Terminal, base station, communication system and communication method

Abstract

To report multiple HARQ (Hybrid automatic repeat request)-ACKs to a base station in inter-terminal direct communication.SOLUTION: A terminal comprises: a reception unit that receives from a base station first information associated with one codebook for transmitting a response related to retransmission control which is applied to transmission and reception in downlink, and second information associated with one or more codebooks for transmitting a response related to retransmission control which is applied to transmission and reception in downlink; and a transmission unit that, when the second information is set, transmits a response related to retransmission control which is applied to transmission and reception in a side-link to the base station using the codebook of a type determined on the basis of the first information .SELECTED DRAWING: Figure 15

Description

[Technical Field]

[0001] The present invention relates to a terminal, a base station, a communication system, and a communication method in a wireless communication system. [Background technology]

[0002] In LTE (Long Term Evolution) and successor systems to LTE (e.g., LTE-A (LTE Advanced) and NR (New Radio) (also known as 5G)), D2D (Device to Device) technology is being considered, which allows terminals to communicate directly with each other without going through a base station (e.g., Non-Patent Document 1).

[0003] D2D reduces traffic between terminals and base stations and enables communication between terminals even when the base station becomes unavailable due to a disaster or other reason. Although 3GPP (3rd Generation Partnership Project) refers to D2D as a "sidelink," the more general term D2D is used in this specification. However, in the description of the embodiments described below, sidelink is also used as needed.

[0004] D2D communication is broadly divided into D2D discovery (also referred to as D2D discovery) for discovering other terminals with which communication is possible, and D2D communication (also referred to as D2D direct communication, D2D communication, terminal-to-terminal direct communication, etc.) for direct communication between terminals. Hereinafter, when there is no particular distinction between D2D communication, D2D discovery, etc., they will be simply referred to as D2D. Furthermore, signals transmitted and received in D2D will be referred to as D2D signals. Various use cases for services related to Vehicle to Everything (V2X) in NR are being studied (for example, Non-Patent Document 2). [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] 3GPP TS 38.211 V16.2.0(2020-06) [Non-patent document 2] 3GPP TR 22.886 V15.1.0(2017-03) Summary of the Invention [Problem to be solved by the invention]

[0006] In NR sidelink Release 16, a terminal can report a sidelink HARQ (Hybrid automatic repeat request)-ACK to a base station via uplink. Furthermore, when multiplexing HARQ-ACK bits in multiple sidelinks, a HARQ-ACK codebook can be used.

[0007] Here, multiple HARQ-ACK codebooks may be configured in the downlink. When multiple HARQ-ACK codebooks are configured, it is unclear which HARQ-ACK codebook a terminal should use when reporting to a base station that multiplexes HARQ-ACK bits in multiple sidelinks.

[0008] The present invention has been made in view of the above points, and has as its object to report multiple HARQ (Hybrid automatic repeat request)-ACKs to a base station in direct communication between terminals. [Means for solving the problem]

[0009] According to the disclosed technology, there is provided a terminal having a receiver that receives from a base station first information regarding one codebook for transmitting a response related to retransmission control applied to transmission and reception in downlink and second information regarding one or more codebooks for transmitting a response related to retransmission control applied to transmission and reception in downlink, and a transmitter that, when the second information is set, transmits a response related to retransmission control applied to transmission and reception in sidelink to the base station using a codebook of a type determined based on the first information. [Effects of the Invention]

[0010] According to the disclosed technology, in direct communication between terminals, multiple HARQ (Hybrid automatic repeat request)-ACKs can be reported to a base station. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram for explaining V2X. [Figure 2] FIG. 1 is a diagram for explaining an example (1) of a V2X transmission mode. [Figure 3] FIG. 10 is a diagram for explaining an example (2) of a V2X transmission mode. [Figure 4] FIG. 10 is a diagram illustrating an example (3) of a V2X transmission mode. [Figure 5] FIG. 10 is a diagram illustrating an example (4) of a V2X transmission mode. [Figure 6] FIG. 10 is a diagram illustrating an example (5) of a V2X transmission mode. [Figure 7] FIG. 1 is a diagram for explaining an example (1) of a V2X communication type. [Figure 8] FIG. 10 is a diagram for explaining an example (2) of a V2X communication type. [Figure 9] FIG. 10 is a diagram for explaining an example (3) of a V2X communication type. [Figure 10] FIG. 1 is a sequence diagram showing an operation example (1) of V2X. [Figure 11]FIG. 10 is a sequence diagram showing an operation example (2) of V2X. [Figure 12] FIG. 10 is a sequence diagram showing an operation example (3) of V2X. [Figure 13] FIG. 10 is a sequence diagram showing an operation example (4) of V2X. [Figure 14] A diagram showing an example of an operation for reporting multiplexed HARQ-ACK. [Figure 15] 10 is a flowchart illustrating an example of an operation for reporting a HARQ-ACK according to an embodiment of the present invention. [Figure 16] 2 is a diagram illustrating an example of a functional configuration of a base station 10 according to an embodiment of the present invention. [Figure 17] FIG. 2 is a diagram illustrating an example of a functional configuration of a terminal 20 according to the embodiment of the present invention. [Figure 18] 2 is a diagram illustrating an example of a hardware configuration of a base station 10 or a terminal 20 according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the embodiment described below is an example, and the embodiment to which the present invention is applied is not limited to the following embodiment.

[0013] In the operation of the wireless communication system according to the embodiment of the present invention, existing technologies are used as appropriate. However, the existing technologies are, for example, but not limited to, the existing LTE. Furthermore, the term "LTE" used in this specification has a broad meaning including LTE-Advanced, a system subsequent to LTE-Advanced (e.g., NR), or a wireless LAN (Local Area Network), unless otherwise specified.

[0014] Furthermore, in the embodiments of the present invention, the duplex method may be a TDD (Time Division Duplex) method, an FDD (Frequency Division Duplex) method, or other methods (for example, Flexible Duplex, etc.).

[0015] Furthermore, in the embodiments of the present invention, when radio parameters and the like are "configured," it may mean that predetermined values are pre-configured, or that radio parameters notified from the base station 10 or the terminal 20 are set.

[0016] Figure 1 is a diagram for explaining V2X. 3GPP is studying the realization of V2X (Vehicle to Everything) or eV2X (enhanced V2X) by extending D2D functions, and is currently working on specifications. As shown in Figure 1, V2X is part of ITS (Intelligent Transport Systems) and is a collective term for V2V (Vehicle to Vehicle), which refers to a form of communication between vehicles; V2I (Vehicle to Infrastructure), which refers to a form of communication between vehicles and roadside units (RSUs) installed on the side of the road; V2N (Vehicle to Network), which refers to a form of communication between vehicles and ITS servers; and V2P (Vehicle to Pedestrian), which refers to a form of communication between vehicles and mobile devices carried by pedestrians.

[0017] Additionally, 3GPP is studying V2X using LTE or NR cellular communications and device-to-device communications. V2X using cellular communications is also called cellular V2X. NR V2X is being studied to achieve high capacity, low latency, high reliability, and quality of service (QoS) control.

[0018] It is expected that future studies of LTE or NR V2X will be conducted beyond the 3GPP specifications, including ensuring interoperability, reducing costs through implementation of higher layers, using or switching between multiple RATs (Radio Access Technologies), complying with regulations in each country, and methods for acquiring, distributing, managing databases, and using data from LTE or NR V2X platforms.

[0019] In the embodiments of the present invention, a communication device is mainly assumed to be mounted on a vehicle, but the embodiments of the present invention are not limited to this. For example, the communication device may be a terminal held by a person, a device mounted on a drone or an aircraft, a base station, an RSU, a relay station (relay node), a terminal with scheduling capability, etc.

[0020] Note that SL (Sidelink) may be distinguished from UL (Uplink) or DL (Downlink) based on any one or a combination of the following 1) to 4). SL may also be called by other names. 1) Time domain resource allocation 2) Frequency domain resource allocation 3) Reference synchronization signal (including SLSS (Sidelink Synchronization Signal)) 4) Reference signal used for path loss measurement for transmission power control

[0021] Furthermore, with regard to SL or UL Orthogonal Frequency Division Multiplexing (OFDM), any of CP-OFDM (Cyclic-Prefix OFDM), DFT-S-OFDM (Discrete Fourier Transform - Spread - OFDM), non-transform precoded OFDM, and transform precoded OFDM may be applied.

[0022] In the LTE SL, Mode 3 and Mode 4 are defined for SL resource allocation to terminal 20. In Mode 3, transmission resources are dynamically allocated by DCI (Downlink Control Information) transmitted from base station 10 to terminal 20. Also, in Mode 3, SPS (Semi Persistent Scheduling) is possible. In Mode 4, terminal 20 autonomously selects transmission resources from a resource pool.

[0023] The term "slot" in the embodiments of the present invention may be interpreted as a symbol, a minislot, a subframe, a radio frame, or a TTI (Transmission Time Interval). The term "cell" in the embodiments of the present invention may be interpreted as a cell group, a carrier component, a BWP, a resource pool, a resource, a RAT (Radio Access Technology), a system (including a wireless LAN), or the like.

[0024] In the embodiment of the present invention, the terminal 20 is not limited to a V2X terminal, and may be any type of terminal that performs D2D communication. For example, the terminal 20 may be a terminal carried by a user, such as a smartphone, or may be an IoT (Internet of Things) device, such as a smart meter.

