Method and apparatus for transmitting and receiving uplink feedback information in communication system

Abstract

A method and apparatus for transmitting and receiving uplink feedback information in a communication system are disclosed. A method of operation of a terminal includes the steps of receiving a DCI containing resource allocation information of a PDSCH from a base station; receiving data #n from the base station through the PDSCH indicated by the DCI; generating a HARQ codebook including a HARQ response bit #n for data #n and a HARQ response bit #n-1 for data #n-1 received from the base station prior to data #n; and transmitting the HARQ codebook to the base station. Accordingly, the performance of the communication system can be improved.

Description

Technology Field

[0001] The present invention relates to feedback technology in a communication system, and more specifically, to a technology for transmitting and receiving uplink feedback information in an unlicensed band. Background Technology

[0002] To handle the rapidly increasing volume of wireless data, communication systems (e.g., new radio (NR) communication systems) that use frequency bands higher than the frequency bands of LTE (long term evolution) (or LTE-A) (e.g., frequency bands below 6 GHz) (e.g., frequency bands above 6 GHz) are being considered. NR communication systems can support frequency bands above 6 GHz as well as frequency bands below 6 GHz, and can support a wider variety of communication services and scenarios compared to LTE communication systems. For example, usage scenarios for NR communication systems may include eMBB (enhanced Mobile BroadBand), URLLC (Ultra Reliable Low Latency Communication), mMTC (massive Machine Type Communication), etc.

[0003] Meanwhile, in LTE communication systems, a single numerology related to OFDM (orthogonal frequency division multiplexing) waveforms may be used. In NR communication systems, multiple numerologies related to OFDM waveforms may be used. TDD (time division duplex)-based communication systems can support both eMBB and URLLC. In this case, the low-latency performance of URLLC needs to be improved. In the downlink communication procedure, the transmission of a HARQ (hybrid automatic repeat request) response for downlink data may be required. Therefore, in the downlink communication procedure, the transmission delay time can be determined based on the repetition period of "DL (downlink) slot - UL (uplink) slot". In the uplink communication procedure, the base station can transmit a UL grant to the terminal through the DL slot. Therefore, in the uplink communication procedure, the transmission delay time can be determined based on the repetition period of "DL slot - UL slot".

[0004] In an NR communication system, the slot type can be changed dynamically. Slot types can be classified into DL slots, UL slots, and FL (flexible) slots. FL slots can be changed into DL slots or UL slots. The terminal can check the slot type on a symbol-by-symbol basis. In an LTE communication system, the subframe type can be changed. Subframe types can be classified into DL subframes, UL subframes, and special subframes.

[0005] Meanwhile, in the unlicensed band, the terminal can determine the channel occupancy status by performing a listen before talk (LBT) operation and transmit uplink feedback information to the base station using an idle channel. However, if the channel occupancy status is busy, the terminal may be unable to transmit uplink feedback information. In this case, since a transmission delay of the uplink feedback information occurs, methods to resolve this problem are required. The problem to be solved

[0006] The objective of the present invention to solve the above-mentioned problems is to provide a method and apparatus for transmitting and receiving uplink feedback information in a communication system operating in an unlicensed band. means of solving the problem

[0007] A method of operation of a terminal according to a first embodiment of the present invention for achieving the above objective comprises: receiving a DCI containing resource allocation information of a PDSCH from a base station; receiving data #n from the base station through the PDSCH indicated by the DCI; generating a HARQ codebook including a HARQ response bit #n for data #n and a HARQ response bit #n-1 for data #n-1 received from the base station prior to data #n; and transmitting the HARQ codebook to the base station, wherein the HARQ response bit #n and the HARQ response bit #n-1 are arranged in the HARQ codebook according to the order of HARQ process numbers, and n is a natural number.

[0008] Here, the HARQ codebook may further include NDI #n associated with the HARQ response bit #n and NDI #n-1 associated with the HARQ response bit #n-1.

[0009] Here, the HARQ response bit #n can be concatenated with the NDI #n, and the HARQ response bit #n-1 can be concatenated with the NDI #n-1, and the concatenated "HARQ response bit #n + NDI #n" and the concatenated "HARQ response bit #n-1 and NDI #n-1" can be placed in the HARQ codebook according to the order of the HARQ process numbers.

[0010] Here, the HARQ codebook may include "HARQ response bits associated with all HARQ processes set on the terminal" or "HARQ response bits generated by concatenating HARQ process identifiers in sequence and NDIs associated with said HARQ response bits".

[0011] Here, the DCI may include a field indicating whether to trigger the transmission of the HARQ codebook.

[0012] Here, the HARQ codebook can be transmitted via PUCCH, and information indicating the index of the RB set to which the PUCCH belongs and the interlaced index of the PUCCH in the RB set can be received from the base station.

[0013] Here, information indicating the index of the RB set and the interlaced index can be received from the base station through an RRC message.

[0014] Here, if decoding for the data #n is not completed, the value of the HARQ response bit #n included in the HARQ codebook may not be set as the HARQ response bit for the data #n.

[0015] A method of operation of a base station according to a second embodiment of the present invention for achieving the above objective comprises the steps of: transmitting a DCI containing resource allocation information of PDSCH #n to a terminal; transmitting the PDSCH #n to the terminal through resources indicated by the resource allocation information; and receiving a HARQ codebook from the terminal containing a HARQ response bit #n for the PDSCH #n and a HARQ response bit #n-1 for the PDSCH #n-1, wherein the HARQ response bit #n and the HARQ response bit #n-1 are arranged in the HARQ codebook according to the order of PDSCH #n and PDSCH #n-1, and n is a natural number.

[0016] Here, the above PDSCH #n and the above PDSCH #n-1 may belong to the same PDSCH group.

[0017] Here, the above PDSCH #n and the above PDSCH #n-1 may belong to different PDSCH groups.

[0018] Here, the DCI may further include a field indicating the number of PDSCH groups to be feedbacked, and the field set to a first value may indicate feedback of a HARQ response for one PDSCH group, and the field set to a second value may indicate feedback of a HARQ response for multiple PDSCH groups.

[0019] Here, the HARQ codebook can be received via PUCCH, and information indicating the index(s) of the RB set to which the PUCCH belongs and the interlaced index(s) of the PUCCH in the RB set can be transmitted to the terminal via upper layer signaling.

[0020] A terminal according to a third embodiment of the present invention for achieving the above objective comprises a processor, a memory that communicates electronically with the processor, and instructions stored in the memory, wherein when the instructions are executed by the processor, the instructions operate to cause the terminal to receive a DCI containing resource allocation information of a PDSCH from a base station, receive data #n from the base station via the PDSCH indicated by the DCI, generate a HARQ codebook including a HARQ response bit #n for data #n and a HARQ response bit #n-1 for data #n-1 received from the base station prior to data #n, and transmit the HARQ codebook to the base station, wherein the HARQ response bit #n and the HARQ response bit #n-1 are placed in the HARQ codebook in the order of HARQ process numbers, and n is a natural number.

[0021] Here, the HARQ codebook may further include NDI #n associated with the HARQ response bit #n and NDI #n-1 associated with the HARQ response bit #n-1.

[0022] Here, the HARQ response bit #n can be concatenated with the NDI #n, and the HARQ response bit #n-1 can be concatenated with the NDI #n-1, and the concatenated "HARQ response bit #n + NDI #n" and the concatenated "HARQ response bit #n-1 and NDI #n-1" can be placed in the HARQ codebook according to the order of the HARQ process numbers.

[0023] Here, the HARQ codebook may include "HARQ response bits associated with all HARQ processes set on the terminal" or "HARQ response bits generated by concatenating HARQ process identifiers in sequence and NDIs associated with said HARQ response bits".

[0024] Here, the DCI may include a field indicating whether to trigger the transmission of the HARQ codebook.

[0025] Here, the HARQ codebook can be transmitted via PUCCH, and information indicating the index(s) of the RB set to which the PUCCH belongs and the interlaced index(s) of the PUCCH in the RB set can be received from the base station.

[0026] Here, if decoding for the data #n is not completed, the value of the HARQ response bit #n included in the HARQ codebook may not be set as the HARQ response bit for the data #n. Effects of the invention

[0027] According to the present invention, a terminal can transmit a plurality of HARQ (hybrid automatic repeat request) responses to a base station through a single PUCCH (physical uplink control channel). Here, the plurality of HARQ responses may include a HARQ response for a PDSCH (physical downlink shared channel) scheduled by the current DCI (downlink control information) and a HARQ response for a PDSCH scheduled by the previous DCI. Accordingly, the transmission delay of uplink feedback information in a communication system operating in an unlicensed band can be reduced. The performance of the communication system can be improved. Brief explanation of the drawing

[0028] FIG. 1 is a conceptual diagram illustrating a first embodiment of a communication system. FIG. 2 is a block diagram illustrating a first embodiment of a communication node constituting a communication system. FIG. 3a is a conceptual diagram illustrating a first embodiment of a method for arranging UL control channels in a communication system. FIG. 3b is a conceptual diagram illustrating a second embodiment of a method for arranging UL control channels in a communication system. FIG. 4a is a flowchart illustrating a first embodiment of an initial connection procedure in a communication system. FIG. 4b is a flowchart illustrating a second embodiment of an initial connection procedure in a communication system. FIG. 5 is a conceptual diagram illustrating a first embodiment of RAR in a communication system. FIG. 6 is a conceptual diagram illustrating a first embodiment of a UL grant included in a RAR in a communication system. Specific details for implementing the invention

[0029] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the invention to specific embodiments, and it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0030] Terms such as "first," "second," etc., may be used to describe various components, but said components should not be limited by said terms. These terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the first component. The term "and / or" includes a combination of a plurality of related described items or any of a plurality of related described items.

[0031] When it is stated that one component is "connected" or "connected" to another component, it should be understood that while it may be directly connected or connected to that other component, there may also be other components in between. On the other hand, when it is stated that one component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between.

[0032] The terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, terms such as "comprising" or "having" are intended to specify the presence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0033] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0034] Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the attached drawings. In order to facilitate an overall understanding of the present invention, the same reference numerals are used for identical components in the drawings, and redundant descriptions of identical components are omitted.

[0035] A communication system to which embodiments according to the present invention are applied will be described. The communication system to which embodiments according to the present invention are applied is not limited to the details described below, and embodiments according to the present invention may be applied to various communication systems. Here, the term "communication system" may be used interchangeably with "communication network."

[0036] FIG. 1 is a conceptual diagram illustrating a first embodiment of a communication system.

[0037] Referring to FIG. 1, the communication system (100) may include a plurality of communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, 130-6). The plurality of communication nodes may support 4G communication (e.g., LTE (long term evolution), LTE-A (advanced)), 5G communication (e.g., NR (new radio)), etc., as defined in the 3GPP (3rd generation partnership project) standard. 4G communication may be performed in a frequency band of 6 GHz or lower, and 5G communication may be performed not only in a frequency band of 6 GHz or lower but also in a frequency band of 6 GHz or higher.

[0038] For example, for 4G communication and 5G communication, multiple communication nodes can support communication protocols based on CDMA (code division multiple access), WCDMA (wideband CDMA), TDMA (time division multiple access), FDMA (frequency division multiple access), OFDM (orthogonal frequency division multiplexing), Filtered OFDM, CP (cyclic prefix)-OFDM, DFT-s-OFDM (discrete Fourier transform-spread-OFDM), OFDMA (orthogonal frequency division multiple access), SC (single carrier)-FDMA, NOMA (Non-orthogonal Multiple Access), GFDM (generalized frequency division multiplexing), FBMC (filter bank multi-carrier) based communication protocol, UFMC (universal filtered multi-carrier) based communication protocol, SDMA (Space Division Multiple Access) based communication protocol, etc.

[0039] Additionally, the communication system (100) may further include a core network. If the communication system (100) supports 4G communication, the core network may include an S-GW (serving-gateway), a P-GW (PDN (packet data network)-gateway), an MME (mobility management entity), etc. If the communication system (100) supports 5G communication, the core network may include a UPF (user plane function), an SMF (session management function), an AMF (access and mobility management function), etc.

[0040] Meanwhile, each of the plurality of communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, 130-6) constituting the communication system (100) may have the following structure.

[0041] FIG. 2 is a block diagram illustrating a first embodiment of a communication node constituting a communication system.

[0042] Referring to FIG. 2, the communication node (200) may include at least one processor (210), a memory (220), and a transceiver (230) that is connected to a network to perform communication. Additionally, the communication node (200) may further include an input interface device (240), an output interface device (250), a storage device (260), etc. Each component included in the communication node (200) may be connected by a bus (270) to communicate with one another.

[0043] However, each component included in the communication node (200) may be connected via individual interfaces or individual buses centered around the processor (210), rather than via a common bus (270). For example, the processor (210) may be connected via a dedicated interface to at least one of a memory (220), a transmission / reception device (230), an input interface device (240), an output interface device (250), and a storage device (260).

[0044] The processor (210) can execute a program command stored in at least one of the memory (220) and the storage device (260). The processor (210) may mean a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which methods according to embodiments of the present invention are performed. Each of the memory (220) and the storage device (260) may be composed of at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory (220) may be composed of at least one of read-only memory (ROM) and random access memory (RAM).

[0045] Referring again to FIG. 1, the communication system (100) may include a plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) and a plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6). The communication system (100) including the base stations (110-1, 110-2, 110-3, 120-1, 120-2) and terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) may be referred to as an "access network". Each of the first base station (110-1), the second base station (110-2), and the third base station (110-3) can form a macro cell. Each of the fourth base station (120-1) and the fifth base station (120-2) can form a small cell. The fourth base station (120-1), the third terminal (130-3), and the fourth terminal (130-4) may be located within the cell coverage of the first base station (110-1). The second terminal (130-2), the fourth terminal (130-4), and the fifth terminal (130-5) may be located within the cell coverage of the second base station (110-2). The fifth base station (120-2), the fourth terminal (130-4), the fifth terminal (130-5), and the sixth terminal (130-6) may be located within the cell coverage of the third base station (110-3). The first terminal (130-1) may be located within the cell coverage of the fourth base station (120-1). The sixth terminal (130-6) may be located within the cell coverage of the fifth base station (120-2).

[0046] Here, each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) may be referred to as Node B, evolved Node B, gNB, base transceiver station (BTS), radio base station, radio transceiver, access point, access node, etc. Each of the plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) may be referred to as User Equipment (UE), terminal, access terminal, mobile terminal, station, subscriber station, mobile station, portable subscriber station, node, device, etc.

[0047] Meanwhile, each of the multiple base stations (110-1, 110-2, 110-3, 120-1, 120-2) may operate in different frequency bands or in the same frequency band. Each of the multiple base stations (110-1, 110-2, 110-3, 120-1, 120-2) may be connected to each other via an ideal backhaul link or a non-ideal backhaul link, and may exchange information with each other via an ideal backhaul link or a non-ideal backhaul link. Each of the multiple base stations (110-1, 110-2, 110-3, 120-1, 120-2) may be connected to a core network via an ideal backhaul link or a non-ideal backhaul link. Each of the multiple base stations (110-1, 110-2, 110-3, 120-1, 120-2) can transmit a signal received from the core network to the corresponding terminal (130-1, 130-2, 130-3, 130-4, 130-5, 130-6), and can transmit a signal received from the corresponding terminal (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) to the core network.

[0048] In addition, each of the multiple base stations (110-1, 110-2, 110-3, 120-1, 120-2) can support MIMO transmission (e.g., SU (single user)-MIMO, MU (multi user)-MIMO, massive MIMO, etc.), CoMP (coordinated multipoint) transmission, CA (carrier aggregation) transmission, transmission in an unlicensed band, device-to-device communication (D2D) (or ProSe (proximity services)), etc. Here, each of the plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) can perform an operation corresponding to the base station (110-1, 110-2, 110-3, 120-1, 120-2) and an operation supported by the base station (110-1, 110-2, 110-3, 120-1, 120-2). For example, the second base station (110-2) can transmit a signal to the fourth terminal (130-4) based on the SU-MIMO method, and the fourth terminal (130-4) can receive a signal from the second base station (110-2) based on the SU-MIMO method. Alternatively, the second base station (110-2) can transmit a signal to the fourth terminal (130-4) and the fifth terminal (130-5) based on the MU-MIMO method, and each of the fourth terminal (130-4) and the fifth terminal (130-5) can receive a signal from the second base station (110-2) by the MU-MIMO method.

[0049] Each of the first base station (110-1), the second base station (110-2), and the third base station (110-3) can transmit a signal to the fourth terminal (130-4) based on the CoMP method, and the fourth terminal (130-4) can receive a signal from the first base station (110-1), the second base station (110-2), and the third base station (110-3) by the CoMP method. Each of the multiple base stations (110-1, 110-2, 110-3, 120-1, 120-2) can transmit and receive signals based on the CA method with terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) within its cell coverage area. Each of the first base station (110-1), the second base station (110-2), and the third base station (110-3) can control D2D between the fourth terminal (130-4) and the fifth terminal (130-5), and each of the fourth terminal (130-4) and the fifth terminal (130-5) can perform D2D by controlling each of the second base station (110-2) and the third base station (110-3).

[0050] Next, methods for transmitting and receiving uplink feedback information in a communication system will be described. Even when a method performed by a first communication node among the communication nodes (e.g., transmission or reception of a signal) is described, the corresponding second communication node may perform a method corresponding to the method performed by the first communication node (e.g., reception or transmission of a signal). That is, when the operation of a terminal is described, the corresponding base station may perform an operation corresponding to the operation of the terminal. Conversely, when the operation of a base station is described, the corresponding terminal may perform an operation corresponding to the operation of the base station.

