Method and apparatus for sidelink communication

Abstract

A method for reporting sidelink HARQ response information performed by a terminal comprises the steps of: receiving information on allocation of PSSCH resources for PSSCH transmission from a base station; determining a PSFCH resource for PSFCH reception corresponding to the PSSCH transmission; determining a transmission time point corresponding to the HARQ response information transmitted by the PSSCH; and transmitting HARQ response information corresponding to the PSSCH transmission to the base station at the determined time point, where the transmission time point of the HARQ response information is represented as a time offset L from the time point of the PSFCH resource, and information on the transmission time point of the HARQ response information may be transmitted from the base station to the terminal.

Description

[0001] This patent application is a divisional application based on the Chinese invention patent application with application date of June 9, 2020, application number 202080043832.5, and invention name “Method and device for side link communication”. Technical Field

[0002] The present invention relates to device-to-device communication or side link communication, and more particularly to a method and apparatus for sending and receiving signals between a base station and a terminal or between terminals in a mobile communication system supporting side link communication. Background Art

[0003] A communication system (hereinafter referred to as a new radio (NR) communication system) using a higher frequency band (e.g., a frequency band of 6 GHz or higher) than the frequency band of Long Term Evolution (LTE or LTE-A) (e.g., a frequency band below 6 GHz) is being considered for processing the rapidly growing wireless data. Compared with the LTE communication system, the NR communication system can support not only frequency bands below 6 GHz, but also frequency bands above 6 GHz, and can support various communication services and scenarios. For example, the use scenarios of the NR communication system may include enhanced mobile broadband (eMBB), ultra-reliable low latency communication (URLLC), massive machine type communication (mMTC), etc., and various technical requirements for supporting them should be met.

[0004] Direct communication between terminals is a communication scheme in which adjacent terminals directly send and receive signals to each other without the intervention of a base station. Direct communication can be classified into a scheme that is mainly performed in an unlicensed frequency band such as Wi-Fi or Bluetooth without network control or a scheme based on a cellular communication system (e.g., LTE system, NR system, etc.). Specifically, the cellular-based scheme is able to improve spectrum efficiency, perform interference and conflict control, and support QoS through appropriate intervention of a base station or network, and provide cellular communication for various combination scenarios, making it expected to be widely used in fields such as vehicle communication, the Internet of Things, etc. Therefore, there is a need for an efficient signal transmission / reception method between terminals for cellular-based direct communication between terminals, as well as a signal transmission method and process for base station control of direct communication. Summary of the invention

[0005] Technical issues

[0006] An object of the present invention for solving the above-mentioned problems is to provide a method for reporting sidelink HARQ-ACK / NACK information and a method for receiving sidelink HARQ-ACK / NACK information.

[0007] Another object of the present invention to solve the above-mentioned problem is to provide an apparatus (e.g., a base station or a terminal) for executing the method for reporting sidelink HARQ-ACK / NACK information and / or the method for receiving sidelink HARQ-ACK / NACK information.

[0008] Technical Solution

[0009] An exemplary embodiment of the present invention as a method for reporting sidelink hybrid automatic repeat request (HARQ) response information performed by a terminal to achieve this purpose may include: receiving allocation information of a physical sidelink shared channel (PSSCH) for transmission of PSSCH from a base station; determining PSFCH resources for receiving a physical sidelink feedback channel (PSFCH) corresponding to the transmission of the PSSCH; determining a time point for sending HARQ response information corresponding to the transmission of the PSSCH; and sending HARQ response information corresponding to the transmission of the PSSCH to the base station at the determined time point, wherein the time point for sending the HARQ response information is represented by a time offset L from the time point of the PSFCH resources, and information about the time point for sending the HARQ response information is sent from the base station to the terminal.

[0010] The time offset L (L is an integer equal to or greater than 0) may mean the number of time slots, and when the time point of the PSFCH resource is time slot n, the time point of sending the HARQ response information may be determined as time slot (n+L).

[0011] Each of time slot n and time slot (n+L) can be one of the time slots in the uplink carrier or the uplink bandwidth part in which the HARQ response information is sent, the number of time slots indicated by the time offset L can be the number of time slots in the uplink carrier or the uplink bandwidth part, and time slot n can be one of the time slots in the uplink carrier or the uplink bandwidth part that overlaps with the PSFCH resource.

[0012] The HARQ response information may be transmitted to the base station through a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH).

[0013] The HARQ response information may include an acknowledgement (ACK), may include a negative ACK (NACK), or may include an ACK or a NACK.

[0014] The PSSCH resources may be PSSCH resources scheduled by dynamic grant or PSSCH resources scheduled by configured grant.

[0015] The PSFCH resource may be the earliest PSFCH resource among the PSFCH resources that appear in a time slot after K (K is an integer equal to or greater than 0) time slots have passed since the time slot to which the PSSCH resource belongs, and K may be a predefined value, a value configured by the base station to the terminal, or a value pre-configured for the terminal.

[0016] The K time slots may be time slots belonging to a sidelink resource pool for transmission of the PSSCH.

[0017] The method may further include: sending, by the terminal, a PSSCH to a corresponding terminal through a PSSCH resource; and receiving, by the terminal, a PSFCH from the corresponding terminal through a PSFCH resource.

[0018] The PSFCH may include reception response information for the PSSCH, and the HARQ response information may be generated based on the reception response information for the PSSCH received through the PSFCH.

[0019] Another exemplary embodiment of the present invention for achieving this purpose as a method for receiving sidelink hybrid automatic repeat request (HARQ) response information performed by a base station may include: sending allocation information of a physical sidelink shared channel (PSSCH) resource for transmission of PSSCH to a terminal; determining a physical sidelink feedback channel (PSFCH) resource for the terminal to receive PSFCH resources corresponding to the transmission of PSSCH; determining a time point for receiving HARQ response information corresponding to the transmission of PSSCH; and receiving HARQ response information corresponding to the transmission of PSSCH from the terminal at the determined time point, wherein the time point for receiving the HARQ response information is represented by a time offset L from the time point when the terminal receives the PSFCH resource of the PSFCH corresponding to the transmission of PSSCH, and information about the time point for receiving the HARQ response information is sent from the base station to the terminal.

[0020] The time offset L (L is an integer equal to or greater than 0) may mean the number of time slots, and when the time point of the PSFCH resource is time slot n, the time point of receiving the HARQ response information may be determined as time slot (n+L).

[0021] Each of time slot n and time slot (n+L) may be one of the time slots of the uplink carrier or the uplink bandwidth part for receiving HARQ response information, the number of time slots indicated by the time offset L may be the number of time slots of the uplink carrier or the uplink bandwidth part, and time slot n may be one of the time slots of the uplink carrier or the uplink bandwidth part overlapping with the PSFCH resource.

[0022] The HARQ response information may be received from the terminal through a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH).

[0023] The PSFCH resource may be the earliest PSFCH resource among the PSFCH resources that appear in a time slot after K (K is an integer equal to or greater than 0) time slots have passed since the time slot to which the PSSCH resource belongs, and K may be a predefined value, a value configured by the base station to the terminal, or a value pre-configured for the terminal.

[0024] The K time slots may be time slots belonging to a sidelink resource pool for transmission of the PSSCH.

[0025] An exemplary embodiment of the present invention as a terminal for performing sidelink communication for achieving another purpose may include: a processor; a memory that electronically communicates with the processor; and at least one instruction that is stored in the memory and can be executed by the processor, wherein, when executed by the processor, the at least one instruction causes the terminal to: receive allocation information of a physical sidelink shared channel (PSSCH) for transmission of a PSSCH from a base station; determine PSFCH resources for receiving a physical sidelink feedback channel (PSFCH) corresponding to the transmission of the PSSCH; determine a time point for sending HARQ response information corresponding to the transmission of the PSSCH; and send HARQ response information corresponding to the transmission of the PSSCH to the base station at the determined time point, wherein the time point for sending the HARQ response information is represented by a time offset L from the time point of the PSFCH resources, and information about the time point for sending the HARQ response information is sent from the base station to the terminal.

[0026] The time offset L (L is an integer equal to or greater than 0) may mean the number of time slots, and when the time point of the PSFCH resource is time slot n, the time point of sending the HARQ response information may be determined as time slot (n+L).

[0027] Each of time slot n and time slot (n+L) can be one of the time slots of the uplink carrier or the uplink bandwidth part for sending HARQ response information, the number of time slots indicated by the time offset L can be the number of time slots of the uplink carrier or the uplink bandwidth part, and time slot n can be one of the time slots of the uplink carrier or the uplink bandwidth part overlapping with the PSFCH resource.

[0028] The PSFCH resource may be the earliest PSFCH resource among the PSFCH resources that appear in a time slot after K (K is an integer equal to or greater than 0) time slots have passed since the time slot to which the PSSCH resource belongs, and K may be a predefined value, a value configured by the base station to the terminal, or a value pre-configured for the terminal.

[0029] Beneficial effects

[0030] According to the exemplary embodiments of the present invention as described above, a sidelink feedback signal can be efficiently transmitted and received between terminals or between a terminal and a base station in a sidelink communication system. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a conceptual diagram illustrating a scenario of side link communication to which an exemplary embodiment of the present invention is applied.

[0032] Figure 2 is a sequence diagram showing a signal transmission process for first mode side link resource allocation.

[0033] Figure 3 is a conceptual diagram showing a first exemplary embodiment of a periodic PSFCH resource configuration.

[0034] Figure 4 is a conceptual diagram showing a first exemplary embodiment of a PSSCH HARQ-ACK feedback timing method, and Figure 5 is a conceptual diagram illustrating a second exemplary embodiment of a PSSCH HARQ-ACK feedback timing method.

[0035] Figure 6 is a conceptual diagram showing a first exemplary embodiment of a PSSCH retransmission method, and Figure 7 is a conceptual diagram illustrating a second exemplary embodiment of a PSSCH retransmission method.

[0036] Figure 8 is a conceptual diagram showing a first exemplary embodiment of sidelink reserved resource allocation by a base station.

[0037] Fig. 9 is a conceptual diagram showing a first exemplary embodiment of PSSCH resource allocation, and Fig.10 is a conceptual diagram showing a second exemplary embodiment of PSSCH resource allocation.

[0038] Fig.11 is a conceptual diagram showing a first exemplary embodiment of side link reserved resource allocation.

[0039] Fig.12 is a conceptual diagram illustrating a second exemplary embodiment for sidelink reserved resource allocation.

[0040] Fig.13 is a block diagram illustrating a communication node according to an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION

[0041] Although the present invention is susceptible to various modifications and alternative forms, specific embodiments are shown and described in detail by way of example in the accompanying drawings. However, it should be understood that the description is not intended to limit the present invention to specific embodiments, but on the contrary, the present invention covers all modifications, equivalents and substitutions that fall within the spirit and scope of the present invention.

[0042] Although the terms "first", "second", etc. may be used herein with respect to various elements, such elements should not be understood to be limited to these terms. These terms are only used to distinguish one element from another element. For example, without departing from the scope of the present invention, a first element may be referred to as a second element, and a second element may be referred to as a first element. The term "and / or" includes any and all combinations of one or more associated listed items.

[0043] It will be understood that when an element is referred to as being "connected to" or "coupled to" another element, it can be directly connected or coupled to the other element, or there may be intervening elements. Conversely, when an element is referred to as being "directly connected to" or "directly coupled to" another element, there are no intervening elements.

[0044] The terms used herein are only for the purpose of describing specific embodiments and are not intended to limit embodiments of the present invention. As used herein, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are also intended to include plural forms. It should also be understood that when the terms "comprise", "comprises", "includes" and / or "comprising" are used herein, the specified features, integers, steps, operations, elements, parts and / or combinations thereof are present, but the presence of one or more other features, integers, steps, operations, elements, parts and / or combinations thereof or such additions are not excluded.

[0045] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. It should also be understood that terms defined in common dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and will not be interpreted in an ideal or overly formal sense unless explicitly defined as such herein.

[0046] Hereinafter, preferred exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0047] Hereinafter, a wireless communication network to which an exemplary embodiment of the present invention is applied will be described. The wireless communication network to which an exemplary embodiment of the present invention is applied is not limited to the content described below, and the exemplary embodiment of the present invention can be applied to various wireless communication networks.

[0048] The present invention relates to direct communication (device-to-device communication) or side link communication between terminals, and more specifically to a method for sending and receiving signals between a base station and a terminal or between terminals in a communication system supporting direct communication between terminals, and an apparatus supporting the method. For the sake of convenience of description, a 3GPP New Radio (NR) communication system will be described as an example of a communication system applied according to an exemplary embodiment of the present invention, but the spirit or exemplary embodiments of the present invention are not limited thereto and can be applied to various communication systems.

[0049] Compared with the system bandwidth provided by the LTE communication system, the NR communication system can support a wider system bandwidth (e.g., carrier bandwidth) in order to efficiently use the wide frequency band. For example, the maximum bandwidth supported by the LTE communication system may be 20 MHz. On the other hand, the NR communication system may support a carrier bandwidth of up to 100 MHz in a frequency band of 6 GHz or below, and a carrier bandwidth of up to 400 MHz in a frequency band of 6 GHz or above.

[0050] In order to meet various technical requirements, the parameter set parameter set applied to the physical signals and channels in the NR communication system may vary. In a communication system to which OFDM waveform technology based on cyclic prefix (CP) is applied, the parameter set parameter set may include a subcarrier spacing and a CP length (or CP type). The following Table 1 may be a first exemplary embodiment of the configuration of a parameter set for OFDM based on CP. The subcarrier spacing may have a multiplication relationship of powers of 2, and the CP length may be scaled in the same proportion as the OFDM symbol length. Depending on the frequency band in which the communication system operates, certain parameter sets in Table 1 may be supported. When the subcarrier spacing is 60kHz, an extended CP may be additionally supported.

