KR20210125414A - Method and apparatus for sidelink communication based on feedback - Google Patents

Abstract

A method and apparatus for feedback-based sidelink communication are disclosed. The method of operation of a receiving terminal includes receiving one or more TBs from a transmitting terminal, generating HARQ responses for CBGs included in each of the one or more TBs, and based on a priority, one or more of the HARQ responses selecting HARQ responses, and transmitting the one or more HARQ responses to the transmitting terminal through a PSFCH resource.

Description

METHOD AND APPARATUS FOR SIDELINK COMMUNICATION BASED ON FEEDBACK

The present invention relates to a sidelink communication technique in a communication system, and more particularly, to a sidelink communication technique based on feedback on data.

For processing of rapidly increasing radio data, a frequency band (eg, 6 GHz) higher than a frequency band (eg, a frequency band of 6 GHz or less) of a long term evolution (LTE) communication system (or LTE-A communication system) A communication system (eg, a new radio (NR) communication system) using the above frequency bands) is being considered. The NR system may support a frequency band of 6 GHz or less as well as a frequency band of 6 GHz or higher, and may support various communication services and scenarios compared to the LTE system. In addition, the requirements of the NR system may include enhanced Mobile BroadBand (eMBB), Ultra Reliable Low Latency Communication (URLLC), massive Machine Type Communication (mMTC), and the like.

Sidelink communication may be performed in the NR system. In order to improve the performance of sidelink communication, transmission of feedback information (eg, acknowledgment (ACK) or negative ACK (NACK)) for sidelink data may be performed. For example, the first terminal may transmit data to the second terminal, and the second terminal may transmit feedback information on the data to the first terminal. In order to support this operation, a resource setting method for transmitting feedback information in the sidelink, a method of transmitting feedback information, and the like are required.

An object of the present invention for solving the above problems is to provide a method and apparatus for transmitting and receiving hybrid automatic repeat request (HARQ) feedback information in a communication system.

A method of operating a receiving terminal according to a first embodiment of the present invention for achieving the above object, receiving one or more TBs from a transmitting terminal, generating HARQ responses for CBGs included in each of the one or more TBs selecting one or more HARQ responses from among the HARQ responses based on priority, and transmitting the one or more HARQ responses to the transmitting terminal through a PSFCH resource.

Here, the PSFCH resource may be determined based on a CBG index associated with each of the one or more HARQ responses.

Here, the priority may be a priority of a TB, and when a plurality of TBs are received from the transmitting terminal, HARQ responses to CBGs included in a TB having a high priority among the plurality of TBs are preferentially can be selected.

Here, the priority may be a priority of a CBG, and a HARQ response to a CBG having a low index among the CBGs may be preferentially selected.

Here, the priority may be a priority of a HARQ response, and a HARQ response indicating ACK may be preferentially selected from among the HARQ responses.

Here, PSFCH format 1 for transmission of the one or more HARQ responses may be configured, and the PSFCH resource may be a resource for the PSFCH format 1.

Here, the PSFCH format 1 may share the same resource region as PSFCH format 0 for transmission of one HARQ response, and the transmission resource of the PSFCH format 1 may be indicated in the same way as the transmission resource of the PSFCH format 0. have.

Here, the resource region of the PSFCH format 1 may be configured independently of the resource region of the PSFCH format 0 for transmission of one HARQ response, and the resource region of the PSFCH format 1 is indicated by a higher layer message and/or SCI can be

Here, when PSFCH format 0 and PSFCH format 1 are configured, a PSFCH format used for transmission of the one or more HARQ responses may be selected according to a preset rule.

In a method of operating a transmitting terminal according to a second embodiment of the present invention for achieving the above object, transmitting one or more TBs to a receiving terminal through n subchannels, CBGs included in each of the one or more TBs Receiving one or more HARQ responses selected based on a priority among HARQ responses from the receiving terminal through a PSFCH resource, and retransmission for some CBGs among all CBGs included in the one or more TBs. case, retransmitting the some CBGs to the receiving terminal through m subchannels, wherein each of n and m is a natural number.

Here, n may be greater than m, and a subchannel having a lower index may be preferentially selected from among the n subchannels, and the m subchannels selected from the n subchannels may be the partial CBGs. can be used for retransmission of

Here, a first MCS may be used for transmission of the one or more TBs, a second MCS may be used for retransmission of the some CBGs, and the coding rate according to the second MCS is the coding rate according to the first MCS. It may be lower, and the modulation order according to the second MCS may be lower than the modulation order according to the first MCS.