[0051] A terminal may receive a physical downlink shared channel (PDSCH) from a base station and transmit a hybrid automatic repeat request (HARQ) response (e.g., acknowledgment (ACK) or negative ACK (NACK)) for the PDSCH to the base station. The HARQ response may be a "HARQ-ACK" or "HARQ-ACK bit" as defined in the technical specification. Alternatively, the HARQ response may refer to a HARQ codebook generated based on the HARQ-ACK bit. If the HARQ response received from the terminal is a NACK, the base station may retransmit the same transport block (TB). If the HARQ response received from the terminal is an ACK, the base station may perform operations for transmitting another TB.

[0052] The radio resources used for transmitting HARQ responses may be configured by the base station. For example, the base station may transmit resource configuration information for uplink feedback to the terminal, and the terminal may transmit a HARQ response to the base station using the radio resources indicated by the resource configuration information. The method of configuring resources for uplink feedback may vary depending on the operating state of the terminal. The first operating state of the terminal may be "when a terminal that has not established a radio resource control (RRC) connection with the base station performs an initial connection procedure (e.g., cell search procedure, random access procedure)" or "when the terminal transmits a HARQ response to PDSCH during an RRC connection reconfiguration procedure." The second operating state of the terminal may be "when a terminal operating in an RRC connected state transmits a HARQ response to PDSCH."

[0053] In the first operating state of the terminal, because an RRC connection between the terminal and the base station is not established (for example, because a specific RRC connection between the terminal and the base station cannot be assumed), the base station may transmit resource configuration information for uplink feedback to unspecified terminals using upper layer signaling. Additionally, the base station may inform the terminal using physical layer signaling of the radio resource(s) of the UL control channel that the terminal will use among the radio resources configured by the upper layer signaling.

[0054] In the second operating state of the terminal, the base station may inform the terminal of the radio resources of the UL control channel available to the terminal in the RRC connection establishment procedure using upper layer signaling. Additionally, the base station may inform the terminal of the radio resource(s) of the UL control channel to be used by the terminal among the radio resources established by the upper layer signaling using physical layer signaling.

[0055] Here, upper-layer signaling may refer to the procedure for transmitting and receiving RRC messages, MAC (medium access control) layer signaling may refer to the procedure for transmitting and receiving MAC CE (control element), and physical layer signaling may refer to the procedure for transmitting and receiving PDCCH (physical downlink control channel) (e.g., DCI (downlink control information)). In the embodiments below, a channel (e.g., PDCCH, PDSCH, PUCCH, PUSCH, etc.) may refer to a "signal containing data and / or control information" or a "radio resource through which data and / or control information is transmitted." Additionally, the signal may be a concept that includes a channel and a reference signal.

[0056] In order to comply with frequency regulations (e.g., spectrum regulations) in a communication system operating in an unlicensed band, a UL control channel may occupy many frequency resources. Within a bandwidth, a single UL control channel may occupy physical resource blocks (PRBs) that are spaced at regular intervals in the frequency domain. In the embodiments, the unlicensed band may refer to a shared band.

[0057] FIG. 3a is a conceptual diagram illustrating a first embodiment of a method for arranging UL control channels in a communication system, and FIG. 3b is a conceptual diagram illustrating a second embodiment of a method for arranging UL control channels in a communication system.

[0058] Referring to FIGS. 3a and 3b, the bandwidth of the communication system may be 20 MHz, and the subcarrier spacing may be 30 kHz. In this case, the frequency band may consist of 51 PRBs. UL control channels may be arranged every 5 PRBs. The arrangement structure of the UL control channels may be an interlace structure. In the embodiment illustrated in FIG. 3a, one UL control channel may occupy one PRB in the frequency domain and two symbols in the time domain. In the embodiment illustrated in FIG. 3b, one UL control channel may occupy one PRB in the frequency domain and four symbols in the time domain.

[0059] The UL control channel may include a demodulation-reference signal (DM-RS) resource. The DM-RS resource may be a time division multiplexing (TDM) or frequency division multiplexing (FDM) resource with an uplink control information (UCI) resource. Five interlaces may be defined across the entire band of the communication system. Each interlace may have 10 PRBs or 11 PRBs. "If the bandwidth of the communication system is 20 MHz and the subcarrier spacing is a value other than 30 kHz (e.g., 15 kHz, 60 kHz, 120 kHz, 240 kHz, etc.)," ​​the number of PRBs constituting each interlace may differ from the number of PRBs in the above-described embodiment.

[0060] Meanwhile, the base station may transmit search signals and system information. The search signal may be an "SS / PBCH block composed of a PSS (primary synchronization signal), SSS (secondary synchronization signal), and PBCH (physical broadcast channel)" or a "DRS (discovery reference signal) block composed of an SS / PBCH block and a reference signal (e.g., CSI-RS (channel state information-reference signal), etc."). If the communication system operates in a licensed band, the base station may transmit the search signal periodically. Conversely, if the communication system operates in an unlicensed band, the base station may transmit the search signal non-periodically. The base station may transmit system information via PDSCH and information for decoding system information via PDCCH. The terminal may recognize the presence of the base station by receiving the search signal, derive the resource location of the PDSCH based on information obtained from the PDCCH (e.g., information elements included in the DCI), and decode the system information contained in the PDSCH. System information may include resource allocation information for a PRACH (physical random access channel). The terminal can establish an RRC connection with the base station by performing an initial connection procedure using the PRACH indicated by the resource allocation information included in the system information.

[0061] FIG. 4a is a flowchart illustrating a first embodiment of an initial connection procedure in a communication system, and FIG. 4b is a flowchart illustrating a second embodiment of an initial connection procedure in a communication system.

[0062] Referring to FIGS. 4a and 4b, a base station can transmit a search signal (e.g., SS / PBCH block, DRS block) and system information to a terminal (S401). The terminal can receive the search signal and system information from the base station and can check the resource allocation information of the PRACH included in the system information. The terminal can transmit a random access (RA) preamble (e.g., MSG1) to the base station through the PRACH indicated by the resource allocation information (S402).

[0063] A base station may receive RA preamble(s) from unspecified terminal(s) and may transmit a random access response (RAR) message (e.g., MSG2) via PDSCH in response to the RA preamble (S403). The RAR may include an index of the RA preamble detected by the base station. Additionally, DCI and / or uplink resource allocation information (e.g., UL grant) containing scheduling information (e.g., DL grant) of the PDSCH to which the RAR is transmitted in step S403 may be transmitted from the base station to the terminal. Here, the UL grant may be included in the RAR. In the embodiments, the DCI containing the DL grant may be referred to as "DL-DCI", and the DCI containing the UL grant may be referred to as "UL-DCI".

[0064] The terminal can receive a RAR from the base station and compare the index of the RA preamble included in the RAR with the index of the RA preamble transmitted by the terminal in step S402. If the index of the RA preamble included in the RAR is different from the index of the RA preamble transmitted by the terminal in step S402, the terminal can perform step S402 again. If the index of the RA preamble included in the RAR is the same as the index of the RA preamble transmitted by the terminal in step S402, the terminal can transmit an MSG3 via a PUSCH directed by the UL grant received in step S403 (S404). The MSG3 may be an RRC connection request message. The terminal can perform an encoding operation on the RRC connection request message and map the encoded RRC connection request message to a PUSCH.

[0065] The base station may receive MSG3 (e.g., an RRC connection request message) from the terminal. The base station may transmit MSG4 to the terminal via PDSCH (S405-1, S405-2). MSG4 may be an RRC connection setup message, and the RRC connection setup message may include a terminal identifier (e.g., a C-RNTI (cell-radio network temporary identifier)). In step S405-1 shown in FIG. 4a, a DCI containing scheduling information of the PDSCH to which MSG4 is transmitted may be transmitted from the base station to the terminal. In step S405-2 shown in FIG. 4b, a DCI containing scheduling information of the PDSCH to which MSG4 is transmitted and an UL grant may be transmitted from the base station to the terminal. The terminal may receive MSG4 from the base station and check whether a contention (e.g., a collision) has been resolved based on the terminal identifier included in MSG4.

[0066] In step S406-1 illustrated in FIG. 4a, the terminal may transmit an ACK for MSG4 to the base station via PUSCH if MSG4 was successfully received in step S405-1. The HARQ response (e.g., ACK) may be MSG5. The PUSCH to which the ACK is transmitted may be indicated by the UL grant received in step S405-1. On the other hand, if MSG4 was not successfully received in step S405-1 (e.g., if a NACK for MSG4 occurred), the terminal may not perform the subsequent procedures. In this case, the terminal may not transmit a NACK for MSG4 to the base station via PUSCH. Alternatively, in step S406-1, the terminal may transmit a NACK for MSG4 to the base station via PUSCH.

[0067] If an ACK for MSG4 is received from the terminal, the base station may determine that MSG4 has been successfully received by the terminal. If a HARQ response for MSG4 is not received from the terminal within a preset time interval, or if a NACK for MSG4 is received, the base station may determine that MSG4 has not been received by the terminal. That is, the base station may determine that a collision of MSG4 has occurred. If MSG4 is not received, the terminal may expect to receive MSG4 again from the base station. If a collision is detected during the verification procedure of the terminal identifier (e.g., C-RNTI, TC-RNTI (temporary C-RNTI)), the terminal may perform the initial connection procedure again.

[0068] If no terminal has transmitted MSG5 in step S406-1, the base station may not be able to distinguish whether "the decoding operation of MSG4 at the terminal failed" or "the MSG5s of the terminals collided." In this case, the base station may retransmit MSG4 within a specific time window to establish an RRC connection with the terminal. Alternatively, the base station may not perform the MSG4 retransmission procedure. If MSG4 is not retransmitted, the time window may be unnecessary.

[0069] Meanwhile, in step S406-2 illustrated in FIG. 4b, the terminal may transmit a HARQ response (e.g., ACK or NACK) for MSG4 to the terminal via PUCCH. The PUCCH to which the HARQ response for MSG4 is transmitted may be set to the terminal during the initial connection procedure. The base station may receive the HARQ response from the terminal and, based on the HARQ response, verify whether MSG4 has been successfully received by the terminal. The base station may transmit a DCI containing a UL grant (e.g., UL-DCI) to the terminal (S407). The terminal may receive the DCI from the base station and transmit MSG5 to the base station using a PUCCH indicated by the UL grant included in the DCI (S408). The base station may receive MSG5 from the terminal.

[0070] Energy detection boundary value

[0071] The energy detection threshold value used for LBT (listen before talk) operation may be indicated by "information included in a UL grant belonging to the RAR" or "information other than a UL grant." A terminal performing LBE operation may compare the energy detection result in a sensing slot(s) belonging to a defer duration with the energy detection threshold value. If the energy detection result is smaller than the energy detection threshold value, the terminal may determine that the corresponding sensing slot(s) are in an idle state. If the energy detection result is greater than or equal to the energy detection threshold value, the terminal may determine that the corresponding sensing slot(s) are in a busy state. Here, the length of the sensing slot may be 9 μs.

[0072] A sensing slot can be distinguished from a slot used for the transmission of data and / or control information. An energy detection threshold offset may be used instead of an energy detection threshold value. The energy detection threshold value may be "maxEnergyDetectionThreshold" defined in the technical specification, and the energy detection threshold offset may be "energyDetectionThresholdOffset" defined in the technical specification. The terminal may derive an energy detection threshold value in dB units based on the contents specified in section 4.2.3 of 3GPP TS (technical specification) 37.213.

[0073] Unlicensed In a communication system operating in a band RMSI (remaining minimum system information)

[0074] The terminal can synchronize with the base station by receiving a search signal (e.g., SS / PBCH block or DRS block) from the base station, and can obtain configuration information for CORESET 0 (or Type0-PDCCH common search space) from the PBCH of the search signal. The terminal can perform a PDCCH monitoring operation in search space 0 within CORESET 0, and can obtain SIB (system information block) 1 (e.g., RMSI) from PDSCH-1_0 indicated by the DCI obtained by the PDCCH monitoring operation. The terminal can obtain configuration information for an initial connection procedure from SIB 1. The RMSI (e.g., SIB 1) may include one or more of the following information elements (PRACH configuration information, energy detection threshold value, PUCCH configuration information, common radio identifier).

[0075] PRACH Configuration Information

[0076] The RMSI may include PRACH configuration information. The PRACH configuration information may include time resource information and frequency resource information of the PRACH in which the RA preamble is transmitted. Additionally, information indicating the subcarrier spacing used for the transmission of the RA preamble may be included in the RMSI.

[0077] Energy detection boundary value

[0078] RMSI may include an energy detection threshold value. The terminal may perform an LBT operation to transmit an RA preamble. In this case, the terminal may transmit an RA preamble when all sensing slots within the dipper interval are determined to be in an idle state. The terminal may detect the energy of the received signal in each sensing slot (or a portion of each sensing slot) within the dipper interval, and may determine that the corresponding sensing slot is in an idle state if the energy detection result is less than the energy detection threshold value. Conversely, if the energy detection result is greater than or equal to the energy detection threshold value, the terminal may determine that the corresponding sensing slot is in a busy state. The energy detection threshold value may be used to determine whether a channel is available for connection.

[0079] An energy detection threshold offset may be used instead of an energy detection threshold value. The energy detection threshold value may be "maxEnergyDetectionThreshold" defined in the technical specification, and the energy detection threshold offset may be "energyDetectionThresholdOffset" defined in the technical specification. The terminal may derive the energy detection threshold value in dB units based on the provisions of Section 4.2.3 of 3GPP TS 37.213.

[0080] PUCCH Configuration Information

[0081] The RMSI may include PUCCH configuration information. The PUCCH configuration information may include time resource information and frequency resource information of the PUCCH to which the HARQ response is transmitted during the initial connection procedure. The PUCCH configuration information may be included in the UL grant.

[0082] Common radio identifier (e.g., RNTI )

[0083] The RMSI may include a radio identifier (e.g., a common radio identifier). The terminal(s) may transmit a PUSCH according to a trigger method. When a terminal transmits a PUSCH according to a trigger method within a time interval secured by the base station (e.g., channel occupancy time (COT)), the LBT operation may be simplified, and it may be ensured that the PUSCHs transmitted from multiple terminals are orthogonal at the base station.

[0084] The PUSCH initially transmitted by the terminal during the initial connection procedure may be MSG3, and MSG3 may be a HARQ response to the RAR. The common RNTI may be included in the RAR instead of the RMSI. Information obtained through the RMSI may be used in the initial connection procedure or the RRC connection reset procedure. In the RRC connection reset procedure, the base station may not know how the corresponding RRC message has been reflected by the terminal until a HARQ response (e.g., ACK) to the RRC message is received from the terminal. Therefore, it may be desirable to use information that can be obtained when the terminal is in an RRC idle state. It may be desirable for the common RNTI to be included in the RMSI. On the other hand, if information excluding the common RNTI is exchanged via RRC messages during the RRC connection reset procedure, the common RNTI may not be included in the RMSI.

[0085] Unlicensed In a communication system operating in a band RAR

[0086] If the base station operates in a licensed band, the RAR can be set in byte units. For example, the size of the RAR can be n × bytes. n can be a natural number.

[0087] FIG. 5 is a conceptual diagram illustrating a first embodiment of RAR in a communication system, and FIG. 6 is a conceptual diagram illustrating a first embodiment of a UL grant included in RAR in a communication system.

[0088] Referring to FIG. 5, a RAR (e.g., MAC RAR) may include a TA (timing advance) command, a UL grant, and temporary identifier information (e.g., temporary C-RNTI). The MAC layer of the terminal may generate a RAR, the RAR may be encoded, and the encoded RAR may be mapped to PUSCH.

[0089] Referring to FIG. 6, the UL grant included in the RAR may include a frequency hopping flag, PUSCH frequency resource allocation information, PUSCH time resource allocation information, MCS (modulation and coding scheme) information, TPC (transmission power control) commands for PUSCH, and CSI request information. On the other hand, in a communication system operating in an unlicensed band, the UL grant included in the RAR may include one or more information elements shown in FIG. 6 and additional information element(s). New field(s) may be introduced into the UL grant for the additional information element(s). Existing fields included in the UL grant may be unnecessary.

[0090] RAR Included UL Grant

[0091] A UL grant may include one or more of the following information elements. Since a UL grant is included in a MAC message, the entire fields constituting the UL grant can be set in byte units. To support this operation, specific bit(s) may be set as reserve fields. Alternatively, specific bit(s) may be set to predefined values ​​(e.g., 0 or 1). The terminal can generate a codeword by performing an encoding operation on the UL grant and map the codeword to PUSCH.

[0092] trigger Field

[0093] A UL grant belonging to a RAR may include trigger fields. The number of trigger fields included in a UL grant may vary depending on the triggering method of the PUSCH. One trigger field (e.g., Trigger A field) or two trigger fields (e.g., Trigger A field and Trigger B field) may be required for triggering a PUSCH transmission. The Trigger A field and the Trigger B field may be included in different UL grants (or different PDCCHs).

[0094] The Trigger A field included in the UL Grant may indicate two different values. The terminal may determine whether to perform the monitoring operation of the Trigger B field based on the value indicated by the Trigger A field. The Trigger A field set to a first value (e.g., 0) may indicate a non-triggered mode. In this case, the terminal may transmit a PUSCH based on the UL Grant. For example, the terminal may identify the slot where the LBT operation for PUSCH transmission begins based on the slot offset field included in the UL Grant. The Trigger A field set to a second value (e.g., 1) may indicate a triggered mode. In this case, the terminal may receive a separate PDCCH that triggers the transmission of the PUSCH. The separate PDCCH may include a Trigger B field. The terminal may identify the slot where the LBT operation for PUSCH transmission begins based on the information element(s) (e.g., the Trigger B field) included in the separate PDCCH.