[0051] [Form 1]

[0052]

[0053] In the following description, the frame structure in a communication system (e.g., an NR communication system) will be described. In the time domain, the constituent blocks may be subframes, time slots, micro time slots, etc. A subframe may be used as a transmission unit, and the length of a subframe may have a fixed value (e.g., 1 ms) regardless of the subcarrier spacing. A time slot may include continuous symbols (e.g., 14 OFDM symbols). The length of a time slot may be variable, different from the length of a subframe, and may be inversely proportional to the subcarrier spacing. A time slot may be used as a scheduling unit, and may be used as a configuration unit for scheduling and hybrid automatic repeat request (HARQ) timing. However, the scheduling interval or transmission duration may not necessarily match the length of the time slot. The base station may schedule a data channel (e.g., a physical downlink shared channel (PDSCH)) to a terminal by using some or all of the symbols constituting the time slot, or may schedule a data channel by using multiple time slots.

[0054] A microslot may refer to a time unit having a shorter length than a time slot. Scheduling based on microslots may be used for transmission of partial time slots, URLLC transmission, multi-user scheduling based on analog beamforming, etc. in unlicensed bands or in bands where NR and LTE coexist. NR may support transmission based on microslots by configuring a physical downlink control channel (PDCCH) that monitors the periodicity and duration of a data channel shorter than a time slot.

[0055] In the NR communication system, the frequency domain constituent blocks of the frame structure may include resource blocks (RBs), subcarriers, and the like. One RB may include contiguous subcarriers. For example, one RB may consist of 12 contiguous subcarriers. The number of subcarriers constituting one RB may be a constant regardless of the parameter set. In this case, the bandwidth occupied by one RB may be proportional to the subcarrier spacing of the parameter set. RBs may be used as frequency domain resource allocation units for control channels and data channels. In the case of a downlink control channel, the minimum unit of resource allocation is a control channel element (CCE), and one CCE may include one or more RBs. Resource allocation for data channels may be performed in units of RBs or in units of RB groups (e.g., resource block groups (RBGs)). One RBG may include one or more contiguous RBs.

[0056] In an exemplary embodiment, RB may mean a common RB (CRB). Alternatively, RB may mean a physical RB (PRB) or a virtual RB (VRB). In a communication system (e.g., an NR communication system), CRB may mean an RB (i.e., a common RB grid) constituting a set of RBs arranged continuously based on a reference frequency (e.g., point A). Carriers, bandwidth parts, etc. may be arranged on a common RB grid. That is, carriers, bandwidth parts, etc. may be composed of at least one CRB. At the same time, the RBs constituting the bandwidth part may be referred to as PRBs, and each PRB may correspond to a CRB. Within the bandwidth part, the CRB index may be appropriately converted to a PRB index. In some exemplary embodiments, RB may mean an interleaved RB (IRB). In an exemplary embodiment, PRB may mean a CRB, a VRB, etc. corresponding to a PRB. In addition, CRB may mean a PRB, a VRB, etc. corresponding to a CRB.

[0057] A time slot (e.g., a time slot format) may consist of a combination of one or more time periods in a downlink period, a flexible (or unknown) period, and an uplink period. Each period may consist of one or more consecutive symbols. A flexible period may be inserted between a downlink period and an uplink period, between a downlink period and a downlink period, between an uplink period and an uplink period, etc. When a flexible period is inserted between a downlink period and an uplink period, the flexible period may be used as a guard period.

[0058] A time slot may include one or more flexible periods. Alternatively, a time slot may not include a flexible period. In addition, the flexible period may be used to perform uplink or downlink operations according to a configuration from a base station or a terminal. The time slot format may be semi-statically configured to the terminal through high-layer signaling, or may be dynamically indicated through physical layer signaling (e.g., downlink control information (DCI), time slot format indicator (SFI)).

[0059] Although not specifically mentioned herein, signaling may refer to physical layer signaling (e.g., DCI), medium access control (MAC) layer signaling (e.g., MAC control unit (CE)), RRC layer signaling (e.g., master information block (MIB), system information block (SIB), cell-specific RRC signaling, UE-specific RRC signaling, etc.), etc., and may refer to a combination of two or more signaling in the signaling. In addition, the signaling process may be performed between a base station and a terminal, between a terminal and a terminal, and between a base station and a base station. In the present disclosure, the signaling between a base station and a terminal and between a terminal and a terminal will be mainly considered.

[0060] In the present disclosure, unless otherwise specified, in some cases, configuration may mean configuration performed through a signaling process between communication nodes, may mean pre-configuration not based on a signaling process, or may mean both cases. As an example of pre-configuration, certain information (or parameters) for performing communication may be stored in the terminal in advance. These may be stored in the terminal through a medium such as a universal IC card (UICC), a subscriber identity module (SIM) or a universal SIM (USIM), or may be directly stored in a mobile equipment (ME). Specifically, unless otherwise specified, the expression of configuring the terminal with certain information may include all meanings of configuration from a base station, configuration from another terminal, pre-configuration, etc. In addition, for the convenience of description, 'signaling' for certain information of a communication node may mean the configuration of certain information, and as described above, this may also be interpreted as the pre-configuration of certain information. Specifically, the expression of configuring the terminal with certain information from a base station may include the meaning of notifying certain information with a signal from the base station through a wireless link (e.g., a Uu interface to be described later), and also includes the meaning of configuring or pre-configuring certain information by a base station (or network) or a service provider running it.

[0061] In addition, in the present disclosure, signal can be used to mean both physical layer signals and channels. For example, a downlink signal may include a downlink signal and a downlink channel of a physical layer, such as PDCCH, PDSCH, DM-RS, a channel state information reference signal (CSI-RS), a phase tracking reference signal (PT-RS), a synchronization signal / physical broadcast channel (SS / PBCH) block, etc. In addition, an uplink signal may include an uplink signal and an uplink channel of a physical layer, such as a physical uplink control channel (PUCCH), PUSCH, DM-RS, a sounding reference signal (SRS), PT-RS, PRACH (physical random access channel), etc. In addition, a sidelink signal may include a sidelink signal and a sidelink channel of a physical layer, such as a physical sidelink control channel (PSCCH), a physical sidelink shared channel (PSSCH), a physical sidelink feedback channel (PSFCH), a physical sidelink discovery channel (PSDCH), a physical sidelink broadcast channel (PSBCH), DM-RS, CSI-RS, PT-RS, etc.

[0062] The terminal can perform downlink operation, uplink operation, side link operation, etc. in the bandwidth part. The bandwidth part can be defined as a set of continuous PRBs in the frequency domain. The terminal performing the initial access process can obtain the configuration information of the initial bandwidth part from the base station through system information. The terminal operating in the RRC connection state can obtain the configuration information of the bandwidth part from the base station through terminal-specific high-level signaling. The configuration information of the bandwidth part may include a parameter set (e.g., subcarrier spacing and CP length) applied to the bandwidth part. In addition, the configuration information of the bandwidth part may include information indicating the position of the starting PRB of the bandwidth part and information indicating the number of PRBs constituting the bandwidth part. At least one bandwidth part configured in the terminal can be activated. The base station can configure multiple bandwidth parts for the terminal within one carrier and switch the activated bandwidth part. The switching of the bandwidth part can be configured by semi-static signaling (e.g., RRC signaling) or the switching of the bandwidth part can be indicated by physical layer dynamic signaling (e.g., DCI). In addition, the switching of the bandwidth part can be performed based on a timer.

[0063] In a mobile communication system (e.g., LTE or NR), a link formed between a terminal and a terminal for direct communication between terminals may be referred to as a side link different from an uplink and a downlink. A source terminal may send data directly to a target terminal (or destination terminal) via a side link without passing through a base station. In this case, the source terminal and the target terminal may correspond to a transmitting terminal and a receiving terminal, respectively. Side link transmission may include broadcast, multicast (or multicast), and unicast transmission. In the case of broadcast and multicast, a source terminal may send the same data to multiple target terminals using the same signal. Direct communication between terminals may also be referred to as side link communication, side link transmission, device-to-device (D2D) communication, and the like.

[0064] A typical application example of direct communication between terminals is vehicle-to-everything (V2X) communication for vehicles. V2X communication is a communication scheme that implements various services such as accident prevention, platooning, and providing entertainment information by communicating with nearby vehicles and objects. V2X includes vehicle-to-vehicle (V2V) communication between vehicles, vehicle-to-infrastructure (V2I) communication between vehicles and infrastructure, and vehicle-to-pedestrian (V2P) communication between vehicles and pedestrians, and they may all correspond to direct communication between terminals. Because communication for vehicles traveling at high speeds should basically ensure high transmission reliability and high mobility of the terminals, it is essential to consider these requirements when designing a direct communication system between terminals.

[0065] Figure 1 is a conceptual diagram illustrating a scenario of side link communication to which an exemplary embodiment of the present invention is applied.

[0066] refer to Figure 1 , the link between the terminals 110, 120 and 130 can be defined as a PC5 interface, and the link between each terminal and the base station 100 can be defined as a Uu interface. The first terminal 110 and the second terminal 120 can be terminals located in the coverage of the base station (i.e., within the coverage), and the third terminal 130 can be located outside the coverage of the base station (i.e., outside the coverage). The first terminal 110, the second terminal 120 and the third terminal 130 can exchange data with each other through the PC5 interface (i.e., side link), and the first terminal 110 and the second terminal 120 located in the coverage of the base station can exchange data with the base station 100 through the Uu interface.

[0067] The source terminal may send sidelink data (i.e., transport blocks (TBs)) to the target terminal via a physical sidelink shared channel (PSSCH). One PSSCH may include one TB. Alternatively, one PSSCH may include at least one TB (e.g., 1 or 2 TBs). In this case, two modes may be considered as methods of allocating sidelink resources for PSSCH.

[0068] The first mode (ie, mode 1) is a scheme in which the side link resource allocation is performed by the base station, and the base station can determine the side link resources for sending the PSSCH and send resource allocation and scheduling information to the source terminal through the Uu downlink. The source terminal can request the side link resources from the base station in order to allocate the PSSCH resources from the base station. For example, the source terminal can send a scheduling request (SR) (or side link SR), a buffer status report (BSR) (or side link BSR), etc. to the base station to request the side link resources from the base station. The source terminal can send PSSCH to the target terminal through the side link resources allocated by the base station based on the resource allocation and scheduling information. In this case, the source terminal can send the resource allocation and scheduling information of PSSCH to the target terminal together with PSSCH, or can send the resource allocation and scheduling information of PSSCH to the target terminal separately from PSSCH in advance. For example, the information can be included in the side link control information (SCI) and sent through the physical side link control channel (PSCCH). For another example, the information may be included in the first SCI or the second SCI constituting the level 2 SCI and transmitted via PSCCH, PSSCH, resources defined for the second SCI transmission, etc. The SCI format may be defined for SCI transmission. In addition, according to the first mode, other side link signals and channels (e.g., PSCCH, channel state information-reference signal (CSI-RS), physical side link feedback channel (PSFCH), etc.) and resources of PSSCH may be determined by the base station, and the terminal may be notified of the relevant configuration information by signaling.

[0069] On the other hand, the second mode (ie, mode 2) may be a scheme in which the side link resource allocation is performed by a terminal (eg, a source terminal). The terminal may determine the available resource region within the side link resource pool by energy sensing (eg, using sensing of a signal received by a side link resource), allocate the PSSCH to part or all of the available resource region, and send the PSSCH to the target terminal. As in the first mode, the source terminal may send the resource allocation and scheduling information of the PSSCH together with the PSSCH to the target terminal, or may send the resource allocation and scheduling information of the PSSCH to the target terminal separately from the PSSCH in advance.

[0070] When the source terminal is within the coverage of the base station, the first mode can be used. Figure 1 , the first terminal 110 can send PSSCH to the second terminal 120 and the third terminal 130 through the first mode with the assistance of the base station 100. In addition, the second terminal 120 can send PSSCH to the first terminal 110 through the first mode with the assistance of the base station 100. On the other hand, the second mode can be used when the source terminal is located within the coverage of the base station and when it is located outside the coverage of the base station. Figure 1 , the first terminal 110 can send PSSCH to the second terminal 120 and the third terminal 130 through the second mode, and the second terminal 120 can send PSSCH to the first terminal 110 through the second mode. In addition, the third terminal 130 located outside the coverage of the base station 100 can also send PSSCH to the first terminal 110 through the second mode.

[0071] At the same time, the terminal can be configured with a sidelink bandwidth part for sidelink transmission. The sidelink bandwidth part can be configured for each carrier. Similar to the bandwidth part of the Uu interface, the sidelink bandwidth part can be configured to have a single parameter set and continuous PRBs. In addition, the sidelink bandwidth part may include one or more subchannels in the frequency domain. Each subchannel may be composed of one or more continuous PRBs, and the number of PRBs for each subchannel may be predefined in the technical specification or the number of PRBs for each subchannel may be configured for the terminal.

[0072] In order to perform high-speed exchange between the side link (i.e., PC5 interface) and the Uu interface, the side link bandwidth part (e.g., the activated side link bandwidth part) can be configured to have the same parameter set as the Uu uplink bandwidth part (e.g., the uplink bandwidth part activated by Uu) and / or the Uu downlink bandwidth part (e.g., the downlink bandwidth part activated by Uu). When the parameter set of the side link bandwidth part is different from the parameter set of the Uu uplink (or Uu downlink) bandwidth part, for example, when it is impossible to apply the same parameter set to the side link bandwidth part and the uplink (or downlink) bandwidth part, the side link bandwidth part can be deactivated. The side link bandwidth part can be configured specifically for the serving cell. For example, the configuration information of the side link bandwidth part can be included in the master information block (MIB), the system information block 1 (SIB1) or other system information (OSI), and sent from the base station to the terminal. In addition, the side link bandwidth part can be used to configure the terminal in the RRC connection state through a terminal-specific configuration (e.g., terminal-specific RRC signaling). Alternatively, the sidelink bandwidth portion may be configured for each serving cell group or each base station group, and the same sidelink bandwidth portion configuration may be applied within the serving cell group or base station group.

[0073] The terminal may be configured with one or more side link resource pools. A side link resource pool may be configured for each carrier, and each side link resource pool may be allocated in a side link bandwidth portion. Each side link resource pool may consist of one or more continuous subchannels in a frequency domain. In addition, each side link resource pool may consist of a set of time slots in a time domain. The side link resource pool may be periodic and may include at least one time slot in a cycle. At least one symbol may be included in each time slot included in the side link resource pool. That is, certain symbols in each time slot included in the side link resource pool (e.g., downlink symbols, symbols for transmitting SS / PBCH blocks, CORESET#0, search space set#0, etc., symbols not configured for the side link resource pool) may not be included in the side link resource pool. The terminal may send and receive side link signals (e.g., PSSCH, PSCCH, PSFCH, side link CSI-RS, etc.) in the side link resource pool. The terminal may obtain information about the configuration of the side link bandwidth portion and the side link resource pool through signaling or pre-configuration from the base station.