[0025] FIG. 2 is a diagram illustrating an example of a V2X transmission mode (1). In the transmission mode of sidelink communication illustrated in FIG. 2, in step 1, the base station 10 transmits sidelink scheduling to the terminal 20A. Next, the terminal 20A transmits a PSCCH (Physical Sidelink Control Channel) and a PSSCH (Physical Sidelink Shared Channel) to the terminal 20B based on the received scheduling (step 2). The transmission mode of sidelink communication illustrated in FIG. 2 may be referred to as sidelink transmission mode 3 in LTE. In sidelink transmission mode 3 in LTE, Uu-based sidelink scheduling is performed. Uu is a radio interface between a Universal Terrestrial Radio Access Network (UTRAN) and a User Equipment (UE). The transmission mode of sidelink communication illustrated in FIG. 2 may be referred to as sidelink transmission mode 1 in NR.

[0026] Fig. 3 is a diagram illustrating an example (2) of a V2X transmission mode. In the transmission mode of sidelink communication shown in Fig. 3, in step 1, the terminal 20A transmits the PSCCH and the PSSCH to the terminal 20B using autonomously selected resources. The transmission mode of sidelink communication shown in Fig. 3 may be referred to as sidelink transmission mode 4 in LTE. In sidelink transmission mode 4 in LTE, the UE itself performs resource selection.

[0027] FIG. 4 is a diagram illustrating an example of a V2X transmission mode (3). In the transmission mode of sidelink communication shown in FIG. 4, in step 1, the terminal 20A transmits the PSCCH and the PSSCH to the terminal 20B using autonomously selected resources. Similarly, the terminal 20B transmits the PSCCH and the PSSCH to the terminal 20A using autonomously selected resources (step 1). The transmission mode of sidelink communication shown in FIG. 4 may be referred to as a sidelink transmission mode 2a in NR. In sidelink transmission mode 2 in NR, the terminal 20 itself performs resource selection.

[0028] FIG. 5 is a diagram illustrating an example (4) of a V2X transmission mode. In the transmission mode of sidelink communication illustrated in FIG. 5, in step 0, a sidelink resource pattern is transmitted from the base station 10 to the terminal 20A via RRC (Radio Resource Control) configuration or is configured in advance. Subsequently, the terminal 20A transmits a PSSCH to the terminal 20B based on the resource pattern (step 1). The transmission mode of sidelink communication illustrated in FIG. 5 may be referred to as a sidelink transmission mode 2c in NR.

[0029] Fig. 6 is a diagram illustrating an example (5) of a V2X transmission mode. In the transmission mode of sidelink communication shown in Fig. 6, in step 1, terminal 20A transmits sidelink scheduling to terminal 20B via a PSCCH. Subsequently, terminal 20B transmits a PSSCH to terminal 20A based on the received scheduling (step 2). The transmission mode of sidelink communication shown in Fig. 6 may be referred to as a sidelink transmission mode 2d in NR.

[0030] Fig. 7 is a diagram for explaining an example (1) of a V2X communication type. The sidelink communication type shown in Fig. 7 is unicast. Terminal 20A transmits a PSCCH and a PSSCH to terminal 20. In the example shown in Fig. 7, terminal 20A unicasts to terminal 20B and also unicasts to terminal 20C.

[0031] Fig. 8 is a diagram illustrating an example (2) of a V2X communication type. The sidelink communication type shown in Fig. 8 is groupcast. Terminal 20A transmits PSCCH and PSSCH to a group to which one or more terminals 20 belong. In the example shown in Fig. 8, the group includes terminal 20B and terminal 20C, and terminal 20A performs groupcast to the group.

[0032] FIG. 9 is a diagram for explaining an example (3) of a V2X communication type. The sidelink communication type shown in FIG. 9 is broadcast. Terminal 20A transmits PSCCH and PSSCH to one or more terminals 20. In the example shown in FIG. 9, terminal 20A broadcasts to terminal 20B, terminal 20C, and terminal 20D. Note that terminal 20A shown in FIGS. 7 to 9 may be referred to as a header UE (header-UE).

[0033] In addition, it is expected that NR-V2X will support hybrid automatic repeat request (HARQ) for sidelink unicast and groupcast. Furthermore, NR-V2X will define sidelink feedback control information (SFCI) including an HARQ response. Furthermore, it is being considered to transmit the SFCI via a physical sidelink feedback channel (PSFCH).

[0034] In the following description, the PSFCH is used for transmitting the HARQ-ACK on the side link, but this is just an example. For example, the HARQ-ACK may be transmitted on the side link using the PSCCH, the PSSCH, or another channel.

[0035] For convenience, information reported by terminal 20 in HARQ will be generally referred to as HARQ-ACK below. This HARQ-ACK may also be referred to as HARQ-ACK information. More specifically, a codebook applied to HARQ-ACK information reported from terminal 20 to base station 10 or the like will be referred to as a HARQ-ACK codebook. The HARQ-ACK codebook defines the bit string of the HARQ-ACK information. Note that in addition to ACK, NACK is also transmitted using "HARQ-ACK".

[0036] Fig. 10 is a sequence diagram showing an operation example (1) of V2X. As shown in Fig. 10, the wireless communication system according to the embodiment of the present invention may include terminal 20A and terminal 20B. Note that, although there are actually many user devices, Fig. 10 shows terminal 20A and terminal 20B as an example.

[0037] Hereinafter, when there is no particular distinction between terminals 20A, 20B, etc., they will be simply referred to as "terminal 20" or "user device." While Fig. 10 shows an example in which terminal 20A and terminal 20B are both within the coverage of a cell, the operation in the embodiment of the present invention can also be applied to a case in which terminal 20B is outside the coverage.

[0038] As described above, in this embodiment, the terminal 20 is, for example, a device mounted on a vehicle such as an automobile, and has a cellular communication function as a UE in LTE or NR, and a sidelink function. The terminal 20 may be a general mobile terminal (such as a smartphone). The terminal 20 may also be an RSU. The RSU may be a UE-type RSU having the function of a UE, or a gNB-type RSU having the function of a base station device.

[0039] The terminal 20 does not need to be a device in a single housing. For example, even if various sensors are distributed and arranged inside a vehicle, the terminal 20 may be a device including the various sensors.

[0040] Furthermore, the processing of sidelink transmission data in terminal 20 is basically the same as the processing of UL transmission in LTE or NR. For example, terminal 20 scrambles and modulates codewords of transmission data to generate complex-valued symbols, maps the complex-valued symbols (transmission signals) to one or two layers, and performs precoding. Then, terminal 20 maps the precoded complex-valued symbols to resource elements to generate transmission signals (e.g., complex-valued time-domain SC-FDMA signals), and transmits them from each antenna port.

[0041] Note that the base station 10 has a cellular communication function as a base station in LTE or NR, and a function for enabling communication of the terminal 20 in this embodiment (e.g., resource pool setting, resource allocation, etc.). The base station 10 may also be an RSU (gNB type RSU).

[0042] Furthermore, in the wireless communication system according to the embodiment of the present invention, the signal waveform used by terminal 20 for SL or UL may be OFDMA, SC-FDMA, or another signal waveform.

[0043] In step S101, terminal 20A autonomously selects resources to be used for the PSCCH and PSSCH from a resource selection window having a predetermined period. The resource selection window may be set in terminal 20 by base station 10. Here, the predetermined period of the resource selection window may be defined by implementation conditions of the terminal, such as processing time or maximum allowable packet delay time, or may be defined in advance by specifications, or the predetermined period may be referred to as an interval in the time domain.

[0044] In steps S102 and S103, terminal 20A transmits SCI (Sidelink Control Information) via PSCCH and / or PSSCH using the resources autonomously selected in step S101, and transmits SL data via PSSCH. For example, terminal 20A may transmit PSCCH using frequency resources adjacent to the frequency resources of PSSCH in the same time resources as at least a part of the time resources of PSSCH.

[0045] The terminal 20B receives the SCI (PSCCH and / or PSSCH) and SL data (PSSCH) transmitted from the terminal 20A. The received SCI may include information on the PSFCH resource for the terminal 20B to transmit a HARQ-ACK in response to the reception of the data. The terminal 20A may transmit information on the autonomously selected resource in the SCI.

[0046] In step S104, the terminal 20B uses the PSFCH resource determined from the received SCI to transmit a HARQ-ACK for the received data to the terminal 20A.

[0047] In step S105, if the HARQ-ACK received in step S104 indicates a request for retransmission, that is, if it is a NACK (negative acknowledgement), the terminal 20A retransmits the PSCCH and PSSCH to the terminal 20B. The terminal 20A may retransmit the PSCCH and PSSCH using autonomously selected resources.

[0048] If HARQ control involving HARQ feedback is not performed, steps S104 and S105 may not be performed.

[0049] 11 is a sequence diagram showing an operation example (2) of V2X. Blind retransmission without HARQ control may be performed to improve the transmission success rate or reach.

[0050] In step S201, the terminal 20A autonomously selects resources to be used for the PSCCH and the PSSCH from a resource selection window having a predetermined period. The resource selection window may be set to the terminal 20 by the base station 10.

[0051] In steps S202 and S203, terminal 20A transmits SCI via PSCCH and / or PSSCH and transmits SL data via PSSCH using the resources autonomously selected in step S201. For example, terminal 20A may transmit PSCCH using frequency resources adjacent to the frequency resources of the PSSCH in the same time resources as at least a part of the time resources of the PSSCH.

[0052] In step S204, the terminal 20A uses the resource autonomously selected in step S201 to retransmit the SCI via the PSCCH and / or PSSCH and the SL data via the PSSCH to the terminal 20B. The retransmission in step S204 may be performed multiple times.

[0053] If blind retransmission is not performed, step S204 does not have to be performed.

[0054] 12 is a sequence diagram showing an operation example (3) of V2X. The base station 10 may perform sidelink scheduling. That is, the base station 10 may determine sidelink resources to be used by the terminal 20 and transmit information indicating the resources to the terminal 20. Furthermore, when HARQ control involving HARQ feedback is applied, the base station 10 may transmit information indicating PSFCH resources to the terminal 20.

