JP7738151B2 - Terminal and communication method - Google Patents

Description

The present invention relates to a terminal and a communication method in a wireless communication system.

For LTE (Long Term Evolution) and its successor systems (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 (see, for example, Non-Patent Document 1).

D2D reduces traffic between terminals and base stations, enabling communication between terminals even when base stations become unavailable due to disasters or other reasons. While the 3GPP (3rd Generation Partnership Project) refers to D2D as "sidelink," this specification uses the more general term D2D. However, sidelink will also be used as needed in the explanation of the embodiments described below.

D2D communication can be broadly divided into D2D discovery (also referred to as D2D discovery) for discovering other terminals with which it can communicate, 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 simply be referred to as D2D. Furthermore, signals transmitted and received via D2D will be referred to as D2D signals. Various use cases for services related to V2X (Vehicle to Everything) in NR are being considered (for example, Non-Patent Document 2).

3GPP TS 38.211 V16.2.0 (2020-06) 3GPP TR 22.886 V15.1.0 (2017-03)

Power saving is being considered as an enhancement to the NR sidelink. For example, in Resource allocation mode 2, in which a terminal autonomously selects resources, the terminal performs partial sensing, sensing limited resources within the sensing window, and based on the results, selects available resource candidates from the resource selection window.

In addition, the NR sidelink supports HARQ (Hybrid automatic repeat request) feedback. Here, the timing of PSFCH (Physical Sidelink Feedback Channel) transmission depends on the timing of the transmission of the corresponding data, and therefore cannot be controlled by the terminal transmitting the PSFCH. Therefore, depending on the timing, overlap between the PSFCH and other channels may occur.

The present invention was made in consideration of the above points, and aims to improve the efficiency of retransmission control in direct terminal-to-terminal communication.

The disclosed technology provides a terminal having a control unit that selects resources from a portion of a resource selection window based on at least one of information related to PSFCH (Physical Sidelink Feedback Channel) opportunities received from other terminals, including at least one of a first terminal and a second terminal, and information related to PSFCH opportunities that the terminal plans to transmit or receive, and a transmission unit that transmits data to the second terminal using the selected resources.

The disclosed technology can improve the efficiency of retransmission control in direct terminal-to-terminal communication.

FIG. 1 is a diagram for explaining V2X. FIG. 10 is a diagram illustrating an example (1) of a V2X transmission mode. FIG. 10 is a diagram illustrating an example (2) of a V2X transmission mode. FIG. 10 is a diagram illustrating an example (3) of a V2X transmission mode. FIG. 10 is a diagram illustrating an example (4) of a V2X transmission mode. FIG. 10 is a diagram illustrating an example (5) of a V2X transmission mode. FIG. 1 is a diagram for explaining an example (1) of a V2X communication type. FIG. 10 is a diagram for explaining an example (2) of a V2X communication type. FIG. 10 is a diagram illustrating an example (3) of a V2X communication type. FIG. 1 is a sequence diagram showing an example (1) of V2X operation. FIG. 10 is a sequence diagram showing an operation example (2) of V2X. FIG. 10 is a sequence diagram showing an example of V2X operation (3). FIG. 10 is a sequence diagram showing an example (4) of V2X operation. FIG. 10 is a diagram illustrating an example of a sensing operation. FIG. 10 is a diagram illustrating an example of a partial sensing operation. FIG. 2 is a diagram illustrating an example of communication according to an embodiment of the present invention. FIG. 10 is a diagram for explaining an example (1) of information related to a PSFCH opportunity in an embodiment of the present invention. FIG. 10 is a diagram for explaining an example (2) of information related to a PSFCH opportunity in an embodiment of the present invention. FIG. 10 is a diagram for explaining an example (3) of information related to a PSFCH opportunity in an embodiment of the present invention. FIG. 10 is a diagram for explaining an example (4) of information related to PSFCH opportunities in an embodiment of the present invention. FIG. 10 is a diagram illustrating an example of resource selection according to an embodiment of the present invention. 10 is a flowchart illustrating an example of resource selection according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of a functional configuration of a base station 10 according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of a functional configuration of a terminal 20 according to an embodiment of the present invention. 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. FIG.

Embodiments of the present invention will be described below with reference to the drawings. Note that the embodiments described below are merely examples, and embodiments to which the present invention can be applied are not limited to the following embodiments.

Existing technologies are used as appropriate when operating the wireless communication system of an embodiment of the present invention. However, such existing technologies may be, but are not limited to, existing LTE. Furthermore, the term "LTE" used in this specification has a broad meaning, including LTE-Advanced, systems subsequent to LTE-Advanced (e.g., NR), and wireless LAN (Local Area Network), unless otherwise specified.

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

Furthermore, in the embodiments of the present invention, "configuring" radio parameters etc. may mean that predetermined values are pre-configured, or that radio parameters notified from the base station 10 or terminal 20 are configured.

Figure 1 is a diagram explaining V2X. 3GPP is considering realizing V2X (Vehicle to Everything) or eV2X (enhanced V2X) by expanding D2D functionality, 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 communication between vehicles; V2I (Vehicle to Infrastructure), which refers to communication between vehicles and roadside units (RSUs) installed on the side of the road; V2N (Vehicle to Network), which refers to communication between vehicles and ITS servers; and V2P (Vehicle to Pedestrian), which refers to communication between vehicles and mobile devices carried by pedestrians.

In addition, 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 QoS (Quality of Service) control.

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

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

The SL (Sidelink) may be distinguished from the UL (Uplink) or DL (Downlink) based on any one or a combination of the following 1) to 4). The SL may also be called by other names.
1) Resource allocation in the time domain; 2) Resource allocation in the frequency domain; 3) Reference synchronization signal (including SLSS (Sidelink Synchronization Signal));
4) Reference signal used for path loss measurement for transmission power control

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), OFDM without transform precoding, or OFDM with transform precoding may be applied.

In LTE SL, Mode 3 and Mode 4 are specified for SL resource allocation to terminals 20. In Mode 3, transmission resources are dynamically allocated based on DCI (Downlink Control Information) transmitted from the base station 10 to the terminal 20. Mode 3 also enables SPS (Semi Persistent Scheduling). In Mode 4, terminals 20 autonomously select transmission resources from a resource pool.

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

Note that in the embodiment of the present invention, the terminal 20 is not limited to a V2X terminal, but 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 an IoT (Internet of Things) device, such as a smart meter.

Figure 2 is a diagram illustrating an example of a V2X transmission mode (1). In the sidelink communication transmission mode shown in Figure 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 sidelink communication transmission mode shown in Figure 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 the radio interface between the Universal Terrestrial Radio Access Network (UTRAN) and the User Equipment (UE). The sidelink communication transmission mode shown in Figure 2 may also be referred to as sidelink transmission mode 1 in NR.