[0074] HARQ-ACK timing indication method

[0075] In the case of multicast transmission and unicast transmission, the target terminal may send information about whether the PSSCH has been successfully received to the source terminal (i.e., HARQ confirmation (ACK) corresponding to the PSSCH). The HARQ-ACK for the PSSCH may be referred to as 'side link HARQ-ACK', which may be sent from the target terminal to the source terminal via the PSFCH. The side link HARQ-ACK information may include ACK or negative acknowledgment (NACK), and in some cases (e.g., in the case of multicast transmission), only NACK may be included. More specifically, when PSSCH reception fails, the terminal receiving multicast data from the source terminal may send side link HARQ-ACK information including NACK to the source terminal via the group common side link resource. The group common side link resource may be the PSFCH. That is, the terminal may send a HARQ-ACK including NACK via the PSFCH. Alternatively, the group common side link resource may be a side link signal or channel other than the PSFCH. In addition to the ACK / NACK information, discontinuous transmission (DTX) information may also be included in the side link HARQ-ACK information. Hereinafter, sidelink HARQ-ACK may mean HARQ-ACK for one PSSCH or HARQ-ACK for multiple PSSCHs.

[0076] When performing the first mode sidelink resource allocation, the source terminal may report the sidelink HARQ-ACK or corresponding information received from the target terminal to the base station. In addition, when the source terminal expected to receive the sidelink HARQ-ACK from the target terminal does not receive the corresponding sidelink HARQ-ACK (for example, when the PSFCH reception fails), the source terminal may generate the sidelink HARQ-ACK information corresponding to the PSSCH based on predefined rules, and report the generated sidelink HARQ-ACK information to the base station. In addition, when the source terminal is not expected to receive the sidelink HARQ-ACK from the target terminal, the source terminal may arbitrarily or based on predefined rules to generate the sidelink HARQ-ACK information corresponding to the PSSCH, and report the generated sidelink HARQ-ACK information to the base station. For example, when the source terminal performs PSSCH transmission based on blind retransmission, the source terminal may not receive a HARQ-ACK response from the target terminal. In this case, the source terminal may send a NACK to the base station for the purpose of requesting retransmission resources for the corresponding PSSCH, otherwise it may send an ACK. In addition, when the source terminal does not send PSSCH through the PSSCH resources allocated from the base station (for example, the configured authorized PSSCH resources), the source terminal can generate sidelink HARQ-ACK information corresponding to the PSSCH resources based on predefined rules, and report the generated sidelink HARQ-ACK information to the base station.

[0077] Hereinafter, information for reporting the sidelink HARQ-ACK corresponding to the PSSCH or the allocated PSSCH resource by the source terminal to the base station may be represented as 'sidelink HARQ-ACK reporting information'. The sidelink HARQ-ACK reporting information may be sent via a Uu uplink channel (e.g., PUCCH, PUSCH, etc.). The base station may determine whether to perform scheduling for retransmission of the corresponding PSSCH based on the sidelink HARQ-ACK reporting information received from the source terminal.

[0078] Figure 2 is a sequence diagram showing a signal transmission process for first mode side link resource allocation.

[0079] refer to Figure 2, the base station 200 may send scheduling information for PSSCH (hereinafter referred to as 'PSSCH scheduling information') to the source terminal 210 through the Uu downlink (e.g., PDCCH, PDSCH, resources defined for transmission of the second DCI in the 2-level DCI, etc.) (S210). The source terminal 210 may send PSSCH scheduling information generated based on the PSSCH scheduling information received from the base station 200 to the target terminal 220 through the side link (e.g., PSCCH, PSSCH, resources defined for transmission of the second SCI in the 2-level SCI, etc.) (S220). In this case, the source terminal 210 may send part or all of the PSSCH scheduling information received from the base station 200 to the target terminal 220, or send the PSSCH scheduling information generated based on part or all of the PSSCH scheduling information received from the base station 200 to the target terminal (220). Alternatively, the source terminal 210 may send other information together with the PSSCH scheduling information to the target terminal 220. The source terminal 210 may send a PSSCH to the target terminal 220 through a side link based on the PSSCH scheduling information sent to the target terminal 220 (S230). The target terminal 220 may receive the PSSCH and send a HARQ-ACK for the PSSCH to the source terminal 210 through a side link (e.g., PSFCH, resources defined for transmission of a sidelink HARQ-ACK consisting of only NACK, etc.) (S240). Finally, the source terminal 210 may send a sidelink HARQ-ACK report information corresponding to the PSSCH to the base station 200 through a Uu uplink (e.g., PUCCH, PUSCH, etc.) (S250). In this case, the source terminal 210 may generate a sidelink HARQ-ACK report information by using or processing part or all of the sidelink HARQ-ACK received from the target terminal 220, or may generate a sidelink HARQ-ACK report information without using the sidelink HARQ-ACK received from the target terminal 220. The source terminal may transmit information other than the sidelink HARQ-ACK report information to the base station 200 together with the sidelink HARQ-ACK report information.

[0080] At least some of steps S210 to S250 in the above process may be omitted. For example, when the target terminal and / or the source terminal is configured not to perform HARQ-ACK feedback in multicast transmission and unicast transmission, or in the case of broadcast transmission, step S240 and / or step S250 may be omitted. For another example, in the case of PSSCH transmission based on the configured authorization, steps S210 and / or S220 may be omitted. In addition, some steps in the above process may be repeatedly performed several times. For example, in the case of PSSCH transmission based on the configured authorization, step S210 may be performed once, and thus steps S220 to S250 may be repeated several times. Alternatively, steps S210 and S220 may be performed once, and thus steps S230 to S250 may be repeated several times.

[0081] In the above process, PSSCH (and PSCCH) and the corresponding PSFCH can be sent in the same side link bandwidth part. In addition, PSSCH (and PSCCH) and PSFCH can be sent in the same side link resource pool. For example, the source terminal can perform the transmission operation of PSSCH (and PSCCH) and the reception operation of PSFCH in the same side link resource pool. In addition, the target terminal can perform the reception operation of PSSCH (and PSCCH) and the transmission operation of PSFCH in the same side link resource pool. At the same time, when the terminal aggregates and uses multiple side link carriers, in the above process, PSSCH (and PSCCH) and the corresponding PSFCH can be sent in different carriers and different side link bandwidth parts. In addition, PSSCH (and PSCCH) and PSFCH can be sent in different side link resource pools on the same carrier or in different carriers.

[0082] The PSFCH resources (or PSFCH transmission opportunity resources) configured for the terminal may have periodicity. When at least one PSFCH resource exists in a time slot, the PSFCH resource may refer to a set of PSFCH resources in each PSFCH resource or the same time slot according to the situation. The periodicity of the PSFCH resource may be set to N time slots or M symbols (where N and M are natural numbers). The terminal may construct PSFCH resources for each side link bandwidth portion or for each side link resource pool. Depending on the configuration, the PSFCH resource may not exist in certain side link resource pools.

[0083] Figure 3 is a conceptual diagram showing a first exemplary embodiment of a periodic PSFCH resource configuration.

[0084] refer to Figure 3PSFCH resources can be configured for the terminal from the base station. PSFCH resources can be configured for a specific side link bandwidth portion and / or a specific side link resource pool configured in the terminal. The periodicity of PSFCH resources can be 2 time slots (i.e., N=2). That is, PSFCH resources can be configured in every second time slot (e.g., time slot n, time slot (n+2), time slot (n+4), etc.). In addition, PSFCH resources can be mapped to the same time-frequency resources in every Nth time slot. Reference Figure 3 , each of the multiple PSFCH resources can be allocated in the same symbol (e.g., the last symbol) within each corresponding time slot and can be composed of the same PRB.

[0085] The target terminal may send a PSFCH to the source terminal through one of the PSFCH resources that appear at a time point after a predetermined time has passed from the time point when the source terminal receives the PSSCH. For example, the target terminal may send the PSFCH in the earliest PSFCH resource among the PSFCH resources that appear at a time point after a predetermined time has passed from the time point when the PSSCH is received. The PSSCH and the PSFCH may be sent in the same side link bandwidth part and / or the same side link resource pool. Alternatively, in the case of carrier aggregation, the PSSCH and the PSFCH may be sent in different side link bandwidth parts and / or different side link resource pools.

[0086] The scheduled time may correspond to the PSSCH reception processing time and PSFCH transmission preparation time of the terminal, or may be a value determined by at least considering these. The scheduled time may be defined in the technical specification or configured by the base station to the terminal. The scheduled time may be expressed as the time distance or time offset (e.g., symbol offset or slot offset) between the PSSCH reception time point and the PSFCH transmission time point. For example, when the time slot in which the target terminal receives PSSCH (and / or PSCCH) is time slot n, the target terminal may send PSFCH in the PSFCH resource of the earliest time slot in the time slot (n+L) where the PSFCH resource exists and the subsequent time slot. In this case, L may be a natural number, may be predefined in the technical specification and may be shared with the source terminal, the target terminal, and / or the base station. Alternatively, L may be configured by the base station to the terminal or by one terminal (e.g., the source terminal) to another terminal (e.g., the target terminal). When the parameter set (e.g., subcarrier spacing) of the resource pool transmitting the PSSCH is different from the parameter set of the resource pool transmitting the PSFCH, the time slot can be interpreted as a time slot of one of the two resource pools. When determining the PSFCH transmission timing, the terminal's uplink timing advance (TA) can be considered together.

[0087] Figure 4is a conceptual diagram showing a first exemplary embodiment of a PSSCH HARQ-ACK feedback timing method, and Figure 5 is a conceptual diagram illustrating a second exemplary embodiment of a PSSCH HARQ-ACK feedback timing method.

[0088] exist Figure 4 and Figure 5 In the exemplary embodiment shown in Figure 3 As in the exemplary embodiment of , it can be assumed that the terminals (ie, the source terminal and the target terminal) have been configured with a PSFCH resource having a periodicity of 2 slots by the base station. Figure 4 and Figure 5 In the exemplary embodiment shown in FIG. 1 , a first mode side link resource allocation scheme is used, and the use of the side link resources may be controlled by the base station.

[0089] refer to Figure 4 , the base station can send PSSCH resource allocation and scheduling information to the source terminal through the Uu downlink in time slot n. For example, PSSCH resource allocation and scheduling information can be sent through PDCCH, and a specific DCI format for sidelink resource allocation (e.g., DCI format 3_0, DCI format 3_1, etc.) and / or a CRC scrambled with a specific RNTI (e.g., sidelink RNTI, SL-RNTI, SL-CS-RNTI, SL-L-CS-RNTI, etc.) can be applied to the transmission of PDCCH. In addition, the base station can notify the terminal of information about the time offset (e.g., symbol offset, time slot offset) between the resources for sending PDCCH (or DCI, DCI format, etc.) and the PSSCH resources through a signaling process (e.g., RRC signaling and / or DCI signaling). Information about the time offset can be included in the PSSCH resource allocation and scheduling information. According to Figure 4 In an exemplary embodiment, the time offset may be a time slot offset between a time slot (i.e., time slot n) in which a PDCCH (or DCI, DCI format) is transmitted and a time slot (i.e., time slot (n+1)) to which a PSSCH is allocated, and the value of the time slot offset may be 1. Alternatively, the time offset may be a time distance (e.g., a symbol offset) between an end time of receiving a PDCCH (or DCI, DCI format) (e.g., the end time of the last symbol or the last symbol of the PDCCH) and a start time of an allocated PSSCH resource (e.g., the start time of the first symbol or the first symbol of the PSSCH). The time offset may be greater than or equal to a reference value. The reference value may correspond to a PDCCH reception processing time of a terminal and a PSSCH (and PSCCH) transmission preparation time, or at least take these determined values ​​into account, and may be predefined in the technical specification.

[0090] The source terminal can send SCI including PSSCH resource allocation and scheduling information and the corresponding PSSCH to the target terminal in time slot (n+1). Specific SCI formats (e.g., SCI format 1-A, SCI format 2-A, SCI format 2-B, etc.) can be used to send SCI. In addition, SCI can be sent through PSCCH, a portion of PSSCH resources, etc. For example, when SCI is configured with 2 levels, the first SCI can be sent through PDCCH, and the second SCI can be sent through a portion of PSSCH resources. Here, sending SCI and PSSCH in the same time slot is only an exemplary embodiment, and according to another exemplary embodiment, SCI and PSSCH can be sent in different time slots. In addition, according to another exemplary embodiment, SCI and PSSCH can be sent in the same time slot as the time slot of PDCCH (e.g., time slot n).

[0091] Reference again Figure 4 , after receiving the PSSCH, the target terminal may send HARQ-ACK (i.e., sidelink HARQ-ACK) for the PSSCH to the source terminal through a side link (e.g., PSFCH). In this case, as described above, the target terminal may send the PSFCH from a time point after a predetermined time (e.g., L time slots) has passed since the time point when the PSSCH was received. Figure 4 In an exemplary embodiment, the target terminal can send PSFCH from the next time slot (i.e., time slot (n+2)) of the time slot in which PSSCH is received (i.e., time slot (n+1)). Therefore, the target terminal can send PSFCH in the PSFCH resource (i.e., the PSFCH resource allocated in time slot (n+2)) at the earliest time point in time slot (n+2) (which is the next time slot in which PSSCH is received) and the subsequent time slots (i.e., L=1).

[0092] The source terminal can receive the sidelink HARQ-ACK for PSSCH from the target terminal, and send the sidelink HARQ-ACK report information related thereto to the base station via the Uu uplink (e.g., PUCCH or PUSCH). In this case, the time offset (e.g., symbol offset, time slot offset) between the resources for sending PSFCH and the resources for sending the sidelink HARQ-ACK report information (e.g., PUCCH resources or PUSCH resources) can be equal to or greater than a reference value. The reference value can correspond to the PSFCH reception processing time and the PUCCH (or PUSCH) transmission preparation time of the terminal, or can be a value determined by at least taking these into consideration, and can be predefined in the technical specification. According to Figure 4In an exemplary embodiment, the source terminal may send side link HARQ-ACK report information to the base station in the next time slot (ie, time slot (n+3)) of the time slot in which the PSFCH is received (ie, time slot (n+2)).

