to the length that the responding node intends to transmit, there may be restrictions on the transmission condition within the MCOT set by the initiating node and the maximum length of the additional responding node.

Method 2) Also, when the gap between transmissions of the responding node after the transmission of the initiating node is finished is 16 microseconds (here, 16 us may include tolerances for implementation), the responding node senses for a period of 16 us In the Cat-2 LBT method for performing , it is possible to enable the responding node to perform transmission through sensing of a single interval of a channel. However, the initiating node may indicate the Cat-2 LBT method to the responding node to perform sensing during the 16us period, implicitly or explicitly, for example, through a UL grant.

Method 3) In addition, when the gap between consecutive scheduled or granted transmissions within the same COT (Channel Occupancy time) within the MCOT set by the initiating node is not greater than 25us, the Cat- to perform sensing for a period of 25us 2 LBT method can be used, and even when downlink transmission following uplink transmission within the same COT does not follow, Cat-2 LBT method for performing sensing for 25 us section for corresponding uplink transmission can be used, and , Also, even when the gap for downlink transmission following uplink transmission within the same COT is greater than 16us and not greater than 25us, the Cat-2 LBT method to perform sensing for 25 us interval may be used.

When the gap between transmissions of the responding node after the transmission of the initiating node is finished is not greater than 16 us (microsecond), method 1), that is, Cat-1 LBT method is applied to immediately transmit after the corresponding gap without sensing the channel For the distinction between the method of performing , method 2), that is, the method of sensing a single interval for a channel in the Cat-2 LBT method for performing sensing for a 16us interval, the transmission of the responding node can be divided into traffic. A method of classifying a Cat-1 LBT and a 16us Cat-2 LBT may be used according to whether data traffic that can be enabled or a channel access priority class can be determined is included.

As an embodiment, with respect to the transmission of the responding node for transmitting HARQ-ACK feedback for the data traffic transmitted from the initiating node, the gap between transmissions of the responding node after the transmission of the initiating node is 16 us (microsecond) , method 1) is applied to set to use Cat-1 LBT, and the transmission of the responding node including data traffic that can be scheduled or configured from the initiating node or that can be classified into the configured data traffic or the channel access priority class can be determined. For method 2), 16us Cat-2 LBT can be set to be used.

As another embodiment, with respect to the transmission of the responding node for transmitting uplink control information (UCI) for data traffic transmitted from the initiating node, the gap between transmissions of the responding node after the transmission of the initiating node is completed is 16 us (microsecond). When , method 1) is applied to set to use Cat-1 LBT, and the responding node including data traffic that can be scheduled or configured from the initiating node or can be classified as a channel access priority class is determined. For transmission, method 2) can be applied to set to use 16us Cat-2 LBT.

As another embodiment, for the transmission of the responding node transmitting the SRS (Sounding Reference Signal), when the gap between transmissions of the responding node after the transmission of the initiating node is 16 us (microsecond), method 1) is applied, Set to use Cat-1 LBT, and apply method 2) to the transmission of the responding node including data traffic that can be scheduled or configured by the initiating node or can be classified as a channel access priority class It can be configured to use 16us Cat-2 LBT.

As another embodiment, for transmission of a responding node transmitting a physical random access channel (PRACH), when the gap between transmissions of the responding node after the transmission of the initiating node is completed is 16 us (microsecond), method 1) is applied to use Cat-1 LBT, and method 2) is applied to the transmission of the responding node including data traffic that can be scheduled or configured from the initiating node or that can be classified as a channel access priority class or can be determined by a channel access priority class to use 16us Cat-2 LBT.

When the gap between initiating node transmissions following transmission of the responding node within the COT set by the initiating node is not greater than 16 us (microsecond), method 1), i.e., Cat-1 LBT method, is applied to correspond without sensing the channel. For the distinction between the method of performing immediate transmission after the gap and the method 2), that is, the Cat-2 LBT method to perform sensing for a 16us interval, for a method of sensing a single interval for a channel, the transmission of the initiating node is A method of classifying Cat-1 LBT and 16us Cat-2 LBT may be used according to whether data traffic that can be classified as traffic or channel access priority class can be determined is included.