[0095] commonness RNTI

[0096] A RAR (e.g., a UL grant belonging to the RAR) may include a radio identifier (e.g., a common RNTI). Terminal(s) may transmit a PUSCH based on a trigger method. If a terminal transmits a PUSCH according to a trigger method within a time interval (e.g., COT) secured by a base station, the LBT operation may be simplified, and it may be ensured that PUSCHs transmitted from multiple terminals are orthogonal at the base station.

[0097] The terminal may generate a PUSCH using a UL grant belonging to a RAR to transmit MSG3. The method of indicating the transmission time of the PUSCH may depend on the value of the trigger field included in the UL grant. For example, a UL grant (e.g., a UL grant belonging to a RAR) may include information indicating the transmission time of the PUSCH. Alternatively, a separate UL grant scrambled by a common RNTI may include information indicating the transmission time of the PUSCH.

[0098] A UL grant (e.g., a common DCI) addressed by a common RNTI can be transmitted to unspecified terminal(s) and may not contain PUSCH resource allocation information. The common DCI can perform the role of indicating a slot where PUSCH can be transmitted (e.g., a trigger role).

[0099] Slot offset field

[0100] A UL grant belonging to a RAR may include a slot offset field. A terminal may identify the slot in which an LBT operation for PUSCH transmission begins based on the time offset indicated by the slot offset field. The time offset(s) may be defined in the technical specifications. A base station may transmit to the terminal a UL grant that includes a slot offset field indicating the index of one of the time offset(s) defined in the technical specifications.

[0101] "If the RAR does not include a trigger field," "if the trigger field is not set in the terminal by upper-layer signaling," or "if the trigger A field is set to a first value," the terminal can determine the slot in which the LBT operation for PUSCH transmission begins by applying a time offset from the slot in which the RAR is received. If the trigger A field is set to a second value, the terminal can determine the slot in which the LBT operation for PUSCH transmission begins by applying a time offset from the slot in which the trigger B field is received. The trigger B field may be included in the common DCI.

[0102] start symbol and length fields

[0103] A UL grant belonging to a RAR may include a "start symbol and length field." The "start symbol and length field" may represent the "start symbol of PUSCH" or the "start and end symbols of PUSCH" as a single index. The terminal can determine the number of PUSCH start symbols and symbols belonging to PUSCH based on the index indicated by the "start symbol and length field." PUSCH may be configured based on a Type A mapping method or a Type B mapping method.

[0104] Starting point field

[0105] A UL grant belonging to a RAR may include a start time field, and the start time field may indicate the start time of the PUSCH. The transmission of the PUSCH may begin at the boundary of the symbol. Alternatively, considering the time and / or TA required for the LBT operation, the PUSCH transmission may begin at a time other than the boundary of the symbol. The PUSCH transmission may begin at "symbol j," "symbol j+1," or "a time point between symbol j and symbol j+1." Alternatively, the PUSCH transmission may begin at "a time point after a preset time (e.g., 25 μs or 16 μs) from the start time of symbol j" or "a time point after [a preset time (e.g., 25 μs or 16 μs) + TA] from the start time of symbol j." In this case, the transmission of the PUSCH may be performed by extending the CP (cyclic prefix) of symbol j+1. According to this operation, the phase of the waveform of the symbol can be expressed continuously, and the PAPR (peak to average power ratio) of symbol j+1 can be reduced. The slot and start symbol in which the PUSCH is transmitted can be indicated by a RAR (e.g., a UL grant belonging to the RAR). Additionally, the transmission time of the PUSCH within the start symbol can be indicated by a RAR (e.g., a UL grant belonging to the RAR).

[0106] Frequency resource field

[0107] A UL grant belonging to a RAR may include a frequency resource field, and the frequency resource field may indicate the frequency resources of a PUSCH. The frequency resources of a PUSCH may be indicated by one or more interlaced indices. The terminal may identify the PRB(s) where the PUSCH is transmitted based on the interlaced index indicated by the frequency resource field. Only a small number of bits may be required to represent all interlacs. Therefore, the frequency resource field included in a UL grant may consist of only a small number of bits.

[0108] The transmission operation of a PUSCH (e.g., a PUSCH containing MSG3) in response to a RAR may be performed in a single LBT subband. An LBT subband may refer to a set of RBs (resource blocks). A base station may transmit information to a terminal indicating that the transmission operation of the PUSCH is performed on a licensed carrier (e.g., a SUL (supplementary uplink) carrier) or an unlicensed carrier. Here, a licensed carrier may refer to a carrier located in a licensed band, and an unlicensed carrier may refer to a carrier located in an unlicensed band. The carrier to which the RA preamble is transmitted may be the same as the carrier to which the PUSCH containing MSG3 is transmitted. Alternatively, the carrier to which the RA preamble is transmitted may be different from the carrier to which the PUSCH containing MSG3 is transmitted.

[0109] When the terminal transmits the RA preamble and MSG3 (e.g., PUSCH containing MSG3) from a licensed carrier, a conventional initial connection procedure may be performed. "When the RA preamble is transmitted from an unlicensed carrier and the MSG3 (e.g., PUSCH containing MSG3) is transmitted from a licensed carrier," the UL grant belonging to the RAR may include a field indicating the licensed carrier (e.g., license band) to which the MSG3 is transmitted. For example, the UL grant may include a carrier field indicating a carrier index. The carrier indicated by the carrier field included in the UL grant may be the carrier used for the transmission of the MSG3 (e.g., a licensed carrier or an unlicensed carrier).

[0110] In the proposed method, a RAR can be mapped to a single interlace. Thus, a UL grant belonging to a RAR may include a single interlace index. A UL grant scheduling a PUSCH may include one or more interlace indices. In this case, the UL grant may include a bitmap or a "code point indicating a combination of one or more interlace indices." Each bit included in the bitmap may correspond to one interlace index. When code points are used, the size of the frequency resource field included in the UL grant may be reduced.

[0111] In another proposed method, the RAR may be mapped to a preset number or fewer of interlace(s). A UL grant belonging to the RAR may include a bitmap or code point indicating one or more interlace indices. The maximum number of interlaces to which the MSG3 (e.g., PUSCH containing MSG3) is mapped may be limited. The maximum number of interlaces for the MSG3 may be defined in the technical specification. Alternatively, the base station may transmit information indicating the maximum number of interlaces for the MSG3 to the terminal using upper-layer signaling.

[0112] Channel connection information field

[0113] A UL grant belonging to a RAR may include a channel connection information field. The channel connection field may indicate the type of LBT operation performed for the transmission of PUSCH. For example, a channel connection information field set to a first value may indicate a first type of LBT operation. A channel connection information field set to a second value may indicate a second type of LBT operation.

[0114] When the first type of LBT operation is used, the terminal may randomly select a backoff value within a contention window and perform a backoff operation based on the selected backoff value. The backoff value may be determined by a contention window, a random variable, and / or separate parameter(s). The separate parameter(s) may include the priority of PUSCH. The size of the contention window may be determined according to the priority of PUSCH. Additionally, the separate parameter(s) may include configuration information of the MCOT (maximum COT) and / or the length of the dipper interval (T d It may include more ).

[0115] When a PUSCH is transmitted based on a UL grant belonging to a RAR, the priority of the PUSCH may have a single value. The priority of the PUSCH may be defined in the technical specifications. In this case, the base station may not signal information indicating the priority of the PUSCH to the terminal. The terminal may perform a channel sensing operation (e.g., energy detection operation) in a time interval (e.g., a dipper interval) corresponding to a selected backoff value, and may transmit an MSG3 (e.g., a PUSCH containing MSG3) if the energy detection result in all sensing slots belonging to the dipper interval is smaller than the energy detection threshold value.

[0116] When the second type of LBT operation is used, the terminal can perform a channel sensing operation (e.g., an energy detection operation) in all sensing slots within the dipper interval without a random backoff operation. If the energy detection result in all sensing slots within the dipper interval is smaller than the energy detection threshold value, the terminal can transmit MSG3 (e.g., a PUSCH containing MSG3). Here, the length of the dipper interval may be several tens of μs (e.g., 25 μs or 16 μs).

[0117] According to another method, the channel connection information field may indicate three or more values. For example, the channel connection information field may indicate at least a first value, a second value, a third value, or a fourth value. A channel connection information field set to the first value may indicate a first type of LBT operation. A channel connection information field set to the second value may indicate a second type of LBT operation. A channel connection information field set to the third value may indicate a third type of LBT operation. A channel connection information field set to the fourth value may indicate a fourth type of LBT operation.

[0118] When the first type of LBT operation is used, the terminal may transmit a signal after performing a random backoff operation. The channel access method according to the second type of LBT operation may be the same as the channel access method according to the third type of LBT operation, and the parameter(s) used for channel access according to the second type of LBT operation may be different from the parameter(s) used for channel access according to the third type of LBT operation. When the second or third type of LBT operation is used, the terminal may perform a channel sensing operation in a preset dipper interval without a random backoff operation. However, the length of the dipper interval according to the second type of LBT operation (e.g., 25 μs) may be different from the length of the dipper interval according to the third type of LBT operation (e.g., 16 μs). When the fourth type of LBT operation is used, the terminal may transmit a signal without performing a channel sensing operation.

[0119] sequence Field

[0120] A UL grant belonging to a RAR may include a sequence field. The sequence field included in the UL grant may include a scrambling sequence of a PUSCH and / or an initialization sequence of a PUSCH DM-RS. The PUSCH DM-RS may be a DM-RS used for demodulation of a PUSCH. If the above-described sequence is generated based on cell identification information (e.g., a physical cell identifier (PCI)) and / or time information (e.g., a slot index or a symbol index), the base station may not signal to the terminal information indicating the sequence (e.g., information indicated by the sequence field).

[0121] Unlicensed In the band MSG4 Korea HARQ Response method

[0122] In the embodiments illustrated in FIGS. 4a and 4b, the base station may transmit a DL-DCI containing scheduling information for MSG4 to the terminal, and may transmit MSG4 to the terminal via a PDSCH indicated by the scheduling information included in the DL-DCI. The terminal may receive the DL-DCI from the base station and may receive MSG4 from the base station via a PDSCH indicated by the scheduling information included in the DL-DCI. The terminal may generate a HARQ response for MSG4 and transmit the HARQ response to the base station via a PUCCH or PUSCH.

[0123] To transmit a PUCCH containing MSG4, the base station may provide the terminal with the PUCCH's time resource information, the PUCCH's frequency resource information, and sequence information. The PUCCH's time resource information, the PUCCH's frequency resource information, and sequence information may be included in a DL-DCI (e.g., a DL-DCI containing MSG4 scheduling information). Some of the PUCCH's configuration information may be indicated by the DL-DCI, and the remaining PUCCH's configuration information may be indicated to the terminal before the transmission of the PUCCH. Various methods may be applied depending on the DL transmission.

[0124] PUCCH's including resource allocation information MSG4

[0125] In the proposed method, a base station may transmit an MSG4 containing resource allocation information for a PUCCH to a terminal. The terminal may receive the MSG4 from the base station and verify the resource allocation information for a PUCCH included in the MSG4. If the terminal successfully receives the MSG4, it may determine that no collision has occurred. Therefore, the resource allocation information for a PUCCH may be indicated by the MSG4 or by a DL transmission prior to the MSG4.

[0126] Meanwhile, if MSG4 is not received from the base station, it may be desirable for the terminal to send a NACK for MSG4 to the base station. Since the reason for the NACK for MSG4 is channel fading, it may be desirable for the base station to retransmit MSG4 to the terminal. If the base station does not retransmit MSG4 to the terminal, the terminal may have to perform the initial connection procedure again because it cannot determine whether the reason for the MSG4 reception failure is a collision or channel fading.

[0127] In an unlicensed band, MSG4 may include information indicating resource allocation information for PUCCH (e.g., slot offset) and / or the type of LBT operation (e.g., LBT Category 2 or LBT Category 4). Additionally, MSG4 may include information indicating the transmission method of PUCCH (e.g., triggered method or non-triggered method).

[0128] "If MSG4 contains resource allocation information for PUCCH and reception of MSG4 fails," the terminal may not be able to transmit a NACK for MSG4 to the base station via PUCCH because it does not know the resource allocation information for PUCCH. To solve this problem, the base station may inform the terminal of the resource allocation information for PUCCH through a DL-DCI that schedules MSG4 or a DL transmission prior to DL-DCI.

[0129] PUCCH's including resource allocation information MSG2 and / or other DL channels

[0130] A base station may transmit a RAR (e.g., MSG2) containing some configuration information among the configuration information of a PUCCH (e.g., resource allocation information), and may transmit a DL channel containing the remaining configuration information of a PUCCH (e.g., a DL-DCI scheduling MSG4, MSG4, or a "combination of DL-DCI and MSG4"). A terminal may check the configuration information of a PUCCH (e.g., resource allocation information) based on the RAR and DL channel received from the base station. If the remaining configuration information of a PUCCH is included in the DL-DCI, the resource allocation information of a PUCCH (i.e., the remaining configuration information) may be explicitly included in the DL-DCI. Alternatively, the resource allocation information of a PUCCH may be indicated based on a function of the CCE (control channel element) index to which the DL-DCI is mapped. Alternatively, the resource allocation information of a PUCCH may be indicated based on a combination of a field included in the DL-DCI and the CCE index to which the DL-DCI is mapped.

[0131] Since MSG2 is transmitted before the transmission of MSG4, it may contain resource allocation information of PUCCH (e.g., PUCCH to which the HARQ response for MSG4 is transmitted). For example, MSG2 may contain resource allocation information of PUCCH to which the HARQ response for MSG4 is transmitted, as well as UL grants for MSG3.

[0132] Since RAR is transmitted to unspecified terminal(s), the resource allocation information of the PUCCH included in the RAR can be used by multiple terminals. That is, the RAR may include common resource allocation information, and the common resource allocation information may indicate the PUCCH to which the HARQ response for MSG4 is transmitted. Therefore, terminals can transmit HARQ responses for MSG4 through the same PUCCH. If a collision (e.g., contention) between terminals is not resolved, the base station may receive an ACK for the MSG4 of the first terminal and a NACK for the MSG4 of the second terminal through the PUCCH. In this case, the base station may determine that a collision exists between terminals. That is, the base station may determine that the contention has not been resolved. If only an ACK for MSG4 is received through the PUCCH, the base station may determine that the collision between terminals has been resolved.

[0133] Some configuration information of the PUCCH included in the RAR may not include time resource information of the PUCCH to which the HARQ response to MSG4 is transmitted. For example, the RAR may include sequence information of the PUCCH, frequency allocation information of the PUCCH (e.g., interlaced index), sequence information of the PUCCH DM-RS, etc. The remaining configuration information of the PUCCH not included in the RAR may include time resource information of the PUCCH (e.g., slot offset) and / or information indicating the LBT type (e.g., LBT Category 2 or LBT Category 4). Additionally, the configuration information of the PUCCH may include information indicating the transmission method of the PUCCH (e.g., triggered method or non-triggered method).

[0134] RAR and DL- DCI

[0135] RAR may include resource set information of a PUCCH. A base station may transmit a RAR containing resource set information of a PUCCH used in the initial access procedure to unspecified terminal(s). The resource set information of a PUCCH included in the RAR may include information indicating the first symbol of the PUCCH, the number of symbols constituting the PUCCH in the time domain, and / or interlaced index(s) of the PUCCH. The remaining configuration information of the PUCCH not included in the RAR may be transmitted via a DL channel.

[0136] The terminal can receive an SS / PBCH block from the base station and obtain cell identification information from the SS / PBCH block. The terminal can use the cell identification information to initialize the sequence of PUCCH DM-RS. The terminal can use the cell identification information to perform scrambling operations on data and / or control information transmitted over the uplink channel (e.g., PUCCH).

[0137] The DL-DCI scheduling MSG4 may include a PUCCH resource indicator, a slot offset for the transmission of the HARQ response, and / or information indicating the transmission method of the PUCCH (e.g., the trigger A field). If the remaining configuration information of the PUCCH is included in the DL-DCI, the resource allocation information of the PUCCH (i.e., the remaining configuration information) may be explicitly included in the DL-DCI scheduling MSG4. Alternatively, the resource allocation information of the PUCCH may be indicated based on a function of the index of the CCE to which the DL-DCI is mapped. Alternatively, the resource allocation information of the PUCCH may be indicated based on a combination of the fields included in the DL-DCI and the index of the CCE to which the DL-DCI is mapped. Additionally, the DL-DCI scheduling MSG4 may further include an offset of the first symbol to which the PUCCH is transmitted. The offset may indicate that the transmission time of PUCH is "the start time of the symbol (e.g., the symbol boundary)", "the transmission time of PUCH is 16 μs or 25 μs after the start time of the symbol", or "the transmission time of PUCH is [16 μs or 25 μs + TA] after the start time of the symbol".

[0138] The configuration information of the PUCCH can be included in the RMSI as well as the RAR. This is because when the size of the HARQ response to the MSG4 is 1 bit, the number of bits required to indicate the PUCCH resource is small. If the initial connection procedure is performed in the licensed band, the configuration information of the PUCCH, to which the HARQ response to the MSG4 is transmitted, can be included in the RMSI. In the RRC connection reset procedure, the configuration information of the PUCCH may not be indicated by the RAR. In this case, the base station may inform the terminal of the PUCCH configuration information through separate signaling.