[0055] In step S301, base station 10 performs SL scheduling by transmitting DCI (Downlink Control Information) via PDCCH to terminal 20 A. Hereinafter, for convenience, DCI for SL scheduling will be referred to as SL scheduling DCI.

[0056] Also, in step S301, it is assumed that the base station 10 also transmits DCI for DL scheduling (which may also be called DL allocation) to the terminal 20A via the PDCCH. Hereinafter, for convenience, DCI for DL scheduling will be called DL scheduling DCI. The terminal 20A that has received the DL scheduling DCI receives DL data via the PDSCH using resources specified in the DL scheduling DCI.

[0057] In steps S302 and S303, terminal 20A transmits SCI (Sidelink Control Information) via PSCCH and / or PSSCH using resources specified in the SL scheduling DCI, and also transmits SL data via PSSCH. Note that only PSSCH resources may be specified in the SL scheduling DCI. In this case, for example, terminal 20A may transmit PSCCH using frequency resources adjacent to the frequency resources of PSSCH, in the same time resources as at least a part of the time resources of PSSCH.

[0058] The terminal 20B receives the SCI (PSCCH and / or PSSCH) and SL data (PSSCH) transmitted from the terminal 20A. The SCI received via the PSCCH and / or PSSCH includes information on the PSFCH resource used by the terminal 20B to transmit a HARQ-ACK in response to reception of the data.

[0059] The resource information is included in the DL scheduling DCI or SL scheduling DCI transmitted from the base station 10 in step S301, and the terminal 20A acquires the resource information from the DL scheduling DCI or SL scheduling DCI and includes it in the SCI. Alternatively, the resource information may not be included in the DCI transmitted from the base station 10, and the terminal 20A may autonomously include the resource information in the SCI and transmit it.

[0060] In step S304, the terminal 20B uses the PSFCH resource determined from the received SCI to transmit a HARQ-ACK for the received data to the terminal 20A.

[0061] In step S305, the terminal 20A transmits a HARQ-ACK, for example, at a timing (for example, slot-by-slot timing) specified by the DL scheduling DCI (or the SL scheduling DCI) using a PUCCH (Physical uplink control channel) resource specified by the DL scheduling DCI (or the SL scheduling DCI), and the base station 10 receives the HARQ-ACK. The codebook for the HARQ-ACK may include an ARQ-ACK generated based on the HARQ-ACK received from the terminal 20B or a PSFCH that was not received, and a HARQ-ACK for DL data. However, if no DL data is allocated, for example, a HARQ-ACK for DL data is not included. In NR Rel. 16, the codebook for the HARQ-ACK does not include a HARQ-ACK for DL data.

[0062] If HARQ control involving HARQ feedback is not performed, step S304 and / or step S305 may not be performed.

[0063] FIG. 13 is a sequence diagram showing an operation example (4) of V2X. As described above, in the NR sidelink, it is supported that an HARQ response is transmitted on a PSFCH. Note that the PSFCH format may be the same as, for example, PUCCH (Physical Uplink Control Channel) format 0. That is, the PSFCH format may be a sequence-based format in which the PRB (Physical Resource Block) size is 1 and ACKs and NACKs are identified by differences in sequence and / or cyclic shifts. The PSFCH format is not limited to this. The PSFCH resource may be allocated to the last symbol or the last multiple symbols of a slot. Furthermore, a period N is set or predefined for the PSFCH resource. The period N may be set or predefined on a slot-by-slot basis.

[0064] In FIG. 13, the vertical axis corresponds to the frequency domain, and the horizontal axis corresponds to the time domain. The PSCCH may be placed in the first symbol of a slot, or in multiple symbols from the first, or in multiple symbols from a symbol other than the first. The PSFCH may be placed in the last symbol of a slot, or in multiple symbols from the last. Note that the above-mentioned "first symbol of a slot" and "last symbol of a slot" may not take into account symbols for AGC (Automatic Gain Control) and symbols for transmission / reception switching. That is, for example, when one slot is composed of 14 symbols, the "first symbol of a slot" and the "last symbol of a slot" may refer to the first and last symbols, respectively, of the 12 symbols excluding the first and last symbols. In the example shown in FIG. 13, three subchannels are configured in the resource pool, and two PSFCHs are placed three slots after the slot in which the PSSCH is placed. The arrow from the PSSCH to the PSFCH indicates an example of a PSFCH associated with the PSSCH.

[0065] When the HARQ response in NR-V2X groupcast is groupcast option 2, which transmits an ACK or NACK, it is necessary to determine the resources to be used for transmitting and receiving the PSFCH. As shown in FIG. 13, in step S401, terminal 20A, which is a transmitting terminal 20, performs groupcast via SL-SCH to terminals 20B, 20C, and 20D, which are receiving terminals 20. In the following step S402, terminal 20B uses PSFCH#B, terminal 20C uses PSFCH#C, and terminal 20D uses PSFCH#D to transmit a HARQ response to terminal 20A. Here, as shown in the example of FIG. 13, if the number of available PSFCH resources is smaller than the number of receiving terminals 20 belonging to the group, it is necessary to determine how to allocate the PSFCH resources. Note that the transmitting terminal 20 may know the number of receiving terminals 20 in the groupcast. Note that in groupcast option 1, only a NACK is transmitted as the HARQ response, and an ACK is not transmitted.

[0066] In NR Sidelink Release 16, the terminal 20 can report a sidelink HARQ-ACK to the base station 10. The terminal 20 can also multiplex multiple sidelink HARQ-ACKs and report the multiplexed sidelink HARQ-ACKs to the base station 10. A set of HARQ-ACK bits when transmitting one or more HARQ-ACK bits via one channel may be called an HARQ-ACK codebook. Both semi-static Type 1 and dynamic Type 2 HARQ-ACK codebooks are supported. When reporting a sidelink HARQ-ACK from the terminal 20 to the base station 10, whether to use Type 1 or Type 2 HARQ-ACK codebook may depend on the codebook used for the downlink HARQ-ACK.

[0067] Regarding the codebook for HARQ feedback corresponding to downlink reception, NR eURLLC (enhanced Ultra-Reliable and Low Latency Communications) Release 16 allows up to two codebook types to be configured for a given terminal 20. One codebook type corresponds to low priority, and the other corresponds to high priority.

[0068] Furthermore, with regard to the codebook for HARQ feedback corresponding to downlink reception, in NR Release 16, when two PUCCH groups are configured in a certain cell group, up to two codebook types can be configured for a certain terminal 20. One codebook type is configured for each PUCCH group.

[0069] As described above, when multiple codebook types are configured for the codebook used in HARQ-ACK in downlink, it is unclear which codebook should be used for sidelink HARQ feedback (when HARQ-ACK in sidelink is reported from terminal 20 to base station 10). Note that the sidelink HARQ-ACK codebook is applied to the HARQ-ACK transmitted on the PUCCH or PUSCH in step S305 shown in Fig. 12, but may also be applied to the HARQ-ACK transmitted on the PSFCH in step S303.

[0070] In the above-mentioned NR eURLLC Release 16, up to two codebook types for a certain terminal 20 are set as semi-static or dynamic by the RRC information element "pdsch-HARQ-ACK-CodebookList-r16" notified from the base station 10. The first codebook type included in this RRC information element corresponds to low priority, and the second codebook type corresponds to high priority. Hereinafter, "pdsch-HARQ-ACK-CodebookList-r16" will be referred to as "pdsch-HARQ-ACK-CodebookList."

[0071] Furthermore, in the above-mentioned NR Release 16, when two PUCCH groups are configured in a certain cell group, the codebook type corresponding to the secondary PUCCH group is set to semi-static or dynamic by the RRC information element "pdsch-HARQ-ACK-Codebook-secondaryPUCCHgroup-r16" notified from the base station 10. Hereinafter, "pdsch-HARQ-ACK-Codebook-secondaryPUCCHgroup-r16" will be referred to as "pdsch-HARQ-ACK-Codebook-secondaryPUCCHgroup".

[0072] Note that the codebook type that is normally used, or the codebook type that corresponds to the primary PUCCH group when two PUCCH groups are configured in a cell group, is set to semi-static or dynamic by the RRC information element "pdsch-HARQ-ACK-Codebook" notified from base station 10. Note that the parameter names in the embodiments of the present invention are not limited to those described above and may be other names.

[0073] (HARQ-ACK codebook) In the following embodiment, an example of transmission of SL HARQ-ACK from terminal 20 to base station 10 using a HARQ-ACK codebook will be described. For this purpose, an overview of the HARQ-ACK codebook corresponding to DL transmission will be first described. When generating a HARQ-ACK codebook related to transmission of SL HARQ-ACK, downlink may be replaced with sidelink.

[0074] The HARQ-ACK codebook defines how to aggregate one or more HARQ-ACKs when they are multiplexed and transmitted together. The HARQ-ACK codebook may be configured to include bits for HARQ-ACK in at least one unit of the time domain (e.g., slot), frequency domain (e.g., component carrier (CC)), spatial domain (e.g., layer), transport block (TB), and group of code blocks constituting a TB (code block group (CBG)). Note that CC is also referred to as cell, serving cell, carrier, etc. These bits are also referred to as HARQ-ACK bits, HARQ-ACK information, HARQ-ACK information bits, etc. The HARQ-ACK codebook is also referred to as PDSCH-HARQ-ACK codebook (pdsch-HARQ-ACK-Codebook), codebook, HARQ codebook, HARQ-ACK size, etc.

[0075] The number of bits (size) included in the HARQ-ACK codebook may be determined semi-statically or dynamically. A semi-static HARQ-ACK codebook is also called a Type I HARQ-ACK codebook, a semi-static codebook, etc. A dynamic HARQ-ACK codebook is also called a Type II HARQ-ACK codebook, a dynamic codebook, etc.

[0076] Whether to use the Type I HARQ-ACK codebook or the Type II HARQ-ACK codebook may be configured in terminal 20 by a higher layer parameter (for example, pdsch-HARQ-ACK-Codebook).