Here, the priority may be a priority of a TB, and when a plurality of TBs are transmitted, HARQ responses to CBGs included in a TB having a high priority among the plurality of TBs may be preferentially selected. .

Here, the priority may be a priority of a CBG, and a HARQ response to a CBG having a low index among the CBGs may be preferentially selected.

Here, the priority may be a priority of a HARQ response, and a HARQ response indicating ACK may be preferentially selected from among the HARQ responses.

Here, the method of operating the transmitting terminal may further include transmitting a bitmap indicating the partial CBGs to be retransmitted among all the CBGs.

A receiving terminal according to a third embodiment of the present invention for achieving the above object includes a processor, a memory in electronic communication with the processor, and instructions stored in the memory, wherein the instructions are executed by the processor case, the instructions cause the receiving terminal to receive one or more TBs from a transmitting terminal, generate HARQ responses for CBGs included in each of the one or more TBs, and generate one of the HARQ responses based on priority. select one or more HARQ responses, and cause transmission of the one or more HARQ responses to the transmitting terminal via a PSFCH resource.

Here, the PSFCH resource may be determined based on a CBG index associated with each of the one or more HARQ responses.

Here, PSFCH format 1 for transmission of the one or more HARQ responses may be configured, and the PSFCH format 1 may share the same resource region as PSFCH format 0 for transmission of one HARQ response, and the PSFCH format 1 The transmission resource of may be indicated in the same manner as the transmission resource of the PSFCH format 0.

Here, PSFCH format 1 for transmission of the one or more HARQ responses may be configured, and the resource region of PSFCH format 1 may be configured independently of the resource region of PSFCH format 0 for transmission of one HARQ response, The resource region of the PSFCH format 1 may be indicated by a higher layer message and/or SCI.

According to the present invention, a CBG (code block group)-based transmission scheme may be used in sidelink communication. In this case, the feedback procedure may be performed in units of CBG. The receiving terminal may transmit one or more HARQ responses selected according to priority among a plurality of hybrid automatic repeat request (HARQ) responses to the transmitting terminal. A new physical sidelink feedback channel (PSFCH) format may be used for transmission of a plurality of HARQ responses. The transmitting terminal may perform a retransmission procedure for some CBGs. A changed modulation and coding scheme (MCS) may be used in the retransmission procedure. In addition, the retransmission procedure may be performed using some subchannels. Accordingly, the feedback procedure in sidelink communication can be efficiently performed, and the performance of the communication system can be improved.

1 is a conceptual diagram illustrating a first embodiment of a communication system.
2 is a block diagram showing a first embodiment of a communication node constituting a communication system.
3 is a conceptual diagram illustrating a first embodiment of a type 1 frame structure.
4 is a conceptual diagram illustrating a first embodiment of a type 2 frame structure.
5 is a conceptual diagram illustrating a first embodiment of a method for transmitting an SS/PBCH block in a communication system.
6 is a conceptual diagram illustrating a first embodiment of an SS/PBCH block in a communication system.
7 is a conceptual diagram illustrating a second embodiment of a method for transmitting an SS/PBCH block in a communication system.
8A is a conceptual diagram illustrating an RMSI CORESET mapping pattern #1 in a communication system.
8B is a conceptual diagram illustrating RMSI CORESET mapping pattern #2 in a communication system.
8C is a conceptual diagram illustrating RMSI CORESET mapping pattern #3 in a communication system.
9 is a conceptual diagram illustrating embodiments of a method for multiplexing a control channel and a data channel in sidelink communication.
10A is a conceptual diagram illustrating a first embodiment of a PSFCH resource allocation method.
10B is a conceptual diagram illustrating a second embodiment of a PSFCH resource allocation method.

Since the present invention can have various changes and can have various embodiments, specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to specific embodiments, and it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

Terms such as first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component. and/or includes a combination of a plurality of related listed items or any of a plurality of related listed items.

When a component is referred to as being “connected” or “connected” to another component, it is understood that the other component may be directly connected or connected to the other component, but other components may exist in between. it should be On the other hand, when it is mentioned that a certain element is "directly connected" or "directly connected" to another element, it should be understood that the other element does not exist in the middle.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does not

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings. In describing the present invention, in order to facilitate the overall understanding, the same reference numerals are used for the same components in the drawings, and duplicate descriptions of the same components are omitted.