[0093] At the same time, as described above, the source terminal may not receive the side link HARQ-ACK from the target terminal. This may correspond to the situation where the quality of the side link wireless channel between the terminals is poor and the source terminal does not detect the PSFCH, or the target terminal does not send the side link HARQ-ACK. In this case, the source terminal may send NACK to the base station as the side link HARQ-ACK report information in order to request PSSCH retransmission from the base station. In general, the exemplary embodiment can be described based on the situation where the source terminal successfully receives the side link HARQ-ACK from the target terminal, but the exemplary embodiment can also be applied to the opposite situation. In addition, 'reception success' may include detection errors, that is, the situation where the target terminal sends ACK (or NACK) but the source terminal receives NACK (or ACK), and the situation where the target terminal does not send HARQ-ACK but the source terminal receives ACK or NACK.

[0094] refer to Figure 5 , the base station may send PSSCH resource allocation and scheduling information to the source terminal through the Uu downlink (e.g., PDCCH) in time slot (n+1). The source terminal may send SCI and corresponding PSSCH including PSSCH resource allocation and scheduling information to the target terminal in time slot (n+2). SCI may be sent through PSCCH, a portion of PSSCH resources, etc. Considering the above transmission / reception processing time, the target terminal may send PSFCH in the earliest PSFCH resource (i.e., time slot (n+4)) allocated in time slot (n+3) (which is the next time slot of the time slot in which PSSCH is received) and the subsequent time slot (i.e., L=1). The source terminal may send the side link HARQ-ACK report information for the received side link HARQ-ACK to the base station through PUCCH (or PUSCH) in the next time slot (i.e., time slot (n+5)) of the time slot in which PSFCH is received (i.e., time slot (n+4)).

[0095] Reference again Figure 4 In an exemplary embodiment, the base station may receive the side link HARQ-ACK report information sent by the source terminal in a time slot (i.e., time slot (n+3)) after two time slots have passed from the time slot (i.e., time slot (n+1)) in which the PSSCH is sent. Alternatively, the base station may receive the side link HARQ-ACK report information sent by the source terminal in a time slot (i.e., time slot (n+3)) after three time slots have passed from the time slot (i.e., time slot n) in which the PDCCH is sent. On the other hand, in Figure 5 In an exemplary embodiment, the base station can receive the side link HARQ-ACK report information sent by the source terminal in a time slot (i.e., time slot (n+5)) after three time slots have passed from the time slot in which the PSSCH is sent (i.e., time slot (n+2)). Alternatively, the base station can receive the side link HARQ-ACK report information sent by the source terminal in a time slot (i.e., time slot (n+5)) after four time slots have passed from the time slot in which the PDCCH is sent (i.e., time slot (n+1)). According to a comparison of the above exemplary embodiments, when the time slot-based periodicity N of the PSFCH resources configured for the terminal is greater than 1, the distance between the time slot in which the PSSCH (or PDCCH) is sent and the time slot in which the PSFCH is sent (i.e., the time slot offset) can be changed according to the position of the time slot in which the PSSCH (or PDCCH) is sent. In addition, when the time slot-based periodicity N of the PSFCH resources configured for the terminal is greater than 1, the distance (i.e., time slot offset) or the minimum distance (i.e., minimum time slot offset) between the time slot for sending PSSCH (or PDCCH) and the time slot for sending side link HARQ-ACK report information can be changed according to the position of the time slot for sending PSSCH (or PDCCH).

[0096] On the other hand, the base station can configure the timing or transmission time of sending the side link HARQ-ACK report information to the source terminal through the Uu uplink (e.g., PUCCH or PUSCH) (hereinafter, referred to as 'side link HARQ-ACK report timing'). As a method for this, the side link HARQ-ACK report timing can be defined as the relative distance from the PSSCH transmission time point (i.e., time offset (hereinafter referred to as 'K')), and the base station can explicitly or implicitly configure or indicate the value of K to the source terminal. This can be referred to as 'method 100'.

[0097] K may be configured in units of time slots. That is, K may be defined as an offset in units of time slots (i.e., the distance between the time slot when the PSSCH is transmitted and the time slot when the sidelink HARQ-ACK report information is transmitted). Figure 4 Exemplary embodiments and Figure 5In an exemplary embodiment of, the base station can dynamically indicate the time slot offsets K=2 and K=3 to the source terminal respectively through method 100. Alternatively, K can be configured in symbols. That is, K can be defined as an offset in symbols (i.e., the distance between one of the symbols when sending PSSCH and one of the symbols when sending side link HARQ-ACK report information). The source terminal can send side link HARQ-ACK report information to the base station based on the side link HARQ-ACK report timing determined by the PSSCH reception time and the value of K. However, according to method 100, because the source terminal should be configured with multiple side link HARQ-ACK report timings or multiple K values ​​when the time slot-based periodicity N of the PSFCH resources configured for the terminal is greater than 1, the base station may need to dynamically change the value of K according to the position of the time slot allocated by the PSSCH. This may increase scheduling complexity and DCI overhead.

[0098] As a method for solving the above problem, the base station may configure or indicate the side link HARQ-ACK report timing to the source terminal as a relative distance from the PSSCH transmission time point (i.e., time offset (=K)), and the source terminal may add an additional offset (hereinafter referred to as 'K') to the value of K received from the base station. offset ') to derive the corrected side link HARQ-ACK report timing, and send the side link HARQ-ACK report information to the base station according to the corrected timing. This may be referred to as 'method 110'. As in method 100, K may be configured in units of time slots or symbols, and K may also be configured in units of time slots or symbols. offset . K offset The configuration unit of can be the same as the configuration unit of K.

[0099] In method 110, the sidelink HARQ-ACK reporting timing (ie, K) that the base station signals to the source terminal may be a nominal value. That is, when K offset When K is not 0, the timing at which the source terminal actually sends the sidelink HARQ-ACK report information to the base station may not match the sidelink HARQ-ACK report timing signaled by the base station to the source terminal. In method 110, K can be determined by the distance between the PSSCH transmission time and the PSFCH reception time of the source terminal (e.g., the time distance expressed in time slots or symbols). offset . In addition, K may be a value obtained by considering the distance between the PSSCH transmission time point and the PSFCH reception time point as a specific value. For example, K may be a value obtained by assuming the shortest distance or the longest distance among the possible distances between the PSSCH transmission time point and the PSFCH reception time point.

[0100] exist Figure 4Exemplary embodiments and Figure 5 In an exemplary embodiment of , the base station can jointly configure or indicate the time slot offset K=2 to the source terminal through method 110. The value of K may not necessarily match the actual distance between the PSSCH transmission time and the sidelink HARQ-ACK report timing. For example, the value of K can be a value assuming the shortest distance (i.e., one time slot) among the possible distances between the PSSCH transmission time and the PSFCH reception time. Figure 4 In the case of the exemplary embodiment of the present invention, since the actual distance between the PSSCH transmission time and the PSFCH reception time is equal to the distance assumed to be one time slot, the source terminal can obtain the value of K by applying offset = 0 and applies the sidelink HARQ-ACK report timing (i.e., K) received from the base station as is to send the sidelink HARQ-ACK report information to the base station in time slot (n+3). Figure 5 In the exemplary embodiment of FIG. 1 , since the actual distance between the PSSCH transmission time and the PSFCH reception time is 2 time slots (which is one time slot larger than the assumed distance), the source terminal can add K to it. offset =1 to correct the sidelink HARQ-ACK report timing signaled from the base station, and send the sidelink HARQ-ACK report information to the base station in time slot (n+5) according to the corrected sidelink HARQ-ACK report timing.

[0101] As another method for solving the above problem, the side link HARQ-ACK report timing can be defined as the relative distance from the PSFCH transmission time, that is, the time offset (hereinafter referred to as 'L'), and the base station can explicitly or implicitly configure or indicate the value of L to the source terminal. This can be referred to as 'method 120'. Similarly, L can be configured in units of symbols or time slots. For example, L can be defined as an offset in units of time slots (i.e., the distance between the time slot when the PSFCH is sent and the time slot when the side link HARQ-ACK report information is sent). For another example, L can be defined as an offset in units of symbols (i.e., the distance between one of the symbols when the PSFCH is sent and one of the symbols when the side link HARQ-ACK report information is sent). The symbol or time slot can be a symbol or time slot belonging to a side link resource pool (e.g., a side link resource pool for PSSCH and / or PSFCH transmission). For example, L can indicate the number of time slots belonging to the side link resource pool. In this case, the actual physical offset between the time slot when the PSFCH is sent and the time slot when the sidelink HARQ-ACK report information is sent may be greater than or equal to L. For another example, L may indicate the number of symbols belonging to the sidelink resource pool. In this case, the actual physical offset between one of the symbols when the PSFCH is sent and one of the symbols when the sidelink HARQ-ACK report information is sent may be greater than or equal to L. In method 120, the base station and the source terminal may understand the transmission time of the PSFCH corresponding to each PSSCH transmission, so the transmission time of the PSFCH may be used as a reference time for the sidelink HARQ-ACK report timing.

[0102] exist Figure 4 Exemplary embodiments and Figure 5 In an exemplary embodiment of , the base station may indicate a time slot offset of 1 (i.e., L=1) to the source terminal through method 120. That is, the base station may configure or indicate that the distance between the time slot when the source terminal expects to receive the PSFCH from the target terminal and the time slot when the source terminal sends the HARQ-ACK report information to the base station is 1. The source terminal may send the sidelink HARQ-ACK report information to the base station according to the sidelink HARQ-ACK report timing determined by the value of L received from the base station. Reference Figure 4 , the source terminal may send the side link HARQ-ACK report information corresponding to the PSFCH to the base station through the Uu link (e.g., PUCCH or PUSCH) in a time slot (i.e., time slot (n+3)) after L (=1) time slots have passed from the time slot (i.e., time slot (n+2)) in which the PSFCH is received. Figure 5, the source terminal can send side link HARQ-ACK report information corresponding to PSFCH to the base station through the Uu link (e.g., PUCCH or PUSCH) in the time slot (i.e., time slot (n+5)) after L (=1) time slots have passed from the time slot in which PSFCH is received (i.e., time slot (n+4)).

[0103] As described above, according to method 110 or method 120 in the above exemplary embodiments, even when N>1, one value can be used as the side link HARQ-ACK report timing of the source terminal, and in this case, semi-statically configuring the side link HARQ-ACK report timing through RRC signaling may be sufficient. Therefore, compared with method 100, scheduling complexity and DCI overhead can be reduced. In addition, because method 120 does not include a step of correcting the timing by the terminal, it can provide low implementation complexity compared to method 110.

[0104] As another method of indicating the sidelink HARQ-ACK report timing to the terminal, the sidelink HARQ-ACK report timing can be defined as the relative distance from the PDCCH transmission time of the Uu downlink. Alternatively, the sidelink HARQ-ACK report timing can be defined as the relative distance from the SCI transmission time (e.g., PSCCH transmission time). The base station can determine the value of the sidelink HARQ-ACK report timing according to the above definition and configure or indicate it to the source terminal. Similarly, the timing value can be configured in units of time slots or symbols.

[0105] In an exemplary embodiment, a parameter set for transmission of the PSFCH (hereinafter referred to as a 'first parameter set') may be the same as a parameter set for transmission of the PUCCH (or PUSCH) (hereinafter referred to as a 'second parameter set'). For example, the first parameter set may be a parameter set for the (activated) sidelink bandwidth part. For example, the second parameter set may be a parameter set for the uplink bandwidth part, a parameter set determined in the parameter sets for the uplink and downlink bandwidth parts, etc.

[0106] Alternatively, in an exemplary embodiment, the first parameter set may be generally different from the second parameter set (i.e., may be the same as or different from it). In this case, the sidelink HARQ-ACK report timing of the terminal, the time offset indicating the sidelink HARQ-ACK report timing, the reference time for determining the time offset, etc. may be interpreted based on the parameter set (i.e., the second parameter set) for the transmission of the sidelink HARQ-ACK report information. For example, in the case of method 120, the time slot when the PSFCH is transmitted, the time slot when the PUCCH (or PUSCH) is transmitted, and the time offset (e.g., the time slot offset) may be the time slot in the uplink bandwidth portion where the PUCCH (or PUSCH) is transmitted. The value of L may mean the number of time slots in the uplink bandwidth portion where the PUCCH (or PUSCH) is transmitted. In addition, the time slot for transmitting the PUCCH (or PUSCH) corresponding to L=0 may be one of the uplink time slots (e.g., the last time slot) that overlaps in time with the PSFCH transmission time (including the sidelink time slot of the PSFCH).

[0107] Alternatively, the sidelink HARQ-ACK report timing of the terminal, the time offset indicating the sidelink HARQ-ACK report timing, the reference time for determining the time offset, etc. may be interpreted based on the first parameter set. Alternatively, the sidelink HARQ-ACK report timing of the terminal, the time offset indicating the sidelink HARQ-ACK report timing, the reference time for determining the time offset, etc. may be interpreted based on a specific parameter set. For example, the specific parameter set may be one of the first and second parameter sets (e.g., a parameter set with a larger or smaller subcarrier spacing). For another example, the specific parameter set may be a parameter set configured separately for the terminal (e.g., a reference parameter set).

[0108] In an exemplary embodiment, the time slot offset or the number of time slots indicated (or configured) from the base station to the source terminal may be the number of physical time slots (e.g., time slots that are continuous in time). Alternatively, the time slot offset or the number of time slots indicated (or configured) from the base station to the source terminal may be the number of logical time slots (e.g., sequential time slots that satisfy a specific condition). For example, a logical time slot may mean a time slot belonging to a side link resource pool. Logically adjacent time slots may be discontinuous in time. That is, a time slot that does not belong to a side link resource pool may exist between logically adjacent time slots.