[0077] In the case of a Type I HARQ-ACK codebook, terminal 20 may feed back HARQ-ACK bits corresponding to a predetermined range (for example, a range set based on higher layer parameters) regardless of whether PDSCH is scheduled or not.

[0078] The predetermined range may be determined based on at least one of a predetermined period (for example, a set of a predetermined number of candidate occasions for receiving a PDSCH, or a predetermined number of monitoring occasions for a PDCCH), the number of CCs configured or activated in terminal 20, the number of TBs (number of layers or ranks), the number of CBGs per TB, and whether spatial bundling is applied. The predetermined range is also referred to as a HARQ-ACK bundling window, a HARQ-ACK feedback window, a bundling window, a feedback window, etc.

[0079] With the Type I HARQ-ACK codebook, within a predetermined range, terminal 20 feeds back NACK bits even if no PDSCH is scheduled for terminal 20. For this reason, when the Type I HARQ-ACK codebook is used, it is expected that the number of HARQ-ACK bits to be fed back will increase.

[0080] On the other hand, in the case of a Type II HARQ-ACK codebook, the terminal 20 may feed back a HARQ-ACK bit for the scheduled PDSCH within the predetermined range.

[0081] Specifically, the terminal 20 may determine the number of bits of the Type II HARQ-ACK codebook based on a predetermined field in the DCI (for example, a Downlink Assignment Indicator (Index) (DAI) field). The DAI field may be split into a counter DAI (cDAI) and a total DAI (tDAI).

[0082] The counter DAI may indicate a counter value of downlink transmissions (PDSCH, data, TB) scheduled within a predetermined period. For example, the counter DAI in a DCI that schedules data within the predetermined period may indicate the number counted first in the frequency domain (e.g., CC) and then in the time domain within the predetermined period.

[0083] The total DAI may indicate the sum (total number) of data scheduled within a predetermined period. For example, the total DAI in a DCI that schedules data at a predetermined time unit (e.g., a PDCCH monitoring opportunity) within the predetermined period may indicate the total number of data scheduled up to the predetermined time unit (also referred to as a point, timing, etc.) within the predetermined period.

[0084] The terminal 20 may transmit one or more HARQ-ACK bits determined (generated) based on the above-described Type I or Type II HARQ-ACK codebook using at least one of an uplink control channel (Physical Uplink Control Channel (PUCCH)) and an uplink shared channel (Physical Uplink Shared Channel (PUSCH)).

[0085] In the case of a Type I HARQ-ACK codebook, terminal 20 generates a number of HARQ-ACK bits according to the number of candidates for PDCCH / PDSCH transmission that may be transmitted from base station 10, rather than the actual PDCCH / PDSCH transmission from base station 10. That is, for a PDCCH / PDSCH transmission opportunity at which base station 10 may transmit the PDCCH / PDSCH, terminal 20 transmits the HARQ-ACK bits regardless of whether or not the base station 10 actually transmits the PDCCH / PDSCH. For example, if the base station 10 does not transmit the PDCCH for a PDCCH transmission opportunity from base station 10, terminal 20 may transmit a NACK.

[0086] In the case of a Type II HARQ-ACK codebook, terminal 20 generates a number of HARQ-ACK bits corresponding to the number of PDCCH / PDSCH signals that are expected to be actually transmitted from base station 10. Note that, since terminal 20 may not be able to receive PDCCH signals from base station 10, it is possible for base station 10 to notify terminal 20 of the number of PDCCH signals to be transmitted by including DAI in DCI. For example, as shown on the left side of FIG. 14, even if terminal 20 is unable to detect the DL DCI indicated by (3, 0) among the DL DCIs indicated by (1, 0), (2, 0), (3, 0), and (0, 0), terminal 20 has detected the DL DCI indicated by (2, 0) and the DL DCI indicated by (0, 0), and therefore recognizes that (3, 0) exists between (2, 0) and (0, 0), and can set the HARQ-ACK bit corresponding to (3, 0) to NACK and transmit. In this way, in the case of a Type II HARQ-ACK codebook, it is possible to make the number of HARQ-ACK bits transmitted by terminal 20 the same as the number of HARQ-ACK bits assumed on the base station 10 side.

[0087] Here, a specific example of using a HARQ-ACK codebook corresponding to downlink reception will be described with reference to Fig. 14. Fig. 14 is a diagram illustrating an example of reporting multiplexed HARQ responses. When a PUCCH including HARQ-ACK collides with a PUSCH, HARQ-ACK may be multiplexed onto the PUSCH (in some cases, when a PUCCH including HARQ-ACK collides with a PUSCH, the PUSCH may be dropped). A DAI (Downlink assignment indicator) is transmitted in DCI that schedules PUSCH, and the number of HARQ-ACKs to be multiplexed onto PUSCH is notified based on the value of the DAI. The DAI in DCI that schedules PUSCH is referred to as UL-DAI. Note that the DAI in DCI that schedules PDSCH is referred to as C-DAI (counter DAI) and / or T-DAI (total DAI). By using the DAI, it is possible to avoid a mismatch in the number of HARQ-ACK bits even when erroneous detection of PDCCH occurs. Note that, hereinafter, C-DAI, UL-DAI, and T-DAI are defined as values starting from 0 and defined modulo 4, but this definition is an example, and DAI may be defined in other ways.

[0088] FIG. 14 shows an example in which terminal 20 fails to receive the PDCCH in the fourth slot in the DL association set, where (C-DAI, T-DAI)=(0,0). There are eight multiplexed HARQ-ACKs, where (C-DAI, T-DAI) corresponds to (1,0), (2,0), (3,0), (0,0), (1,2), (2,2), (3,3), and (0,0), and therefore UL-DAI is 8 mod 4=0. That is, as shown in FIG. 14, the value of UL-DAI included in the DCI that allocates the PUSCH is 0. Since UL-DAI=0 differs from the UL-DAI value (=3) expected from (C-DAI, T-DAI)=(3,3) in the last DCI received, terminal 20 can see that it failed to receive the PDCCH after the last DCI. That is, even though terminal 20 has received seven PDCCHs due to a failure in receiving the PDCCHs, terminal 20 can recognize that the number of bits in the HARQ-ACK codebook is eight.

[0089] As described above, when multiple codebook types are configured, it is necessary to determine which codebook to use for sidelink HARQ feedback. Fig. 15 is a flowchart showing an example of an operation for reporting HARQ-ACK in an embodiment of the present invention. In step S501, multiple HARQ-ACK codebook types for DL-HARQ-ACK are configured. In the subsequent step S502, terminal 20 determines a HARQ-ACK codebook type for SL-HARQ-ACK. Then, terminal 20 may report multiple HARQ-ACKs to base station 10 using the determined HARQ-ACK codebook types.

[0090] If "pdsch-HARQ-ACK-CodebookList" is set, in step S502, the terminal 20 may report the SL-HARQ-ACK to the base station 10 using the codebook type according to "pdsch-HARQ-ACK-Codebook." That is, "pdsch-HARQ-ACK-Codebook" may not be used to determine the codebook type for DL-HARQ-ACK, but may be used to determine the codebook type for SL-HARQ-ACK.

[0091] The above operation makes it possible to determine the codebook for SL-HARQ-ACK regardless of the presence or absence of "pdsch-HARQ-ACK-CodebookList," thereby simplifying the configuration of the terminal.

[0092] Also, if "pdsch-HARQ-ACK-CodebookList" is set, in step S502, the terminal 20 may report SL-HARQ-ACK to the base station 10 using the codebook type according to "pdsch-HARQ-ACK-CodebookList".

[0093] For example, the first HARQ-ACK codebook type (associated with a priority index of 0, which is the lowest priority) in "pdsch-HARQ-ACK-CodebookList" may be used.

[0094] Also, for example, the second HARQ-ACK codebook type (associated with a priority index of 1, which is the highest priority) of "pdsch-HARQ-ACK-CodebookList" may be used.

[0095] Also, for example, among "pdsch-HARQ-ACK-CodebookList", which codebook type to use may be determined based on the priority of the SL-HARQ-ACK report to the base station 10. For example, when the priority is from 0 to X (corresponding to a higher priority) within the priority range of 0-7, the second HARQ-ACK codebook type may be used. Also, when the priority is from X+1 to 7 (corresponding to a lower priority) within the priority range of 0-7, the first HARQ-ACK codebook type may be used. X or X+1 may be determined based on a specific upper layer parameter, and may be, for example, either "sl-PriorityThreshold" or "sl-PriorityThreshold-UL-URLLC".

[0096] By the above operation, the same codebook type as that actually used as the HARQ-ACK codebook type for DL-HARQ-ACK can be applied to the SL, and the optimal codebook type can be applied based on the priority of the SL.

[0097] Furthermore, when "pdsch-HARQ-ACK-CodebookList" is set, in step S502, terminal 20 may determine the codebook type regardless of the HARQ-ACK codebook type for DL-HARQ-ACK or higher layer parameters related to the HARQ-ACK codebook type for DL-HARQ-ACK, and report the SL-HARQ-ACK to base station 10. For example, the specifications may stipulate that either a semi-static or dynamic codebook type be used. Furthermore, for example, the codebook type may be determined by setting higher layer parameters for determining the HARQ-ACK codebook type for SL-HARQ-ACK (e.g., "pssch-HARQ-ACK-Codebook" and "pssch-HARQ-ACK-CodebookList"). Note that when multiple codebook types are set by "pssch-HARQ-ACK-CodebookList," the codebook type may be determined in the same manner as the method of determining the codebook type based on "pdsch-HARQ-ACK-CodebookList" described above.

[0098] The above operation makes it possible to flexibly set the HARQ-ACK codebook type for SL-HARQ-ACK regardless of the HARQ-ACK codebook type for DL-HARQ-ACK.