[0139] PUCCH's including resource allocation information RMSI and DL channel

[0140] A base station may transmit an RMSI containing some configuration information among the configuration information of a PUCCH (e.g., resource allocation information) and may transmit a DL channel containing the remaining configuration information of a PUCCH (e.g., a DL-DCI, MSG4, RAR, or a combination of two or more of DL-DCI, MSG4, and RAR that schedules MSG4). A terminal may check the configuration information of a PUCCH (e.g., resource allocation information) based on the RAR and DL channel received from the base station. If the remaining configuration information of a PUCCH is included in the DL-DCI, the resource allocation information of a PUCCH (i.e., the remaining configuration information) may be explicitly included in the DL-DCI. Alternatively, the resource allocation information of a PUCCH may be indicated based on a function of the index of the CCE to which the DL-DCI is mapped. Alternatively, the resource allocation information of a PUCCH may be indicated based on a combination of a field included in the DL-DCI and the index of the CCE to which the DL-DCI is mapped.

[0141] In an NR communication system operating in a licensed band, a base station may transmit an RMSI containing a set of resources of a PUCCH to unspecified terminal(s) and transmit a DL-DCI (e.g., a DL-DCI scheduling MSG4) indicating one element among the set of resources of the PUCCH included in the RMSI to the terminal. The terminal may receive the RMSI from the base station and identify the set of resources of the PUCCH included in the RMSI. Additionally, the terminal may receive the DL-DCI scheduling MSG4 from the base station, select one resource among the set of resources of the PUCCH based on the information included in the DL-DCI, and transmit a HARQ response for MSG4 to the base station using the selected resource.

[0142] Since the RMSI is transmitted to unspecified terminal(s), the resource allocation information of the PUCCH included in the RMSI can be used by multiple terminals. That is, the RMSI may include common resource allocation information, and the common resource allocation information may indicate the PUCCH through which the HARQ response for MSG4 is transmitted. Therefore, terminals can transmit HARQ responses for MSG4 through the same PUCCH. If a collision (e.g., contention) between terminals is not resolved, the base station may receive an ACK for the MSG4 of the first terminal and a NACK for the MSG4 of the second terminal through the PUCCH. In this case, the base station may determine that a collision exists between terminals. That is, the base station may determine that the contention has not been resolved. If only an ACK for MSG4 is received through the PUCCH, the base station may determine that the collision between terminals has been resolved.

[0143] Some configuration information of the PUCCH included in the RMSI may not include time resource information of the PUCCH to which the HARQ response to MSG4 is transmitted. For example, the RMSI may include sequence information of the PUCCH, frequency allocation information of the PUCCH (e.g., interlaced index), sequence information of the PUCCH DM-RS, etc. The remaining configuration information of the PUCCH not included in the RMSI may include time resource information of the PUCCH (e.g., slot offset) and / or information indicating the LBT type (e.g., LBT Category 2 or LBT Category 4). Additionally, the configuration information of the PUCCH may include information indicating the transmission method of the PUCCH (e.g., triggered method or non-triggered method).

[0144] RMSI and DL- DCI

[0145] The RMSI may include resource set information of the PUCCH. The base station may transmit the RMSI, which includes resource set information of the PUCCH used in the initial access procedure, to unspecified terminal(s). The resource set information of the PUCCH included in the RMSI may include information indicating the first symbol of the PUCCH, the number of symbols constituting the PUCCH in the time domain, and / or interlaced index(s) of the PUCCH. The remaining configuration information of the PUCCH not included in the RMSI may be transmitted via a DL channel.

[0146] The terminal can receive an SS / PBCH block from the base station and obtain cell identification information from the SS / PBCH block. The terminal can use the cell identification information to initialize the sequence of PUCCH DM-RS. The terminal can use the cell identification information to perform scrambling operations on data and / or control information transmitted over the uplink channel (e.g., PUCCH).

[0147] A DL-DCI scheduling MSG4 may include a PUCCH resource indicator, a slot offset for the transmission of a HARQ response, and / or information indicating the transmission method of PUCCH (e.g., a trigger A field). Additionally, a DL-DCI scheduling MSG4 may further include an offset of the first symbol to which PUCCH is transmitted. The offset may indicate that the transmission time of PUCCH is "the start time of the symbol (e.g., a symbol boundary)," "the transmission time of PUCCH is 16 μs or 25 μs after the start time of the symbol," or "the transmission time of PUCCH is [16 μs or 25 μs + TA] after the start time of the symbol."

[0148] If the remaining configuration information of PUCCH is included in the DL-DCI, the resource allocation information of PUCCH (i.e., the remaining configuration information) may be explicitly included in the DL-DCI scheduling MSG4. Alternatively, the resource allocation information of PUCCH may be indicated based on a function of the index of the CCE to which the DL-DCI is mapped. Alternatively, the resource allocation information of PUCCH may be indicated based on a combination of the fields included in the DL-DCI and the index of the CCE to which the DL-DCI is mapped.

[0149] Resource allocation information of PUCCH included in RMSI can be used in the initial connection procedure as well as the RRC connection reset procedure. The base station can transmit an RRC message to the terminal via PDSCH, and the terminal can transmit an RRC message containing a HARQ response (e.g., ACK) to the RRC message received from the base station to the base station via PUSCH.

[0150] In the RRC connection reset procedure, the PUCCH resource may be a fallback resource or a default resource. The base station may transmit an RMSI containing information about the PUCCH fallback resource to the terminal. The terminal may receive the RMSI from the base station and verify the PUCCH fallback resource information included in the RMSI. Since the base station does not use two or more codewords in the initial connection procedure or the RRC connection reset procedure, the size of the HARQ response may be 1 bit.

[0151] Unlicensed A communication system operating in the band that includes a UL grant MSG4

[0152] In the initial connection procedure, the base station may transmit MSG4 via PDSCH and receive a HARQ response for MSG4 from the terminal. If an ACK for MSG4 is received, the base station may determine that the collision between the terminals has been resolved and that an RRC connection with the terminal has been established. Subsequently, the base station may perform a procedure to exchange RRC messages with the terminal. This operation may be an embodiment illustrated in FIGS. 4a and 4b.

[0153] A terminal that has transmitted an ACK for MSG4 can establish an RRC connection with the base station. After that, the terminal can exchange other RRC messages (e.g., MSG5, UE capability signaling messages, etc.) with the base station. Before the transmission and reception procedure of MSG5, the base station may transmit control information to the terminal using PHY signaling and / or MAC signaling.

[0154] MSG5 may be an RRC message transmitted from the terminal after the transmission of MSG4. MSG5 may be transmitted via PUSCH. The terminal may receive a UL grant from the base station and transmit MSG5 to the base station via the PUSCH directed by the UL grant. MSG5 may be an RRC message transmitted and received when an RRC connection is established between the base station and the terminal. Therefore, the base station may consider MSG5 to be received from the terminal that transmitted an ACK for MSG4.

[0155] In the proposed method, the PDSCH to which MSG4 is transmitted may include a UL grant for MSG5. The UL grant for MSG5 may include one or more of information indicating the trigger method of PUCSH (e.g., a trigger field), a slot offset field of PUSCH, a start symbol and length field of PUSCH, a start time field of PUSCH, a frequency resource field of PUSCH, a channel access field of PUSCH, and a sequence field of PUSCH DM-RS.

[0156] A PUSCH containing MSG5 can be transmitted based on a trigger method. Thus, a base station can transmit two UL grants for MSG5. A PDSCH in which MSG4 is transmitted may include information for receiving two UL grants (e.g., a first UL grant, a second UL grant (e.g., common DCI)). The UL grant for MSG5 may include resource allocation information for the PUSCH, information for receiving the common DCI (e.g., common identifier information (e.g., RNTI)), etc.

[0157] A UL grant scheduling MSG5 transmission can take various forms and can be transmitted through a PDSCH through which MSG4 is transmitted. For example, a UL grant for MSG5 can be included in MSG4. An encoding operation can be performed on the MSG4 containing the UL grant, and the encoded MSG4 can be mapped to a PDSCH. Alternatively, a UL grant for MSG5 can be defined as an RRC message. In this case, an RRC message consisting of a UL grant for MSG5 can be multiplexed with an RRC message consisting of MSG4. An encoding operation can be performed on the multiplexed RRC messages, and the encoded RRC messages can be mapped to a PDSCH. Alternatively, a UL grant for MSG5 can be defined as a MAC message (e.g., MAC CE). In this case, a MAC message consisting of a UL grant for MSG5 can be multiplexed with an RRC message consisting of MSG4. Encoding operations can be performed on multiplexed messages, and the encoded messages can be mapped to PDSCH.

[0158] The terminal may receive a UL grant for MSG5 from the base station. Based on the UL grant, the terminal may transmit MSG5, which is a HARQ response to MSG4, to the base station. In this case, the end time of the initial connection procedure may be earlier than the end time of the existing initial connection procedure. After the initial connection procedure is completed, the procedure for exchanging RRC messages between the terminal and the base station may be performed.

[0159] When the above-described initial access procedure is performed in a communication system operating in an unlicensed band, interference and / or channel occupancy time affecting other terminals can be minimized. Consequently, the throughput of the communication system can be increased. When the proposed methods are used, considering the signaling overhead of resource allocation information for PUCCH, the time required for PUCCH transmission, and the time required for UL grant transmission, there is an advantage that the HARQ response to MSG4 is not fed back to the base station.

[0160] "When a NACK for MSG4 occurs during the initial connection procedure" may be "when the retransmission procedure for MSG4 fails" or "when a collision between terminals is not resolved." In this case, the initial connection procedure may be restarted. That is, the terminal may retransmit the RA preamble. When a NACK for MSG4 is received from the terminal during the initial connection procedure, the base station may not be able to distinguish the reason for the NACK for MSG4 (e.g., channel fading, collision between terminals).

[0161] In the proposed method, when a PUSCH containing MSG5 is received from a terminal, the base station may not be able to distinguish between "channel fading" and "collision between terminals." In this case, the base station may reassign MSG4 to the terminal(s). Since a collision between terminals (e.g., contention) must be resolved within a preset time (e.g., a timer for contention resolution, mac-ContentionResolutionTimer), the base station may retransmit MSG4 before the expiration of the preset time.

[0162] MSG5's Triggering method

[0163] In the embodiments below, the slot in which MSG4 is received may be referred to as slot n. If the trigger field belonging to the UL grant indicates a first value (e.g., 0), the terminal may transmit PUSCH to the base station in slot n+l+k based on one UL grant (e.g., the first UL grant). Here, l may be indicated from the base station to the terminal via upper layer signaling. For example, l may be 3 or 4. If l is not indicated by upper layer signaling, l may be one value (e.g., 4) among a plurality of values ​​(e.g., natural numbers).

[0164] Here, k may represent an offset included in the UL grant. The base station may inform the terminal of k. Alternatively, k may be one of the values ​​defined in the technical specification. For example, referring to Table 8-2d of 3GPP TS 36.213, k may have a value from 0 to 15. The UL grant may include an index indicating k, and the size of the index indicating k may be 4 bits. The terminal may determine the slot for transmitting the PUSCH by performing an LBT operation. For example, the terminal may transmit the PUSCH in slot n+l+k+i. Here, "i=0, 1, …, N-1" may be defined, and N may indicate the number of PUSCHs. N may be a natural number. N may be fixed as a single value depending on the type of the UL grant (e.g., UL grant format, UL-DCI format, RNTI).

[0165] On the other hand, if the trigger field belonging to a UL grant (e.g., the first UL grant) indicates a second value (e.g., 1), the terminal may receive an additional UL grant (e.g., the second UL grant or the common DCI) and transmit a PUSCH based on the additional UL grant. Here, the terminal may assume that it receives the common DCI in slot m. Slot n may be the same as slot m. Or, slot n may be different from slot m. If slot n is different from slot m, slot m may be located after slot n. If the time interval between slot n and slot m is longer than the time interval defined in the technical specification, the UL grant (e.g., the UL grant received in slot n and / or slot m) may be considered invalid.

[0166] For example, in Table 8-2f of TS 36.213, the maximum time interval of a slot or subframe is defined in four ways. An index included in a UL grant may indicate one of the four maximum time intervals defined in the technical specification. A terminal can determine the maximum time interval based on the index included in the UL grant received from the base station, and can determine that the corresponding UL grant is invalid if the time interval between slot n and slot m is greater than or equal to the maximum time interval.

[0167] Additionally, the common DCI may include a trigger field. The identifier (e.g., RNTI) used for scrambling the common DCI (e.g., the cyclic redundancy check (CRC) of the common DCI) may be different from the identifier used for scrambling the UL grant. If the trigger field of the common DCI indicates a first value (e.g., 1), the terminal may transmit PUSCH in slot m+l+k, where k may be an offset included in the UL grant. The base station may inform the terminal of k using upper-layer signaling. Alternatively, k may be defined in the technical specification. For example, k defined in Table 8-2e of 3GPP TS 36.213 may be set to a value from 0 to 3. The UL grant may include an index indicating k, and the size of the index indicating k may be 2 bits.

[0168] The UL offset (l) and UL interval (d) can be derived from specific indices included in the common DCI. The base station may inform the terminal of one of the specific indices defined in the technical specifications. For example, 32 specific indices are defined in Table 13A-2 of 3GPP TS 36.213. The base station may transmit to the terminal a DCI containing information indicating one of the 32 specific indices.

[0169] The terminal can determine the slot for transmitting PUSCH by performing an LBT operation. For example, the terminal can transmit PUSCH in slot n+l+k+i. Here, "i=0, 1, …, N-1" can be defined, and N can indicate the number of PUSCHs. N can be a natural number. N can be fixed to a single value depending on the type of UL grant (e.g., UL grant format, UL-DCI format, RNTI). The terminal may not receive PDCCH in the slot(s) where PUSCH transmission is possible, and the slot(s) may be slot m+l+i. "i=0, 1, …, d-1" can be defined.

[0170] commonness DCI Applying MSG5

[0171] A UL grant belonging to MSG4 may include information indicating the type of LBT operation to be performed for MSG5 transmission. Accordingly, the terminal can determine the type of LBT operation to be performed for MSG5 transmission based on the information included in the UL grant belonging to MSG4. The type of LBT operation indicated by the UL grant belonging to MSG4 may be LBT Category 2 (hereinafter referred to as "C2 LBT") or LBT Category 4 (hereinafter referred to as "C4 LBT").

[0172] When a UL grant belonging to MSG4 indicates a C4 LBT, the terminal can determine whether transmission of PUSCH is possible on the radio resources indicated by the UL grant by performing a C4 LBT operation. Even when a UL grant belonging to MSG4 indicates a C4 LBT within the time interval (e.g., COT) obtained by the base station performing an LBT operation, the terminal can perform a C2 LBT operation for uplink transmission. Thus, the terminal can determine whether the time resources (e.g., slots or subframes) for PUSCH transmission fall within the time interval (e.g., COT) secured by the base station.

[0173] To support this operation, the base station may transmit a DCI containing configuration information of the COT obtained by the LBT operation to the terminal(s). The configuration information of the COT may include pattern information of slot(s) or subframe(s) belonging to the COT. The pattern information may include one or more of the number of DL slots, the number of UL slots, the number of slots consisting of "DL symbol, UL symbol, and FL symbol", the order of slots, and the order of symbols. The pattern information may be represented as a bitmap or an index. A DCI containing the configuration information of the COT (e.g., a common DCI) may be transmitted to unspecified terminal(s). Accordingly, a DCI containing the configuration information of the COT (e.g., the CRC of the DCI) may be scrambled based on a common RNTI.

[0174] The common DCI may include time window information (e.g., the number of slots or subframes constituting the time window). The time window information included in the common DCI may indicate time resource(s) to which a C2 LBT operation is applicable. The terminal(s) may perform a C2 LBT operation for PUSCH transmission at the time resource(s) indicated by the time window information included in the common DCI.

[0175] sequence based PUCCH of OCC How to apply (orthogonal cover code)

[0176] A UCI can consist of one or two bits. In this case, a PUCCH containing the UCI can be defined based on the application method of the spreading sequence. A UCI consisting of three bits can be generated by appending a pre-set bit(s) to an existing UCI. For example, a UCI consisting of three bits can be generated by appending "3-a" zeros to a UCI consisting of a number of bits in a channel coding procedure. For example, when a Reed Muller code is applied, the codeword can be represented as a linear combination of the results of the multiplication between the matrix defined in the technical specification and the UCI (e.g., the column vector or row vector of the matrix). In particular, when the UCI consists of one bit, the UCI can be interpreted as spreading into a vector defined by the Reed Muller code.

[0177] When a PUCCH is transmitted in an unlicensed band, PRBs belonging to the PUCCH resource may be spaced at regular intervals across the entire frequency band to satisfy frequency regulations. For example, PRBs belonging to the PUCCH resource may have an interlaced structure. This operation may mean that the number of FDM terminals across the entire frequency band is equal to the number of interlacs. If the number of bits of information transmitted by a single terminal through the PUCCH is small, many terminals may be multiplexed across the entire frequency band. In particular, a method is required to multiplex PUCCHs using the same interlacing (e.g., UCIs of different terminals). It may be desirable to apply a spreading code to a portion of the PUCCH where a UCI consisting of one or more bits is transmitted.

[0178] In the proposed method, OCC can be applied symbol-wise in the time domain. In this case, the number of symbols (z) in PUCCH may be the length of OCC. To support this operation, it may be desirable for DM-RS to be mapped to the same RE (resource element) in PRB. For example, OCC may be a DFT (discrete Fourier transform) sequence or a Hadamard sequence. If z is expressed as a power of 2, it may be desirable to apply a Hadamard sequence. Otherwise, it may be desirable to apply a DFT sequence.