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

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

Figure 5 is a diagram illustrating an example of a V2X transmission mode (4). In the sidelink communication transmission mode shown in Figure 5, in step 0, the base station 10 transmits a sidelink grant to the terminal 20A via RRC (Radio Resource Control) configuration. Next, the terminal 20A transmits a PSSCH to the terminal 20B based on the received resource pattern (step 1). The sidelink communication transmission mode shown in Figure 5 may also be referred to as sidelink transmission mode 2c in NR.

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

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

Figure 8 is a diagram illustrating an example of a V2X communication type (2). The sidelink communication type shown in Figure 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 Figure 8, the group includes terminal 20B and terminal 20C, and terminal 20A performs groupcast to the group.

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

It is also 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) that includes a HARQ response. Furthermore, it is being considered to transmit SFCI via the physical sidelink feedback channel (PSFCH).

Note that in the following description, the PSFCH is used to transmit HARQ-ACK on the sidelink, but this is just one example. For example, the PSCCH may be used to transmit HARQ-ACK on the sidelink, or the PSSCH may be used to transmit HARQ-ACK on the sidelink, or another channel may be used to transmit HARQ-ACK on the sidelink.

For convenience, the general information reported by terminal 20 in HARQ will be referred to as HARQ-ACK below. This HARQ-ACK may also be referred to as HARQ-ACK information. More specifically, the codebook applied to the HARQ-ACK information reported from terminal 20 to base station 10, etc., will be referred to as the HARQ-ACK codebook. The HARQ-ACK codebook defines the bit string of the HARQ-ACK information. Note that in addition to ACK, NACK can also be transmitted using "HARQ-ACK."

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

Hereinafter, when terminals 20A, 20B, etc. are not particularly distinguished from one another, they will be referred to simply as "terminal 20" or "user equipment." Figure 10 shows, as an example, a case where terminals 20A and 20B are both within the coverage of a cell, but the operation of this embodiment of the present invention can also be applied when terminal 20B is outside the coverage.

As mentioned above, in this embodiment, the terminal 20 is, for example, a device mounted on a vehicle such as an automobile, and has cellular communication functionality as a UE in LTE or NR, and sidelink functionality. 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 that has the functionality of a UE, or a gNB-type RSU that has the functionality of a base station device.

Note that the terminal 20 does not have to be a device in a single housing; for example, even if various sensors are distributed throughout the vehicle, the device including those various sensors may be the terminal 20.

Furthermore, the processing of sidelink transmission data by terminal 20 is basically the same as the processing of UL transmission in LTE or NR. For example, terminal 20 scrambles and modulates the codeword of the transmission data to generate complex-valued symbols, maps the complex-valued symbols (transmission signal) to one or two layers, and performs precoding. Then, it maps the precoded complex-valued symbols to resource elements to generate a transmission signal (e.g., a complex-valued time-domain SC-FDMA signal), which is then transmitted from each antenna port.

The base station 10 has cellular communication functions as a base station in LTE or NR, as well as functions to enable communication with the terminal 20 in this embodiment (e.g., resource pool configuration, resource allocation, etc.). The base station 10 may also be an RSU (gNB-type RSU).

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

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

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 the PSSCH, using time resources that are the same as at least part of the time resources of the PSSCH.

Terminal 20B receives the SCI (PSCCH and/or PSSCH) and SL data (PSSCH) transmitted from terminal 20A. The received SCI may include information about the PSFCH resource used by terminal 20B to transmit a HARQ-ACK in response to the reception of the data. Terminal 20A may also transmit information about the autonomously selected resource in the SCI.

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

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

Note that if HARQ control involving HARQ feedback is not performed, steps S104 and S105 do not need to be performed.

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

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

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

In step S204, terminal 20A retransmits SCI via PSCCH and/or PSSCH and SL data via PSSCH to terminal 20B using the resources autonomously selected in step S201. The retransmission in step S204 may be performed multiple times.

Note that if blind retransmission is not performed, step S204 does not need to be performed.

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

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

In step S301, it is also 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, the DCI for DL scheduling will be referred to as DL scheduling DCI. Having received the DL scheduling DCI, the terminal 20A receives DL data via the PDSCH using the resources specified in the DL scheduling DCI.

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

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

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.

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

In step S305, terminal 20A transmits a HARQ-ACK using PUCCH (Physical uplink control channel) resources specified by the DL scheduling DCI (or SL scheduling DCI) at the timing (e.g., slot-by-slot timing) specified by the DL scheduling DCI (or SL scheduling DCI), and base station 10 receives the HARQ-ACK. The HARQ-ACK codebook may include an ARQ-ACK generated based on the HARQ-ACK received from terminal 20B or the PSFCH that was not received, as well as 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 HARQ-ACK codebook does not include a HARQ-ACK for DL data.

Note that if HARQ control involving HARQ feedback is not performed, step S304 and/or step S305 may not be performed.

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

In Figure 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 the slot, or in multiple symbols from the first, or in multiple symbols from symbols other than the first. The PSFCH may be placed in the last symbol of the slot, or in multiple symbols from the last. Note that the above-mentioned "first symbol of the slot" and "last symbol of the slot" may not take into account symbols for AGC (Automatic Gain Control) and symbols for transmission/reception switching. In other words, for example, if one slot consists of 14 symbols, the "first symbol of the slot" and "last symbol of the 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 Figure 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.

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 the transmitting terminal 20, performs groupcast via SL-SCH to terminals 20B, 20C, and 20D, which are receiving terminals 20. In the subsequent step S402, terminal 20B uses PSFCH#B, terminal 20C uses PSFCH#C, and terminal 20D uses PSFCH#D to transmit the HARQ response to terminal 20A. Here, as shown in the example of FIG. 13, if the number of available PSFCH resources is less than the number of receiving terminals 20 belonging to the group, it is necessary to determine how to allocate the PSFCH resources. The transmitting terminal 20 may be aware of the number of receiving terminals 20 in the groupcast. In Groupcast Option 1, only NACKs are sent as HARQ responses; ACKs are not sent.

Figure 14 is a diagram showing an example of sensing operation. When partial sensing is not configured by a higher layer in the LTE sidelink, the terminal 20 selects resources and performs transmission as shown in Figure 14. As shown in Figure 14, the terminal 20 performs sensing in a sensing window within a resource pool. Through sensing, the terminal 20 receives a resource reservation field included in an SCI transmitted from another terminal 20 and, based on the field, identifies available resource candidates within the resource selection window within the resource pool. The terminal 20 then randomly selects a resource from the available resource candidates. The resource selection window is a set of candidate resources configured within the resource pool. The resource selection window may be referred to by other names, such as resource selection settings or a target interval for resource selection. In LTE, a sensing window may be a period from a predetermined point in time prior to a trigger, such as packet generation, to immediately before the trigger. Sensing all resources within the sensing window may be referred to as full sensing. Note that the sensing window may also be referred to by other names indicating the interval in which sensing is performed.