[0099] Furthermore, when "pdsch-HARQ-ACK-Codebook-secondaryPUCCHgroup" is set, in step S502, terminal 20 may report SL-HARQ-ACK to base station 10 using the codebook type "pdsch-HARQ-ACK-Codebook." That is, the SL may not depend on the associated PUCCH group, and "pdsch-HARQ-ACK-Codebook" may be used to determine the codebook type for SL-HARQ-ACK.

[0100] By the above operation, it is possible to determine the codebook for SL-HARQ-ACK regardless of the presence or absence of "pdsch-HARQ-ACK-Codebook-secondaryPUCCHgroup", thereby simplifying the configuration of the terminal.

[0101] Furthermore, when "pdsch-HARQ-ACK-Codebook-secondaryPUCCHgroup" is set, in step S502, terminal 20 may use the codebook type according to "pdsch-HARQ-ACK-Codebook-secondaryPUCCHgroup" to report SL-HARQ-ACK to base station 10. In other words, it is not necessary to depend on the PUCCH group to which the SL is associated, and "pdsch-HARQ-ACK-Codebook-secondaryPUCCHgroup" may be used to determine the codebook type for SL-HARQ-ACK.

[0102] By the above operation, the codebook for SL-HARQ-ACK can be determined by preferentially using the additionally set "pdsch-HARQ-ACK-Codebook-secondaryPUCCHgroup".

[0103] Furthermore, when "pdsch-HARQ-ACK-Codebook-secondaryPUCCHgroup" is set, in step S502, terminal 20 may use a codebook type determined by parameters related to the PUCCH group to which the SL relates to report the SL-HARQ-ACK to base station 10. For example, terminal 20 may report the SL-HARQ-ACK to base station 10 using a codebook type determined by parameters related to the PUCCH group to which the SL-HARQ-ACK is transmitted.

[0104] For example, if the PUCCH group from which terminal 20 transmits the SL-HARQ-ACK is a primary PUCCH group, i.e., if the PUCCH is transmitted in a primary cell or a primary secondary cell group cell, the HARQ-ACK codebook type may be determined based on "pdsch-HARQ-ACK-Codebook".

[0105] For example, if the PUCCH group from which terminal 20 transmits SL-HARQ-ACK is a secondary PUCCH group, i.e., if the PUCCH is transmitted in a secondary cell, the HARQ-ACK codebook type may be determined based on "pdsch-HARQ-ACK-Codebook-secondaryPUCCHgroup".

[0106] By the above operation, the codebook type in the PUCCH group to which the SL is associated can be made common between the DL-HARQ-ACK codebook and the SL-HARQ-ACK codebook.

[0107] Furthermore, when "pdsch-HARQ-ACK-Codebook-secondaryPUCCHgroup" is configured, in step S502, terminal 20 may determine the codebook type regardless of the HARQ-ACK codebook type for DL-HARQ-ACK or higher layer parameters related to the HARQ-ACK codebook type for DL-HARQ-ACK, and report the SL-HARQ-ACK to base station 10. For example, the specifications may stipulate that either a semi-static or dynamic codebook type be used. Furthermore, for example, the codebook type may be determined by setting higher layer parameters for determining the HARQ-ACK codebook type for SL-HARQ-ACK (for example, "pssch-HARQ-ACK-Codebook" and "pssch-HARQ-ACK-CodebookList"). Note that when multiple codebook types are configured by "pssch-HARQ-ACK-CodebookList," the codebook type may be determined in the same manner as the method of determining the codebook type based on "pdsch-HARQ-ACK-CodebookList" described above.

[0108] The above operation allows the SL-HARQ-ACK codebook type to be flexibly set regardless of the DL-HARQ-ACK codebook type.

[0109] Furthermore, when "pdsch-HARQ-ACK-CodebookList" and "pdsch-HARQ-ACK-Codebook-secondaryPUCCHgroup" are set, in step S502, terminal 20 may determine the SL-HARQ-ACK codebook type by any of the above-mentioned methods.

[0110] For example, when "pdsch-HARQ-ACK-CodebookList" is used instead of "pdsch-HARQ-ACK-Codebook-secondaryPUCCHgroup" in the secondary PUCCH group, terminal 20 may determine the SL-HARQ-ACK codebook based on "pdsch-HARQ-ACK-CodebookList". Furthermore, for example, terminal 20 may replace "pdsch-HARQ-ACK-Codebook" with "pdsch-HARQ-ACK-CodebookList" in the method when "pdsch-HARQ-ACK-Codebook-secondaryPUCCHgroup" is set.

[0111] Furthermore, when "pdsch-HARQ-ACK-CodebookList" for the secondary PUCCH group (for example, "pdsch-HARQ-ACK-CodebookList-secondaryPUCCHgroup") is separately configured, in step S502, terminal 20 may determine the SL-HARQ-ACK codebook type by any of all of the methods described above. Note that with regard to "pdsch-HARQ-ACK-CodebookList" for the secondary PUCCH group, the first codebook type included in the RRC information element may correspond to low priority in the secondary PUCCH group, and the second codebook type may correspond to high priority in the secondary PUCCH group.

[0112] For example, in a method in which "pdsch-HARQ-ACK-Codebook-secondaryPUCCHgroup" is configured, terminal 20 may replace "pdsch-HARQ-ACK-Codebook" with "pdsch-HARQ-ACK-CodebookList". Furthermore, for example, in a method in which "pdsch-HARQ-ACK-Codebook-secondaryPUCCHgroup" is configured, terminal 20 may replace "pdsch-HARQ-ACK-Codebook-secondaryPUCCHgroup" with "pdsch-HARQ-ACK-CodebookList-secondaryPUCCHgroup".

[0113] The above-described embodiment is not limited to V2X terminals, and may be applied to terminals that perform D2D communication.

[0114] The operations according to the above-described embodiments may be applied to any of the cases where the transmission is groupcast, where the transmission is unicast, or where the transmission is broadcast.

[0115] It should be noted that the UE or terminal 20 may be a plurality of UEs or terminals 20, and may belong to the same group.

[0116] According to the above-described embodiment, when multiple HARQ-ACK codebooks corresponding to DL reception are configured, the terminal 20 can determine the codebook type to be used for reporting multiple SL-HARQ-ACKs.

[0117] That is, in direct communication between terminals, multiple HARQ (Hybrid automatic repeat request)-ACKs can be reported to the base station.

[0118] (Device configuration) Next, a description will be given of an example of the functional configuration of the base station 10 and the terminal 20 that execute the processes and operations described above. The base station 10 and the terminal 20 include functions for implementing the above-described embodiments. However, the base station 10 and the terminal 20 may each include only a part of the functions of the embodiments.

[0119] <Base station 10> Fig. 16 is a diagram showing an example of the functional configuration of base station 10. As shown in Fig. 16, base station 10 has a transmitting unit 110, a receiving unit 120, a setting unit 130, and a control unit 140. The functional configuration shown in Fig. 16 is merely an example. The names of the functional divisions and functional units may be any as long as they can perform the operations related to the embodiments of the present invention.

[0120] The transmitter 110 has a function of generating a signal to be transmitted to the terminal 20 and transmitting the signal wirelessly. The receiver 120 has a function of receiving various signals transmitted from the terminal 20 and acquiring, for example, information of a higher layer from the received signals. The transmitter 110 also has a function of transmitting an NR-PSS, an NR-SSS, an NR-PBCH, a DL / UL control signal, a DL reference signal, etc. to the terminal 20.

[0121] The setting unit 130 stores in a storage device setting information that is set in advance and various setting information to be transmitted to the terminal 20, and reads out from the storage device as needed. The content of the setting information is, for example, information related to the setting of SL communication.

[0122] As described in the embodiment, the control unit 140 performs processing related to settings for the terminal 20 to perform SL communication. Furthermore, the control unit 140 transmits scheduling for SL communication and DL communication to the terminal 20 via the transmission unit 110. Furthermore, the control unit 140 receives information related to HARQ responses for SL communication and DL communication from the terminal 20 via the reception unit 120. A functional unit related to signal transmission in the control unit 140 may be included in the transmission unit 110, and a functional unit related to signal reception in the control unit 140 may be included in the reception unit 120.

[0123] <Terminal 20> Fig. 17 is a diagram showing an example of the functional configuration of terminal 20. As shown in Fig. 17, terminal 20 has transmitting unit 210, receiving unit 220, setting unit 230, and control unit 240. The functional configuration shown in Fig. 17 is merely an example. The names of the functional divisions and functional units may be any names as long as they can execute the operations related to the embodiment of the present invention.

[0124] The transmitter 210 creates a transmission signal from transmission data and transmits the transmission signal wirelessly. The receiver 220 receives various signals wirelessly and acquires a higher layer signal from the received physical layer signal. The receiver 220 also has a function of receiving an NR-PSS, NR-SSS, NR-PBCH, DL / UL / SL control signal, reference signal, or the like transmitted from the base station 10. For example, the transmitter 210 transmits a PSCCH (Physical Sidelink Control Channel), a PSSCH (Physical Sidelink Shared Channel), a PSDCH (Physical Sidelink Discovery Channel), a PSBCH (Physical Sidelink Broadcast Channel), or the like to another terminal 20 as D2D communication, and the receiver 220 receives the PSCCH, PSSCH, PSDCH, or PSBCH, or the like, from the other terminal 20.

[0125] The setting unit 230 stores various setting information received from the base station 10 or the terminal 20 by the receiving unit 220 in a storage device and reads it from the storage device as needed. The setting unit 230 also stores setting information that is set in advance. The content of the setting information is, for example, information related to the setting of D2D communication.