As one embodiment, control information for scheduling data transmitted from the initiating node (eg, PDCCH only, group common signaling, paging, reference signal only, tracking reference signal (TRS), RACH message 4 or handover command) In the case of only transmission, when the gap between transmissions of the initiating node after the transmission of the responding node is finished is 16 us (microsecond), method 1) is applied to use Cat-1 LBT, and as transmission from the initiating node For transmission of an initiating node including data traffic that can be classified as scheduled or configured data traffic or whose channel access priority class can be determined, method 2) can be applied to use 16us Cat-2 LBT.

As one embodiment, responding to the case where only broadcasting information (eg, discovery reference signal (DRS), SS/PBCH block, Type0-PDCCH, or RMSI (Remaining system information)) transmitted from the initiating node is transmitted When the gap between the transmission of the initiating node after the transmission of the node is finished is 16 us (microsecond), apply method 1) to set to use Cat-1 LBT, and receive scheduled or configured data traffic as transmission from the initiating node. For the transmission of the initiating node including data traffic that can be distinguished or the channel access priority class can be determined, method 2) can be applied to set to use 16us Cat-2 LBT.

<Different UE behavior for 16us LBT failure>

28 is an embodiment of the present invention, when a base station is configured as an initiating node and a terminal is configured as a responding node, and when downlink transmission does not occupy the MCOT within the MCOT set by the base station, the terminal within the MCOT set by the base station It shows a scenario when the transmission is scheduled or configured. In addition, FIG. 28 shows a case where UL transmission continuously comes after 16us gap after ongoing DL transmission within the MCOT set by the initiating node, and FIG. 28-(a) shows a scheduling grant in multiple slots is transmitted to the terminal, This is a case in which uplink transmission is performed in multiple slots by receiving this, and FIG. 28-(b) is a case in which one scheduling grant is transmitted to the terminal and the terminal receives it and performs uplink transmission in multiple slots. In FIG. 28, a scenario in which scheduling for UL transmission is performed within the MCOT set by the initiating node has been described for convenience, but even if the initiating node is scheduled or configured before the MCOT set by the initiating node, the details of the present invention below are the same. It may be possible to apply

Cat-2 for performing sensing for a period of 16us from the base station when the gap between uplink transmissions after downlink transmission from the base station for uplink transmission is 16us when the base station as the initiating node and the terminal as the responding node are configured The LBT method may be implicitly or explicitly signaled, and in this case, the terminal may perform uplink transmission when the channel is sensed as idle by performing the Cat-2 LBT method for performing sensing for a 16us period. However, when the channel is occupied by other wireless communication nodes and the channel is sensed as busy for sensing during the corresponding 16us period, the operation method of the terminal needs to be defined additionally. In general, in the NR-U system, scheduling in slot units can be configured under a slot-based structure, and scheduling grants in units of multiple slots are transmitted to the terminal, and the terminal receives them and performs uplink transmission in multiple slots. Alternatively, the terminal may receive one scheduling grant for scheduling one multiple slot from the base station and perform uplink transmission in multiple slots. Therefore, when the gap between the start of uplink transmission after downlink transmission from the base station is 16us, even if Cat-2 LBT for 16us section fails at the start time of uplink transmission, transmission in multiple slots in uplink is set. In this case, an additional LBT scheme for uplink transmission may be required except for the start of the first slot of uplink transmission. That is, if one slot is scheduled or configured in the uplink and Cat-2 LBT for 16us period fails at the start of uplink transmission, it may not be necessary to perform transmission in the corresponding slot any more, but When two or more slots are scheduled or configured, and Cat-2 LBT for 16us period fails at the start of uplink transmission, or when channel access cannot be performed, the following LBT is performed in order to perform transmission in subsequent slots. The method may be further considered.