[0109] In an exemplary embodiment, the base station may indicate or configure the PUCCH resource for sending the side link HARQ-ACK report information to the source terminal. In addition, the base station may indicate or configure the source terminal not to send the side link HARQ-ACK report information. The information indicating that the side link HARQ-ACK report information will not be sent may be included in the side link HARQ-ACK report timing indication information and / or the PUCCH resource indication information. This may correspond to a specific field value of a specific field of the DCI.

[0110] In an exemplary embodiment, each sidelink HARQ-ACK report performed by the source terminal may correspond to one or more PSFCHs received by the source terminal from the target terminal. For example, the base station may allocate multiple PSSCH resources for the same TB (or TB set) to the source terminal. The source terminal may send multiple PSSCHs to the target terminal and receive multiple PSFCHs corresponding thereto. The source terminal may determine the ACK or NACK for the TB (or TB set) based on the reception of multiple PSFCHs, and send the corresponding sidelink HARQ-ACK report information to the base station via PUCCH (or PUSCH). In this case, the sidelink HARQ-ACK report timing (e.g., PUCCH or PUSCH transmission slot) by method 120 may be determined based on the reception time of one PSFCH (multiple) of at least one PSFCH (i.e., the PSFCH received or expected to be received by the source terminal last or latest) for the same TB (or TB set).

[0111] PSFCH resources can be configured for the terminal through RRC signaling. In this case, the configuration of PSFCH resources can be basically terminal-specific. However, in order to effectively support PSFCH transmission between terminals and sensing operations on PSFCH, it may be necessary to configure PSFCH resources for multiple terminals in common. For this, cell-specific signaling can be used for the configuration of PSFCH resources. For example, the configuration of PSFCH can be common within a serving cell or base station, which can be configured to the terminal through MIB, SIB1 and / or OSI, etc. At the same time, the source terminal and the target terminal can belong to different serving cells or base stations, or PSFCH can be configured from different serving cells or base stations. When the configuration of PSFCH is different, PSFCH transmission and sensing between the source terminal and the target terminal may be difficult. Therefore, the configuration of PSFCH can be commonly applied to a wider unit. For example, the configuration of PSFCH can be common within a group consisting of at least one serving cell or base station. A serving cell group ID or a base station group ID can be used, or an area (e.g., a region) ID can be used to configure the PSFCH for each group. For example, a pair of terminals performing sidelink transmission and reception can perform transmission only when they have the same zone ID. Whether the zone IDs of the terminals belonging to a pair are the same can be identified by a signaling process (e.g., RRC signaling) between the terminals. Signaling can be performed in a bidirectional or handshake form.

[0112] In the above exemplary embodiments, the PSSCH may be a PSSCH scheduled by a dynamic grant. In the first mode of sidelink resource allocation, the dynamic grant for the PSSCH may mean a downlink assignment (or downlink grant) sent by the base station to the source terminal. The downlink assignment for the PSSCH may be a DCI (e.g., DCI format 3_0) and may be sent via the PDCCH. A CRC scrambled with a specific RNTI (e.g., SL-RNTI) may be applied to the downlink assignment of the PSSCH. Alternatively, the dynamic grant for the PSSCH may mean a sidelink grant sent from the source terminal to the target terminal. The sidelink grant for the PSSCH may be an SCI (e.g., SCI format 1-A, 2-A, 2-B, etc.) and may be sent via the PSCCH, a portion of the PSSCH resources, etc.

[0113] In addition, in the above exemplary embodiments, the PSSCH may be a PSSCH scheduled by a configured grant. Hereinafter, for convenience, the PSSCH based on the configured grant will be referred to as a configured grant (CG) PSSCH. The grant scheme of the side link configuration can be classified into a type 1 scheme and a type 2 scheme. In the case of the type 1 scheme, the resource configuration and scheduling of the configured grant PSSCH can be configured semi-statically or semi-persistently by RRC signaling. In the case of the type 2 scheme, the resource configuration and scheduling of the configured grant PSSCH can be configured by a combination of RRC signaling and physical layer signaling (e.g., DCI or SCI). In addition, in the type 2 scheme, the configured grant PSSCH resource can be activated (or initialized), reactivated (or reinitialized) or deactivated by physical layer signaling (e.g., DCI or SCI). Specifically, in the case of the transmission of the configured grant PSSCH, because the base station may not be able to dynamically indicate the side link HARQ-ACK report timing, the effect of method 110 or method 120 can be greater. Alternatively, the base station may configure the granted PSSCH resources so that the time distance (eg, the distance in time slots or symbols) between the configured granted PSSCH resources and the PSFCH resources is a predetermined constant value. In this case, the method 100 may be well applied.

[0114] The configuration of the authorized resources of the side link configuration may be configured by the base station for the source terminal. In addition, the configuration of the authorized resources of the side link configuration may be configured by the source terminal for the target terminal. Alternatively, the configuration of the authorized resources of the side link configuration may be configured by the base station for the target terminal. The authorized resources of the side link configuration may be configured by the same base station or by different base stations for the source terminal and the target terminal.

[0115] The granted resources of the side link configuration may appear periodically. The periodicity of the granted resources of the side link configuration may be configured for the terminal (e.g., source terminal, target terminal), and the granted resources of one or more side link configurations may be arranged in a period. One PSSCH and / or one PSCCH may be sent in the granted resources of each side link configuration. In this case, the source terminal may always send PSSCH and / or PSCCH in the granted resources of all side link configurations.

[0116] On the other hand, in some cases (for example, when the sidelink traffic (for example, the sidelink shared channel (SL-SCH)) occurs irregularly), the source terminal may or may not send PSSCH and / or PSCCH in each authorized resource of the sidelink configuration. In this case, the target terminal may send HARQ-ACK and / or PSCCH for PSSCH to the source terminal only when PSSCH is received in the authorized resources of the sidelink configuration or the corresponding PSCCH is successfully decoded. Alternatively, the target terminal may always send HARQ-ACK and / or PSCCH for PSSCH to the source terminal regardless of whether PSSCH and / or PSCCH are received in the authorized resources of the sidelink configuration. In this case, ACK may be sent when the target terminal successfully receives PSSCH, and in another case, NACK may be sent. Alternatively, in the first mode side link resource allocation, a signal can be sent from the source terminal to the target terminal (e.g., via SCI signaling or PC5-RRC signaling) to inform whether to send the target terminal's HARQ-ACK for PSSCH (e.g., dynamically granted PSSCH, configured granted PSSCH).

[0117] Similarly, the source terminal can report HARQ-ACK to the base station only when PSSCH is sent in the authorized resources of the side link configuration. Alternatively, the source terminal can always report HARQ-ACK to the base station regardless of whether PSSCH is actually sent in the authorized resources of the side link configuration. The latter method can improve the reception performance and transmission delay time of PSSCH by consuming more Uu interface resources. In this case, when PSSCH is not sent in the authorized resources (multiple) of the side link configuration, the source terminal can report ACK to the base station as the side link HARQ-ACK report information about the corresponding TB. The base station may not allocate retransmission resources for the corresponding PSSCH (or corresponding TB) based on the reception of the side link HARQ-ACK report information. Alternatively, when PSSCH is not sent in the authorized resources of the side link configuration, the source terminal can report NACK to the base station as the side link HARQ-ACK report information about the corresponding TB. Alternatively, in the above case, the source terminal may send information (e.g., third information other than ACK / NACK) indicating that the PSSCH has not been sent through the HARQ-ACK transmission resource (e.g., PUCCH or PUSCH) to the base station. The information indicating that the PSSCH has not been sent may be included in the sidelink HARQ-ACK report information. The above operations of the terminal may be predefined in the technical specification, or may be configured or configured by signaling from the base station or another terminal.

[0118] The methods described above can be equally applied to PSSCH based on dynamic grant and configured grant PSSCH. In addition, the methods described above can be applied to previously described methods (e.g., method 100, method 110, method 120, etc.) and their exemplary embodiments. For example, in Figure 4 In an exemplary embodiment of , the source terminal can send sidelink HARQ-ACK report information corresponding to the PSSCH to the base station in time slot (n+3), regardless of whether the PSSCH has been actually sent in time slot (n+1) and / or whether the PSFCH has been actually received in time slot (n+2). The PSSCH allocated to time slot (n+1) can be a dynamically granted PSSCH or a configured granted PSSCH. In addition, Figure 5 In an exemplary embodiment of , the source terminal can send sidelink HARQ-ACK report information corresponding to the PSSCH to the base station in time slot (n+5), regardless of whether the PSSCH has been actually sent in time slot (n+2) and / or whether the PSFCH has been actually received in time slot (n+4). The PSSCH allocated to time slot (n+2) can be a dynamically granted PSSCH or a configured granted PSSCH.

[0119] PSSCH retransmission method

[0120] Hereinafter, a PSSCH retransmission method in case of the first mode of side link resource allocation will be described.

[0121] Figure 6 is a conceptual diagram showing a first exemplary embodiment of a PSSCH retransmission method, and Figure 7 is a conceptual diagram illustrating a second exemplary embodiment of a PSSCH retransmission method.

[0122] refer to Figure 6 and Figure 7 , the first mode sidelink resource allocation can be used, and the use of the sidelink resources can be controlled by the base station. The base station can send PSSCH resource allocation and scheduling information to the source terminal through the Uu downlink (e.g., PDCCH) in time slot n. The source terminal can send SCI including PSSCH resource allocation and scheduling information and the corresponding PSSCH received from the base station to the target terminal in time slot (n+1). For example, SCI can be sent via PSCCH, a portion of PSSCH resources, and the like. The target terminal can successfully receive PSSCH and send ACK as sidelink HARQ-ACK information to the source terminal through the side link (e.g., PSFCH) in time slot (n+2). After receiving ACK from the target terminal, the source terminal can send ACK as sidelink HARQ-ACK report information to the base station through PUCCH (or PUSCH) in time slot (n+3).

[0123] In this case, the base station can receive NACK as sidelink HARQ-ACK report information through the reception of PUCCH (or PUSCH). That is, although the source terminal has sent ACK as sidelink HARQ-ACK report information, the base station will receive NACK due to the detection error (ie, ACK to NACK error) at the receiving end. The base station can schedule the retransmission PSSCH for the same TB or the same HARQ process in time slot (n+6) based on NACK, and send resource allocation and scheduling information of the retransmission PSSCH to the source terminal through the Uu downlink (e.g., PDCCH) in time slot (n+5).

[0124] The source terminal can successfully receive resource allocation and scheduling information for retransmitting PSSCH from the base station. In this case, although the source terminal has received ACK for PSSCH (or TB corresponding to it) from the target terminal and has sent ACK to the base station as the side link HARQ-ACK report information corresponding to it, the source terminal can be instructed by the base station to retransmit the corresponding PSSCH (or TB corresponding to it). The following method can be considered as the operation of the source terminal in this case.

[0125] As a first method, the source terminal may ignore the retransmission instruction of the base station and may not send a retransmission PSSCH to the target terminal. That is, the source terminal may no longer send a PSSCH for a TB. This may be referred to as 'method 200'. Reference Figure 6 According to method 200, the source terminal may ignore the retransmission instruction (eg, downlink DCI) received from the base station via the PDCCH in time slot (n+5) and may not send the PSSCH in time slot (n+6).

[0126] As a second method, the source terminal may send a retransmission PSSCH to the target terminal according to the retransmission instruction of the base station. This may be referred to as 'method 210'. Figure 7 According to method 210, the source terminal may send a retransmission PSSCH for the same TB to the target terminal in time slot (n+6) based on a retransmission instruction (e.g., downlink DCI) received from the base station through the PDCCH in time slot (n+5). In this case, the source terminal may send an SCI including resource allocation and scheduling information of the retransmission PSSCH to the target terminal together with the retransmission PSSCH.

[0127] On the other hand, the base station can configure or indicate reserved resources to the terminal in the side link resources (e.g., a side link bandwidth portion or a side link resource pool) for retransmission of PSSCH or transmission of PSSCH of another TB. That is, reserved resources can be allocated from the base station to the source terminal in the side link resources, and the source terminal can send PSSCH (and / or PSCCH, CSI-RS) to the target terminal through the reserved resources. Reserved resources may mean PSSCH resources, retransmission PSSCH resources, and so on. Reserved resources may mean PSSCH resources including the first scheduled PSSCH resources. Alternatively, reserved resources may mean PSSCH resources after the first (or earliest) PSSCH resource in the scheduled PSSCH resources. In the above exemplary embodiments, the retransmission PSSCH resources (i.e., PSSCH resources allocated to time slot (n+6)) scheduled from the base station to the source terminal can be considered as reserved resources. This will be described by the following exemplary embodiments.

[0128] Figure 8 is a conceptual diagram showing a first exemplary embodiment of sidelink reserved resource allocation by a base station.

[0129] refer to Figure 8 As in the above exemplary embodiment, the base station may send PSSCH resource allocation and scheduling information to the source terminal via the Uu downlink (e.g., PDCCH) in time slot n. In addition, the base station may send the reserved resource allocation information for PSSCH transmission together with the PSSCH resource allocation and scheduling information to the source terminal (e.g., via PDCCH). Figure 8 In, the reserved resources can be allocated to time slot (n+6).

[0130] In addition, the reserved resources allocated by the base station or the source terminal can be released. For example, if the transmission of the signal (e.g., PSSCH, retransmission PSSCH, PSCCH, etc.) scheduled to be sent through the reserved resources becomes unnecessary, the reserved resources can be released. In the released reserved resources, another resource can be allocated or another signal can be sent. The entity that determines the release of the reserved resources can be the base station or the source terminal.