Furthermore, as shown in Fig. 14, the resource pool may be set periodically. For example, the period may be 10,240 milliseconds. Fig. 14 shows an example in which subframes _t0SL to _tTmaxSL are set as the ^resource pool. The resource pool within the period may have regions set by, for example ^, a bitmap.

Also, as shown in FIG. 14 , assume that a transmission trigger in terminal 20 occurs in subframe n, and the priority of the transmission is p _TX . Terminal 20 can detect, for example, that another terminal 20 is transmitting with priority p _RX in the sensing window from subframe t _n-10×Pstep ^SL to subframe t _n-1 ^SL . If SCI is detected in the sensing window and the RSRP (Reference Signal Received Power) exceeds a threshold, the resource in the resource selection window corresponding to the SCI is excluded. Also, if SCI is detected in the sensing window and the RSRP is less than a threshold, the resource in the resource selection window corresponding to the SCI is not excluded. The threshold may be, for example, a threshold Th _pTX,pRX that is set or defined for each resource in the sensing window based on the priority p _TX and the priority p _RX .

Also, resources in the resource selection window that are candidates for resource reservation information corresponding to resources in the sensing window that were not monitored for transmission, such as subframe t _Z ^SL shown in FIG. 14, are excluded.

As shown in FIG. 14 , in the resource selection window from subframe n+ _T1 to subframe n+ _T2 , resources occupied by other UEs are identified, and the resources from which these resources are excluded become available resource candidates. If the set of available resource candidates is S _A , if S _A is less than 20% of the resources in the resource selection window, the threshold Th _pTX,pRX set for each resource in the sensing window may be increased by 3 dB and resource identification may be performed again. That is, by increasing the threshold Th _pTX,pRX and performing resource identification again, the number of resources that are not excluded because their RSRP is below the threshold may be increased. Furthermore, the RSSI (Received Signal Strength Indicator) of each resource in S _A may be measured, and the resource with the smallest RSSI may be added to set S _B. The operation of adding the resource with the smallest RSSI included in S _A to S _B may be repeated until the set of resource candidates S _B accounts for 20% or more of the resource selection window.

The lower layer of the terminal 20 may report S _B to the upper layer. The upper layer of the terminal 20 may perform random selection for S _B to determine the resources to use. The terminal 20 may perform sidelink transmission using the determined resources. After reserving resources once, the terminal 20 may periodically use the resources without performing sensing for a predetermined number of times (e.g., C _resel times).

Figure 15 is a diagram showing an example of partial sensing operation. When partial sensing is configured by a higher layer in the LTE sidelink, the terminal 20 selects resources and performs transmission as shown in Figure 15. As shown in Figure 15, the terminal 20 performs partial sensing on a portion of the sensing window in the resource pool. The resources on which partial sensing is performed may also be referred to as sensing targets, sensing subjects, sensing subframes, or sensing slots. With partial sensing, the terminal 20 receives a resource reservation field included in an SCI transmitted from another terminal 20 and identifies available resource candidates in the resource selection window in the resource pool based on the field. The terminal 20 then randomly selects a resource from the available resource candidates.

Furthermore, as shown in Fig. 15, the resource pool may be set periodically. For example, the period may be 10,240 milliseconds. Fig. 15 shows an example in which subframes _t0SL to _tTmaxSL are set as the ^resource pool. The target area of the resource pool within the period may be set by, for example ^, a bitmap.

As shown in Figure 15, it is assumed that a transmission trigger in terminal 20 occurs in subframe n, and the priority of the transmission is p _TX . As shown in Figure 15, among subframes n+ _T1 to n+ _T2 , Y subframes from ^subframe _tySL to subframe ty _+Y-1SL ^may be set as a resource selection window. Furthermore, as shown in Figure 15, it is assumed that a transmission trigger in terminal 20 occurs in subframe n, and the priority of the transmission is p _TX .

The terminal 20 can detect, for example, that another terminal 20 is transmitting with priority p RX in one or more sensing targets from subframe t _y-k×Pstep ^SL to subframe t _{y+Y-k×Pstep-1 SL} ^, which has a length of Y subframes. k may be, for example, a 10-bit bitmap. FIG. 15 shows an example in which the third and sixth bits of bitmap k are set to "1," indicating that partial sensing is being performed. That is, in FIG. 15, subframes t _y-6×Pstep ^SL to subframe t _{y+Y-6×Pstep-1} ^SL and subframes t _y-3×Pstep ^SL to subframe t _{y+Y-3×Pstep-1} ^SL are set as sensing targets. As described above, the i-th bit of bitmap k may correspond to the sensing target from subframe t _y-i×Pstep ^SL to subframe t _{y+Y-i×Pstep-1} ^SL .

Here, y is an index within the Y subframe, k is set by a 10-bit bitmap or is predefined, and P _step is 100 ms. However, when SL communication is performed on DL and UL carriers, P _step is (U/(D+S+U))*100 ms. U corresponds to the number of UL slots, D corresponds to the number of DL slots, and S corresponds to the number of special slots.

If SCI is detected in one or more sensing targets and the RSRP is greater than a threshold, resources in the resource selection window corresponding to the resource reservation field of the SCI are excluded. Also, if SCI is detected in a sensing target and the RSRP is less than a threshold, resources in the resource selection window corresponding to the resource reservation field of the SCI are not excluded. The threshold may be, for example, a threshold Th _pTX,pRX that is set or defined for each resource in the sensing window based on the priority p _TX and the priority p _RX .

As shown in FIG. 15 , in a resource selection window in which Y subframes are set within the interval [n+T ₁ , n+T ₂ ], terminal 20 identifies resources occupied by other UEs, and the resources excluding these resources become available resource candidates. Note that Y subframes do not have to be consecutive. If a set of available resource candidates is S _A , if S _A is less than 20% of the resources in the resource selection window, the threshold Th _pTX,pRX set for each resource in the sensing window may be increased by 3 dB and resource identification may be performed again. In other words, by increasing the threshold Th _pTX,pRX and performing resource identification again, the number of resources that are not excluded because their RSRP is below the threshold may be increased. Furthermore, the RSSI of each resource in S _A may be measured, and the resource with the smallest RSSI may be added to set S _B. The operation of adding the resource with the smallest RSSI included in S _A to set S _B may be repeated until the resource candidate set S _B accounts for 20% or more of the resource selection window.

The lower layer of the terminal 20 may report S _B to the upper layer. The upper layer of the terminal 20 may perform random selection for S _B to determine the resources to use. The terminal 20 may perform sidelink transmission using the determined resources. After reserving resources once, the terminal 20 may periodically use the resources without performing sensing for a predetermined number of times (e.g., C _resel times).

The operation of the transmitting terminal 20 has been described above in Figures 14 and 15, but the receiving terminal 20 may also detect data transmission from another terminal 20 based on the results of sensing or partial sensing, and receive data from that other terminal 20.