For the description of the present invention, as an example, a scheduled or configured received slot is {slot(n), slot (n+1), slot (n+2), ... , slot(n+k-1)}, where k is the number of scheduled or configured slots.

1) First, when scheduling to perform transmission of multiple slots in uplink, from the viewpoint of allowing Cat-2 LBT for 16us period, in case of transmission of the multiple slot, Cat-2 LBT for 16us period for each slot is Considering that it can be allowed, even if Cat-2 LBT fails during the 16us period in slot(n) at the start time for transmission of multiple slots in uplink or even if channel access could not be performed, after slot(n) ({slot (n+1), slot (n+2), …, slot(n+k-1)}, k is the number of scheduled or configured slots) 16us interval for uplink transmission A method in which the UE continuously attempts to make transmission in the slot after the failure by continuously performing Cat-2 LBT during the period may be used.

2) The second and 1) methods are used as they are, but as a method of limiting the number of attempts of Cat-2 LBT during the 16us section, a method of limiting the number of attempts to the number of scheduled or configured slots can be considered. For example, a scheduled or configured received slot is {slot(n), slot (n+1), slot (n+2), ... , slot(n+k-1)}, the number of scheduled or configured slots is k, and the limited number may be limited to k.

3) Third, after failing Cat-2 LBT for the 16us section, set the channel to continuously perform channel sensing during the T_sl (here, T_sl means the sensing slot length for channel sensing), but during the 16us section If the channel is continuously sensed as idle after failing Cat-2 LBT, the UE transmits the next slot for transmission in the slot after the 16us LBT failure, that is, slot (n+1), that is, slot (n+1). A method of setting the UE to perform subsequent uplink transmission by performing Cat-2 LBT for a period of 16us immediately before may be used. However, if the channel is not continuously sensed as idle after failing Cat-2 LBT for 16us, use Cat-4 LBT with random back-off for slot (n+1) and subsequent slot transmission. A setting method may be used. At this time, only the slot (n) or slot (n+1), . , when Cat-4 channel access is indicated as the LBT type for slot (n+k-1), uplink transmission can be performed after performing Cat-4 LBT with the channel access priority class indicated by DCI. have. However, slot (n) or slot (n+1), . , scheduling when another LBT type (eg, 25us Cat-2 LBT, or 16us Cat-2 LBT) is instructed without Cat-4 channel access being instructed as the LBT type for slot (n+k-1) Uplink transmission may be performed after performing Cat-4 LBT with a channel access priority class indicated through DCI. However, if the base station indicates the channel access priority class used to obtain access to the channel in the DCI in DCI indicating 25us Cat-2 LBT, even if the base station indicates 16us Cat-2 LBT, DCI may be configured to indicate the channel access priority class used for the base station to obtain access to the channel in the corresponding DCI.

4) Fourth, after failing the Cat-2 LBT for the 16us section, set the channel to continuously perform channel sensing during the T_sl (here, T_sl means the sensing slot length for channel sensing), but during the 16us section If the channel is continuously sensed as idle after failing Cat-2 LBT, the UE transmits the next slot for transmission in the slot after the 16us LBT failure, that is, slot (n+1), that is, slot (n+1). A method of setting the UE to perform subsequent uplink transmission by performing Cat-2 LBT for a period of 25us immediately before may be used. This is basically considering that the use of LBT for a period of 16us can be allowed only when the gap with the previous transmission (eg, it may be downlink or uplink) is 16us, in the first slot (n) For the transmission of , the gap with the previous transmission was 16us, but the later slot (n+1), … Considering that the gap is not 16us for , slot (n+k-1), if it is an uplink transmission that is entered in the COT initiated by the base station, not to perform LBT for the 16us interval, 25us interval Cat-2 LBT during the period may be possible, so a method to perform this may be used. However, if the channel is not continuously sensed as idle after failing Cat-2 LBT for 16us, use Cat-4 LBT with random back-off for slot (n+1) and subsequent slot transmission. A setting method may be used. At this time, only the slot (n) or slot (n+1), . , when Cat-4 channel access is instructed as the LBT type for slot (n+k-1), uplink transmission can be performed after performing Cat-4 LBT with the channel access priority class indicated by DCI. have. However, slot (n) or slot (n+1), . , scheduling when another LBT type (eg, 25us Cat-2 LBT, or 16us Cat-2 LBT) is instructed without Cat-4 channel access as the LBT type for slot (n+k-1) Uplink transmission may be performed after performing Cat-4 LBT with a channel access priority class indicated through DCI. However, if the base station indicates the channel access priority class used to obtain access to the channel in the DCI in DCI indicating 25us Cat-2 LBT, even if the base station indicates 16us Cat-2 LBT, DCI can be configured to indicate the channel access priority class used for the base station to obtain access to the channel in the corresponding DCI.