[0131] Reserved resources may be allocated for PSSCH retransmission and signaled to the target terminal. That is, the source terminal may perform signaling (e.g., SCI signaling) of resource allocation and scheduling information about reserved resources allocated from the base station to the target terminal. The source terminal may notify the target terminal of information indicating that the reserved resources are resources for PSSCH retransmission. In this case, when the target terminal successfully receives the previous PSSCH for the same TB, the target terminal may not receive the retransmission PSSCH (and the SCI including the scheduling information of the retransmission PSSCH) through the reserved resources. In addition, the target terminal may send ACK to the source terminal for the previous PSSCH that has been successfully received. ACK may be sent through PSFCH. In this case, the target terminal may assume that the reserved resources have been released. For example, the target terminal may assume that the allocated reserved resources are released after the time point of sending ACK. Alternatively, if there is no separate signaling from the source terminal, the target terminal may not assume that the reserved resources are released despite successfully receiving the previous PSSCH and feeding back ACK. That is, when the target terminal receives separate signaling from the source terminal after sending ACK to the source terminal, the target terminal may assume that the reserved resources are released. When the target terminal is a terminal that performs sensing for second mode resource allocation, the assumption about the release of the reserved resources may affect the sensing process. That is, when the target terminal assumes that the reserved resources are released, the target terminal may regard the reserved resources as belonging to a set of resources that can be used for transmission.

[0132] Another terminal (hereinafter referred to as 'neighboring terminal') may exist around the target terminal or the source terminal. For example, the neighboring terminal may be a terminal configured to perform the second mode side link resource allocation, or a terminal configured to perform a sensing process for resource allocation. In this case, the neighboring terminal may receive a signal including information about the ACK sent by the target terminal to the source terminal and obtain the ACK information through a sensing process. For example, the neighboring terminal may obtain the ACK by monitoring the resources (e.g., PSFCH resources) that send the ACK information and detecting the signal corresponding to the ACK or the energy corresponding to the ACK in the PSFCH resources. The neighboring terminal may predict that the reserved resources (e.g., reserved resources allocated for PSSCH retransmission) will be released based on the ACK information, so the neighboring terminal may regard the reserved resources as belonging to a set of resources available for transmission. The step of including the reserved resources in the set of resources available for transmission may be performed within the sensing process for the second mode performed by the neighboring terminal.

[0133] According to method 200, the source terminal may not send the retransmission PSSCH in the reserved resources. Figure 6 and Figure 7 ,like Figure 8As shown in , the base station can allocate the side link reserved resources in time slot (n+6). In addition, the neighboring terminals around the target terminal (e.g., the terminals performing the second mode side link resource allocation) can receive the signal including the information about the ACK sent by the target terminal in time slot (n+2), and it is assumed that the reserved resources of time slot (n+6) are released. In addition, the neighboring terminals can occupy the released reserved resources and send signals (e.g., PSSCH) like the source terminal. In this case, if the source terminal follows the retransmission instruction of the base station according to method 210 and as in Figure 7 If the source terminal transmits the PSSCH in time slot (n+6) as in the exemplary embodiment of , the PSSCH may collide with the signal transmitted by the neighboring terminal, and they may interfere with each other. On the other hand, if the source terminal ignores the retransmission instruction of the base station according to method 200, and transmits the PSSCH in time slot (n+6) as in Figure 6 If PSSCH is not transmitted in time slot (n+6) as in the exemplary embodiment of , collision may not occur.

[0134] When using method 200, the entity that releases the reserved resources (from the perspective of transmission) may be the source terminal. In the first mode resource allocation, the allocation of the reserved resources may be performed by the base station, and in this case, the entity that allocates the reserved resources and the entity that releases the reserved resources may be different. In this case, the source terminal may partially or conditionally intervene to determine whether to retransmit the PSSCH. For example, when the source terminal receives an ACK for the previous PSSCH from the target terminal, the source terminal may determine whether to retransmit the PSSCH. Here, the expression of the source terminal receiving the ACK for the PSSCH may include the case when the source terminal determines the ACK (for example, not receiving the NACK in the PSFCH resource for group NACK transmission). On the other hand, when the source terminal receives (or determines) the NACK for the previous PSSCH from the target terminal, the base station may determine whether to retransmit the PSSCH. Alternatively, a method in which the source terminal always determines whether to retransmit the PSSCH may be used. Whether to use the above method may be configured by the base station to the source terminal, or pre-configured to the source terminal. On the other hand, when using method 210, the entity that releases the reserved resources may be the base station. In this case, in the first mode resource allocation, the entity that allocates the reserved resources and the entity that releases the reserved resources may be identical.

[0135] On the other hand, as described above, from the perspective of reception, when the target terminal sends an ACK related to the reserved resources or the neighboring terminal receives an ACK related to the reserved resources sent by another terminal (e.g., the target terminal), the target terminal or the neighboring terminal can autonomously assume that the reserved resources are released. Alternatively, the target terminal or the neighboring terminal can assume that the reserved resources are released through signaling from the base station or the source terminal.

[0136] When using method 210, the source terminal may send a sidelink HARQ-ACK report information about the retransmission PSSCH to the base station. The source terminal may receive a sidelink HARQ-ACK for the retransmission PSSCH sent by the source terminal from the target terminal, and generate a sidelink HARQ-ACK report information to be reported to the base station based on the sidelink HARQ-ACK. The specific method used for this may follow the above exemplary embodiments. For example, when receiving ACK (or NACK) from the target terminal, the source terminal may send ACK (or NACK) as a sidelink HARQ-ACK report information to the base station. In addition, when the sidelink HARQ-ACK information is not received from the target terminal, the source terminal may send NACK as a sidelink HARQ-ACK report information to the base station. When the sidelink HARQ-ACK report corresponds to multiple PSSCHs (or multiple PSFCHs) for the same TB, the source terminal may send ACK as a sidelink HARQ-ACK report information to the base station when at least one of the HARQ-ACK information received from the target terminal indicates ACK. The sidelink HARQ-ACK report information sent to the base station may be multiplexed or encoded with other information and sent.

[0137] At the same time, according to method 200, the source terminal may not send a retransmission PSSCH without following the retransmission instruction of the base station. Nevertheless, the source terminal may send sidelink HARQ-ACK report information about the retransmission PSSCH to the base station (when the base station requests a sidelink HARQ-ACK report). For example, in this case, the source terminal may report ACK to the base station as sidelink HARQ-ACK report information about the retransmission PSSCH. The sidelink HARQ-ACK report information may be sent via a Uu uplink (e.g., PUCCH, PUSCH), and specifically the sidelink HARQ-ACK report information may be sent via an uplink resource allocated by the base station. For example, the sidelink HARQ-ACK report information may be sent via a PUCCH allocated by the base station, or the sidelink HARQ-ACK report information may be derived by a predetermined rule at a time point allocated by the base station. Alternatively, the sidelink HARQ-ACK report information may be sent as piggybacked in the PUSCH at the corresponding time point. Alternatively, the source terminal may not send the sidelink HARQ-ACK report information about the retransmitted PSSCH to the base station.

[0138] Meanwhile, the above-described methods and exemplary embodiments may also be applied in the same manner to the case of transmission of a configured grant PSSCH. Figure 6 , Figure 7 and Figure 8In an exemplary embodiment, the PDCCH of time slot n may include a DCI that initializes (or activates, reinitializes) the configured authorized PSSCH resources. Alternatively, the PDCCH transmission process of time slot n may be omitted. In other words, the PSSCH sent in time slot (n+1) may be an authorized PSSCH of the side link configuration, and the PSSCH may be sent via resources allocated in advance by RRC configuration and / or DCI. In this case, the PSCCH or an SCI including scheduling information for the PSSCH may be sent together with the PSSCH (for example, in the same time slot), may not be sent, or may be sent at different times. In addition, the above exemplary embodiments may be applied to both the authorization schemes of type 1 and type 2 side link configurations.

[0139] In addition, in the case of a configured authorized PSSCH, reserved resources can be allocated in the same manner as described above. That is, the source terminal can regard the configured authorized PSSCH resources as reserved resources, and can send PSSCH through the reserved resources. In the case of the first mode resource allocation, resource allocation and scheduling information of the reserved resources can be configured or indicated from the base station to the source terminal. This can be performed by RRC signaling, MAC signaling (e.g., MAC CE), physical layer signaling (e.g., DCI), etc. In addition, the source terminal can configure or indicate resource allocation and scheduling information of the reserved resources to the target terminal. This can be performed by RRC signaling (e.g., PC5-RRC signaling), MAC signaling (e.g., side link MAC CE) physical layer signaling (e.g., SCI), etc. In addition, the above-described method for retransmitting PSSCH through reserved resources, releasing reserved resources, etc. can be similarly applied to the configured authorized PSSCH. For example, when applying method 200, when the source terminal receives ACK from the target terminal as HARQ-ACK feedback about PSSCH or determines ACK, the source terminal may not perform retransmission of PSSCH, regardless of whether the base station indicates retransmission of PSSCH. In addition, the source terminal may release the reserved resources allocated for retransmission of PSSCH.

[0140] Whether to apply method 200 or method 210 can be configured by the base station to the source terminal through a signaling process, or the source terminal can be pre-configured. At the same time, in a terminal that supports both method 200 and method 210, method 200 or method 210 can be selectively used. In this case, the base station can configure which method to apply in method 200 and method 210 to the source terminal. The configuration can be a semi-static configuration performed by RRC signaling. Alternatively, if not pre-configured, the configuration can be a dynamic indication performed by physical layer signaling. For example, the base station can notify the source terminal whether to apply method 200 or method 210 when sending allocation information of reserved resources. Such information can be included in a DCI including PSSCH resource allocation information, and can be sent via PDCCH. Alternatively, such information can be included in a DCI separate from the DCI including PSSCH resource allocation information, and can be similarly sent via PDCCH.

[0141] Mode 2 Resource Selection Method

[0142] The PSFCH resources for sending HARQ-ACK for PSSCH can be determined based on the location of the resource area where PSSCH and / or PSCCH (hereinafter referred to as PSSCH) are sent. For example, the PSFCH resources can be determined based on the time (e.g., time slot or symbol) when PSSCH is sent, the frequency area (e.g., subchannel) when PSSCH is sent, the resource pool for sending PSCCH, etc. Here, PSFCH resources can be used as a meaning including part or all of time domain resources, frequency domain resources, and code domain resources. In this case, basically, a one-to-one correspondence can be established between PSSCH resources and PSFCH resources. That is, once the PSSCH resources are determined, the PSFCH resources corresponding to the PSSCH resources can be uniquely determined.

[0143] However, in some cases, multiple PSSCH resources may correspond to one PSFCH resource. In this case, when multiple PSSCHs are sent to one terminal through multiple PSSCH resources, multiple HARQ-ACK information for multiple PSSCHs may be fed back through a corresponding PSFCH resource through methods such as bundling. Here, multiple PSSCHs may include different TBs. On the other hand, when multiple PSSCHs are sent to multiple terminals through multiple PSSCH resources, multiple terminals may send PSFCHs separately through a corresponding PSFCH resource in response to the reception of PSSCH. Therefore, conflicts between PSFCH transmissions may occur.

[0144] As a method for solving the above problem, one or more PSSCH resources corresponding to the same PSFCH resource can be considered as a PSSCH resource group, and the terminal can perform sensing and resource selection for the second mode resource allocation for each PSSCH resource group. That is, when at least one PSSCH resource constituting a PSSCH resource group is occupied or expected to be occupied by another terminal, the terminal can exclude all PSSCH resources of the PSSCH resource group from the set of resources available for transmission. Here, 'PSSCH resource' is a term used for the convenience of description, and can generally refer to a unit of physical resources (e.g., time-frequency resources) used for sensing and resource selection of the terminal. For example, a PSSCH resource can mean a resource area consisting of a time slot and a subchannel. Signals and / or channels other than PSSCH and / or PSCCH can also be sent through PSSCH resources.

[0145] The frequency regions of multiple PSSCH resources (e.g., the first resource and the second resource) within the same PSSCH resource group may be different from each other. For example, the first resource and the second resource may occupy different subchannel sets. In addition, the time regions of the first resource and the second resource may be the same. For example, the first resource and the second resource may occupy the same time slot set.

[0146] The above method (i.e., sensing and resource selection based on PSSCH resource groups) may be used only in certain cases. For example, when the terminal (i.e., source terminal) performing sensing and resource selection expects to receive HARQ-ACK from the target terminal, the above method may be used. In the opposite case, that is, when the source terminal does not expect to receive HARQ-ACK from the target terminal, the collision of PSFCH caused by the PSSCH transmission of the source terminal may not occur. Therefore, in this case, the source terminal may perform the sensing and resource selection process without applying the above method.

[0147] At the same time, one PSSCH resource can correspond to multiple PSFCH resources. This scheme can be used for sidelink transmission in unlicensed bands. That is, the target terminal receiving the PSSCH can send the PSFCH through one or more of the multiple PSFCH resources corresponding to the PSSCH according to whether the LBT operation is successful or not and the time point of the success of the LBT operation.

[0148] PSSCH retransmission resource allocation

[0149] In the case of the first mode resource allocation, the base station can allocate PSSCH resources to the source terminal through the Uu interface and configure (or indicate) allocation information for the PSSCH resources. As described above, the PSSCH can be a PSSCH made by dynamic authorization or a PSSCH made by a configured authorization, and the resource allocation information can be indicated by DCI, configured by RRC signaling, or configured / indicated by a combination of DCI and RRC signaling.

[0150] Hereinafter, a method for allocating PSSCH retransmission resources will be described.The following exemplary embodiments will be described based on DCI signaling, but the contents of the following exemplary embodiments can be easily applied to other various signaling schemes (eg, sidelink RRC signaling, SCI signaling, etc.) as described above.

[0151] The PSSCH retransmission scheme can be classified into a retransmission scheme based on HARQ feedback and a blind retransmission scheme without HARQ feedback. In the case of initial transmission PSSCH scheduling, the base station can allocate initial transmission resources to the source terminal through DCI, and additionally allocate retransmission (or repeated transmission) resources together with the initial transmission resources. In the case of retransmission PSSCH scheduling, the base station can allocate at least one retransmission resource to the source terminal through DCI. In the following, the number of retransmission resources allocated outside a PSSCH resource scheduled by DCI can be expressed as R.

[0152] The source terminal can perform blind retransmission (or repeated transmission) of PSSCH through retransmission resources. Alternatively, the source terminal can perform PSSCH retransmission based on HARQ feedback through retransmission resources. The source terminal can send retransmission PSSCH to the target terminal through retransmission resources, and can send its resource allocation information through PSCCH (or transmission resources of level 2 SCI). On the other hand, the base station can perform side link resource allocation in a state where information such as side link traffic and channel state is not accurately identified, and in this case, a larger number of retransmission resources than must be allocated can be allocated to the source terminal. In this case, the source terminal may not send retransmission PSSCH through some or all of the retransmission resources. In addition, the source terminal can send retransmission PSSCH through retransmission resources based on HARQ feedback from the target terminal. In this case, when receiving ACK as a HARQ response from the target terminal, the source terminal may not send PSSCH in at least a portion of the retransmission resources.