For the NR Release 17 sidelink, power saving based on the above-mentioned random resource selection and partial sensing is being considered. For example, to save power, the random resource selection and partial sensing of the sidelink in LTE Release 14 may be applied to resource allocation mode 2 of the NR Release 16 sidelink. A terminal 20 to which partial sensing is applied performs reception and sensing only in specific slots within the sensing window.

In addition, for NR Release 17 sidelink, enhanced Ultra Reliable Low Latency Communication (eURLLC) is being considered, with inter-UE coordination as the baseline. For example, terminal 20A may share information indicating a resource set with terminal 20B, and terminal 20B may take that information into account when selecting resources for transmission.

In addition, the NR sidelink supports HARQ (Hybrid automatic repeat request) feedback. Here, the timing of PSFCH (Physical Sidelink Feedback Channel) transmission depends on the timing of the transmission of the corresponding data, and therefore cannot be controlled by the terminal transmitting the PSFCH. Therefore, depending on the timing, overlap between the PSFCH and other channels may occur.

For example, if overlap occurs between PSFCH transmission and PSFCH reception, one of the PSFCHs must be dropped. Also, if overlap occurs between PSFCH transmission and PSFCH transmission, it may be necessary to reduce the transmission power or drop some of the PSFCHs. This results in degradation of reliability and delay characteristics.

Figure 16 is a diagram showing an example of communication in an embodiment of the present invention. In this embodiment of the present invention, as shown in Figure 16, a case is assumed in which terminals 20A, 20B, 20C, and 20D exist, and the case in which terminal 20C transmits data to terminal 20B is assumed. Furthermore, a situation in which terminal 20D transmits data to terminal 20C is also assumed.

To reduce the possibility of overlap between the PSFCH and other channels, terminal 20C performs resource allocation operations based on at least one of the pieces of information shown in 1)-3) below.

1) Information related to the PSFCH opportunity received by the terminal 20C from the terminal 20A; 2) Information related to the PSFCH opportunity received by the terminal 20C from the terminal 20B; and 3) Information related to the PSFCH opportunity that the terminal 20C plans to transmit or receive.

The following provides a detailed explanation of the definition and acquisition method of the information shown in 1)-3) above, and the operations related to resource allocation. Unless otherwise specified, the information shown in 1)-3) above is information used by terminal 20C, and the operations related to resource allocation are operations performed by terminal 20C. The time resource assignment field in this embodiment of the present invention may be any field for indicating future time resources, and may indicate one or more slots in the future. Similarly, the resource reservation period field may be any field for indicating periodic time resources based on a specific periodicity, and may indicate that specific periodicity.

Figure 17 is a diagram illustrating example (1) of information related to PSFCH opportunities in an embodiment of the present invention. The information related to PSFCH opportunities received by terminal 20C from terminal 20A above (1) may include the information shown in a)-c) below.

a) Information indicating a PSFCH opportunity corresponding to the PSCCH/PSSCH transmitted by terminal 20A to terminal 20B, which is also received by terminal 20C. This PSFCH opportunity is hereinafter referred to as, for example, PSFCH opportunity X1 shown in FIG. 17.

b) Information indicating a PSFCH opportunity corresponding to a resource based on (e.g., indicating) a time resource assignment field included in the SCI in the PSCCH/PSSCH transmitted by terminal 20A to terminal 20B, which is also received by terminal 20C. This PSFCH opportunity is hereinafter referred to, for example, as PSFCH opportunity X2 shown in FIG. 17.

c) Information indicating a PSFCH opportunity corresponding to resources based on (e.g., indicated by) the resource reservation period field included in the SCI in the PSSCH/PSSCH received by terminal 20C and transmitted from terminal 20A to terminal 20B. Hereinafter, this PSFCH opportunity will be referred to as PSFCH opportunity X3.

That is, example (1) of information related to PSFCH opportunities may be PSFCH opportunities determined from signals for data transmission and/or resource reservation. The PSCCH/PSSCH transmitted by terminal 20A to terminal 20B above may be addressed to a group including terminal 20B. Furthermore, the information shown in a)-c) above may be valid only when the PSCCH/PSSCH transmitted from terminal 20A or the resource selected by terminal 20A requests HARQ feedback. Note that, in PSFCH opportunity X1, PSFCH opportunity X2, and PSFCH opportunity X3, terminal 20B transmits the PSFCH, and terminal 20A receives the PSFCH.

Figure 18 is a diagram illustrating example (2) of information related to PSFCH opportunities in an embodiment of the present invention. The information related to PSFCH opportunities received by terminal 20C from terminal 20B in 2) above may include the information shown in a)-c) below.

a) Information indicating a PSFCH opportunity corresponding to the PSCCH/PSSCH transmitted from terminal 20B to terminal 20A, which is also received by terminal 20C. This PSFCH opportunity is hereinafter referred to as, for example, PSFCH opportunity X4 shown in FIG. 18.

b) Information indicating a PSFCH opportunity corresponding to resources based on (e.g., indicating) the time resource allocation field included in the SCI in the PSCCH/PSSCH transmitted by terminal 20B to terminal 20A, which is also received by terminal 20C. This PSFCH opportunity is hereinafter referred to, for example, as PSFCH opportunity X5 shown in FIG. 18.

c) Information indicating a PSFCH opportunity corresponding to a resource based on (e.g., indicating) the resource reservation period field included in the SCI in the PSCCH/PSSCH transmitted by terminal 20B to terminal 20A, which is also received by terminal 20C. This PSFCH opportunity is hereinafter referred to as PSFCH opportunity X6.

That is, a)-c) in example (2) of information related to PSFCH opportunities may be PSFCH opportunities determined from signals for data transmission and/or resource reservation. The PSCCH/PSSCH transmitted by terminal 20B to terminal 20A above may be addressed to a group including terminal 20A. Furthermore, the information shown in a)-c) above may be valid only when the PSCCH/PSSCH transmitted from terminal 20B or the resource selected by terminal 20B requests HARQ feedback. Note that, in PSFCH opportunity X4, PSFCH opportunity X5, and PSFCH opportunity X6, terminal 20A transmits the PSFCH, and terminal 20B receives the PSFCH.

Furthermore, the information related to PSFCH opportunities received by terminal 20C from terminal 20B in 2) above may further include at least one piece of information related to the resource usage schedule transmitted by terminal 20B to terminal 20C, as shown in d1)-d7) below. The information related to the resource usage schedule may be notified from terminal 20B to terminal 20C via, for example, RRC signaling, MAC signaling, or PHY layer signaling.

d1) Information indicating a PSFCH opportunity corresponding to the PSCCH/PSSCH received by the terminal 20B. This PSFCH opportunity will be referred to hereinafter as a PSFCH opportunity X7a.
d2) Information indicating (e.g., indicating) resources based on a time resource allocation field in the PSCCH/PSSCH received by the terminal 20B.
d3) Information indicating a PSFCH opportunity corresponding to a resource based on (for example, indicating) a time resource allocation field in the PSCCH/PSSCH received by the terminal 20B. This PSFCH opportunity will be referred to hereinafter as a PSFCH opportunity X7b.
d4) Information indicating (for example, indicating) resources based on the resource reservation period field in the PSCCH/PSSCH received by the terminal 20B.
d5) Information indicating a PSFCH opportunity corresponding to a resource based on (for example, indicating) a resource reservation period field in the PSCCH/PSSCH received by the terminal 20B. This PSFCH opportunity will be referred to hereinafter as a PSFCH opportunity X7c.
d6) Information indicating a resource selected for transmission in terminal 20B. For example, the resource may be a resource not reserved by terminal 20B.
d7) Information indicating a PSFCH opportunity corresponding to a resource selected for transmission in terminal 20B. This PSFCH opportunity is hereinafter referred to as PSFCH opportunity X7d. For example, this resource may be a resource that is not reserved by terminal 20B.