5) Fifth, when the LBT type is indicated in DCI, according to the channel access type indicated in DCI, Cat-2 LBT for 16us interval is set to perform the channel access procedure for transmission in the subsequent slot. This can be considered. In the case of indicating the LBT type through one scheduling grant for scheduling multiple slots once, in the case of indicating Cat-2 LBT for 16us period as the LBT type in DCI, it may be the same method as 1) or 2), Although DCI did not indicate Cat-2 LBT for the 16us period as the LBT type, a 16us gap occurred between the transmission from the base station and the uplink transmission that the terminal wanted to transmit, so the LBT type was switched to Cat-2 LBT during the 16us period. There may be differences from 1) or 2) as cases can also be considered. In addition, when a scheduling grant in units of multiple slots is transmitted to the UE and the UE receives them and performs uplink transmission in multiple slots, the DCI, which is a scheduling grant in units of individual slots, may indicate the LBT type, so the corresponding individual slot According to the LBT type indicated by the base station through the scheduling grant in the unit, a method of setting to perform the channel access procedure for transmission in the slot after the failure of Cat-2 LBT for the 16us period may be used.

6) Sixth, if one or more slots are scheduled or configured in the uplink and Cat-2 LBT for 16us period fails at the start of uplink transmission, the corresponding channel is not idle and to nodes using other unlicensed bands. Considering that there is a possibility that the channel is in use by the user, a method of setting to use Cat-4 LBT with random back-off may be used. This means that if the channel during the 16us period is not idle and is sensed as busy, it is highly likely that the channel is not idle but busy because the channel is being used by other nodes despite continuously performing 16us or 25us Cat-2 LBT. Therefore, a method of configuring Cat-4 LBT with random back-off to be used for slot (n+1) and subsequent slot transmission and performing uplink transmission after performing Cat-4 LBT can be used.

In addition to the case of receiving and transmitting scheduling, resources in time and frequency units are set by RRC configuration, and in the case of transmission through an uplink configured grant that allows the terminal to perform transmission, in the time and frequency units specified from the configured grant The method applied to the scheduling grant based on the resource of may be used in the same way.

The present invention is to perform LBT in a manner to perform energy measurement in a deferral period of a specific length that can be commonly used and a structure of a basic sensing slot for performing LBT when trying to perform an LBT operation in a band of 52.6 GHz or higher. We propose a sensing structure during the slot for

First, assuming that the base station or terminal, i.e., wireless devices, perform sensing in the 5us observation slot in the band above 52.6GHz, the section where the wireless devices perform sensing in the 5us observation slot is not precisely defined, but rather in the 5us observation slot. If the detected power by performing sensing for at least T [us] anywhere within the range is below the energy detection threshold at which each channel can be determined to be idle, the channel can be set to be determined to be idle in the corresponding observation slot. Here, the energy detection threshold (EDT) may be set to be calculated through the following equation. As an input parameter, Pout is RF output power (EIRP), Pmax is the RF out power limit, and Pout can always be set to be less than or equal to Pmax. In addition, it is possible to set the operating channel BW [MHz] to operate when the device performs sensing, which can be set to one of the basic LBT bandwidth or channel BW for performing transmission BW or LBT.