[0179] DM- in the frequency domain RS and UCI's Multiplexing method

[0180] The number of symbols constituting the PUCCH resource may be smaller than a preset number (e.g., 4). For example, the number of symbols constituting the PUCCH resource may be 1 or 2. In this case, the PUCCH DM-RS may be multiplexed with the UCI (e.g., REs mapped to encoded UCI) in the frequency domain. Here, the PUCCH DM-RS may be a DM-RS used for demodulating the PUCCH (e.g., UCI). In a single symbol belonging to the PUCCH resource, among the REs included in a single PRB, the number of REs mapped to the DM-RS (hereinafter referred to as "DM-RS REs") may be x, and the number of REs mapped to the UCI (hereinafter referred to as "UCI REs") may be y (= 12-x). x and y may each be natural numbers. The UCI REs may be REs mapped to encoded UCI.

[0181] In the proposed method, an OCC of length y can be applied to a UCI RE. By applying an OCC of length y to a UCI RE, the number of PUCCHs multiplexed in the frequency domain can be increased. That is, the multiplexing capability or multiplexing order can be increased.

[0182] Meanwhile, OCC can be applied at the PRB level. Since interlacing for PUCCH involves discontinuous PRBs, it may be preferable to apply OCC to a single PRB. This is because if a spreading code is applied such that discontinuous PRBs are code division multiplexed (CDM) to each other, the frequency resources mapped by the spreading code may have different channel values ​​due to the frequency selective nature of the radio channel. Consequently, the decoding performance of the spreading code may be degraded. OCC can be a DFT sequence or a Hadamard sequence. A Hadamard sequence may be applied when y is expressed as a power of 2.

[0183] DM in the time domain RS and UCI's Multiplexing method

[0184] If the number of symbols constituting the PUCCH resource is greater than or equal to a preset number (e.g., 4), the PUCCH DM-RS can be multiplexed with a UCI (e.g., an RE mapped to an encoded UCI) in the time domain. In this case, OCC can be applied in the same manner as in the embodiments described above. OCC can be applied within one of the PRBs constituting the PUCCH. The number of UCI REs included in one PRB can be 12.

[0185] In the proposed method, an OCC of length 12 can be applied to UCI RE. Thus, the number of PUCCHs multiplexed in the time domain can be increased. The OCC can be a DFT sequence or a Hadamard sequence. For example, a DFT sequence of length 12 can be applied.

[0186] improved PUCCH Format 2

[0187] When PUCCH format 2 is used in an NR communication system, four DM-RS REs and eight UCI REs can be allocated within the PRB. Therefore, an OCC of length 8 can be applied to the UCI REs. For example, the OCC can be a Hadamard sequence or a DFT sequence.

[0188] To apply OCC stepwise, a recursively defined Hadamard sequence can be applied. Length 2 n+ 1 The Hadamard sequence is 2 times longer. n It can be obtained by repeatedly adding a Hadamard sequence of length 2 to a Hadamard sequence.

[0189] Hadamard sequences can have indices of various orders. This can be represented as a matrix. The indices of a Hadamard sequence can be assigned according to the order of the column vectors of the matrix. Tables 2 through 4 below represent Hadamard sequences with different orders. In Tables 2 through 4, the horizontal axis may be the RE index within the PRB, and in Tables 2 through 5, the vertical axis may be the index of the sequence (e.g., Hadamard sequence). In Tables 2 through 4, "+1" and "-1" may represent the values ​​of the Hadamard sequence.

[0190] Table 1 below may represent the matrix of the Reed Muller code. When the size of the UCI is 1 bit, a codeword can be obtained by multiplying the Reed Muller code (e.g., the generation matrix defined in Table 1) by a row vector (e.g., an information bit or an information bit of length 11 generated by appending 0s to the information). According to this operation, a vector consisting of 32 1s (i.e., [1, 1, …, 1]) can be represented. The UCI can be spread by a Hadamard sequence, and the spread UCI can be mapped to all PRBs of the interlaced for PUCCH.

[0191]

[0192]

[0193]

[0194]

[0195] One or more of the eight OCC indices (e.g., indices of the Hadamard sequence) may be used. The number of one or more OCC indices may be w, and w may be less than 8. In this case, the w OCC indices defined in Table 4 (e.g., 0, 1, …, w-1) may be used in order. This is because the OCC can be interpreted as a subsequence of the OCC based on adjacent REs (e.g., REs to which the OCC is to be applied). Since the DM-RS maps to REs 1, 4, 7, and 10 within the PRB, two UCI REs located between adjacent DM-RS REs can form a subsequence of the OCC. It may be desirable for the subsequences of the OCC to form a single OCC. Due to the nested nature in which the OCC is established stepwise, the above-described embodiments may be preferably used in a wireless channel having frequency-selective characteristics.

[0196] Improved PUCCH Format 3

[0197] When PUCCH Format 3 is used in an NR communication system, 12 UCI REs can be assigned. Therefore, an OCC of length 12 can be applied to the UCI REs. For example, the OCC can be a DFT sequence. A DFT sequence can be a column vector of a DFT matrix. Table 5 below can represent a DFT sequence. The horizontal axis of Table 5 can be the RE index in the PRB, and the vertical axis can be the OCC index. In Table 5, w is e 2πi / 12 It could be.

[0198]

[0199] One or more OCC indices may be used out of 12 OCC indices. The number of one or more OCC indices may be q, and q may be less than 12. To select q OCC indices, αs satisfying [condition] may be selected. It may be preferable to select α from Table 5. This is because the selected column vectors have the property of being orthogonal to each other. In addition, since the complex argument of the q-th root of unity has a constant interval, the above-described embodiments can be preferably applied to a wireless channel having frequency-selective characteristics.

[0200] Feedback method for HARQ responses in the unlicensed band

[0201] The PUCCH resource may include a PUCCH format, a frequency resource of the PUCCH, a time resource of the PUCCH, and a sequence resource for the PUCCH. If the size of the UCI is 3 bits or more, a Reed Muller code or a Polar code may be used in the encoding procedure of the UCI, and the encoded UCI may be mapped to the PUCCH. If the size of the UCI is 1 bit or 2 bits, a UCI having a size of 3 bits or more may be generated by appending a predefined bit (e.g., 0) to the UCI in the encoding procedure of the UCI.

[0202] PUCCH DM-RS can be TDM or FDMed with a UCI codeword. For example, if the number of symbols constituting PUCCH is small, PUCCH DM-RS can be FDMed with a UCI codeword. Here, the number of symbols constituting PUCCH can be 1 or 2. If the number of symbols constituting PUCCH is large, PUCCH DM-RS can be TDMed with a UCI codeword. Here, the number of symbols constituting PUCCH can be 3 or more.

[0203] A base station may transmit an RRC message to a terminal that includes a resource set or resource list of a PUCCH. Additionally, the base station may transmit a DL-DCI to the terminal that includes information (e.g., an index) indicating one or more resources belonging to the resource set or resource list indicated by the RRC message. Here, the DL-DCI may include resource allocation information for a PDSCH. The terminal may receive an RRC message from the base station and identify the resource set or resource list of a PUCCH included in the RRC message. Additionally, the terminal may receive a DL-DCI for scheduling a PDSCH from the base station, identify one or more resources indicated by the DL-DCI among the resources belonging to the resource set or resource list of a PUCCH, and transmit a PUCCH to the base station using the identified one or more resources.

[0204] The PUCCH resource can be fixed as a single unit, and additional information may be required to transmit the PUCCH. For example, if a HARQ response to a PDSCH is transmitted via the PUCCH, the slot corresponding to the HARQ-ACK feedback timing may be indicated by a slot offset. Additionally, PUCCH transmission in the unlicensed band may be performed based on the triggering method.

[0205] In the proposed method, the DL-DCI that schedules the PDSCH may include other information (e.g., time resource information for PUCCH transmission (e.g., slot offset) and trigger method). The size of the DL-DCI may be increased to include other information. Since one DCI includes resource allocation information for one PDSCH and feedback information for the HARQ response for that PDSCH (e.g., configuration information for PUCCH), the burden on the PDCCH decoding procedure may not increase.

[0206] In another proposed method, other information (e.g., time resource information for PUCCH transmission (e.g., slot offset) and trigger method) may be included in a different DCI (e.g., a common DCI, a UL-DCI that schedules PUSCH) instead of a DL-DCI that schedules PDSCH. The terminal may receive a UL-DCI containing other information. In this case, the terminal may transmit a HARQ response using PUSCH instead of PUCCH. The DL-DCI may include resource allocation information for PUCCH and may not include information indicating the trigger method for PUCCH transmission and / or information indicating the channel access method. Thus, the size of the DL-DCI may be reduced. In this case, the terminal must receive two DCIs (e.g., a DL-DCI that schedules PDSCH, a UL-DCI containing information for transmitting a HARQ response) to perform a PDSCH reception operation and a transmission operation of a HARQ response for the PDSCH. Therefore, the burden of the PDCCH decoding procedure may increase.

[0207] How to instruct a PUCCH transmission using DL-DCI

[0208] A DL-DCI may include one or more of the following fields, and a DL-DCI including one or more fields may direct a PUCCH transmission.

[0209] Trigger field for PUCCH

[0210] A DL-DCI may include trigger fields. The number of trigger fields may vary depending on the triggering method of the PUCCH. For triggering a PUCCH transmission, one trigger field (e.g., Trigger A field) or two trigger fields (e.g., Trigger A field and Trigger B field) may be required. The Trigger A field and the Trigger B field may be included in different DL-DCIs.

[0211] The Trigger A field included in the DL-DCI can indicate two different values. The terminal can determine whether to perform the monitoring operation of the Trigger B field based on the value indicated by the Trigger A field. The Trigger A field set to a first value (e.g., 0) can indicate a non-triggered method. In this case, the terminal can transmit a PUCCH based on the DL-DCI. For example, the terminal can identify a slot capable of transmitting a PUCCH based on the slot offset field included in the DL-DCI. The Trigger A field set to a second value (e.g., 1) can indicate a triggered method. In this case, the terminal can receive a separate DCI (e.g., a common DCI) that triggers the transmission of a PUCCH. The separate DCI may include a Trigger B field. The terminal can identify a slot capable of transmitting a PUCCH based on the information element(s) (e.g., the Trigger B field) included in the separate DCI.

[0212] Slot offset field for PUCCH

[0213] DL-DCI may include a slot offset field. The slot in which the HARQ response is transmitted may be indicated by the slot offset field included in the DL-DCI. For example, the terminal may determine that the slot after the offset indicated by the slot offset field from the slot in which the PDSCH was received is the slot in which the PUCCH (e.g., the PUCCH containing the HARQ response) is transmitted. The terminal may perform an LBT operation, and if the channel is determined to be busy as a result of performing the LBT operation, the PUCCH may not be transmitted in the slot indicated by the slot offset field.

[0214] The slot offset field for PUCCH may indicate an integer or a non-numerical value. If the slot offset field indicates an integer, the terminal may determine that the slot after the value indicated by the slot offset field, starting from the slot where PDSCH was received, is the slot to which PUCCH is transmitted. On the other hand, if the slot offset field indicates a non-numerical value, the terminal may not transmit PUCCH unless a separate instruction is received from the base station (e.g., a separate DCI that triggers one or more transmissions from the HARQ codebook(s).

[0215] HARQ-ACK codebook group indicator

[0216] HARQ response bits instructed to be transmitted on the same PUCCH may be assumed to belong to the same HARQ codebook. A PUCCH transmitted in an unlicensed band may contain a single HARQ codebook. A HARQ codebook may be a bit sequence composed of HARQ response bits, and a single HARQ codebook may correspond to a single PUCCH transmission. For convenience of explanation, an "augmented HARQ codebook" or "extended HARQ codebook" may be defined as containing all HARQ response bits belonging to one or more HARQ codebook(s). An augmented HARQ codebook may mean an extended HARQ codebook. Within an augmented HARQ codebook, bit sequences may be arranged according to a predetermined order among the HARQ codebooks (e.g., HARQ response bits). An incremented HARQ codebook may consist of HARQ response bit(s), and an incremented HARQ codebook may be a type of HARQ codebook. One incremented HARQ codebook may correspond to one PUCCH transmission. An incremented HARQ codebook may be generated according to the method described below. In the embodiments below, the HARQ codebook may be an incremented HARQ codebook, an extended HARQ codebook, or a standard HARQ codebook. A standard HARQ codebook may be a HARQ codebook that is neither an incremented HARQ codebook nor an extended HARQ codebook.

[0217] The terminal may not be able to transmit a PUCCH as a result of an LBT operation. Therefore, the terminal may still possess an untransmitted HARQ codebook (e.g., a HARQ response). The base station may not receive a PUCCH from the terminal. The base station may determine the reason for not detecting the PUCCH as "the terminal did not receive the DL-DCI," "the terminal transmitted a PUCCH but the base station did not receive it correctly," or "the terminal failed to transmit a PUCCH as a result of an LBT operation."

[0218] The signaling overhead for retransmission procedures for all HARQ processes associated with a HARQ codebook not received from the terminal can be large. Therefore, it may be desirable for the base station to transmit information to the terminal instructing it to perform a retransmission procedure for the HARQ codebook. The base station may transmit to the terminal a corresponding DL-DCI containing a field instructing it to feed back an enlarged HARQ codebook by multiplexing the HARQ codebook(s) containing the HARQ response to the PDSCH scheduled by the DL-DCI and the HARQ codebook (e.g., HARQ response) that has already failed to transmit. The size of the enlarged HARQ codebook may change dynamically. For example, the size of the enlarged HARQ codebook may change according to the number of HARQ response bits to be fed back to the base station. The HARQ codebooks constituting the enlarged HARQ codebook (e.g., each of the HARQ codebooks) may represent a group of PDSCHs associated with that HARQ codebook. A HARQ codebook containing HARQ responses for PDSCHs scheduled by DL-DCI may represent a single PDSCH group. PDSCHs corresponding to HARQ responses belonging to a HARQ codebook that has already failed to transmit may represent a different PDSCH group. Therefore, the codebook group field may be used as a field indicating a PDSCH group.

[0219] A DL-DCI may include a codebook group field, and the codebook group field may be a HARQ-ACK codebook group indicator. The codebook group field included in the DL-DCI may indicate to feed back an increased HARQ codebook by multiplexing the HARQ codebook for the PDSCH scheduled by the DL-DCI (e.g., HARQ response) as well as the HARQ codebook for the PDSCH scheduled by the previous DL-DCI (e.g., HARQ codebook that failed to transmit). If the codebook group field has a first value, the terminal can generate an augmented HARQ codebook by multiplexing the HARQ codebook (e.g., the HARQ codebook containing the current HARQ response) associated with the current DL-DCI (e.g., the DL-DCI containing the codebook group field having the first value) and the previous HARQ codebook that failed to transmit (e.g., the HARQ codebook containing the previous HARQ response), perform an encoding operation on the augmented HARQ codebook, and map the encoded augmented HARQ codebook to PUCCH. On the other hand, if the codebook group field has a second value, the terminal can perform an encoding operation on the HARQ codebook associated with the current DL-DCI and map the encoded HARQ codebook to PUCCH. The augmented HARQ codebook may consist of only one HARQ codebook (e.g., one HARQ response bit). Even if a previous HARQ codebook that failed to transmit (e.g., HARQ response bit) exists, the incremented HARQ codebook may not include the previous HARQ codebook that failed to transmit (e.g., HARQ response bit).

[0220] If the number of failed HARQ codebooks is two or more and the codebook group field has a first value, the terminal may generate a single HARQ codebook containing all failed HARQ codebook(s) (e.g., HARQ response bit(s) associated with all failed HARQ process(s). Within the generated HARQ codebook, the arrangement order of the previous HARQ codebook(s) (e.g., HARQ response bit(s)) may be the same as the existing arrangement order. A single HARQ codebook may be generated by concatenating the previous HARQ codebooks (e.g., failed HARQ codebooks). Alternatively, a single HARQ codebook may be generated by concatenating the HARQ response bit(s) belonging to the previous HARQ codebook(s) (e.g., failed HARQ codebook(s)) in the order of the HARQ process identifiers. Previous HARQ codebook(s) can be multiplexed with a HARQ codebook associated with the current DL-DCI (e.g., a HARQ codebook containing a HARQ response to a PDSCH assigned by the current DL-DCI), an augmented HARQ codebook containing the multiplexed HARQ codebook can be created, an encoding operation can be performed on the augmented HARQ codebook, and the encoded augmented HARQ codebook can be mapped to a PUCCH.

[0221] If the increased HARQ codebook consists of HARQ codebook(s) that failed to transmit, the size of a single HARQ codebook (e.g., the number of HARQ response bits) can be large. Therefore, the base station may transmit information to the terminal instructing the retransmission of some HARQ codebooks. To support this operation, specific fields may indicate various information.

[0222] The proposed new field (hereinafter referred to as the "HARQ indication field") may indicate one or more HARQ codebook(s) or HARQ process identifier(s) (e.g., HARQ process numbers or HARQ process IDs). The HARQ indication field may be included in DL-DCI. The HARQ indication field may consist of multiple bits. Among the multiple bits constituting the HARQ indication field, one bit may indicate one or more HARQ codebook(s), one or more HARQ codebook group(s), one or more HARQ process identifier(s), or one or more HARQ process identifier group(s).