[0153] Fig. 9 is a conceptual diagram showing a first exemplary embodiment of PSSCH resource allocation, and Fig.10 is a conceptual diagram showing a second exemplary embodiment of PSSCH resource allocation.

[0154] refer to Fig. 9 and Fig.10 , the source terminal can send PSSCH to the target terminal via the side link. PSSCH can be sent for the same TB and can be sent a total of four times. The source terminal can send PSCCH including resource allocation information of PSSCH to the target terminal together with each PSSCH. In some cases (for example, in the case of authorized PSSCH configured in the side link), PSCCH transmission can be omitted. In addition, PSCCH can be sent only for a part of PSSCH (for example, the first PSSCH (initial transmission PSSCH)).

[0155] In the case of the second mode resource allocation, the PSSCH resources may be determined by the source terminal. On the other hand, in the case of the first mode resource allocation, the PSSCH resources may be determined by the base station, and the allocation information of the determined PSSCH resources may be sent to the source terminal via DCI. Fig. 9 and Fig.10 In the example, the first PSSCH may be an initial transmission PSSCH or a retransmission PSSCH. As described above, this exemplary embodiment may correspond to the case when R=3. Each PSSCH resource may be mapped to one time slot. In addition, according to this exemplary embodiment, the distance between adjacent PSSCH resources may be a constant, such as two time slots. In this case, the time domain resource allocation information of the PSSCH may include the time slot to which the first PSSCH is allocated or its index (e.g., time slot n) and the distance between the PSSCH resources (e.g., 2 time slots). When the time domain resource allocation information is information from the base station to the source terminal, the time slot indication of the first PSSCH may be or predefined as a relative distance from the time point of DCI transmission (e.g., a time slot offset). When the time domain resource allocation information is information from the source terminal to the target terminal, the time slot indication of the first PSSCH may be or predefined as a relative distance from the time point of PSCCH or SCI transmission (e.g., a time slot offset).

[0156] PSSCH resources allocated by the same DCI may have different durations. Fig. 9 and Fig.10 , the first and fourth PSSCH resources may be mapped to the entire duration of the time slot. On the other hand, the third PSSCH resource may be mapped to symbols belonging to the sidelink bandwidth part or the sidelink resource pool (except symbols belonging to the Uu bandwidth part) in time slot (n+4). In addition, referring to Fig. 9 , the second PSSCH resource may be mapped to a symbol in slot (n+2) other than the symbol to which the PSFCH resource is configured. Fig.10, PSFCH resources can be configured only in the first subchannel set in time slot (n+2). In this case, the second PSSCH resource can be mapped to the entire duration of time slot (n+2) in the second subchannel set. In this case, the source terminal can send PSFCH and the second PSSCH in the same symbol in time slot (n+2).

[0157] refer to Fig. 9 , multiple PSSCH resources can be arranged in the same frequency region (e.g., the same subchannel set). That is, a common frequency domain resource allocation can be applied to multiple PSSCH resources. Fig.10 , where the frequency regions (e.g., subchannel sets) in which the multiple PSSCH resources are arranged may be the same or different. For example, the first and third PSSCH resources may be arranged in the first subchannel set, and the second and fourth PSSCH resources may be arranged in the second subchannel set. The first subchannel set and the second subchannel set may belong to the same side link resource pool. Alternatively, the first subchannel set and the second subchannel set may belong to different side link resource pools. In this case, when the frequency distance between the multiple side link resource pools is long, the frequency diversity gain may be maximized. In this case, the HARQ-ACK for each PSSCH may be sent in one resource pool (e.g., a resource pool that sends the first PSSCH (or the last PSSCH)) or in a resource pool that sends each PSSCH. When the HARQ-ACK for multiple PSSCHs is sent bundled or multiplexed through one PSFCH, these may be sent in one resource pool. The one resource pool may be configured or indicated from the source terminal to the target terminal. Alternatively, the one resource pool may be a resource pool that sends the first PSSCH (or the last PSSCH). Resource allocation and scheduling information (eg, SCI) of the PSSCH may include information on an index (or number) of a resource pool in which the PSSCH is transmitted.

[0158] Some PSSCH resources may not be used for PSSCH transmission. For example, when the time period (e.g., time slot) to which the PSSCH resource is allocated does not include sidelink resources (e.g., sidelink symbols, sidelink bandwidth portions, sidelink resource pools), or includes sidelink resources less than a threshold value (e.g., when the corresponding time period includes S1 or fewer sidelink symbols or when the corresponding time period includes less than S2 or more symbols compared to the number of symbols configured by the base station), the PSSCH transmission may not be valid in the corresponding retransmission resource. The source terminal may discard invalid retransmission resources and may not perform PSSCH transmission in the corresponding resources. Sidelink HARQ-ACK reporting information may not be defined for invalid retransmission resources. Alternatively, the source terminal may not send sidelink HARQ-ACK reporting information corresponding to invalid retransmission resources to the base station. Alternatively, even if the PSSCH transmission is omitted or discarded, the source terminal may send sidelink HARQ-ACK reporting information corresponding to invalid retransmission resources. In this case, the sidelink HARQ-ACK reporting information may be fixed as ACK or NACK. In addition, when there are invalid retransmission resources in the PSSCH retransmission resources allocated from the source terminal to the target terminal, the target terminal may also discard the invalid retransmission resources and not perform the PSSCH reception process in the corresponding resources. HARQ-ACK information may not be defined for invalid retransmission resources. Alternatively, the target terminal may not send HARQ-ACK information corresponding to invalid retransmission resources to the source terminal. Alternatively, even if PSSCH reception is omitted or discarded, the target terminal may send HARQ-ACK information corresponding to invalid retransmission resources to the source terminal. In this case, the HARQ-ACK information may be fixed as ACK or NACK.

[0159] In addition to invalid PSSCH resources, the source terminal may not send PSSCH through part or all of the PSSCH retransmission resources allocated from the base station. That is, the source terminal may release the PSSCH resources allocated from the base station. Information about the released PSSCH resources may be signaled to the target terminal and the neighboring terminal (e.g., a terminal performing the sensing and resource selection process for the second mode resource allocation).

[0160] In the case where a terminal (e.g., a source terminal) simultaneously performs first mode resource allocation and second mode resource allocation, the terminal may include at least a portion of the resources (i.e., PSSCH resources or retransmission PSSCH resources) allocated by the base station in the resource set available for the second mode resource allocation. For example, the terminal may omit the sensing process for the PSSCH resources released by the terminal itself in the PSSCH resources allocated by the base station, and determine that they belong to the resource set available for transmission. The time (e.g., a specific time slot) when the released PSSCH resources are included in the resource set available for transmission may be determined by a predetermined rule. For example, the released PSSCH resources may be included in the resource set available for transmission at the time (e.g., the corresponding time slot) when the terminal releases the corresponding PSSCH resources. Alternatively, the terminal may include the corresponding PSSCH resources in the resource set available for transmission at the time when the PSSCH resources are allocated from the base station (e.g., the time (e.g., time slot or symbol) of receiving a signal including resource allocation information of the PSSCH resources). When PSSCH resources are configured through RRC signaling (for example, in the case of a grant scheme of a type 1 side link configuration), the terminal may include the corresponding PSSCH resources in a set of resources available for transmission at the time the terminal receives the corresponding RRC message (for example, a PDSCH including the RRC message).

[0161] The source terminal may use the retransmission PSSCH resources allocated from the base station for purposes other than retransmission. For example, the source terminal may send side link signals other than PSSCH and / or PSCCH by using PSSCH resources other than the first PSSCH resources (i.e., R resources) allocated by DCI. Alternatively, the source terminal may send a PSSCH and / or a PSCCH corresponding to a TB different from the TB scheduled by DCI through resources.

[0162] At the same time, the target terminal may assume a quasi co-location (QCL) for the reception of PSSCH and / or PSCCH through PSSCH resources. The receiving node may assume that QCL is established between certain signals and channels, and the type of QCL may include delay spread, Doppler spread, Doppler shift, average gain, average delay, spatial Rx parameters, and the like. In terms of spatial reception parameters, QCL may mean that the receiving beam (e.g., simulated receiving beam), receiving channel spatial correlation, transmission beam, and transmission / receiving beam pair are the same between objects. In the case of NR, the receiving node may assume or be configured with QCL types A, B, C, and / or D. The QCL information may be included in the transmission configuration information (TCI) state and configured for the receiving node. The TCI state may include one or more signals (e.g., reference signals, synchronization signals, etc.) as a reference for the QCL type and QCL assumptions.

[0163] The source terminal can configure (or indicate) QCL information for receiving PSSCH and / or PSCCH to the target terminal. When multiple PSSCH resources are configured through one signaling, QCL information can be configured for each PSSCH resource. Alternatively, QCL information can be configured for PSSCH resources other than the first PSSCH resource (in the time domain). The same QCL information can be applied to multiple PSSCH resources in common. At the same time, the PSSCH resource allocation information sent by the base station to the source terminal may not include QCL information for receiving the target terminal. That is, the entity that configures the QCL of the terminal receiving the side link signal can be the source terminal.

[0164] Side link resource reservation method

[0165] As described above, the side link resources can be reserved considering the possibility of future side link transmission. For example, the side link resources can be reserved for future PSSCH and / or PSCCH transmission. The terminal (e.g., the source terminal) can determine that specific resources are reserved resources, and send information about the reserved resources to other terminals (e.g., the target terminal) through signaling. This can correspond to the first mode resource allocation and the second mode resource allocation. In addition, the base station can determine that specific resources are reserved resources, and send information about the reserved resources to the terminal (e.g., the source terminal) through signaling. This can correspond to the first mode resource allocation. In addition, the allocation information of the reserved resources can be received by an adjacent terminal (e.g., a terminal that performs at least the second mode resource allocation) through a sensing process.

[0166] The PSSCH retransmission resources described above may be considered as reserved resources. Specifically, when a method is applied in which a source terminal for a purpose other than retransmission uses retransmission PSSCH resources allocated by a base station, at least in terms of terminal operation, the PSSCH resources configured by the base station to the source terminal may be indistinguishable from the reserved resources configured by the base station to the source terminal. At least in the case of first mode resource allocation, at least in terms of terminal operation, the PSSCH resources configured by the base station to the source terminal may be indistinguishable from the reserved resources configured by the base station to the source terminal.

[0167] A separate resource other than the PSSCH resource may be allocated as a reserved resource. The reserved resource may be configured as a combination of a specific time resource and a frequency resource. Because the reserved resource may be substantially allocated for PSSCH transmission, the time and frequency resource allocation unit (or granularity) of the reserved resource may be equal to or greater than the unit of the PSSCH. For example, the time resource allocation unit of the reserved resource may be a time slot, and its frequency resource allocation unit may be a subchannel. Alternatively, the time resource allocation unit of the reserved resource may be a plurality of time slots, and the frequency resource allocation unit may be a plurality of subchannels. A reserved resource may belong to a side link resource pool. Even when the reserved resource is allocated in units of time slots (multiple) in the time domain, certain symbols of the time slot, i.e., symbols defined or configured for purposes other than PSSCH and / or PSCCH transmission (e.g., symbols not included in the side link resource pool, Uu downlink symbols, Uu flexible symbols, symbols for configuring PSFCH resources, symbols for automatic gain control (AGC), symbols for transmission direction switching, symbols for bandwidth part switching, etc.) may be excluded from the reserved resource. Alternatively, a method may be considered in which the reserved resources themselves are configured to include the symbols described above and the symbols are excluded in the step of sending PSSCH and / or PSCCH through the reserved resources. The resource allocation unit of the reserved resources may follow a predefined value or may be configured for the terminal. When the resource allocation unit of the reserved resources is the same as the PSSCH resource allocation unit, the resource allocation unit of the reserved resources may not be configured separately for the terminal.

[0168] Other information besides the time and frequency resource information may be included in the allocation information of the reserved resources. For example, spatial resource information (e.g., the antenna port number of the signal or channel to be allocated to the reserved resources), scheduling information of the channel to be allocated to the reserved resources (e.g., the number of HARQ processes of PSSCH, the modulation and coding scheme (MCS), the redundancy version (RV), the new data indicator (NDI), whether the same TB is applied, the number of transmission layers, the number of TBs, precoding information, etc.) may be included in the allocation information of the reserved resources. In the case where the information is configured when the reserved resources are allocated, transmission through the reserved resources may be performed based on the information. Alternatively, new information or updated information may be configured after the reserved resources are configured, and transmission through the reserved resources may be performed based on the new information.

[0169] Multiple reserved resources may be configured (or indicated). For example, a terminal may be configured with multiple reserved resources for multiple retransmissions of the same TB. For another example, a terminal may be configured with multiple reserved resources for the transmission of multiple different TBs. For another example, a terminal may be configured with multiple reserved resources for the retransmission of the same TB and the transmission of another TB. Multiple reserved resources may be configured simultaneously via one (or one) signaling (e.g., SCI format, DCI format, RRC parameter, etc.), or may be configured once via signaling. Alternatively, multiple reserved resources may be configured via multiple signalings. The maximum number of reserved resources that can be configured via one signaling may be predefined.

[0170] The allocation information of the reserved resources may be included in the SCI and may be sent from the source terminal to the target terminal via a side link (e.g., PSCCH, two-stage SCI transmission resources). In addition, in the case of the first mode, the allocation information of the reserved resources may be included in the DCI (e.g., group common DCI) and sent from the base station to the terminal (e.g., source terminal) via the Uu downlink (e.g., PDCCH). The SCI and DCI may be SCI and DCI including scheduling information of a PSSCH (hereinafter referred to as the first PSSCH), respectively. In this case, the first PSSCH may be a PSSCH through dynamic authorization, and the DCI may correspond to the dynamic authorization. Alternatively, the first PSSCH may be a PSSCH of an authorization configured by a side link (e.g., an authorization configured by a type 2 side link), and the DCI may be a DCI indicating activation, initialization, etc. of a configured authorization PSSCH resource configuration.