<Equation>

Also, 8us can be used as a deferral period commonly used when sensing wireless devices. However, it may be necessary to define the method of setting the sensing slot in the corresponding 8us and the section to perform sensing of wireless devices, and it may be necessary to define how many sensing, ie, energy measurements, should be set within the 8us deferral period. can The present invention proposes a sensing structure for such energy measurement.

First, in case that only one energy measurement is performed within the 8us deferral period, the following method can be considered for the sensing structure.

First, in order not to miss that the channel is not idle within 8us, i.e., the channel is busy, the 8us deferral period sets one observation slot, i.e., 5us, within the last 5us of 8us, and at least the channel occurs in the observation slot. If it is sensed that the channel is idle for the entire period of at least 5us with less than 5us, for example 3us (or 4us), it can be set to determine that the channel is idle within the corresponding 8us deferral period.

In the second method, in order not to miss that the channel is not idle within 8us, that is, the channel is busy, the 8us deferral period sets one observation slot, that is, 5us, within the last 5us of 8us, and the channel is not idle in the deferral period. If it is sensed that the channel is idle for the entire period of at least 5us with less than the actual 5us, for example 3us (or 4us), it can be set to judge that the channel is idle within the corresponding 8us deferral period.

In the third method, when the sensing operation and the channel are idle after sensing to actually perform transmission, at least Y[us] at the end of the deferral period is preset to the Rx to Tx switching period in order to guarantee the Rx to Tx switching period. and set the last 5 [us] observation slots within the remaining (8 - Y) [us] interval. If the channel is sensed as idle by one channel sensing within the 5us observation slot, the 8us deferral period It can be set to judge that the channel is idle within the interval.

In the fourth method, when sensing and the channel is idle after sensing to actually perform transmission, at least Y[us] at the end of the deferral period is preset to Rx to Tx switching section to guarantee the Rx to Tx switching section. and set an observation slot of the last 5 [us] within the remaining (8 - Y) [us] interval so that the channel has an entire interval of at least 5us which is at least smaller than the actual 5us occurring in the observation slot, for example 3us (or 4us). If it is sensed that the channel is idle during the period, it can be set to determine that the channel is idle within the corresponding 8us deferral period.

In the fifth method, when the sensing operation and the channel idle after sensing to actually perform transmission, at least Y[us] at the end of the deferral period is preset as the Rx to Tx switching period to guarantee the Rx to Tx switching period. If the channel is sensed as idle for the entire period of at least 5 us, the channel has at least 3us (or 4us) smaller than the actual 5us occurring during the remaining (8 - Y) [us] period, the corresponding 8us deferral period period It can be set to judge that the channel is idle in the

Next, in the case of performing two energy measurements within the 8us deferral period, the following method can be considered for the sensing structure.

The first is to set the 8us deferral period as one observation slot in the preceding 3us interval and the following 5us interval, that is, the last 5us of the 8us deferral period, in order not to miss whether the channel is not idle within 8us, that is, the channel is busy. , set to perform energy measurement once within the preceding 3us section, and perform energy measurement once more within the last 5us observation slot section. If both energy measurements are sensed that the channel is idle, the corresponding 8us deferral period section It can be set to judge that the channel is idle in the

The second is to set the 8us deferral period as one observation slot in the preceding 3us period and the following 5us period, that is, the last 5us of the 8us deferral period, in order not to miss whether the channel is not idle within 8us, that is, the channel is busy. , set to perform energy measurement once within the preceding 3us section, and perform energy measurement once more in the last 3us section even within the last 5us observation slot section. It can be set to judge that the channel is idle within the 8us deferral period.