[0223] The base station may transmit an RRC message or DCI to the terminal containing information indicating the aforementioned mapping relationship (e.g., a HARQ codebook, HARQ codebook group, HARQ process identifier, HARQ process identifier group mapped to a single bit belonging to the HARQ instruction field). Alternatively, the base station may implicitly inform the terminal of the aforementioned mapping relationship based on a relationship defined in the technical specification (e.g., a formula) without transmitting a separate RRC message.

[0224] Channel connection information field for PUCCH

[0225] The fields included in DL-DCI may include information regarding channel connections for PUCCH. The channel connection information field may indicate the type of LBT operation performed for the transmission of PUCCH. The channel connection information field set to a first value may indicate a first type of LBT operation. The channel connection information field set to a second value may indicate a second type of LBT operation.

[0226] When the first type of LBT operation is used, the terminal may randomly select a backoff value within a contention window and perform a backoff operation based on the selected backoff value. The backoff value may be determined by a contention window, a random variable, and / or separate parameter(s). The separate parameter(s) may include the priority of the PUCCH (e.g., p=1). The size of the contention window may be determined according to the priority of the PUCCH. Additionally, the separate parameter(s) may include MCOT configuration information and / or the length of the diff interval (T d It may include more ).

[0227] The terminal can perform a channel sensing operation (e.g., energy detection operation) in a time interval (e.g., a dipper interval) corresponding to a selected backoff value, and can transmit a PUCCH when the energy detection result in all sensing slots belonging to the dipper interval is smaller than the energy detection threshold value. The length of the sensing slot may be 9 μs, and the sensing slot may be distinguished from the slot used for transmitting and receiving signals.

[0228] When the second type of LBT operation is used, the terminal can perform a channel sensing operation (e.g., energy detection operation) in all sensing slots within the dipper interval without a random backoff operation. If the energy detection result in all sensing slots within the dipper interval is smaller than the energy detection threshold value, the terminal can transmit a PUCCH. Here, the length of the dipper interval may be several tens of μs (e.g., 25 μs or 16 μs).

[0229] Meanwhile, the channel connection information field may indicate three or more values ​​(e.g., three or more types of LBT operation). For example, the channel connection information field may indicate a first value, a second value, or a third value. A channel connection information field set to the first value may indicate a first type of LBT operation. A channel connection information field set to the second value may indicate a second type of LBT operation. A channel connection information field set to the third value may indicate a third type of LBT operation.

[0230] When the third type of LBT operation is used, the terminal can perform a channel sensing operation (e.g., an energy detection operation) in all sensing slots within the dipper period without a random backoff operation. If the energy detection result in all sensing slots within the dipper period is smaller than the energy detection threshold value, the terminal can transmit a PUCCH. Here, the length of the dipper period may be 16 μs. For example, the length of the dipper period for the third type of LBT operation may be 16 μs, and the length of the dipper period for the second type of LBT operation may be 25 μs.

[0231] The base station can transmit information indicating the length of the diff interval to the terminal using upper-layer signaling. The terminal can check the length of the diff interval set by the base station and can perform an LBT operation (e.g., a second type of LBT operation or a third type of LBT operation) during the diff interval.

[0232] UL-DCI directing the transmission of HARQ responses

[0233] Resource allocation information for the PUCCH to which the HARQ response to the PDSCH is transmitted may not be included in the DL-DCI. In this case, the base station may transmit a UL-DCI to the terminal that includes a separate UL grant for the feedback of the HARQ response. The terminal may receive the UL-DCI from the base station and transmit the HARQ response to the base station via the PUCCH indicated by the UL grant included in the UL-DCI. The UL-DCI may include resource allocation information for the transmission of other signals as well as resource allocation information for the transmission of the HARQ response. For example, the UL-DCI may further include resource allocation information for UCI transmission (e.g., CSI report) and / or resource allocation information for UL-SCH transmission (e.g., TB (transport block)). Resource allocation information may be indicated by the field(s) included in the UL-DCI.

[0234] Method to explicitly specify the transmission resource of a HARQ response

[0235] UL-DCI may include a HARQ codebook trigger field, and the HARQ codebook trigger field may instruct the terminal to feed back a HARQ response. If the HARQ codebook trigger field is set to a first value, the terminal may generate a single HARQ codebook containing HARQ responses for all HARQ processes. The number of bits included in the HARQ codebook may be equal to the number of HARQ processes set by upper-layer signaling. If the HARQ codebook trigger field is set to a second value, the terminal may not map a HARQ response to PUSCH.

[0236] Alternatively, the HARQ codebook trigger field included in the UL-DCI may consist of multiple bits. The HARQ codebook trigger field may indicate HARQ codebook(s) and / or HARQ process identifier(s). One bit in the HARQ codebook trigger field may indicate that feedback is requested from one or more HARQ codebooks, one or more HARQ codebook groups, one or more HARQ process identifiers, or one or more HARQ process identifier groups. Another bit in the HARQ codebook trigger field may indicate to the terminal not to map a HARQ response to PUSCH.

[0237] The base station may transmit an RRC message to the terminal indicating the mapping relationship described above (e.g., a mapping relationship between a single bit and "HARQ codebook(s), HARQ codebook group(s), HARQ process identifier(s), or HARQ process identifier group(s)"). Alternatively, the terminal may determine the mapping relationship described above based on a relationship defined in the technical specification (e.g., a mathematical expression) without receiving an RRC message. Code block group transmission information (CBGTI) included in the UL-DCI may be used to indicate the transmission of a HARQ response. In this case, the UL-DCI may not include resource allocation information of the UL-SCH and may include PUSCH resource information for the transmission of the UCI (e.g., HARQ response, CSI).

[0238] Method to implicitly indicate the transmission resource of a HARQ response

[0239] UL-DCI may not include a field that explicitly requests the transmission of a HARQ response (e.g., HARQ feedback). However, the request for the transmission of a HARQ response may be implicitly indicated by a combination of fields included in UL-DCI.

[0240] In the proposed method, if "the UL-DCI received from the base station does not include a field indicating the transmission resource of the UL-SCH, and the DAI (downlink assignment index) field included in the UL-DCI is set to a specific value (e.g., a value other than 00)," the terminal can determine that the UL-DCI requests feedback of a HARQ response.

[0241] Alternatively, a terminal receiving UL-DCI may interpret the CBGTI for UL-SCH as indicating an index of a HARQ codebook group. This behavior may apply when a CBG transmission is established to the terminal by an RRC message. Alternatively, the terminal may interpret the DAI field included in UL-DCI as indicating an index of a HARQ codebook group.

[0242] NFI (new feedback indicator) and / or NDI (new data indicator) Method of providing feedback on HARQ responses by considering

[0243] Due to the characteristics of the unlicensed band, the terminal may not receive the PDCCH as a result of the base station's LBT operation. Additionally, the terminal may not be able to transmit the PUCCH as a result of the LBT operation. Therefore, the number of bits in the HARQ response predicted by the base station may differ from the number of bits in the HARQ response transmitted by the terminal. To resolve this issue, DL-DCI may include an NFI for a PDSCH group (or, HARQ codebook). The size of the NFI may be 1 bit. When the PUCCH is received from the terminal, the base station may change the value of the NFI for the HARQ codebook (or, GID (group identifier)) included in the PUCCH to a different value. If the value of the NFI received from the base station is changed, the terminal may determine that HARQ responses for all HPIDs (HARQ process identifiers) belonging to the GID associated with that NFI have been received from the base station.

[0244] The base station may transmit an NDI for the HARQ process to the terminal. The size of the NDI may be 1 bit. The terminal may receive the NDI from the base station and determine whether the transmission of the DL-SCH associated with the NDI is a supertransmission or a retransmission. Accordingly, the terminal may determine whether to perform a soft combining operation in the decoding procedure of the DL-SCH. The base station may generate a DCI containing one or more of DAI, NFI, NDI, and GID, and may transmit the generated DCI to the terminal. The terminal may receive the DCI from the base station and verify the information contained in the DCI.

[0245] In the proposed method, the value of the HARQ response can be verified based on the NFI associated with the HARQ process. Here, the HARQ response may be a NACK. Alternatively, the HARQ response may be an ACK or a NACK, which is the decoding result for the DL-SCH.

[0246] The terminal can know the NFI and NDI for the HPID in advance and can receive the DL-DCI from the base station. The DL-DCI can be received at time t (e.g., slot t), and the terminal can compare the NFI and NDI included in the DL-DCI with each of the already known NFI and NDI. Based on the comparison result, the terminal can determine whether each of the NFI and NDI has changed. For example, the terminal can compare the NFI and NDI included in the DL-DCI received at time r, which is prior to time t, with the NFI and NDI included in the DL-DCI received at time t. Here, the DL-DCI received at time r and the DL-DCI received at time t may have the same GID.

[0247] Meanwhile, the terminal may not know the reference value of the NFI. For example, if the base station first transmits the DL-DCI for HPID and GID at time t (i.e., if there is no DL-DCI received prior to time t), the terminal may not know the reference value of the NFI. If it is determined that the NFI has changed, the terminal may know "the GID x to which the HPID indicated by the DL-DCI received at time t (e.g., slot t) belongs last" or "GID x at time t".

[0248] The DL-DCI received in slot t may indicate that the corresponding HPID belongs to GID y. x may be the same as y, or x may be different from y. With respect to all HPIDs belonging to GID x, it may be assumed that the terminal knows all HARQ responses transmitted at the time it transmitted its own HARQ response (e.g., time s (≠ t)). The terminal may additionally transmit a HARQ response for the corresponding HPID to the base station in slot t.

[0249] On the other hand, if the NFI included in the DL-DCI received at time t is the same as the NFI received prior to time t, the terminal may interpret that the base station did not successfully receive the PUCCH associated with the GID at time s. The base station may not know the HARQ responses of all HPIDs belonging to the GID. The terminal may transmit the HARQ response for the HPID at time t to the base station, and may also transmit the HARQ response(s) for other HPID(s) belonging to the GID to the base station. The HARQ response(s) for other HPID(s) belonging to the GID may be transmitted at time t.

[0250] In the proposed method, the HARQ response to the HARQ process can be verified based on NFI and NDI. The HARQ response can be expressed as NACK. Alternatively, the HARQ response can be expressed as ACK or NACK.

[0251] The terminal can receive a DL-DCI at time t and can identify NFI and NDI based on the DL-DCI. The terminal can determine whether the NDI has changed by comparing the NDI contained in the DL-DCI received at a time prior to time t (e.g., time t-1) with the NDI contained in the DL-DCI received at time t. Here, the HPID associated with the DL-DCI received at a time prior to time t may be the same as the HPID associated with the DL-DCI received at time t. If the DL-DCI was not received at a time prior to time t, the terminal may not know the reference value of the NDI. It may be difficult for the terminal to determine whether to perform a soft combining operation for the corresponding HPID.

[0252] Based on the DL-DCI received at time t, it can be confirmed that the NFI has changed and that the NDI has not changed. In this case, the transmission operation of the DL-SCH may be meaningless. That is, the base station may change the NFI because it has received a HARQ response for the HPID, and the fact that transmission resources for the new DL-SCH are not allocated can be expressed by the DL-DCI (e.g., the DL-DCI transmitted at time t). Therefore, the terminal does not need to transmit a HARQ response, and the base station does not need to receive a HARQ response.

[0253] However, in cases other than those described above (e.g., “when NDI is changed regardless of NFI” or “when NFI and NDI are not changed”), the terminal may transmit a HARQ response for the DL-SCH associated with the HPID.

[0254] The embodiments described above may be applied in cases where "a DCI associated with HPID is not received at time t" or "a DCI associated with HPID is received at a time prior to time t (e.g., time t-1)." An NFI for HPID may be identified based on the DCI received at time t. This is because HPID and the GID to which HPID belongs (e.g., GID y) are indicated by DL-DCI, and an NFI for GID is indicated by GID.

[0255] In summary, based on the above description, the terminal can check for a change in the NFI for the GID to which the HPID last belonged or the GID to which the HPID currently belongs, based on the DCI received at time t or at a time prior to time t. The terminal can check whether the NFI has changed at time e or at a time prior to time e. Here, "e ≤ t" can be defined. Additionally, the terminal can check whether the NDI has changed at time e or at a time prior to time e. If the NDI has not changed, the terminal can determine that the new DL-SCH has not been supertransmitted. The base station does not need to receive a HARQ response for the HPID. If the NDI has changed, the terminal can determine that the new DL-SCH has been supertransmitted and can transmit a HARQ response for the HPID to the base station.

[0256] The time at which a HARQ response associated with GID x to which HPID belongs was transmitted may be referred to as s, and the time at which a DL-DCI containing a modified NDI was received after the transmission of the HARQ response may be referred to as q. In this case, "s ≤ q ≤ t" may be defined. The time at which the change in NFI was recognized in relation to GID x to which HPID belongs may be referred to as e. In this case, "s ≤ e ≤ t" may be defined.

[0257] "Cases where the terminal feeds back a HARQ response for an HPID" or "cases where the terminal feeds back a predefined value (e.g., ACK or NACK) or an arbitrary value" may be considered. "When e is after s and q is after s", the terminal may feed back a HARQ response to the base station. Here, e may be the same as q. In cases other than those described above, the terminal may feed back a NACK, a predefined value, or an arbitrary value to the base station. In the proposed method, the terminal may perform an encoding operation for a HARQ response for all HPIDs set by upper layer signaling regardless of NFI and NDI, and may transmit the encoded HARQ response to the base station.

[0258] Meanwhile, if all DL-DCIs associated with all HPIDs belonging to the GID are not received from the base station, the terminal may not know whether the NFI has changed. This behavior may occur when "DL-DCIs for the GID are not transmitted from the base station" or "the terminal has failed to decode all DL-DCIs for the GID." In this case, the terminal may not know that the NFI has changed. This case may rarely occur.

[0259] Information contained in the DCI directing the transmission of the HARQ response

[0260] In the proposed method, the DCI (e.g., DL-DCI or UL-DCI) may contain NFIs for all GIDs. The terminal can directly verify the NFI for a GID from the DCI. Thus, the terminal can detect changes in the NFI for any HPID. If the NFI changes, the terminal can observe changes in the NDI associated with the HPID. If the NDI does not change, the terminal does not need to transmit a HARQ response for the HPID. Therefore, the terminal can map a predefined value (e.g., NACK or ACK) or any value to the uplink channel as the HARQ response for the HPID. The base station does not need to be aware of the HARQ response for the HPID.

[0261] In another proposed method, the DCI (e.g., DL-DCI or UL-DCI) may contain only configuration information for the transmission of the HARQ response. That is, the DCI may not contain other information (e.g., NFI and / or NDI) in addition to the configuration information for the transmission of the HARQ response.

[0262] HARQ responses and additional information in the HARQ response feedback process

[0263] In the proposed method, the terminal can perform encoding operations for HARQ responses (e.g., ACK, NACK) for all HPIDs set by upper layer signaling, and can transmit the encoded HARQ responses to the base station.

[0264] For example, a base station may transmit an RRC message to a terminal that includes configuration information for a type 2 codebook and configuration information for a type 3 codebook. The terminal may receive the RRC message from the base station and verify the configuration information for the type 2 codebook and the configuration information for the type 3 codebook included in the RRC message. The type 2 codebook may be the aforementioned enhanced HARQ codebook or extended HARQ codebook. The type 2 codebook may be an enhanced dynamic codebook. The type 2 codebook may include one or two HARQ response bits (e.g., HARQ codebooks). Within the type 2 codebook, the HARQ response bits may be arranged according to the order of the PDSCH (e.g., one or more combinations of the receive order, scheduling order, start symbol order, and end symbol order). For example, HARQ response bits can be placed first according to the order of the time resources of the PDSCH, and then HARQ response bits can be placed according to the order of the frequency resources of the PDSCH.

[0265] A Type 3 codebook may be a semi-static codebook. A Type 3 codebook may include multiple HARQ response bits (e.g., HARQ codebooks). Additionally, a Type 3 codebook may include NDIs in addition to multiple HARQ response bits. In the embodiments, a HARQ codebook containing "HARQ response bits and NDIs" may refer to a Type 3 codebook. Alternatively, a HARQ codebook containing HARQ response bits without NDIs may be interpreted as a Type 3 codebook. Within a Type 3 codebook, multiple HARQ response bits may be arranged in the order of HARQ process numbers. For example, multiple HARQ response bits may be arranged first in the order of HARQ process numbers, and subsequently, multiple HARQ response bits may be arranged in the order of frequency resources of the PDSCH.

[0266] A base station may transmit a DL-DCI containing a field that triggers a Type 3 codebook to a terminal. The size of the field that triggers a Type 3 codebook may be 1 bit. If the field that triggers a Type 3 codebook is set to a first value, the field may trigger the transmission of a Type 3 codebook. If the field that triggers a Type 3 codebook is set to a second value, the field may trigger the transmission of a Type 1 codebook or a Type 2 codebook. That is, if the field that triggers a Type 3 codebook is set to a first value, the terminal may generate a Type 3 codebook and transmit the Type 3 codebook to the base station. If the field that triggers a Type 3 codebook is set to a second value, the terminal may generate a Type 1 codebook or a Type 2 codebook and transmit the Type 1 codebook or a Type 2 codebook to the base station.

[0267] Meanwhile, if some DL-DCIs are not received from the base station, the terminal may interpret the bits of the HARQ response for a specific HARQ process as the original values ​​rather than the updated values ​​because it does not receive the PDSCH. The terminal may not receive a DL-DCI containing a toggled NDI. Since the terminal did not receive the PDSCH associated with the HARQ process indicated by the corresponding DL-DCI, it may not be able to decode the TB. Therefore, the terminal may retain the stored state of the HARQ response associated with the HARQ process indicated by the corresponding DL-DCI. That is, the state of the HARQ process known by the base station may differ from the state of the HARQ process known by the terminal.