In the above d1)-d5), "received by terminal 20B" may be replaced with "transmitted by terminal 20B." Furthermore, the priority of the corresponding PSFCH opportunity or resource may be notified along with the information related to the resource usage schedule transmitted by terminal 20B to terminal 20C as shown in the above d1)-d7). Furthermore, the information shown in the above d1)-d7) may be valid only when the PSCCH/PSSCH transmitted from terminal 20B or the resource selected by terminal 20B requests HARQ feedback.

Figure 19 is a diagram illustrating an example (3) of information related to PSFCH opportunities in an embodiment of the present invention. Figure 20 is a diagram illustrating an example (4) of information related to PSFCH opportunities in an embodiment of the present invention. The information related to PSFCH opportunities that terminal 20C plans to transmit or receive in 3) above may include the information shown in a)-e) below.

a) Information indicating a PSFCH opportunity corresponding to an unreserved resource selected for transmission in terminal 20C. This PSFCH opportunity will be referred to below as, for example, PSFCH opportunity X8 shown in FIG. 19.

b) Information indicating a PSFCH opportunity corresponding to the reserved resource selected for transmission in terminal 20C. This PSFCH opportunity will be referred to below as, for example, PSFCH opportunity X9 shown in FIG. 19.

c) Information indicating a PSFCH opportunity corresponding to the SCI in the PSCCH/PSSCH received by terminal 20C from terminal 20D. Hereinafter, this PSFCH opportunity will be referred to as, for example, PSFCH opportunity X10 shown in FIG. 20.

d) Information indicating a PSFCH opportunity corresponding to a resource based on (e.g., indicating) a time resource allocation field included in the SCI in the PSCCH/PSSCH received by terminal 20C from terminal 20D. Hereinafter, this PSFCH opportunity will be referred to, for example, as PSFCH opportunity X11 shown in FIG. 20.

e) Information indicating the PSFCH opportunity corresponding to the resource based on (e.g., indicating) the resource reservation period field included in the SCI in the PSCCH/PSSCH received by terminal 20C from terminal 20D. Hereinafter, this PSFCH opportunity will be referred to as PSFCH opportunity X12.

The PSCCH/PSSCH transmitted by terminal 20D to terminal 20C above may be addressed to a group including terminal 20C. Furthermore, the information indicated in a)-e) above may be valid only when the PSCCH/PSSCH transmitted from terminal 20C or the resource selected by terminal 20C requests HARQ feedback. Furthermore, terminal 20D may be terminal 20A or terminal 20B. Note that terminal 20C receives the PSFCH at PSFCH opportunity X8 and PSFCH opportunity X9. Note that terminal 20C transmits the PSFCH at PSFCH opportunity X10, PSFCH opportunity X11, and PSFCH opportunity X12.

By terminal 20C obtaining the information shown in 1), 2), and 3) above, it is possible to identify PSFCH opportunities where terminal 20B can transmit and terminal 20C can receive, and to take action to avoid PSFCH overlap. In other words, it is possible to improve the reliability of HARQ feedback.

Figure 21 is a diagram illustrating an example of resource selection for transmitting a transport block in an embodiment of the present invention. In resource identification, all candidate resources included in the resource selection window before the resource exclusion operation is performed are designated as resource set S_A. Furthermore, as shown in Figure 21, based on the information shown in 1), 2), and 3) above, some or all of the resources in S_A are determined as resource set S_B.

S_B is a set of PSCCH/PSSCH resources corresponding to PSFCH opportunity Y at which terminal 20B can transmit a PSFCH corresponding to a transport block transmitted from terminal 20C to terminal 20B and at which terminal 20C can receive. In other words, the PSFCH opportunities corresponding to the resources included in S_B may be those at which terminal 20B can transmit and terminal 20C can receive. Note that resource set S_C shown in FIG. 21 may be resources of S_A that are not included in S_B.

Here, PSFCH opportunity Y may be any of the PSFCH opportunities X1-X12 described above. Furthermore, PSFCH opportunity Y may be any PSFCH opportunity other than PSFCH opportunities X1-X12. Furthermore, PSFCH opportunity Y may be determined based on the number of PSFCHs simultaneously transmitted by terminal 20B. For example, if the number of PSFCHs simultaneously transmitted in a certain PSFCH opportunity exceeds the number of PSFCHs that terminal 20B can simultaneously transmit (i.e., if the number of PSFCHs simultaneously transmitted in that PSFCH opportunity has already reached the maximum number of PSFCHs that can be simultaneously transmitted before the resource selection is performed), that PSFCH opportunity may be excluded from PSFCH opportunity Y. Furthermore, if terminal 20B simultaneously transmits multiple PSFCHs, and the number of simultaneous transmissions requires reducing the transmission power of each PSFCH, the PSFCH opportunity that requires reducing the transmission power may be excluded from PSFCH opportunity Y.

Furthermore, PSFCH opportunity Y may be determined based on priority. For example, if the priority of the PSFCH (or corresponding transport block) that terminal 20B simultaneously transmits or receives in a certain PSFCH opportunity is higher than the priority of the transport block transmitted by terminal 20C, the PSFCH opportunity may be excluded from PSFCH opportunity Y. Furthermore, if the transmission of the PSFCH corresponding to the transport block transmitted by terminal 20C is not performed, for example, by priority control, the PSFCH opportunity may be excluded from PSFCH opportunity Y.

Figure 22 is a flowchart illustrating an example of resource selection in an embodiment of the present invention. Figure 22 shows an example of the operation of terminal 20C selecting resources to transmit to terminal 20B.

In step S1, terminal 20C sets a resource set S_A to be identified. Resource set S_A may be the target of resource selection, or the above-mentioned resource set S_B within S_A may be the target of resource selection. In other words, any of S_A in FIG. 22 may be replaced with S_B. Next, terminal 20C senses the resources corresponding to the resource set that is the target of resource selection (S2).

In step S3, terminal 20C removes resources from the resource set based on the RSRP obtained by sensing and updates the resource set. Here, the threshold value for determining the RSRP for resource removal may be different for resources included in resource set S_B and for resource set S_C not included in S_B. For example, the threshold value applied to resources included in resource set S_C may be smaller than the threshold value applied to resources included in resource set S_B.