A communication system to which embodiments according to the present invention are applied will be described. The communication system to which the embodiments according to the present invention are applied is not limited to the contents described below, and the embodiments according to the present invention can be applied to various communication systems. Here, a communication system may be used in the same sense as a communication network (network).

1 is a conceptual diagram illustrating a first embodiment of a communication system.

1, the communication system 100 is a plurality of communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, 130-6). In addition, the communication system 100 is a core network (core network) (eg, S-GW (serving-gateway), P-GW (packet data network (PDN)-gateway), MME (mobility management entity)) may include more. When the communication system 100 is a 5G communication system (eg, a new radio (NR) system), the core network is an access and mobility management function (AMF), a user plane function (UPF), a session management function (SMF), etc. may include.

The plurality of communication nodes 110 to 130 may support a communication protocol (eg, an LTE communication protocol, an LTE-A communication protocol, an NR communication protocol, etc.) defined in a 3rd generation partnership project (3GPP) standard. The plurality of communication nodes 110 to 130 include a code division multiple access (CDMA) technology, a wideband CDMA (WCDMA) technology, a time division multiple access (TDMA) technology, a frequency division multiple access (FDMA) technology, orthogonal frequency division (OFDM). multiplexing) technology, Filtered OFDM technology, CP (cyclic prefix)-OFDM technology, DFT-s-OFDM (discrete Fourier transform-spread-OFDM) technology, OFDMA (orthogonal frequency division multiple access) technology, SC (single carrier)-FDMA Technology, Non-orthogonal Multiple Access (NOMA) technology, GFDM (generalized frequency division multiplexing) technology, FBMC (filter bank multi-carrier) technology, UFMC (universal filtered multi-carrier) technology, SDMA (Space Division Multiple Access) technology, etc. can support Each of the plurality of communication nodes may have the following structure.

2 is a block diagram showing a first embodiment of a communication node constituting a communication system.

Referring to FIG. 2 , the communication node 200 may include at least one processor 210 , a memory 220 , and a transceiver 230 connected to a network to perform communication. In addition, the communication node 200 may further include an input interface device 240 , an output interface device 250 , a storage device 260 , and the like. Each component included in the communication node 200 may be connected by a bus 270 to communicate with each other.

However, each of the components included in the communication node 200 may not be connected to the common bus 270 but to the processor 210 through an individual interface or an individual bus. For example, the processor 210 may be connected to at least one of the memory 220 , the transceiver 230 , the input interface device 240 , the output interface device 250 , and the storage device 260 through a dedicated interface. .

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

Referring back to FIG. 1 , the communication system 100 includes a plurality of base stations 110 - 1 , 110 - 2 , 110 - 3 , 120 - 1 and 120 - 2 , and a plurality of terminals 130 - 1, 130-2, 130-3, 130-4, 130-5, 130-6). Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 may form a macro cell. Each of the fourth base station 120-1 and the fifth base station 120-2 may form a small cell. The fourth base station 120-1, the third terminal 130-3, and the fourth terminal 130-4 may belong to the cell coverage of the first base station 110-1. The second terminal 130-2, the fourth terminal 130-4, and the fifth terminal 130-5 may belong to the cell coverage of the second base station 110-2. The fifth base station 120-2, the fourth terminal 130-4, the fifth terminal 130-5, and the sixth terminal 130-6 may belong to the cell coverage of the third base station 110-3. have. The first terminal 130-1 may belong to the cell coverage of the fourth base station 120-1. The sixth terminal 130-6 may belong to the cell coverage of the fifth base station 120-2.

Here, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 is a NodeB (NB), an evolved NodeB (eNB), gNB, an advanced base station (ABS), HR -BS (high reliability-base station), BTS (base transceiver station), radio base station (radio base station), radio transceiver (radio transceiver), access point (access point), access node (node), RAS (radio access station) ), MMR-BS (mobile multihop relay-base station), RS (relay station), ARS (advanced relay station), HR-RS (high reliability-relay station), HNB (home NodeB), HeNB (home eNodeB), It may be referred to as a road side unit (RSU), a radio remote head (RRH), a transmission point (TP), a transmission and reception point (TRP), and the like.

Each of the plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, 130-6 includes a user equipment (UE), a terminal equipment (TE), an advanced mobile station (AMS), HR-MS (high reliability-mobile station), terminal, access terminal, mobile terminal, station, subscriber station, mobile station, portable It may be referred to as a portable subscriber station, a node, a device, an on board unit (OBU), and the like.