In the third method, when the sensing operation and the channel are idle after sensing to actually perform transmission, at least Y[us] at the end of the deferral period is preset to the Rx to Tx switching period in order to guarantee the Rx to Tx switching period. In the remaining (8 - Y) [us] section, the preceding 3us section and the rear (8-Y-3) [us] section are set to perform energy measurement once within the preceding 3us section, and the last (8 -Y-3) If the energy measurement is performed once more within the [us] section and both energy measurements are sensed that the channel is idle, it can be set to determine that the channel is idle within the corresponding 8us deferral period. have. However, when the (8-Y-3) [us] section is set to be at least the minimum set section Z [us] for energy measurement, energy measurement is performed within the last (8-Y-3) [us] section. You can do it one more time. (8-Y-3) If the [us] section is smaller than Z [us], it can be set to determine that the channel is idle within the corresponding 8us deferral period only through energy measurement within the preceding 3us section.

22 is a block diagram showing the configurations of a terminal and a base station, respectively, according to an embodiment of the present invention. In an embodiment of the present invention, the terminal may be implemented as various types of wireless communication devices or computing devices that ensure portability and mobility. A terminal may be referred to as a user equipment (UE), a station (STA), a mobile subscriber (MS), or the like. In addition, in an embodiment of the present invention, the base station controls and manages cells (eg, macro cells, femto cells, pico cells, etc.) corresponding to the service area, and performs signal transmission, channel designation, channel monitoring, self-diagnosis, relay, etc. function can be performed. The base station may be referred to as a next generation NodeB (gNB) or an access point (AP).

As shown, the terminal 100 according to an embodiment of the present invention may include a processor 110 , a communication module 120 , a memory 130 , a user interface unit 140 , and a display unit 150 . have.

First, the processor 110 may execute various commands or programs and process data inside the terminal 100 . In addition, the processor 100 may control the entire operation including each unit of the terminal 100 , and may control data transmission/reception between the units. Here, the processor 110 may be configured to perform an operation according to the embodiment described in the present invention. For example, the processor 110 may receive the slot configuration information, determine the slot configuration based on the received slot configuration information, and perform communication according to the determined slot configuration.

Next, the communication module 120 may be 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 120 may include a plurality of network interface cards (NIC), such as cellular communication interface cards 121 and 122 and unlicensed band communication interface card 123, in an internal or external form. . Although the communication module 120 is illustrated as an integrated integrated module in the drawing, each network interface card may be independently disposed according to a circuit configuration or use, unlike the drawing.

The cellular communication interface card 121 transmits and receives a wireless signal to and from at least one of the base station 200, an external device, and a server using a mobile communication network, and based on a command of the processor 110, a cellular communication service using a first frequency band can provide According to an embodiment, the cellular communication interface card 121 may include at least one NIC module using a frequency band of less than 6 GHz. At least one NIC module of the cellular communication interface card 121 independently communicates with at least one of the base station 200, an external device, and a server according to a cellular communication standard or protocol of a frequency band of less than 6 GHz supported by the corresponding NIC module. can be performed.

The cellular communication interface card 122 transmits and receives a wireless signal to and from at least one of the base station 200, an external device, and a server using a mobile communication network, and based on a command of the processor 110, a cellular communication service using a second frequency band can provide According to an embodiment, the cellular communication interface card 122 may include at least one NIC module using a frequency band of 6 GHz or higher. At least one NIC module of the cellular communication interface card 122 independently performs cellular communication with at least one of the base station 200, an external device, and a server according to a cellular communication standard or protocol of a frequency band of 6 GHz or higher supported by the corresponding NIC module. can be done

The unlicensed band communication interface card 123 transmits and receives a wireless signal with at least one of the base station 200, an external device, and a server using a third frequency band that is an unlicensed band, and based on a command of the processor 110, the unlicensed band Provides communication services. The unlicensed band communication interface card 123 may include at least one NIC module using the unlicensed band. For example, the unlicensed band may be a band of 2.4 GHz or 5 GHz. At least one NIC module of the unlicensed band communication interface card 123 is independently or dependently based on the unlicensed band communication standard or protocol of the frequency band supported by the NIC module, at least one of the base station 200, an external device, and a server. Wireless communication can be performed.