In step S4, terminal 20C determines whether a specific resource amount, among the resource amounts included in the resource set updated after resource exclusion, exceeds K% of the resource amount included in a certain resource set. The specific resource amount may be all of the resources included in the updated resource set, or may be resources included in resource set S_B of the updated resource set. The certain resource set may be the initial state of resource set S_A or the initial state of resource set S_B. For example, the certain resource set may be the resource set to be selected as the resource set set in step S1.

For example, if the resources further included in resource set S_B of the updated resource set do not exceed K% of the identified resource set S_A or the initial resource set, the process proceeds to step S6, where terminal 20C changes the threshold for determining RSRP and executes step S3 again. The threshold for determining RSRP may be changed by, for example, an increase of 3 dB. On the other hand, if the resources further included in resource set S_B of the updated resource set exceed K% of the identified resource set S_A or the initial resource set, the process proceeds to step S5.

In step S5, terminal 20C reports the updated resource set to the upper layer. Subsequently, terminal 20C performs resource selection from the updated resource set in the upper layer (S7). Here, terminal 20C may select resources from resource set S_B. For example, if a resource included in S_B is included in the updated resource set, terminal 20C may always select the resource included in S_B. Alternatively, if a resource included in S_B is not included in the updated resource set, terminal 20C may select any resource. Alternatively, the probability of selecting a resource included in S_B that is included in the updated resource set may be increased compared to the probability of selecting a resource not included in S_B.

The operations shown in Figure 22 above may be applied differently depending on the transmission priority. For example, the threshold for determining RSRP or the ratio K% of the updated resource set to the initial resource set may differ depending on the transmission priority. Furthermore, some steps of the operations shown in Figure 22 above may be applied using conventional operations. For example, in step S4, it may be determined whether the updated resource set as a whole exceeds K% of the initial resource set, without limiting it to the resources included in resource set S_B. Note that the operations shown in Figure 22 above may be performed only when transmission requires HARQ feedback. Furthermore, the order of sensing and resource set determination may be reversed.

In addition, if the selected or reserved resource is not included in resource set S_B in terminal 20C, terminal 20C may reselect a resource. Furthermore, terminal 20C may reevaluate resources when it acquires the information shown in 1), 2), and 3) above. Furthermore, the operation shown in FIG. 22 above may be applied to operations related to reevaluation or preemption.

Note that, in step S7 shown in FIG. 22, if a resource not included in resource set S_B is selected, the corresponding PSFCH may be changed. For example, the corresponding PSFCH may be changed to one of the PSFCH opportunities Y described above. Also, for example, a dedicated PSFCH resource may be defined that is used only when a resource not included in resource set S_B is selected. Also, for example, the corresponding PSFCH may be the next PSFCH opportunity in the time domain of the PSFCH opportunity before the change. Also, for example, terminal 20C may notify that the PSFCH will be changed by means of a PSCCH/PSSCH (e.g., SCI) transmitted on the selected resource.

By terminal 20C selecting or allocating resources as described above, it is possible to increase the probability of transmitting data on resources corresponding to PSFCH opportunities that terminal 20B can transmit and terminal 20C can receive. In other words, it is possible to improve the reliability of HARQ feedback.

Embodiments of the present invention may be applied to the operation of one terminal 20 configuring or allocating transmission resources for another terminal 20. That is, the transmission resources of the other terminal 20 may be configured or allocated so as to satisfy the resource selection or resource allocation conditions according to embodiments of the present invention.

The above-described embodiment is not limited to V2X terminals, but may also be applied to terminals performing D2D communication.

The operations according to the above-described embodiments may be performed only in a specific resource pool. For example, the operations according to the above-described embodiments may be performed only in resource pools that are available to terminals 20 of Release 17 or later.

The operations according to the above-described embodiments may also be applied between terminals 20 in which a PC5-RRC connection is established.

The operations of the above-described embodiments may be applied whether the transmission is groupcast or unicast.

Note that there may be multiple UEs or terminals 20, and they may belong to the same group.

The above-described embodiment allows the terminal 20 to identify PSFCH opportunities where the destination terminal 20 can transmit and where the terminal itself can receive, thereby avoiding PSFCH overlap. Furthermore, the terminal 20 can transmit data using resources corresponding to PSFCH opportunities where the terminal itself can transmit and where the terminal itself can receive.

In other words, the efficiency of retransmission control can be improved in direct terminal-to-terminal communication.

(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.

<Base station 10>
Fig. 23 is a diagram showing an example of the functional configuration of the base station 10. As shown in Fig. 23, the 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. 23 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.

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

The setting unit 130 stores pre-configured setting information and various setting information to be transmitted to the terminal 20 in a storage device, and reads it from the storage device as needed. The content of the setting information includes, for example, information related to the settings for D2D communication.

As described in the embodiments, the control unit 140 performs processing related to settings for the terminal 20 to perform D2D communication. Furthermore, the control unit 140 transmits scheduling for D2D 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 D2D communication and DL communication from the terminal 20 via the reception unit 120. Functional units related to signal transmission in the control unit 140 may be included in the transmission unit 110, and functional units related to signal reception in the control unit 140 may be included in the reception unit 120.

<Terminal 20>
Fig. 24 is a diagram showing an example of the functional configuration of the terminal 20. As shown in Fig. 24, the terminal 20 has a transmitting unit 210, a receiving unit 220, a setting unit 230, and a control unit 240. The functional configuration shown in Fig. 24 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.

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

The setting unit 230 stores various setting information received from the base station 10 or 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.

As described in the embodiments, the control unit 240 controls D2D communication that establishes an RRC connection with another terminal 20. The control unit 240 also performs processing related to power saving operation. The control unit 240 also performs processing related to HARQ for D2D communication and DL communication. The control unit 240 also transmits information to the base station 10 related to HARQ responses for D2D communication and DL communication to another terminal 20 scheduled by the base station 10. The control unit 240 may also schedule D2D communication for the other terminal 20. The control unit 240 may also autonomously select resources to be used for D2D communication from a resource selection window based on the sensing results, or may perform re-evaluation or preemption. The control unit 240 also performs processing related to power saving in transmitting and receiving D2D communication. The control unit 240 also performs processing related to inter-terminal coordination in D2D communication. The functional units in the control unit 240 related to signal transmission may be included in the transmitting unit 210, and the functional units in the control unit 240 related to signal reception may be included in the receiving unit 220.

(Hardware configuration)
The block diagrams (FIGS. 23 and 24) 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 directly or indirectly connected (e.g., wired, wireless, etc.) and these multiple devices. The functional block may be realized by combining the single device or the multiple devices with software.

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

For example, the base station 10, 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. Figure 25 is a diagram showing an example of the hardware configuration of the base station 10 and terminal 20 according to an embodiment of the present disclosure. The above-mentioned base station 10 and terminal 20 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.