[0126] As described in the embodiments, the control unit 240 performs processing related to SL communication and HARQ of SL communication. Furthermore, the control unit 240 transmits to the base station 10 information related to a HARQ response of SL communication to another terminal 20 scheduled by the base station 10. Furthermore, the control unit 240 may schedule SL communication for the other terminal 20. A functional unit related to signal transmission in the control unit 240 may be included in the transmitting unit 210, and a functional unit related to signal reception in the control unit 240 may be included in the receiving unit 220.

[0127] (Hardware configuration) The block diagrams (FIGS. 16 and 17) used to explain the above embodiments show functional blocks. These functional blocks (components) are realized by any combination of at least one of hardware and software. Furthermore, the method for realizing each functional block is not particularly limited. That is, each functional block may be realized using a single device that is physically or logically coupled, or may be realized using two or more physically or logically separated devices that are connected directly or indirectly (for example, by wire, wirelessly, etc.) and these multiple devices. The functional block may be realized by combining the single device or the multiple devices with software.

[0128] Functions include, but are not limited to, judgment, determination, judgment, calculation, computation, processing, derivation, investigation, search, confirmation, reception, transmission, output, access, resolution, selection, election, establishment, comparison, assumption, expectation, consideration, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocation, mapping, and assignment. For example, a functional block (component) that performs transmission is called a transmitting unit or transmitter. As mentioned above, there are no particular limitations on how these functions are implemented.

[0129] For example, the base station 10, the terminal 20, etc. according to an embodiment of the present disclosure may function as a computer that performs processing of the wireless communication method of the present disclosure. Fig. 18 is a diagram illustrating an example of the hardware configuration of the base station 10 and the terminal 20 according to an embodiment of the present disclosure. The base station 10 and the terminal 20 described above may be physically configured as a computer device including a processor 1001, a storage device 1002, an auxiliary storage device 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, etc.

[0130] In the following description, the term "apparatus" can be read as a circuit, a device, a unit, etc. The hardware configuration of the base station 10 and the terminal 20 may be configured to include one or more of the apparatuses shown in the drawings, or may be configured to exclude some of the apparatuses.

[0131] Each function in the base station 10 and the terminal 20 is realized by loading predetermined software (programs) onto hardware such as the processor 1001, the memory device 1002, etc., so that the processor 1001 performs calculations, controls communication by the communication device 1004, and controls at least one of reading and writing data in the memory device 1002 and the auxiliary memory device 1003.

[0132] The processor 1001 controls the entire computer by running, for example, an operating system. The processor 1001 may be configured as a central processing unit (CPU) including an interface with peripheral devices, a control device, an arithmetic unit, a register, etc. For example, the above-mentioned control unit 140, control unit 240, etc. may be realized by the processor 1001.

[0133] Furthermore, the processor 1001 reads programs (program codes), software modules, data, etc. from at least one of the auxiliary storage device 1003 and the communication device 1004 into the storage device 1002, and executes various processes in accordance with the programs. The programs used are those that cause a computer to execute at least some of the operations described in the above-described embodiments. For example, the control unit 140 of the base station 10 shown in FIG. 16 may be implemented by a control program stored in the storage device 1002 and running on the processor 1001. Furthermore, for example, the control unit 240 of the terminal 20 shown in FIG. 17 may be implemented by a control program stored in the storage device 1002 and running on the processor 1001. While the above-described various processes have been described as being executed by one processor 1001, they may also be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. The programs may be transmitted from a network via a telecommunications line.

[0134] The storage device 1002 is a computer-readable recording medium and may be configured, for example, by at least one of a read-only memory (ROM), an erasable programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), a random access memory (RAM), etc. The storage device 1002 may also be called a register, a cache, a main memory, etc. The storage device 1002 can store executable programs (program codes), software modules, etc. for implementing a communication method according to an embodiment of the present disclosure.

[0135] The secondary storage device 1003 is a computer-readable recording medium, and may be, for example, at least one of an optical disk such as a CD-ROM (Compact Disc ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., a compact disk, a digital versatile disk, a Blu-ray disc), a smart card, a flash memory (e.g., a card, a stick, a key drive), a floppy disk, a magnetic strip, etc. The above-mentioned storage medium may be, for example, a database, a server, or other suitable medium including at least one of the storage device 1002 and the secondary storage device 1003.

[0136] The communication device 1004 is hardware (transmission / reception device) for communicating between computers via at least one of a wired network and a wireless network, and is also referred to as, for example, a network device, a network controller, a network card, or a communication module. The communication device 1004 may be configured to include a high-frequency switch, a duplexer, a filter, a frequency synthesizer, etc. to realize at least one of frequency division duplex (FDD) and time division duplex (TDD). For example, a transmission / reception antenna, an amplifier unit, a transmission / reception unit, a transmission path interface, etc. may be realized by the communication device 1004. The transmission / reception unit may be implemented as a transmission unit and a reception unit that are physically or logically separated.

[0137] The input device 1005 is an input device (for example, a keyboard, a mouse, a microphone, a switch, a button, a sensor, etc.) that receives input from the outside. The output device 1006 is an output device (for example, a display, a speaker, an LED lamp, etc.) that performs output to the outside. Note that the input device 1005 and the output device 1006 may be integrated into one device (for example, a touch panel).

[0138] Furthermore, each device such as the processor 1001 and the storage device 1002 is connected by a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or may be configured using different buses between each device.

[0139] Furthermore, base station 10 and terminal 20 may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic device (PLD), or a field programmable gate array (FPGA), and some or all of the functional blocks may be realized by the hardware. For example, processor 1001 may be implemented using at least one of these pieces of hardware.

[0140] (Summary of the embodiment) As described above, according to an embodiment of the present invention, there is provided a terminal having a receiving unit that receives from a base station one or more pieces of information that specify a plurality of codebooks for transmitting a response related to retransmission control that is applied to transmission and reception in downlink, a control unit that determines a codebook from the plurality of codebooks that is used to transmit a response related to retransmission control that is applied to transmission and reception in sidelink, and a transmitting unit that transmits one or more responses related to retransmission control that is applied to transmission and reception in sidelink to the base station using the determined codebook.

[0141] With the above configuration, when multiple HARQ-ACK codebooks corresponding to DL reception are configured, terminal 20 can determine the codebook type to be used for reporting multiple SL-HARQ-ACKs. That is, in direct terminal-to-terminal communication, multiple HARQ (Hybrid automatic repeat request)-ACKs can be reported to the base station.

[0142] The information specifying the plurality of codebooks may include a first codebook associated with a lower priority and a second codebook associated with a higher priority. With this configuration, when a plurality of HARQ-ACK codebooks corresponding to DL reception are configured, terminal 20 can determine the codebook type to be used for reporting a plurality of SL-HARQ-ACKs according to the priority.

[0143] The control unit may determine the first codebook when the priority associated with transmission and reception in the sidelink is low, and may determine the second codebook when the priority associated with transmission and reception in the sidelink is high. With this configuration, when multiple HARQ-ACK codebooks corresponding to DL reception are configured, the terminal 20 can determine the codebook type to be used for reporting multiple SL-HARQ-ACKs according to the priority.

[0144] The information specifying the plurality of codebooks may include a first codebook to be applied to a primary physical uplink control channel (PUCCH) group and a second codebook to be applied to a secondary PUCCH group. With the above configuration, when a plurality of HARQ-ACK codebooks corresponding to DL reception are configured, terminal 20 can determine the codebook type to be used for reporting a plurality of SL-HARQ-ACKs.

[0145] The control unit may determine the first codebook or the second codebook corresponding to the PUCCH group for transmitting the one or more responses. With the above configuration, when multiple HARQ-ACK codebooks corresponding to DL reception are configured, terminal 20 can determine the codebook type to be used for multiple SL-HARQ-ACK reports based on the PUCCH group for transmitting the reports.

[0146] Furthermore, according to an embodiment of the present invention, there is provided a communication method including: a receiving procedure for receiving, from a base station, one or more pieces of information specifying a plurality of codebooks for transmitting a response related to retransmission control to be applied to transmission and reception in downlink; a control procedure for determining, from the plurality of codebooks, a codebook for transmitting a response related to retransmission control to be applied to transmission and reception in sidelink; and a transmitting procedure for transmitting, to the base station, one or more responses related to retransmission control to be applied to transmission and reception in sidelink, using the determined codebook.

[0147] With the above configuration, when multiple HARQ-ACK codebooks corresponding to DL reception are configured, terminal 20 can determine the codebook type to be used for reporting multiple SL-HARQ-ACKs. That is, in direct terminal-to-terminal communication, multiple HARQ (Hybrid automatic repeat request)-ACKs can be reported to the base station.

[0148] (Supplementary explanation of the embodiment) Although the embodiments of the present invention have been described above, the disclosed invention is not limited to such embodiments, and those skilled in the art will understand various modifications, alterations, alternatives, and substitutions. While specific numerical examples have been used to facilitate understanding of the invention, unless otherwise specified, these numerical values are merely examples, and any appropriate values may be used. The division of items in the above description is not essential to the present invention; two or more items may be combined as needed, and items described in one item may apply to items described in another item (unless inconsistent). The boundaries between functional units or processing units in the functional block diagram do not necessarily correspond to the boundaries between physical components. The operations of multiple functional units may be performed by a single physical component, or the operations of a single functional unit may be performed by multiple physical components. The order of the processing steps described in the embodiments may be reversed as long as there is no contradiction. For convenience of processing description, the base station 10 and terminal 20 have been described using functional block diagrams. However, such devices may be implemented using hardware, software, or a combination thereof. The software operated by the processor of the base station 10 in accordance with an embodiment of the present invention and the software operated by the processor of the terminal 20 in accordance with an embodiment of the present invention may each be stored in random access memory (RAM), flash memory, read-only memory (ROM), EPROM, EEPROM, registers, hard disk (HDD), removable disk, CD-ROM, database, server or any other suitable storage medium.