[0268] Subsequently, the base station may transmit information to the terminal instructing it to transmit HARQ responses (e.g., HARQ codebook(s)) for all configured HARQ processes over PUCCH or PUSCH. In this case, the base station may misinterpret the HARQ response of the corresponding HARQ process. To resolve this issue, during the HARQ response feedback procedure, the terminal may transmit additional information to the base station in addition to the HARQ response.

[0269] In the proposed method, the NDI corresponding to the HPID can be transmitted along with a HARQ response. The HARQ process can correspond one-to-one with the NDI. The terminal can concatenate the bit sequence of the last NDI for the corresponding HARQ process with the bit sequence of the HARQ response. Here, the bit sequence of the HARQ response can be concatenated with the bit sequence of the NDI. Alternatively, the bit sequence of the HARQ response can be concatenated with the bit sequence of the NDI, and the concatenated bit sequence can be concatenated again with the HPID. The terminal can perform an encoding operation on the concatenated bit sequence and transmit the encoded bit sequence to the base station.

[0270] In another proposed method, the terminal may transmit an NFI for each GID. The GID may represent a PDSCH group and may correspond to a HARQ codebook index. For example, the terminal may concatenate a bit sequence of a HARQ response with a bit sequence of an NFI. Here, the bit sequence of the HARQ response may be concatenated with the bit sequence of the NFI. Alternatively, with respect to the GID, the bit sequence of the NFI may be concatenated with the bit sequence of the HARQ response, and the concatenated bit sequence may be concatenated again with the GID. The terminal may perform an encoding operation on the concatenated bit sequence and transmit the encoded bit sequence to the base station. HARQ responses associated with some HARQ processes may be transmitted along with the NDI.

[0271] According to the methods described above, the terminal may transmit "HARQ responses and NDI associated with the HARQ process" or "HARQ responses associated with the HARQ process." It may not be desirable for "HARQ responses associated with all HARQ processes to be transmitted" or "HARQ responses and NDI associated with all HARQ processes to be transmitted." This is because there are cases where it is difficult to apply the toggle of NDI to a specific HARQ process. For example, the base station may not transmit resource allocation information for the DL-SCH associated with the HARQ process. Alternatively, the base station may instruct the terminal to feed back the HARQ response at a time when it is not possible to process the HARQ response for the HARQ process (e.g., a time when the time corresponding to the N1 symbol has not elapsed since the reception of the DL-SCH). In this case, since the terminal cannot derive a valid HARQ response, the base station may ignore the HARQ response for the HARQ process. HARQ responses and / or NDIs for the relevant HARQ process may be unnecessary. If the characteristics of the HARQ process are shared between the base station and the terminal, unnecessary information may be omitted in the feedback procedure of the HARQ response.

[0272] In the feedback procedure for HARQ responses, the last PDSCH may be determined to correspond to a HARQ response bit that has not yet been updated in a given HARQ process (i.e., a HARQ response bit for a PDSCH scheduled prior to the last PDSCH) depending on the processing capability of the terminal (e.g., the time required to process the PDSCH, or N1 symbols indicated by RRC signaling). With respect to the HARQ response bits corresponding to the last PDSCH and the PDSCH prior to the last PDSCH in a given HARQ process, the HARQ response bits may be transmitted to the base station along with NDI. There may be HARQ response bits and / or NDIs associated with HARQ processes that are not reflected in the HARQ codebook, and useful information may not be transmitted to the base station for these HARQ processes. For these HARQ processes, in the HARQ codebook generation procedure, the terminal may match the full length of the HARQ codebook using a preset value (e.g., NACK, 0) shared between the base station and the terminal.

[0273] How to not distinguish between active and inactive carriers

[0274] The terminal can feed back HARQ responses without distinguishing between active and inactive carriers. DCI, MAC CE, or the expiration of a timer may indicate whether a carrier is active or inactive, and the size of the HARQ codebook may be determined by RRC signaling. Thus, the terminal can feed back a HARQ codebook (e.g., HARQ response) of the same size to the base station without relying on DCI. For a specific carrier, the HARQ response may be transmitted along with NDI. Therefore, the number of HARQ processes may be twice the number of existing HARQ processes.

[0275] Since the base station does not transmit PDSCH on a disabled carrier, the HARQ response and NDI may not be useful values ​​for the base station. Because DCI, MAC CE, or the expiration of a timer indicates whether the carrier is enabled or disabled, and the size of the HARQ codebook is determined by RRC signaling, the terminal may transmit a NACK as a HARQ response on a disabled carrier. The NDI can be set to a preset value (e.g., 0) or any value.

[0276] How to distinguish between active and inactive carriers

[0277] Active carriers can be distinguished from inactive carriers, and HARQ responses can be fed back. Since base stations do not perform scheduling operations on inactive carriers, the transmission of HARQ responses and NDIs may be unnecessary. Therefore, the size of the UCI on inactive carriers can be reduced.

[0278] In the proposed method, the terminal may feed back a HARQ response from an active carrier. That is, the terminal may not generate a HARQ response from an inactive carrier. HARQ responses may be generated for all HARQ processes. Alternatively, the HARQ response may be transmitted along with an NDI. That is, a HARQ response block (e.g., a HARQ codebook) may contain a HARQ response and an NDI. In the embodiments below, a HARQ response block may refer to a HARQ codebook containing a HARQ response bit and an NDI associated with that HARQ response bit. Here, the placement order and / or concatenation order of the HARQ response and NDI within the HARQ response block may be determined according to a pre-set rule (e.g., scheduling order, order of HARQ process identifiers). The placement order and / or concatenation order of the HARQ response and NDI within the HARQ response block may be shared in advance between the base station and the terminal. In this case, a signaling procedure to indicate the HARQ response and the placement and / or connection order of NDIs may be unnecessary.

[0279] In another proposed method, the terminal can generate a HARQ response block containing a HARQ response and an NDI on an active carrier. The terminal can generate a HARQ response block containing only a HARQ response on an inactive carrier. Here, the placement order and / or concatenation order of the HARQ response and NDI within the HARQ response block can be determined according to a preset rule. The placement order and / or concatenation order of the HARQ response and NDI within the HARQ response block can be shared in advance between the base station and the terminal. In this case, signaling to inform the placement order and / or concatenation order of the HARQ response and NDI may be unnecessary. The terminal can reduce the size of each of the HARQ response and NDI included in the HARQ response block. Thus, the polarity coding rate can be reduced, and the error rate at the base station can be reduced.

[0280] Method for generating HARQ responses

[0281] The following embodiments may be applied to a Type 3 codebook. That is, in the following embodiments, the HARQ codebook may refer to a Type 3 codebook. A DCI scheduling PDSCH or PUSCH may include information instructing the transmission of HARQ responses for all HARQ processes. A terminal may map HARQ responses for all HARQ processes (e.g., HARQ codebooks or HARQ response bits) to an uplink channel on all carriers configured by RRC signaling. HARQ responses for all HARQ processes may be arranged according to a pre-set order (e.g., a scheduling order or an order of HARQ process identifiers). For example, within a HARQ codebook, HARQ response bits may be arranged according to the scheduling order of the data channel (e.g., PDSCH) associated with the corresponding HARQ response bits.

[0282] Method for generating a HARQ response (e.g., HARQ codebook) from a preset carrier

[0283] The following embodiments may be applied to a Type 3 codebook. That is, in the following embodiments, the HARQ codebook may refer to a Type 3 codebook. The size of the HARQ codebook may be set by RRC signaling. Depending on the time domain resource allocation (TDRA) index and K1 set by RRC signaling, the order of placement of bits within the HARQ codebook may follow the allocation order of PDSCH. The size of the HARQ codebook may be independent of the number of HARQ processes. The number of HARQ processes may be greater than the number of bits in the HARQ codebook. According to the conventional method, it may be difficult to place the bits of HARQ responses for all HARQ processes within a preset carrier into a single HARQ codebook.

[0284] In the proposed method, a terminal on a preset carrier can generate a HARQ codebook by arranging HARQ responses according to HARQ process identifiers (e.g., HPN (HARQ process number), HPID). For example, if x HARQ processes exist, x HARQ response bits can be arranged within the HARQ codebook according to the order of the x HARQ processes. This operation may be independent of the TDRA index set on the terminal.

[0285] The base station may transmit information to the terminal instructing it to generate a separate HARQ codebook having a semi-fixed size. In this case, the methods for generating the HARQ codebook may differ from each other. Even when the HARQ codebook is simply generated according to the methods described above, the HARQ codebook may be generated according to two or more methods.

[0286] A HARQ codebook can be generated in one way. A single HARQ codebook may include two or more HARQ sub-codebooks. The HARQ sub-codebooks may have features according to the prior art (e.g., features determined by TDRA). In the case of a HARQ process where the transmission time (K1) of the HARQ codebook is a non-numerical value (e.g., a non-numerical value), up to 1 bit may be appended to the HARQ codebook.

[0287] In the proposed method, a terminal can concatenate HARQ subcodebooks in a preset carrier. If there are HARQ process(s) that do not belong to a HARQ subcodebook, the terminal can generate a HARQ codebook comprising the concatenated HARQ subcodebooks and bit(s) preset for the corresponding HARQ process(s). Here, the HARQ subcodebooks included in the HARQ codebook can be generated based on prior art.

[0288] For example, the number of HARQ processes may be x, and the number of HARQ subcodebooks may be two or more. A single HARQ process may not necessarily belong to a specific HARQ subcodebook. The size of a HARQ subcodebook may be determined based on the TDRA and additional bit(s) (e.g., 0 or 1) indicated by upper-layer signaling. Thus, the base station and the terminal can know the size of each HARQ subcodebook. A HARQ codebook may include contiguous HARQ subcodebooks. Additionally, a HARQ codebook may include HARQ responses useful to the base station. Even if there are HARQ process(s) that do not belong to a HARQ subcodebook, the terminal can generate a HARQ codebook based on the total number of HARQ processes. Thus, the terminal can append a value (e.g., NACK) pre-set between the base station and the terminal to the HARQ codebook.

[0289] When carrier aggregation is established, the base station can enable and disable specific carrier(s). A carrier may have one or more bandwidth parts (BWPs). The base station can enable one of the one or more BWPs. In the enabled BWP, the TDRA can be determined by RRC signaling. According to the prior art, in order to generate a HARQ codebook containing a HARQ response from a disabled carrier, one of the BWPs (e.g., firstActiveDownlinkBWP ) can serve as a standard.

[0290] In the proposed method, when a carrier is disabled, HARQ responses may be arranged in order of HARQ process identifiers (e.g., HARQ process ID or HARQ process number) regardless of BWP (e.g., regardless of TDRA). The base station may not assign PDSCH to the disabled carrier. Thus, the HARQ codebook may contain only NACK. In the proposed method, the terminal may generate a HARQ response block containing HARQ responses and NDIs from all carriers, and may map the HARQ response block to PUCCH or PUSCH.

[0291] In another proposed method, the terminal may generate a HARQ response block containing a HARQ response and an NDI from an active carrier, and the terminal may generate a HARQ response block containing only a HARQ response (e.g., a NACK) from a deactivated carrier. That is, the HARQ response block from a deactivated carrier may not contain an NDI.

[0292] NDI and HARQ response placement method

[0293] The following embodiments may be applied to a Type 3 codebook. That is, in the following embodiments, the HARQ codebook may refer to a Type 3 codebook. The arrangement order of the bit sequences of the HARQ response in the carrier may be determined. The terminal may generate a HARQ codebook by concatenating the bit sequences of the HARQ response based on the order of the carrier (e.g., serving cell index).

[0294] In the proposed method, bit sequences of HARQ responses and NDIs can be generated per carrier, and the terminal can generate a HARQ codebook by concatenating the bit sequence of the HARQ response with the bit sequence of the NDI. For the arrangement of HARQ responses and NDIs, a conventional method for generating a HARQ codebook or an arrangement method according to HPN may be used. This operation may also be applied to carriers where NDI is not used. For example, the terminal can generate a HARQ codebook based on the method described in Table 6 below.

[0295]

[0296] Alternatively, the terminal may generate a HARQ codebook based on the method described in Table 7 below. The method of generating the HARQ codebook in an active carrier may differ from the method of generating the HARQ codebook in a deactivated carrier.

[0297]

[0298] In another proposed method, the HARQ response and NDI for a HARQ process can be configured as bit pairs. In the carrier, the bit pair [HARQ response, NDI] can be configured according to a conventional method for generating a HARQ codebook or a configuration method according to HPN. That is, the conventional method for generating a HARQ codebook or a configuration method according to HPN can be applied on a bit pair basis. This operation can be applied to a method for generating a HARQ response block containing HARQ responses and NDIs for all HARQ processes. For example, the terminal can generate a HARQ codebook based on the method described in Table 8 below. In a deactivated carrier, the HARQ response block can be composed of only HARQ responses instead of bit pairs.

[0299]

[0300] Alternatively, the terminal may generate a HARQ codebook based on the method described in Table 9 below. The method of generating the HARQ codebook in an active carrier may differ from the method of generating the HARQ codebook in a deactivated carrier.

[0301]

[0302] In another proposed method, a bit sequence of HARQ responses for all carriers can be arranged, and a bit sequence of NDI for all carriers can be arranged. Then, the bit sequence of HARQ responses can be concatenated with the bit sequence of NDI. This operation can be performed according to a conventional method for generating a HARQ codebook or a method of arrangement according to HPN. The conventional method for generating a HARQ codebook or a method of arrangement according to HPN may also be applied to carriers in which NDI is omitted. For example, a terminal can generate a HARQ codebook based on the method described in Table 10 below.

[0303]

[0304] For example, the terminal can generate a HARQ codebook based on the method described in Table 11 below.

[0305]

[0306] UL-DCI instructing PUCCH transmission

[0307] UL-DCI may include a field instructing a PUCCH transmission. Based on the field included in the UL-DCI, the terminal may transmit a UCI (e.g., a CSI or HARQ response) via PUCCH.

[0308] UL-DCI may include a field that directs the performance of CSI reporting (hereinafter referred to as the "CSI reporting field"). The CSI reporting field may consist of one or more bits. A single bit included in the CSI reporting field may correspond to one or more CSI reports. A single CSI report may be one or more combinations of CQI (channel quality information), PMI (precoding matrix indicator), CRI (CSI-RS resource indicator), SSBRI (SS / PBCH resource block indicator), LI (layer indicator), RI (rank indicator), and L1-RSRP (reference signal received power).

[0309] UL-DCI may include a field indicating the reporting of a HARQ response (hereinafter referred to as the "HARQ reporting field"). The HARQ reporting field may consist of one or more bits. A single bit included in the HARQ reporting field may correspond to one or more HARQ codebooks (e.g., HARQ responses). A single HARQ codebook may consist of one or more HARQ response bits. The base station and the terminal may know in advance the mapping relationship between the HARQ response bit(s) included in the HARQ codebook and the HARQ process identifier.

[0310] A terminal receiving a UL-DCI can identify the transmission resources of the PUSCH based on the information elements contained in the UL-DCI and determine whether to multiplex the UCI and UL-SCH. By multiplexing the UCI with the UL-SCH, the terminal can transmit the UCI and UL-SCH using a single channel (e.g., PUSCH). If the UCI is not multiplexed with the UL-SCH, the terminal can transmit the UCI through the PUCCH and the UL-SCH through the PUSCH. Here, the PUCCH and PUSCH may be located on the same symbol, and the frequency resources of the PUCCH may differ from the frequency resources of the PUSCH. Consequently, the power backoff applied to the terminal's power amplifier may increase, and consequently, the uplink coverage may decrease.

[0311] In order to satisfy frequency regulations in a communication system operating in an unlicensed band, PUSCH and PUCCH may each be configured in an interlaced form. This operation may mean that PUSCH is multiplexed with PUCCH in the frequency domain. Even in this case, power backoff may be required at the terminal's power amplifier. In the unlicensed band, the channel to which UCI is mapped may be different from the channel to which UL-SCH is mapped. UCI may be transmitted via PUCCH, and UL-SCH may be transmitted via PUSCH.

[0312] UL-DCI including PRI (PUCCH resource index)

[0313] UL-DCI may include a field indicating a PRI (hereinafter referred to as the "PRI field"). If the UCI consists of 1 bit or 2 bits, the PUCCH resource may be determined by the index of the CCE mapped to the UL-DCI as well as the PRI indicated by the UL-DCI. If the UCI consists of 3 bits or more, the PUCCH resource may be determined based on the number of bits in the UCI and the PRI indicated by the UL-DCI. Here, the PUCCH resource may be the symbol(s) occupied by the PUCCH within a slot in the time domain. The slot in which the PUCCH is transmitted may refer to the slot indicated by the resource allocation information of the PUCCH included in the UL-DCI.

[0314] The MCS level applied to a UCI may vary depending on the size of the UCI. Since the channel coding method differs depending on the size of the UCI, the MCS level applied to the UCI may vary. If the size of the UCI is less than 3 bits, the first MCS level may be applied to the UCI. If the size of the UCI is 3 bits or more and less than 12 bits, the second MCS level may be applied to the UCI. If the size of the UCI is 12 bits or more, the third MCS level may be applied to the UCI.