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

The functions of the base station 10 and terminal 20 are realized by loading specific software (programs) onto hardware such as the processor 1001 and storage device 1002, causing the processor 1001 to perform calculations, control communications via the communication device 1004, and control at least one of reading and writing data from and to the storage device 1002 and auxiliary storage device 1003.

The processor 1001, for example, runs an operating system to control the entire computer. The processor 1001 may be configured as a central processing unit (CPU) that includes an interface with peripheral devices, a control unit, an arithmetic unit, registers, etc. For example, the above-mentioned control unit 140, control unit 240, etc. may be realized by the processor 1001.

The processor 1001 also loads programs (program code), 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 these. The programs used are those that cause a computer to execute at least some of the operations described in the above-mentioned embodiments. For example, the control unit 140 of the base station 10 shown in FIG. 23 may be implemented by a control program stored in the storage device 1002 and running on the processor 1001. For example, the control unit 240 of the terminal 20 shown in FIG. 24 may be implemented by a control program stored in the storage device 1002 and running on the processor 1001. While the various processes described above have been described as being executed by a single processor 1001, they may also be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented on one or more chips. The programs may also be transmitted from a network via a telecommunications line.

The storage device 1002 is a computer-readable recording medium and may be composed of, for example, at least one of ROM (Read Only Memory), EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM), RAM (Random Access Memory), etc. The storage device 1002 may also be called a register, cache, main memory, etc. The storage device 1002 can store executable programs (program code), software modules, etc. for implementing a communication method according to one embodiment of the present disclosure.

The auxiliary storage device 1003 is a computer-readable recording medium, and may be composed of at least one of, for example, 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 (registered trademark) disk), a smart card, a flash memory (e.g., a card, a stick, a key drive), a floppy (registered trademark) disk, a magnetic strip, etc. The above-mentioned storage medium may also be, for example, a database, a server, or other suitable medium that includes at least one of the storage device 1002 and the auxiliary storage device 1003.

The communication device 1004 is hardware (transmitting/receiving device) for communicating between computers via at least one of a wired network and a wireless network, and is also referred to as a network device, network controller, network card, or communication module. The communication device 1004 may be configured to include high-frequency switches, duplexers, filters, frequency synthesizers, etc. to implement at least one of frequency division duplex (FDD) and time division duplex (TDD). For example, the transmitting/receiving antenna, amplifier, transmitting/receiving unit, transmission path interface, etc. may be implemented by the communication device 1004. The transmitting/receiving unit may be implemented as a physically or logically separated transmitting unit and receiving unit.

The input device 1005 is an input device (e.g., a keyboard, mouse, microphone, switch, button, sensor, etc.) that accepts input from the outside. The output device 1006 is an output device (e.g., a display, speaker, LED lamp, etc.) that outputs to the outside. Note that the input device 1005 and the output device 1006 may be integrated into one device (e.g., a touch panel).

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.

Furthermore, the 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 this hardware. For example, the processor 1001 may be implemented using at least one of these pieces of hardware.

(Summary of the embodiment)
As described above, according to the embodiment of the present invention, there is provided a terminal having: a control unit that selects resources from some resources in a resource selection window based on at least one of information related to PSFCH (Physical Sidelink Feedback Channel) opportunities received from other terminals including at least one of a first terminal and a second terminal, and information related to PSFCH opportunities that the terminal plans to transmit or receive; and a transmission unit that transmits data to the second terminal using the selected resources.

With the above configuration, terminal 20 can identify PSFCH opportunities where the destination terminal 20 can transmit and where the terminal itself can receive, thereby avoiding PSFCH overlap. Furthermore, terminal 20 can transmit data using resources corresponding to PSFCH opportunities where the destination terminal 20 can transmit and where the terminal itself can receive. In other words, the efficiency of retransmission control can be improved in direct terminal-to-terminal communication.

The information regarding the PSFCH opportunity received from the other terminal may include at least one of information regarding the PSFCH opportunity received from the first terminal and information regarding the PSFCH opportunity received from the second terminal. With this configuration, the terminal 20 can identify PSFCH opportunities that the destination terminal 20 can transmit from and that the terminal itself can receive, thereby avoiding PSFCH overlap.

The terminal 20 may further include a receiving unit that receives from the second terminal via signaling at least any of the following information: information indicating a PSFCH opportunity corresponding to a signal received by the second terminal; information indicating a resource based on a time resource allocation field included in control information in the signal received by the second terminal; information indicating a PSFCH opportunity corresponding to a resource based on a time resource allocation field included in control information in the signal received by the second terminal; information indicating a resource based on a resource reservation period field included in control information in the signal received by the second terminal; information indicating a PSFCH opportunity corresponding to a resource based on a resource reservation period field included in control information in the signal received by the second terminal; information indicating a resource selected for transmission by the second terminal; and information indicating a PSFCH opportunity corresponding to a resource selected for transmission by the second terminal. With this configuration, the terminal 20 can identify PSFCH opportunities available for transmission by the destination terminal 20 and reception by the terminal itself, thereby avoiding PSFCH overlap.

The PSFCH opportunities corresponding to the part of resources may be such that the second terminal can transmit a PSFCH corresponding to data to be transmitted to the second terminal, and the terminal itself can receive the PSFCH. With this configuration, the terminal 20 can identify PSFCH opportunities that the destination terminal 20 can transmit and that the terminal itself can receive, thereby avoiding PSFCH overlap. Furthermore, the terminal 20 can transmit data using resources corresponding to PSFCH opportunities that the terminal 20 can transmit and that the terminal itself can receive.

If the portion of resources does not exceed a predetermined proportion of the resource selection window, the threshold for determining RSRP (Reference signal received power) may be changed, and the operation of excluding resources from the resource selection window based on the threshold may be performed again. This configuration allows the terminal 20 to identify PSFCH opportunities where the destination terminal 20 can transmit and where the terminal itself can receive, thereby avoiding PSFCH overlap. Furthermore, the terminal 20 can transmit data using resources corresponding to PSFCH opportunities where the terminal itself can transmit and where the terminal itself can receive.

Furthermore, according to an embodiment of the present invention, there is provided a communication method in which a terminal executes a control procedure for selecting resources from a portion of a resource selection window based on at least one of information related to PSFCH (Physical Sidelink Feedback Channel) opportunities received from other terminals including at least one of a first terminal and a second terminal, and information related to PSFCH opportunities that the terminal plans to transmit or receive, and a transmission procedure for transmitting data to the second terminal using the selected resources.

With the above configuration, terminal 20 can identify PSFCH opportunities where the destination terminal 20 can transmit and where the terminal itself can receive, thereby avoiding PSFCH overlap. Furthermore, terminal 20 can transmit data using resources corresponding to PSFCH opportunities where the destination terminal 20 can transmit and where the terminal itself can receive. In other words, the efficiency of retransmission control can be improved in direct terminal-to-terminal communication.