[0149] Furthermore, the notification of information is not limited to the aspects / embodiments described in the present disclosure, and may be performed using other methods. For example, the notification of information may be performed by physical layer signaling (e.g., Downlink Control Information (DCI), Uplink Control Information (UCI)), higher layer signaling (e.g., Radio Resource Control (RRC) signaling, Medium Access Control (MAC) signaling, broadcast information (Master Information Block (MIB), System Information Block (SIB)), other signals, or a combination thereof. Furthermore, the RRC signaling may be referred to as an RRC message, and may be, for example, an RRC Connection Setup message, an RRC Connection Reconfiguration message, or the like.

[0150] Each aspect / embodiment described in the present disclosure may be applied to at least one of systems using LTE (Long Term Evolution), LTE-Advanced (LTE-A), SUPER 3G, IMT-Advanced, 4G (4th generation mobile communication system), 5G (5th generation mobile communication system), FRA (Future Radio Access), NR (New Radio), W-CDMA (registered trademark), GSM (registered trademark), CDMA2000, UMB (Ultra Mobile Broadband), IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark), IEEE 802.20, UWB (Ultra-Wideband), Bluetooth (registered trademark), or other appropriate systems, and next-generation systems extended based on these. Furthermore, a combination of multiple systems (e.g., a combination of at least one of LTE and LTE-A with 5G, etc.) may also be applied.

[0151] The order of the procedures, sequences, flowcharts, etc. of each aspect / embodiment described herein may be changed unless it is consistent. For example, the methods described in this disclosure present elements of various steps using an example order and are not limited to the particular order presented.

[0152] In this specification, a specific operation that is described as being performed by the base station 10 may also be performed by its upper node in some cases. In a network consisting of one or more network nodes having the base station 10, it is clear that various operations performed for communication with the terminal 20 may be performed by at least one of the base station 10 and another network node other than the base station 10 (such as, but not limited to, an MME or an S-GW). Although the above example illustrates a case where there is one other network node other than the base station 10, the other network node may be a combination of multiple other network nodes (such as an MME and an S-GW).

[0153] The information, signals, etc. described in the present disclosure may be output from a higher layer (or a lower layer) to a lower layer (or a higher layer), or may be input / output via multiple network nodes.

[0154] Input and output information may be stored in a specific location (for example, memory) or may be managed using a management table. Input and output information may be overwritten, updated, or added to. Output information may be deleted. Input information may be sent to another device.

[0155] In the present disclosure, the determination may be made based on a value represented by one bit (0 or 1), a Boolean value (true or false), or a numerical comparison (e.g., comparison with a predetermined value).

[0156] Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

[0157] Software, instructions, information, etc. may also be transmitted or received over a transmission medium. For example, if software is transmitted from a website, server, or other remote source using wired technologies (such as coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL)), and / or wireless technologies (such as infrared, microwave), then these wired and / or wireless technologies are included within the definition of transmission media.

[0158] The information, signals, etc. described in this disclosure may be represented using any of a variety of different technologies. For example, data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof.

[0159] Note that terms explained in this disclosure and terms necessary for understanding this disclosure may be replaced with terms having the same or similar meanings. For example, at least one of a channel and a symbol may be a signal (signaling). Furthermore, a signal may be a message. Furthermore, a component carrier (CC) may be called a carrier frequency, a cell, a frequency carrier, etc.

[0160] As used in this disclosure, the terms "system" and "network" are used interchangeably.

[0161] Furthermore, the information, parameters, etc. described in the present disclosure may be expressed using absolute values, relative values from a predetermined value, or other corresponding information. For example, a radio resource may be indicated by an index.

[0162] The names used for the above-described parameters are not intended to be limiting in any way. Furthermore, the mathematical expressions using these parameters may differ from those explicitly disclosed in this disclosure. The various channels (e.g., PUCCH, PDCCH, etc.) and information elements may be identified by any suitable names, and therefore the various names assigned to these various channels and information elements are not intended to be limiting in any way.

[0163] In this disclosure, terms such as "base station (BS)," "radio base station," "base station," "fixed station," "NodeB," "eNodeB (eNB)," "gNodeB (gNB)," "access point," "transmission point," "reception point," "transmission / reception point," "cell," "sector," "cell group," "carrier," and "component carrier" may be used interchangeably. Base stations may also be referred to by terms such as macrocell, small cell, femtocell, and picocell.

[0164] A base station can accommodate one or more (e.g., three) cells. When a base station accommodates multiple cells, the overall coverage area of the base station can be divided into multiple smaller areas, and each smaller area can be provided with communication service by a base station subsystem (e.g., a small indoor base station (RRH: Remote Radio Head)). The term "cell" or "sector" refers to a part or the entire coverage area of a base station and / or base station subsystem that provides communication service within this coverage.

[0165] In this disclosure, the terms "Mobile Station (MS)," "user terminal," "User Equipment (UE)," "terminal," etc. may be used interchangeably.

[0166] A mobile station may also be referred to by those skilled in the art as a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, or some other suitable terminology.

[0167] At least one of the base station and the mobile station may be called a transmitting device, a receiving device, a communication device, etc. At least one of the base station and the mobile station may be a device mounted on a mobile body, or the mobile body itself. The mobile body may be a vehicle (e.g., a car, an airplane, etc.), an unmanned mobile body (e.g., a drone, an autonomous vehicle, etc.), or a robot (manned or unmanned). At least one of the base station and the mobile station may also include devices that do not necessarily move during communication operations. For example, at least one of the base station and the mobile station may be an IoT (Internet of Things) device such as a sensor.

[0168] Furthermore, a base station in the present disclosure may be read as a user terminal. For example, the aspects / embodiments of the present disclosure may be applied to a configuration in which communication between a base station and a user terminal is replaced with communication between a plurality of terminals 20 (which may be called, for example, D2D (Device-to-Device) or V2X (Vehicle-to-Everything)). In this case, the terminal 20 may be configured to have the functions of the base station 10 described above. Furthermore, terms such as "uplink" and "downlink" may be read as terms corresponding to terminal-to-terminal communication (for example, "side"). For example, terms such as an uplink channel and a downlink channel may be read as a side channel.

[0169] Similarly, the user terminal in the present disclosure may be read as a base station, in which case the base station may be configured to have the functions of the user terminal described above.

[0170] As used in this disclosure, the terms "determining" and "determining" may encompass a wide variety of actions. "Determining" and "determining" may include, for example, judging, calculating, computing, processing, deriving, investigating, looking up, searching, inquiring (e.g., searching in a table, database, or other data structure), ascertaining, and the like. "Determining" and "determining" may also include receiving (e.g., receiving information), transmitting (e.g., sending information), input, output, accessing (e.g., accessing data in memory), and the like. Furthermore, "judgment" and "decision" can include regarding resolving, selecting, choosing, establishing, comparing, etc. as having been "judged" or "decided." In other words, "judgment" and "decision" can include regarding some action as having been "judged" or "decided." Furthermore, "judgment (decision)" can be interpreted as "assuming," "expecting," "considering," etc.

[0171] The terms "connected," "coupled," or any variation thereof, refer to any direct or indirect connection or coupling between two or more elements, and may include the presence of one or more intermediate elements between two elements that are "connected" or "coupled" to each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, "connected" may be read as "access." As used in this disclosure, two elements may be considered to be "connected" or "coupled" to each other using one or more wires, cables, and / or printed electrical connections, as well as electromagnetic energy having wavelengths in the radio frequency range, microwave range, and optical (both visible and invisible) range, as some non-limiting and non-exhaustive examples.

[0172] The reference signal may be abbreviated as RS (Reference Signal) or may be called a pilot depending on the applicable standard.

[0173] As used in this disclosure, the phrase "based on" does not mean "based only on," unless expressly stated otherwise. In other words, the phrase "based on" means both "based only on" and "based at least on."

[0174] As used in this disclosure, any reference to an element using a designation such as "first," "second," etc. does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient method of distinguishing between two or more elements. Thus, a reference to a first and a second element does not imply that only two elements may be employed or that the first element must in some way precede the second element.

[0175] The "means" in the configuration of each of the above devices may be replaced with "part," "circuit," "device," etc.

[0176] When used in this disclosure, the terms "include," "including," and variations thereof are intended to be inclusive, similar to the term "comprising." Furthermore, when used in this disclosure, the term "or" is not intended to be an exclusive or.

[0177] A radio frame may be composed of one or more frames in the time domain. Each of the one or more frames in the time domain may be called a subframe. A subframe may further be composed of one or more slots in the time domain. A subframe may have a fixed time length (e.g., 1 ms) that is independent of numerology.

[0178] Numerology may be communication parameters that apply to at least one of transmission and reception of a signal or channel, such as subcarrier spacing (SCS), bandwidth, symbol length, cyclic prefix length, transmission time interval (TTI), number of symbols per TTI, radio frame structure, specific filtering operations performed by the transceiver in the frequency domain, and specific windowing operations performed by the transceiver in the time domain.

[0179] A slot may be composed of one or more symbols (such as an Orthogonal Frequency Division Multiplexing (OFDM) symbol or a Single Carrier Frequency Division Multiple Access (SC-FDMA) symbol) in the time domain. A slot may be a time unit based on numerology.

[0180] A slot may include multiple minislots. Each minislot may consist of one or multiple symbols in the time domain. A minislot may also be called a subslot. A minislot may consist of fewer symbols than a slot. A PDSCH (or PUSCH) transmitted in a time unit larger than a minislot may be called PDSCH (or PUSCH) mapping type A. A PDSCH (or PUSCH) transmitted using a minislot may be called PDSCH (or PUSCH) mapping type B.

[0181] The radio frame, subframe, slot, minislot, and symbol all represent time units for transmitting signals, and may be referred to by other names corresponding to the radio frame, subframe, slot, minislot, and symbol.