[0315] The base station can set the MCS level applicable to the UCI to the terminal using upper-layer signaling. Therefore, the terminal can map the UCI to the PUCCH using the MCS level set by the upper-layer signaling. Alternatively, the base station can transmit a UL-DCI to the terminal that includes information indicating the MCS level applicable to the UL-SCH. The terminal can derive the MCS level applicable to the UCI by applying an offset to the MCS level indicated by the UL-DCI. Here, the offset may be indicated by the corresponding UL-DCI. Alternatively, the offset may be set by the upper-layer signaling. In an NR communication system, the offset applied to the MCS level may vary depending on the type of UCI. For example, the offset may be defined as betaOffsetACK, betaOffsetCSI-Part1, or betaOffsetCSI-Part2 depending on the type of UCI.

[0316] Meanwhile, UL-DCI may include a UL-SCH indicator, and the UL-SCH indicator may indicate whether UL-SCH is mapped to PUSCH. If the UL-SCH indicator indicates that UL-SCH is not mapped to PUSCH, the terminal may transmit only PUCCH. On the other hand, if the UL-SCH indicator indicates that UL-SCH is mapped to PUSCH, the terminal may transmit PUSCH and PUCCH in the same slot. The time resource of PUCCH indicated by the PRI may overlap with the time resource of PUSCH indicated by the UL-DCI. Alternatively, the time resource of PUCCH indicated by the PRI may not overlap with the time resource of PUSCH indicated by the UL-DCI.

[0317] If the time resources of PUCCH overlap with the time resources of PUSCH, the base station may configure the frequency resources of PUCCH to be different from the frequency resources of PUSCH and transmit frequency resource information for each of PUCCH and PUSCH to the terminal. That is, the frequency resources indicated by the frequency resource information of PUCCH may be different from the frequency resources indicated by the frequency resource information of PUSCH. The LBT subband in which PUCCH is transmitted may be included in the LBT subband(s) in which PUSCH is transmitted. In the LBT subband in which PUCCH is transmitted, the frequency resources corresponding to the interlacing of PUCCH may be different from the frequency resources corresponding to the interlacing of PUSCH.

[0318] It may be defined in the technical specifications that the operation of transmitting only PUCCH based on UL-DCI is not supported. If UL-DCI indicates that UL-SCH should not be mapped to PUSCH, the terminal may ignore the PRI field included in the said UL-DCI.

[0319] UCI transmission method when multi-PUSCH is assigned

[0320] The base station may transmit a single UL-DCI containing resource allocation information for two or more UL-SCHs (e.g., PUSCHs) to the terminal. This operation may be performed when a large amount of UL data exists at the terminal. According to this operation, the probability of successful transmission of UL data may be increased.

[0321] A UL-DCI format containing resource allocation information for multiple PUSCHs can be distinguished from a UL-DCI format containing resource allocation information for a single PUSCH. A base station may inform a terminal of the UL-DCI format containing resource allocation information for multiple PUSCHs and / or the UL-DCI format containing resource allocation information for a single PUSCH using upper-layer signaling. Depending on the configuration of the base station, the terminal may perform search operations for two or more UL-DCI formats in a single search space. In this case, one or more UL-DCIs may be mapped in the same search space.

[0322] In the PUSCH allocation procedure, the base station may transmit information to the terminal instructing the multiplexing of the UCI (e.g., CSI or HARQ response) and the UL-SCH. Alternatively, in the PUSCH allocation procedure, the base station may transmit "information instructing the transmission of the UCI (e.g., CSI or HARQ response) on the PUCCH and the transmission of the UL-SCH on the PUSCH" to the terminal. Here, the PUCCH and PUSCH may be FDMed in the same symbol.

[0323] The base station may transmit to the terminal location information of the PUSCH that is multiplexed with the UL-SCH by the UCI (e.g., the k-th PUSCH among multiple PUSCHs assigned by the UL-DCI). Alternatively, the location information of the PUSCH that is multiplexed with the UL-SCH by the UCI may be defined in the technical specifications. k may be a natural number.

[0324] Regardless of the type of UCI, a field indicating the location information of the PUSCH that the UCI multiplexes with the UL-SCH may be included in the UL-DCI. Alternatively, the field indicating the location information of the PUSCH that the UCI multiplexes with the UL-SCH may be configured differently depending on the type of the UCI. For example, the PUSCH to which the HARQ response is mapped may be different from the PUSCH to which the CSI is mapped. In this case, the UL-DCI may include a field indicating the time resource of the HARQ response (e.g., the PUSCH to which the HARQ response is mapped) and a field indicating the time resource of the CSI (e.g., the PUSCH to which the CSI is mapped). The field indicating the time resource of the HARQ response may be distinguished from the field indicating the time resource of the CSI.

[0325] How the base station informs the time resources for UCI mapping

[0326] In the proposed method, the UL-DCI may include a field (hereinafter referred to as the "UCI mapping instruction field") indicating the location information of the PUSCH to which the UCI (e.g., HARQ response and / or CSI) is mapped (e.g., the k-th PUSCH among a plurality of PUSCHs assigned by the UL-DCI). The UCI mapping instruction field may be an index indicating the PUSCH. For example, if the UL-DCI assigns k PUSCHs, the size of the UCI mapping instruction field included in the corresponding UL-DCI is It may be a bit. If a specific field included in the UL-DCI triggers a mapping operation of the UCI, the terminal can identify a PUSCH in which the UCI is multiplexed based on a combination of the specific field included in the UL-DCI and a field indicating the time resource to which the UCI is mapped. If a specific field included in the UL-DCI does not trigger a mapping operation of the UCI, the terminal can ignore the field in the UL-DCI indicating the time resource to which the UCI is mapped.

[0327] The methods described above may be applied when the UCI is multiplexed with the UL-SCH and transmitted via the PUSCH. The methods described above may not be applied when the PUCCH mapped to the UCI is transmitted together with the PUSCH.

[0328] In the proposed method, UL-DCI can indicate the slot to which UCI is mapped.

[0329] UCI can be transmitted via PUCCH. PUCCH resources can be indicated by UL-DCI. For example, PUCCH resources can be indicated by an "explicit method" or a "combination of an explicit method and an implicit method." The methods described above may not indicate the slot to which PUCCH is transmitted. In this case, the slot to which PUCCH is transmitted may be indicated by another method. In the proposed method, a specific field included in the UL-DCI may indicate the slot to which PUCCH is transmitted. The slot to which PUCCH is transmitted may be one of the slots to which PUCCH(s) are assigned.

[0330] A PUSCH can occupy a small number of symbols. Therefore, even when UL-DCI schedules k PUSCHs, the k PUSCHs may be mapped to k or fewer slots. The number of slots to which the k PUSCHs are mapped can change dynamically, and the size of the UL-DCI field can change. Providing a relative index of the slot may not be appropriate to indicate the slot in which the UCI is transmitted. Here, the relative index of the slot may indicate the slot in which the UCI (or PUCCH) is transmitted among the slots occupied by the PUSCHs. The base station may inform the terminal of the PUSCH in which the UCI is transmitted. In this case, the terminal may transmit the PUCCH based on the time resource derived from the PUCCH resource index within the slot occupied by the PUSCH indicated by the base station.

[0331] According to the two methods described above, the terminal can determine whether to transmit the UCI based on a combination of two fields included in the UL-DCI. Additionally, if it is determined that the UCI is to be transmitted, the terminal can determine the transmission time resource of the UCI based on a combination of two fields included in the UL-DCI. According to another method, the terminal can determine the transmission time resource of the UCI based on a single field included in the UL-DCI. For example, the terminal may use a field indicating the time resource to which the UCI is mapped instead of a field that triggers the transmission of the UCI. The UL-DCI may include a field that triggers the transmission of the UCI and a field indicating the time resource to which the UCI is mapped.

[0332] In the proposed method, UL-DCI includes a field indicating an index, which can indicate both whether the UCI transmission is triggered and the time resource to which the UCI is mapped.

[0333] According to the method described above, the field required to indicate UCI transmission can be reduced. Therefore, the size of the field required to indicate UCI transmission within the UL-DCI can be reduced. For example, an index set to a first value may indicate that UCI transmission is not triggered, and an index set to another value may indicate the "location of the PUSCH where UCI transmission is triggered and the UCI is multiplexed." For example, if the UL-DCI schedules k PUSCHs, the size of the index included in the UL-DCI It could be a bit.

[0334] The time resource to which the UCI is mapped can be determined based on what is defined in the technical specification. In this case, the UL-DCI may not include a field indicating the transmission time of the UCI. The UCI can be transmitted via the PUSCH specified in the technical specification. Therefore, the size of the UL-DCI can be reduced.

[0335] How to multiplex UCI with UL-SCH

[0336] If the UL-DCI schedules the transmission of two or more PUSCHs and the UL-DCI indicates that a UCI transmission is triggered, the terminal can map the UCI to a specific PUSCH. For example, if the UL-DCI schedules the transmission of k PUSCHs (e.g., PUSCH #0, …, PUSCH #(k-1)), the terminal can map the UCI to PUSCH #(k-1) or PUSCH #(k-2). The terminal can transmit a PUSCH after performing an LBT operation. The probability of success of an LBT operation for each of the k PUSCHs may increase in chronological order. This is because if the terminal succeeds in an LBT operation for the current PUSCH, it can transmit the next PUSCH of the current PUSCH. When UL-DCI schedules the transmission of k PUSCHs (e.g., PUSCH #0, …, PUSCH #(k-1)), the transmission probability of PUSCH #(k-1) among the k PUSCHs may be the highest.

[0337] Additionally, when UL-DCI schedules the transmission of k PUSCHs (e.g., PUSCH #0, …, PUSCH #(k-1)), the transmission probability of PUSCH #0 among the k PUSCHs may be the lowest. Therefore, PUSCH #0 may have a short length. The terminal can perform an LBT operation starting from the slot where PUSCH #0 is located, and can start PUSCH transmission if the LBT operation is successful. If the LBT operation fails, the PUSCH may not be transmitted. Therefore, many symbols (e.g., many REs) may be allocated for PUSCH #(k-1). Since rate matching is performed for UL-SCH when UCI is multiplexed with UL-SCH, it may be desirable for UCI to be mapped to PUSCH #(k-1), which has a relatively large size.

[0338] Meanwhile, among the PUSCHs allocated by the base station, the last PUSCH can be multiplexed with the SRS in the time domain. The SRS can be transmitted after the last PUSCH. In this case, the PUSCH with the longest length among the PUSCHs allocated by the base station may not be the last PUSCH. That is, the length of the last PUSCH (e.g., the number of symbols) may be shorter than the length of the PUSCH preceding the last PUSCH. The UCI can be multiplexed with the UL-SCH in the PUSCH preceding the last PUSCH.

[0339] How to map UCI to PUCCH

[0340] The base station may transmit a UL-DCI to the terminal that directly or indirectly indicates a PUCCH resource. The terminal may receive the UL-DCI from the base station and identify the PUCCH resource based on the UL-DCI. The slot in which the PUCCH is transmitted may be a slot in which a specific PUCCH is transmitted as defined in the technical specifications.

[0341] The slot in which the PUCCH is transmitted may be a slot where the probability of success for the LBT operation performed by the terminal is high. If PUCCHs are allocated across multiple slots, the PUCCH transmission may not be performed in the first slot among the multiple slots. It may be preferable for the PUCCH transmission to be performed in the last slot or the slot preceding the last slot among the multiple slots. The terminal may determine a single slot in which the PUCCH is transmitted based on the details defined in the technical specifications. The terminal may transmit a UCI to the base station using the PUCCH resources within a pre-configured slot.

[0342] PUCCH resource configuration method

[0343] The base station may transmit a set of resources or a list of resources for PUCCH to the terminal using an RRC message (e.g., upper layer signaling). Time resources, frequency resources, and sequence resources for PUCCH may be indicated by the field(s) below. The terminal may derive PUCCH resources based on an index included in the DCI received from the base station.

[0344] PUCCH's time resources

[0345] Start symbol field

[0346] The start symbol field can represent the "start symbol of PUCCH" or the "start and end symbols of PUCCH" as a single index. Based on the index indicated by the start symbol field, the terminal can check the number of PUCCH start symbols and symbols belonging to PUCCH.

[0347] Length field

[0348] The length field can represent the number of symbols occupied by PUCCH as a single index.

[0349] PUCCH frequency resources

[0350] RB (resource block) allocation field

[0351] To satisfy frequency regulations in the unlicensed band, PUCCH may have an interlaced structure existing across the entire bandwidth. Therefore, the RB allocation field may represent the interlaced index of PUCCH.

[0352] Meanwhile, if a single BWP (e.g., active BWP) is configured to occupy multiple LBT subbands, the PUCCH may be mapped to a single LBT subband. To indicate the RB to which the PUCCH is assigned, the base station may inform the terminal of the LBT subband to which the PUCCH interlace belongs, as well as the interlace index of the PUCCH. Thus, the RB assignment field may represent not only the interlace index of the PUCCH but also the index of the LBT subband (e.g., RB set) associated with the interlace.

[0353] PUCCH sequence resources

[0354] PUCCH DM-RS resource field

[0355] The terminal can derive DM-RS resources based on the PUCCH DM-RS resource field. If PUCCH DM-RS is generated based on a ZC (Zadoff-Chu) sequence, the terminal can generate a ZC sequence based on the base sequence, and a cyclic shift can be applied to the generated ZC sequence. The base station can inform each terminal of the cyclic shift. The terminal can map the sequence to a resource grid defined based on point A.

[0356] If PUCCH DM-RS is generated based on a PN (Pseudo Random Noise) sequence, the terminal can initialize the PN sequence and map the PN sequence (e.g., the initialized PN sequence) to an RE defined relative to point A. The terminal can know the initial value of the PN sequence based on information indicated by a field received from the base station. For example, in an NR communication system, the base station [requires] the scrambling value required for initializing the PN sequence (e.g., dataScramblingIdentityPUSCH ) This can be communicated to the terminal using upper layer signaling. Alternatively, the terminal can determine the information required for initializing the PN sequence based on cell identification information (e.g., cell ID). The terminal can initialize the PN sequence based on a combination of information received from the base station (e.g., scrambling value, cell identification information) and the terminal's identification information (e.g., RNTI).

[0357] PUCCH OCC field

[0358] When the size of the UCI transmitted via PUCCH is 1 bit or 2 bits, the UCI can be spread in the frequency domain based on OCC. In this case, the base station can transmit a PUCCH OCC field indicating an OCC index to each of the terminals.

[0359] The methods according to the present invention may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, etc., either alone or in combination. The program instructions recorded on the computer-readable medium may be those specifically designed and configured for the present invention, or they may be those known and available to those skilled in the art of computer software.

[0360] Examples of computer-readable media include hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, and flash memory. Examples of program instructions include machine code, such as that produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter, etc. The aforementioned hardware devices may be configured to operate as at least one software module to perform the operation of the present invention, and vice versa.

[0361] Although the invention has been described with reference to the above embodiments, those skilled in the art will understand that various modifications and changes can be made to the invention without departing from the spirit and scope of the invention as described in the following claims.

Claims

Claim 1 A method of a terminal comprising: receiving from a base station a first DCI (downlink control information) containing first scheduling information of a first PDSCH (physical downlink shared channel); performing a first receiving operation for the first PDSCH based on the first DCI; receiving from the base station a second DCI containing a HARQ (hybrid automatic repeat request) instruction field; identifying HARQ processes indicated by the value of the HARQ instruction field; generating a HARQ codebook containing a first HARQ response bit for the first PDSCH associated with the HARQ processes; and transmitting uplink control information (UCI) containing the HARQ codebook to the base station. Claim 2 A method of a terminal according to claim 1, further comprising: receiving a third DCI from the base station including second scheduling information of the second PDSCH; and performing a second receiving operation for the second PDSCH based on the third DCI, wherein the HARQ codebook further comprises a second HARQ response bit for the second PDSCH associated with the HARQ processes. Claim 3 A method of a terminal according to claim 2, wherein the first HARQ response bit and the second HARQ response bit are concatenated within the HARQ codebook according to the order of the HARQ process number. Claim 4 A method of a terminal according to claim 1, further comprising the step of receiving a radio resource control (RRC) message from a base station, the message including first information regarding a plurality of HARQ codebooks and second information regarding a plurality of HARQ processes associated with each of the plurality of HARQ codebooks. Claim 5 A method of a terminal according to claim 1, wherein the UCI is spread by applying an orthogonal cover code (OCC) to consecutive subcarriers in the frequency domain, and the length of the OCC is 2. Claim 6 A method of a base station comprising: transmitting a first DCI (downlink control information) to a terminal that includes first scheduling information of a first PDSCH (physical downlink shared channel); transmitting the first PDSCH to the terminal based on the first DCI; transmitting a second DCI to the terminal that includes a HARQ instruction field indicating HARQ (hybrid automatic repeat request) processes; and receiving an uplink control information (UCI) from the terminal that includes a HARQ codebook that includes a first HARQ response bit for the first PDSCH associated with the HARQ processes. Claim 7 A method of a base station according to claim 6, further comprising: a step of transmitting a third DCI containing second scheduling information of a second PDSCH to the terminal; and a step of transmitting the second PDSCH to the terminal based on the third DCI, wherein the HARQ codebook further comprises a second HARQ response bit for the second PDSCH associated with the HARQ processes. Claim 8 A method of a base station according to claim 7, wherein the first HARQ response bit and the second HARQ response bit are concatenated within the HARQ codebook in the order of the HARQ process number. Claim 9 A method of a base station according to claim 6, further comprising the step of transmitting a radio resource control (RRC) message to a terminal, the message including first information regarding a plurality of HARQ codebooks and second information regarding a plurality of HARQ processes associated with each of the plurality of HARQ codebooks. Claim 10 A base station method according to claim 6, wherein the UCI is spread by applying an orthogonal cover code (OCC) to consecutive subcarriers in the frequency domain, and the length of the OCC is 2.

Images