(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; matters described in two or more items may be used in combination as needed, and matters described in one item may apply to matters described in another item (unless inconsistent). Boundaries between functional units or processing units in functional block diagrams do not necessarily correspond to 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 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, but such devices may be implemented in 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, register, hard disk (HDD), removable disk, CD-ROM, database, server, or any other suitable storage medium.

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 using 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 of these. Furthermore, 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, etc.

Each aspect/embodiment described in this 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-Wide Band), Bluetooth (registered trademark), or other suitable systems, and next-generation systems enhanced based on these. Furthermore, multiple systems may be combined (e.g., a combination of at least one of LTE and LTE-A with 5G, etc.).

The order of the procedures, sequences, flowcharts, etc. of each aspect/embodiment described herein may be rearranged unless inconsistent. 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.

Specific operations described herein 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 including a base station 10, it is clear that various operations performed for communication with a terminal 20 may be performed by at least one of the base station 10 and other network nodes other than the base station 10 (such as, but not limited to, an MME or S-GW). While the above example illustrates a case where there is one other network node other than the base station 10, the other network node may also be a combination of multiple other network nodes (for example, an MME and an S-GW).

The information, signals, etc. described in this disclosure may be output from a higher layer (or lower layer) to a lower layer (or higher layer). They may also be input/output via multiple network nodes.

Input and output information may be stored in a specific location (e.g., memory) or 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.

In this 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).

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.

Software, instructions, information, etc. may also be transmitted and received via 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, or Digital Subscriber Line (DSL)) and/or wireless technologies (such as infrared or microwave), these wired and/or wireless technologies are included within the definition of transmission media.

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.

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.

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

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

The names used for the parameters described above are not intended to be limiting in any way. Furthermore, the mathematical formulas 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.

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.

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

In this disclosure, terms such as "Mobile Station (MS)," "user terminal," "User Equipment (UE)," and "terminal" may be used interchangeably.

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.

At least one of the base station and the mobile station may be referred to as 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 be a device that does 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.

Furthermore, the 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 multiple terminals 20 (which may be referred to as, for example, D2D (Device-to-Device) or V2X (Vehicle-to-Everything)). In this case, the terminals 20 may be configured to have the functions possessed by the base station 10 described above. Furthermore, terms such as "uplink" and "downlink" may be read as terms corresponding to communication between terminals (for example, "side"). For example, terms such as uplink channel and downlink channel may be read as side channel.

Similarly, the term "user terminal" in this disclosure may be interpreted as "base station." In this case, the base station may be configured to have the functions possessed by the user terminal described above.

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 a table, database, or other data structure), and ascertaining something that is considered a "determination." Also, "determining" and "determining" may include receiving (e.g., receiving information), transmitting (e.g., sending information), input, output, accessing (e.g., accessing data in memory), and other actions that are considered a "determination." Furthermore, "judgment" and "decision" can include regarding actions such as resolving, selecting, choosing, establishing, and comparing as having been "judgment" or "decision." In other words, "judgment" and "decision" can include regarding some action as having been "judgment" or "decision." Furthermore, "judgment (decision)" can be interpreted as "assuming," "expecting," "considering," etc.

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.

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

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."

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.

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

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

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.

Numerology may be a communication parameter that applies to at least one of the transmission and reception of a signal or channel. Numerology may indicate, for example, at least one of the following: 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.

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

A slot may include multiple minislots. Each minislot may consist of one or more 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.

Radio frame, subframe, slot, minislot, and symbol all represent time units for transmitting signals. Other names may also be used for radio frame, subframe, slot, minislot, and symbol.

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. In other words, at least one of the subframe and the TTI may be a subframe (1 ms) as in existing LTE, a period shorter than 1 ms (e.g., 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.

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 radio resources (such as frequency bandwidth and transmission power that can be used by each terminal 20) to each terminal 20 in TTI units. However, the definition of TTI is not limited to this.

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

Note that when one slot or one minislot is referred to as a TTI, one or more TTIs (i.e., one or more slots or one or more minislots) may be the smallest time unit for scheduling. Furthermore, the number of slots (minislots) that make up the smallest time unit for scheduling may be controlled.

A TTI with a time length of 1 ms may be referred to as 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 referred to as a shortened TTI, short TTI, partial TTI (partial or fractional TTI), shortened subframe, short subframe, minislot, subslot, slot, etc.

Note that a long TTI (e.g., a normal TTI, 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 that of a long TTI but equal to or greater than 1 ms.

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.

Furthermore, the time domain of an RB may include one or more symbols and may be one slot, one minislot, one subframe, or one TTI in length. One TTI, one subframe, etc. may each be composed of one or more resource blocks.

Note that one or more RBs may also be referred to as a physical resource block (PRB), a sub-carrier group (SCG), a resource element group (REG), a PRB pair, an RB pair, etc.

A resource block may also 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.

A Bandwidth Part (BWP) (which may also be referred to as a partial 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 BWP and numbered within that BWP.

BWPs may include a BWP for UL (UL BWP) and a BWP for DL (DL BWP). One or more BWPs may be configured within one carrier for a terminal 20.

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

The structures of the radio frames, subframes, slots, minislots, and symbols described above 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, as well as the number of symbols in a TTI, symbol length, and cyclic prefix (CP) length can be varied in various ways.

In this disclosure, where articles are added by translation, such as a, an, and the in English, this disclosure may include the noun following these articles being plural.

In this disclosure, the term "A and B are different" may mean "A and B are different from each other." It should be noted that the term may also mean "A and B are each different from C." Terms such as "separate" and "combined" may also be interpreted in the same way as "different."

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

In this disclosure, terminal 20A is an example of a first terminal. Terminal 20B is an example of a second terminal.

Although the present disclosure has been described in detail above, it will be 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, which are 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.

10 Base station 110 Transmitter 120 Receiver 130 Setting unit 140 Control unit 20 Terminal 210 Transmitter 220 Receiver 230 Setting unit 240 Control unit 1001 Processor 1002 Storage device 1003 Auxiliary storage device 1004 Communication device 1005 Input device 1006 Output device

Claims (4)

a receiving unit that receives sidelink control information (SCI) including a resource reservation field from another terminal;
a controller for determining candidate resource sets for sidelink transmissions,
The control unit
determining a first time resource based on the resource reservation field;
and excluding some resources from the candidate resource set based on a Physical Sidelink Feedback Channel (PSFCH) slot corresponding to the first time resource. The control unit reports the candidate resource set excluding at least the part of the resources to an upper layer;
The terminal of claim 1 , wherein the higher layer selects resources for the sidelink transmission from the candidate resource set. The terminal according to claim 1 or 2, wherein the control unit performs the exclusion operation during resource preemption. receiving means for receiving SCI (Sidelink Control Information) including a resource reservation field from another terminal;
a control means for determining a candidate resource set for sidelink transmission;
control means for determining a first time resource based on said resource reservation field;
and a control means for excluding some resources from the candidate resource set based on a PSFCH slot corresponding to the first time resource.