[0182] For example, one subframe may be called a transmission time interval (TTI), multiple consecutive subframes may be called a TTI, or one slot or one minislot may be called a TTI. That is, at least one of the subframe and the TTI may be a subframe (1 ms) in existing LTE, a period shorter than 1 ms (for example, 1-13 symbols), or a period longer than 1 ms. Note that the unit representing the TTI may be called a slot, minislot, etc. instead of a subframe.

[0183] Here, TTI refers to, for example, the smallest time unit for scheduling in wireless communication. For example, in an LTE system, a base station performs scheduling to allocate wireless resources (such as frequency bandwidth and transmission power that can be used by each terminal 20) to each terminal 20 in TTI units. Note that the definition of TTI is not limited to this.

[0184] The TTI may be a transmission time unit for a channel-encoded data packet (transport block), a code block, a code word, etc., or may be a processing unit for scheduling, link adaptation, etc. When a TTI is given, the time interval (e.g., the number of symbols) to which a transport block, a code block, a code word, etc. is actually mapped may be shorter than the TTI.

[0185] When one slot or one minislot is called a TTI, one or more TTIs (i.e., one or more slots or one or more minislots) may be the minimum time unit for scheduling. Also, the number of slots (minislots) constituting the minimum time unit for scheduling may be controlled.

[0186] A TTI having a time length of 1 ms may be called a regular TTI (TTI in LTE Rel. 8-12), normal TTI, long TTI, regular subframe, normal subframe, long subframe, slot, etc. A TTI shorter than a regular TTI may be called a shortened TTI, short TTI, partial or fractional TTI, shortened subframe, short subframe, minislot, subslot, slot, etc.

[0187] In addition, a long TTI (e.g., a normal TTI, a subframe, etc.) may be interpreted as a TTI having a time length of more than 1 ms, and a short TTI (e.g., a shortened TTI, etc.) may be interpreted as a TTI having a TTI length shorter than the TTI length of a long TTI and equal to or greater than 1 ms.

[0188] A resource block (RB) is a resource allocation unit in the time domain and frequency domain, and may include one or more consecutive subcarriers in the frequency domain. The number of subcarriers included in an RB may be the same regardless of numerology, for example, 12. The number of subcarriers included in an RB may also be determined based on numerology.

[0189] The time domain of an RB may include one or more symbols and may have a length of one slot, one minislot, one subframe, or one TTI. One TTI, one subframe, etc. may each be composed of one or more resource blocks.

[0190] Note that one or more RBs may also be called a physical resource block (PRB), a sub-carrier group (SCG), a resource element group (REG), a PRB pair, an RB pair, or the like.

[0191] Furthermore, a resource block may be composed of one or more resource elements (REs). For example, one RE may be a radio resource region of one subcarrier and one symbol.

[0192] A Bandwidth Part (BWP) (which may also be referred to as a fractional bandwidth) may represent a subset of contiguous common resource blocks (RBs) for a given numerology on a given carrier, where the common RBs may be identified by their index relative to a common reference point of the carrier. PRBs may be defined in a given BWP and numbered within that BWP.

[0193] The BWP may include a BWP for UL (UL BWP) and a BWP for DL (DL BWP). One or more BWPs may be set for the terminal 20 within one carrier.

[0194] At least one of the configured BWPs may be active, and the terminal 20 may not expect to transmit or receive a predetermined signal / channel outside the active BWP. Note that the terms "cell," "carrier," and the like in this disclosure may be read as "BWP."

[0195] The above-described structures of radio frames, subframes, slots, minislots, symbols, etc. are merely examples. For example, the number of subframes included in a radio frame, the number of slots per subframe or radio frame, the number of minislots included in a slot, the number of symbols and RBs included in a slot or minislot, the number of subcarriers included in an RB, the number of symbols in a TTI, the symbol length, the cyclic prefix (CP) length, etc. may be changed in various ways.

[0196] In this disclosure, where articles are added by translation, such as a, an, and the in English, the disclosure may include that the nouns following these articles are in the plural form.

[0197] In the present disclosure, the term "A and B are different" may mean "A and B are different from each other." The term may also mean "A and B are each different from C." Terms such as "separate" and "coupled" may also be interpreted in the same way as "different."

[0198] Each aspect / embodiment described in this disclosure may be used alone, in combination, or switched depending on the implementation. Furthermore, notification of predetermined information (e.g., notification that "X is true") is not limited to being done explicitly, but may be done implicitly (e.g., by not notifying the predetermined information).

[0199] In the present disclosure, HARQ-ACK is an example of a response related to retransmission control.

[0200] Although the present disclosure has been described in detail above, it is clear to those skilled in the art that the present disclosure is not limited to the embodiments described herein. The present disclosure can be implemented in modified and altered forms without departing from the spirit and scope of the present disclosure as defined by the claims. Therefore, the description of the present disclosure is intended to be illustrative and does not have any limiting meaning on the present disclosure.

[0201] <Additional Notes> The above-described embodiment can be further described as follows.

[0202] (Appendix 1) a receiving unit that receives, from a base station, one or more pieces of information that specify a plurality of codebooks for transmitting a response related to retransmission control that is applied to transmission and reception in downlink; a control unit for determining a codebook for transmitting a response related to retransmission control to be applied to transmission and reception in a side link from among the plurality of codebooks; A terminal having a transmitter that uses the determined codebook to transmit to the base station one or more responses related to retransmission control applied to transmission and reception in the side link.

[0203] (Appendix 2) 2. The terminal according to claim 1, wherein the information specifying the plurality of codebooks includes a first codebook associated with a lower priority and a second codebook associated with a higher priority.

[0204] (Appendix 3) The terminal according to claim 2, wherein the control unit determines the first codebook when the priority associated with transmission and reception in the side link is low, and determines the second codebook when the priority associated with transmission and reception in the side link is high.

[0205] (Appendix 4) 2. The terminal according to claim 1, wherein the information specifying the plurality of codebooks includes a first codebook applied to a primary PUCCH (Physical uplink control channel) group and a second codebook applied to a secondary PUCCH group.

[0206] (Appendix 5) The terminal according to Supplementary Note 4, wherein the control unit determines the first codebook or the second codebook corresponding to a PUCCH group for transmitting the one or more responses.

[0207] (Appendix 6) a receiving procedure of receiving, from a base station, one or more pieces of information specifying a plurality of codebooks for transmitting a response related to retransmission control applied to transmission and reception in downlink; a control procedure for determining a codebook for transmitting a response related to retransmission control to be applied to transmission and reception in a side link from among the plurality of codebooks; a transmission procedure of transmitting to the base station, using the determined codebook, one or more responses related to retransmission control applied to transmission and reception in the side link. [Explanation of symbols]

[0208] 10 base station 110 Transmitter 120 Receiver 130 Setting section 140 Control Unit 20 terminals 210 Transmitter 220 Receiving unit 230 Setting Section 240 Control Unit 1001 processor 1002 Storage device 1003 Auxiliary storage device 1004 Communication equipment 1005 Input Device 1006 Output Device

Claims

1. a receiving unit that receives, from a base station, first information related to one codebook for transmitting a response related to retransmission control applied to transmission and reception in downlink, and second information related to one or more codebooks for transmitting a response related to retransmission control applied to transmission and reception in downlink; a transmitting unit that, when the second information is set, transmits to the base station a response related to retransmission control to be applied to transmission and reception in a side link using a codebook of a type determined based on the first information.

2. 2. The terminal of claim 1, wherein the second information is information relating to up to two codebooks.

3. When the second information is set, the transmitter transmits to the base station a response related to retransmission control to be applied to transmission and reception in downlink, using a codebook of a type determined based on the second information. The terminal of claim 1.

4. a receiving unit configured to receive, from a base station, first information on one codebook for transmitting a response related to retransmission control applied to transmission and reception in downlink, and third information on a codebook for transmitting a response for a secondary Physical Uplink Control Channel (PUCCH) group related to retransmission control applied to transmission and reception in downlink; a transmitting unit that, when the third information is set, transmits to the base station a response related to retransmission control to be applied to transmission and reception in a side link using a codebook of a type determined based on the first information.

5. when the third information is set, the transmitter transmits to the base station a response for a secondary PUCCH group related to retransmission control applied to transmission and reception in downlink, using a codebook of a type determined based on the third information, and transmits to the base station a response for a primary PUCCH group related to retransmission control applied to transmission and reception in downlink, using a codebook of a type determined based on the first information. The terminal according to claim 4.

6. a transmitter configured to transmit, to a terminal, first information related to one codebook for transmitting a response related to retransmission control applied to transmission and reception in downlink, and second information related to one or more codebooks for transmitting a response related to retransmission control applied to transmission and reception in downlink; a receiving unit that, when the second information is set, receives from the terminal a response related to retransmission control to be applied to transmission and reception in a side link, using a codebook of a type determined based on the first information.

7. A communication system including a terminal and a base station, The terminal a receiving unit that receives, from the base station, first information related to one codebook for transmitting a response related to retransmission control applied to transmission and reception in downlink, and second information related to one or more codebooks for transmitting a response related to retransmission control applied to transmission and reception in downlink; a transmitter configured to transmit to the base station, when the second information is set, a response related to retransmission control to be applied to transmission and reception in a side link, by using a codebook of a type determined based on the first information; The base station a transmitting unit that transmits the first information and the second information to the terminal; a receiving unit that, when the second information is set, receives from the terminal a response related to retransmission control to be applied to transmission and reception in a side link, using a codebook of a type determined based on the first information.

8. receiving, from a base station, first information on one codebook for transmitting a response related to retransmission control applied to transmission and reception in downlink, and second information on one or more codebooks for transmitting a response related to retransmission control applied to transmission and reception in downlink; and if the second information is set, transmitting a response related to retransmission control to be applied to transmission and reception in a side link to the base station using a codebook of a type determined based on the first information.

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