[0171] At the same time, when the reserved resources are allocated for the configured authorized PSSCH, the allocation information of the reserved resources can be sent from the source terminal to the target terminal via RRC signaling and / or SCI. In addition, in the case of the first mode, the allocation information of the reserved resources can be sent from the base station to the terminal (e.g., the source terminal) via RRC signaling and / or DCI. Each of the RRC signaling, SCI and DCI may include at least a portion of the scheduling information of the PSSCH. For convenience, the PSSCH may also be referred to as the first PSSCH. When the first PSSCH is a PSSCH based on the authorization configured by type 1, the reserved resources can be configured only by RRC signaling.

[0172] In this case, the reserved resources may be allocated for the purpose of retransmission of the first PSSCH. The resource region of the reserved resources may be configured based on the resource region of the first PSSCH. This may be referred to as 'method 300'. According to method 300, the frequency region of the reserved resources may be derived based on the frequency region of the first PSSCH. In addition, the duration of the reserved resources may be derived based on the duration of the first PSSCH.

[0173] Fig.11 is a conceptual diagram showing a first exemplary embodiment of side link reserved resource allocation.

[0174] refer to Fig.11 , the PSSCH can be sent through the side link resources, and the PSSCH can be scheduled through the PSCCH. That is, the scheduling information of the PSSCH can be sent through the PSCCH. In addition, the allocation information for the side link reserved resources can be included in the PSCCH. The reserved resources can be used for the retransmission of the PSSCH or for the transmission of the PSSCH of another TB other than the TB of the PSSCH. In this case, according to method 300, the frequency region (i.e., B1) of the reserved resources can be the same as the frequency region of the PSSCH. In addition, the duration of the reserved resources (i.e., D1) can be the same as the duration of the PSSCH.

[0175] In addition, in this case, the time domain position (e.g., time slot or symbol) of the reserved resource can be derived with reference to the time domain position (e.g., time slot or symbol) of the first PSSCH. For example, the time domain position of the reserved resource can be determined by the time offset between the reserved resource and the first PSSCH. When multiple reserved resources are configured, multiple time offsets can be used to arrange the reserved resources. Multiple time offsets can have the same or different values. The time offset can be predefined in the technical specification or configured for the terminal. When the first PSSCH is scheduled to be repeatedly sent through multiple resources, one reserved resource can be configured to include multiple resources. Alternatively, regardless of whether the first PSSCH is repeatedly sent, one reserved resource can be configured as one resource.

[0176] At the same time, the allocation information of the reserved resources may be included in a separate SCI instead of the SCI for PSSCH scheduling, and may be sent from the source terminal to the target terminal via a side link (e.g., PSCCH, two-stage SCI). In addition, in the case of the first mode, the allocation information of the reserved resources may be included in a separate DCI (e.g., group common DCI) instead of the DCI for PSSCH scheduling, and may be sent from the base station to the terminal (e.g., source terminal) via a Uu downlink (e.g., PDCCH). For example, a separate SCI (or DCI) may have a different SCI format (or DCI format) from the SCI (or DCI) format for PSSCH scheduling, or a different payload size from the payload size of the SCI (or DCI) for PSSCH scheduling. Alternatively, the CRC of the separate SCI (or DCI) may be scrambled using a different RNTI from the RNTI of the SCI (or DCI) for PSSCH scheduling. In this case, the reserved resources may not be associated with a specific PSSCH or a specific TB. For example, the reserved resources may be used for PSSCH transmission of an initial transmission or for retransmission of any TB.

[0177] In this case, the resource region of the reserved resources may be configured through a resource allocation process that is independent of PSSCH resource allocation. This may be referred to as 'method 310'.

[0178] Fig.12 is a conceptual diagram illustrating a second exemplary embodiment for sidelink reserved resource allocation.

[0179] refer to Fig.12 , the PSSCH can be sent through the side link resources. In addition, the side link reserved resources can be allocated, and the allocation information of the side link reserved resources can be sent to the terminal through the PSCCH. The reserved resources can be used for retransmission of the PSSCH or for transmission of the PSSCH of a TB different from the TB of the PSSCH. In this case, according to method 310, the time and frequency resource region of the reserved resources can be configured independently of the time and frequency resource region of the PSSCH (for example, the above PSSCH). That is, in Fig.12 , D1 and D2 may be the same or different, and B1 and B2 may be the same or different.

[0180] In method 310, the resource allocation unit of the reserved resources may be the same as or similar to the resource allocation unit of the PSSCH. In addition, the configuration of the resource allocation information of the reserved resources, its parameters, its signaling method, etc. may be the same as or similar to those of the PSSCH resource allocation. For example, when the reserved resources are allocated by SCI and / or DCI, the time and frequency domain resource assignment fields of the reserved resources may be the same as or similar to the time and frequency domain resource assignment fields of the PSSCH, and the interval of the reserved resources may be configured in the form of a time offset (e.g., time slot offset) from the time (e.g., time slot) of sending the SCI and / or DCI. In addition, the resource allocation of the PSSCH and the resource allocation of the reserved resources may be configured only by RRC signaling or by a combination of RRC signaling and SCI (or DCI).

[0181] Method 300 and method 310 may be used selectively or adaptively. As described above, when reserved resources are allocated by signaling for scheduling PSSCH or for retransmission of the same TB, method 300 may be used, otherwise method 310 may be used. Alternatively, which method of method 300 and method 310 is to be applied may be configured by the base station to the side link terminal.

[0182] Method 300 may not be limited to a specific case and may be general. For example, method 300 may be used even when reserved resources are allocated by signaling other than signaling for scheduling PSSCH. In this case, the signaling may include information about a resource region (e.g., a resource region of a specific PSSCH), which is a reference for deriving a resource region of the reserved resources. Similarly, method 310 may not be limited to a specific case and may be general. For example, method 310 may be used even when reserved resources are allocated by signaling for scheduling PSSCH. In this case, signaling may include multiple resource allocation information for multiple resources (e.g., multiple time domain resource assignment fields / parameters, multiple frequency domain resource assignment fields / parameters). According to the method described above, the same configuration method may be used for the case where the reserved resources are used for the same TB and the case where the reserved resources are not used for the same TB. In this case, according to an exemplary embodiment, multiple reserved resources may be configured by one signaling, and retransmission PSSCH for the same TB may be sent in some of the multiple reserved resources, and PSCCH for another TB may be sent in some other of the multiple reserved resources.

[0183] The reserved resource ID can be used for the configuration of the reserved resource. When multiple reserved resources are configured, an ID can be assigned to each reserved resource. Alternatively, the same ID can be assigned to multiple reserved resources (e.g., a reserved resource group). The ID of the reserved resource or reserved resource group (hereinafter collectively referred to as 'reserved resources') can be included in the reserved resource configuration information. In this case, for each reserved resource, the ID or information about the ID can be sent (together with the allocation information of the reserved resource). For example, two reserved resources can be allocated to the target terminal from the source terminal through RRC signaling or SCI, the ID of the first reserved resource can be set to 0, and the ID of the second reserved resource can be set to 3. This method has a disadvantage - because information about the ID should be sent for each reserved resource, the signaling overhead is large.

[0184] Alternatively, an ID of a reserved resource or information about the ID may be sent (together with the allocation information of the reserved resource), and the ID of another reserved resource may be derived from the ID or information about the ID. For example, two reserved resources may be allocated to the source terminal from the base station via RRC signaling or DCI, and the ID of the first reserved resource may be set to 0. The source terminal may determine the ID of the second reserved resource based on the ID of the first reserved resource. For example, the rule of mapping IDs in ascending order may be applied to multiple reserved resources configured at the same time, and in this case, the source terminal may determine that the ID of the second reserved resource is 1.

[0185] As another method, the ID of the reserved resource can be assigned sequentially in a predetermined order. For example, a circular counter from 0 to C can be used, and the ID of the reserved resource can be assigned in the order of 0, 1, ..., C, 0, 1, ..., C, etc. The assignment of the reserved resource ID can be determined based on the order in which the corresponding reserved resources are allocated to the terminal. Information about the counter (e.g., the last count value) (together with the allocation information of the reserved resource) can be sent to the terminal configured with the reserved resource. As another method, the information about the ID of the reserved resource may not be explicitly configured and can be determined by an implicit method. For example, the ID of the reserved resource can be determined from the position of the time domain resource and / or frequency domain resource to which the reserved resource is allocated. Alternatively, the ID of the reserved resource can be configured by a combination of an explicit method and an implicit method.

[0186] The ID of the reserved resource can be configured repeatedly. That is to say, the terminal (for example, the target terminal and the source terminal) can receive the reserved resource with the same ID as the ID of the previous reserved resource. In this case, the validity of the previously assigned reserved resource ID can be considered as a condition for determining whether the corresponding ID is repeated. For the reserved resource, when the signal transmission is valid in the corresponding reserved resource, the ID of the reserved resource can be considered as valid. For example, at a time point earlier than the period in which the reserved resource is allocated (for example, until a time point L time slots (or symbols) earlier than the first time slot (or symbol) constituting the reserved resource), the ID of the reserved resource can be considered as valid. Here, L can be an integer equal to or greater than 0. Although the ID of the reserved resource with the same ID as the ID of the reserved resource that has ended in the period is assigned, the terminal may not consider the ID as a repeated ID. When the ID of the reserved resource is determined to be repeated, the terminal may consider that the reserved resource configured later for the corresponding ID is valid. The terminal may consider that the reserved resource previously configured for the corresponding ID is no longer valid. On the other hand, as another method, when the ID of the reserved resource is repeated, the terminal may consider this as an error and regard all reserved resources having the same ID as invalid. Alternatively, the terminal may not expect the ID of the reserved resource to be repeatedly configured.

[0187] When PSSCH is sent to the target terminal by reserving resources, the source terminal can notify the scheduling information of PSSCH together. In this case, the source terminal can notify the target terminal of the ID of the reserved resources instead of the resource allocation information of PSSCH (e.g., time domain and frequency domain resource assignment information). When the target terminal has been previously allocated the reserved resources and their IDs, the scheduled PSSCH can be considered to be allocated to the entire area of ​​the reserved resources.

[0188] As described above, the reserved resources can be released. When it is determined that the reserved resources are unnecessary, the node (e.g., base station or source terminal) that has been configured with the reserved resources or the node (e.g., source terminal) that has been configured with the reserved resources can release the corresponding reserved resources. The information about the release of the reserved resources can be notified to the node (e.g., target terminal, source terminal, adjacent terminal performing the sensing process, etc.) that is configured with the reserved resources. For example, the information about the release of the reserved resources can be indicated from the base station to the source terminal by the Uu downlink (e.g., PDCCH). The information about the release of the reserved resources can include the ID of the reserved resources to be released.

[0189] Communication node composition

[0190] Fig.13 is a block diagram illustrating a communication node according to an exemplary embodiment of the present disclosure.

[0191] Fig.13The communication node shown in the figure may be a terminal or a base station, which is a device for executing the method according to the exemplary embodiments of the present disclosure.

[0192] refer to Fig.13 , the communication node 300 may include at least one processor 310, a memory 320, and a transceiver 330 connected to a network to perform communication. In addition, the communication node 300 may also include an input interface device 340, an output interface device 350, a storage device 360, etc. The components included in the communication node 300 may be connected through a bus 370 to communicate with each other.

[0193] However, each component included in the communication node 300 may be connected to the processor 310 through a separate interface or a separate bus instead of the common bus 370. For example, the processor 310 may be connected to at least one of the memory 320, the transceiver 330, the input interface device 340, the output interface device 350, and the storage device 360 ​​through a dedicated interface.

[0194] The processor 310 may execute at least one instruction stored in at least one of the memory 320 and the storage device 360. The processor 310 may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which a method according to an exemplary embodiment of the present invention is executed. Each of the memory 320 and the storage device 360 ​​may be configured as at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory 320 may be configured using at least one of a read-only memory (ROM) and a random access memory (RAM).

[0195] The exemplary embodiments of the present disclosure may be implemented as various computer executable and program instructions recorded on a computer readable medium. The computer readable recording medium may include program instructions, data files, data structures, or a combination thereof. The program instructions recorded on the computer readable medium may be specifically designed and configured for the present disclosure, and are well known and available to those skilled in the art of computer software.

[0196] Examples of computer readable media may include hardware devices such as ROM, RAM, and flash memory, which are specifically configured to store and execute program instructions. Examples of program instructions include machine codes made by, for example, a compiler, and high-level language codes executable by a computer using an interpreter. The above exemplary hardware devices can be configured to operate as at least one software module to perform embodiments of the present disclosure, and vice versa.

[0197] Although the embodiments of the present disclosure and their advantages have been described in detail, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the scope of the disclosure.

Claims

1. A method for reporting sidelink hybrid automatic repeat request (HARQ) response information performed by a terminal, the method comprising: receiving allocation information of a physical sidelink shared channel (PSSCH) resource for transmission of a PSSCH from a base station; identifying a physical sidelink feedback channel (PSFCH) resource for reception of a PSFCH corresponding to the transmission of the PSSCH; determining a time to send HARQ response information corresponding to the transmission of the PSSCH; as well as sending the HARQ response information corresponding to the transmission of the PSSCH to the base station at the determined time, The time for sending the HARQ response information is represented by a time offset L from the PSFCH resource, and information about the time for sending the HARQ response information is sent from the base station to the terminal.

2. A method for receiving sidelink hybrid automatic repeat request (HARQ) response information reported by a terminal, performed by a base station, the method comprising: Sending allocation information of a physical sidelink shared channel (PSSCH) resource for transmission of a PSSCH to the terminal; Identifying a physical sidelink feedback channel (PSFCH) resource for the terminal to receive a transmission corresponding to the PSSCH; determining a time to receive HARQ response information corresponding to the transmission of the PSSCH; as well as receiving the HARQ response information corresponding to the transmission of the PSSCH from the terminal at the determined time, The time of receiving the HARQ response information is represented by a time offset L from the PSFCH resource used by the terminal to receive the PSFCH corresponding to the transmission of the PSSCH, and information about the time of receiving the HARQ response information is sent from the base station to the terminal.

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