Next, the memory 130 stores a control program used in the terminal 100 and various data corresponding thereto. The control program may include a predetermined program required for the terminal 100 to perform wireless communication with at least one of the base station 200, an external device, and a server.

Next, the user interface 140 includes various types of input/output means provided in the terminal 100 . That is, the user interface 140 may receive a user input using various input means, and the processor 110 may control the terminal 100 based on the received user input. In addition, the user interface 140 may perform an output based on a command of the processor 110 using various output means.

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

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

First, the processor 210 may execute various commands or programs and process data inside the base station 200 . In addition, the processor 210 may control the overall operation including each unit of the base station 200 , and may control data transmission/reception between the units. Here, the processor 210 may be configured to perform an operation according to the embodiment described in the present invention. For example, the processor 210 may signal slot configuration information and perform communication according to the signaled slot configuration.

Next, the communication module 220 may be 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 120 may include a plurality of network interface cards such as the cellular communication interface cards 221 and 222 and the unlicensed band communication interface card 223 in an internal or external form. Although the communication module 220 is shown as an integrated integrated module in the drawing, each network interface card may be independently disposed according to a circuit configuration or use, unlike the drawing.

The cellular communication interface card 221 transmits/receives a wireless signal to and from at least one of the above-described terminal 100, an external device, and a server using a mobile communication network, and based on a command from the processor 210, cellular by the first frequency band Communication services can be provided. According to an embodiment, the cellular communication interface card 221 may include at least one NIC module using a frequency band of less than 6 GHz. At least one NIC module of the cellular communication interface card 221 independently communicates with at least one of the terminal 100, an external device, and a server according to a cellular communication standard or protocol of a frequency band of less than 6 GHz supported by the corresponding NIC module. can be performed.

The cellular communication interface card 222 transmits and receives a wireless signal to and from at least one of the terminal 100, an external device, and a server using a mobile communication network, and based on a command of the processor 210, a cellular communication service using a second frequency band can provide According to an embodiment, the cellular communication interface card 222 may include at least one NIC module using a frequency band of 6 GHz or higher. At least one NIC module of the cellular communication interface card 222 is supported by the corresponding NIC module. Cellular communication may be independently performed with at least one of the terminal 100 , an external device, and a server according to a cellular communication standard or protocol of a frequency band of 6 GHz or higher.

The unlicensed band communication interface card 223 transmits and receives a wireless signal with at least one of the terminal 100, an external device, and a server using a third frequency band that is an unlicensed band, and based on a command of the processor 210, Provides communication services. The unlicensed band communication interface card 223 may include at least one NIC module using the unlicensed band. For example, the unlicensed band may be a band of 2.4 GHz or 5 GHz. At least one NIC module of the unlicensed band communication interface card 223 is independently or dependently connected to at least one of the terminal 100, an external device, and a server according to the unlicensed band communication standard or protocol of the frequency band supported by the NIC module. Wireless communication can be performed.

The terminal 100 and the base station 200 shown in FIG. 22 are block diagrams according to an embodiment of the present invention. Separately indicated blocks are logically separated and illustrated for device elements. Accordingly, the elements of the above-described device may be mounted as one chip or a plurality of chips according to the design of the device. In addition, some components of the terminal 100 , for example, the user interface 140 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 necessary.

The foregoing description of the present invention is for illustration, and those of ordinary skill in the art to which the present invention pertains can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a distributed manner, and likewise components described as distributed may also be implemented in a combined form.

The scope of the present invention is indicated by the following claims rather than the above detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention. do.

Claims (1)

Method, apparatus, and system for channel access in a base station and a terminal in a wireless communication system

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