Meanwhile, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may operate in different frequency bands or may operate in the same frequency band. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to each other through an ideal backhaul link or a non-ideal backhaul link. , information can be exchanged with each other through an ideal backhaul link or a non-ideal backhaul link. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to the core network through an ideal backhaul link or a non-ideal backhaul link. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 transmits a signal received from the core network to the corresponding terminals 130-1, 130-2, 130-3, 130 -4, 130-5, 130-6), and the signal received from the corresponding terminal (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) is transmitted to the core network can be sent to

In addition, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 transmits MIMO (eg, single user (SU)-MIMO, multi user (MU)- MIMO, massive MIMO, etc.), coordinated multipoint (CoMP) transmission, carrier aggregation (CA) transmission, transmission in an unlicensed band, direct communication between terminals (device to device communication, D2D) (or , Proximity Services (ProSe)), Internet of Things (IoT) communication, dual connectivity (DC), and the like may be supported. Here, each of the plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, 130-6 is the base station 110-1, 110-2, 110-3, and 120-1. , 120-2) and corresponding operations, and operations supported by the base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be performed. For example, the second base station 110-2 may transmit a signal to the fourth terminal 130-4 based on the SU-MIMO method, and the fourth terminal 130-4 may transmit a signal based on the SU-MIMO method. A signal may be received from the second base station 110 - 2 . Alternatively, the second base station 110-2 may transmit a signal to the fourth terminal 130-4 and the fifth terminal 130-5 based on the MU-MIMO scheme, and the fourth terminal 130-4. and each of the fifth terminals 130 - 5 may receive a signal from the second base station 110 - 2 by the MU-MIMO method.

Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 may transmit a signal to the fourth terminal 130-4 based on the CoMP scheme, and the fourth The terminal 130-4 may receive signals from the first base station 110-1, the second base station 110-2, and the third base station 110-3 by the CoMP method. A plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) each of the terminals (130-1, 130-2, 130-3, 130-4) belonging to its own cell coverage , 130-5, 130-6) and the CA method can transmit and receive signals. Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 controls D2D between the fourth terminal 130-4 and the fifth terminal 130-5. and each of the fourth terminal 130-4 and the fifth terminal 130-5 may perform D2D under the control of the second base station 110-2 and the third base station 110-3, respectively. .

Meanwhile, the communication system may support three types of frame structures. The type 1 frame structure may be applied to a frequency division duplex (FDD) communication system, the type 2 frame structure may be applied to a time division duplex (TDD) communication system, and the type 3 frame structure may be applied to an unlicensed band-based communication system (eg, For example, it may be applied to a licensed assisted access (LAA) communication system.

3 is a conceptual diagram illustrating a first embodiment of a type 1 frame structure.

Referring to FIG. 3 , a radio frame 300 may include 10 subframes, and the subframe may include 2 slots. Accordingly, the radio frame 300 may include 20 slots (eg, slot #0, slot #1, slot #2, slot #3, ..., slot #18, slot #19). The radio frame 300 length T _f may be 10 ms (millisecond), the subframe length may be 1 ms, and the slot length T _slot may be 0.5 ms. Here, T _s may indicate a sampling time, and may be 1/30,720,000s (second).

A slot may be composed of a plurality of OFDM symbols in the time domain and may be composed of a plurality of resource blocks (RBs) in the frequency domain. A resource block may be composed of a plurality of subcarriers in the frequency domain. The number of OFDM symbols constituting a slot may vary according to the configuration of a cyclic prefix (CP). The CP may be classified into a normal CP and an extended CP. When a normal CP is used, a slot may consist of 7 OFDM symbols, and in this case, a subframe may consist of 14 OFDM symbols. If the extended CP is used, a slot may be composed of 6 OFDM symbols, and in this case, a subframe may be composed of 12 OFDM symbols.

4 is a conceptual diagram illustrating a first embodiment of a type 2 frame structure.

Referring to FIG. 4 , a radio frame 400 may include two half frames, and a half frame may include five subframes. Accordingly, the radio frame 400 may include 10 subframes. The length of the radio frame 400 (T _f ) may be 10 ms. The length of the half frame may be 5 ms. The subframe length may be 1 ms. Here, T _s may be 1/30,720,000s.

The radio frame 400 may include a downlink subframe, an uplink subframe, and a special subframe. Each of the downlink subframe and the uplink subframe may include two slots. The slot length (T _slot ) may be 0.5 ms. Among the subframes included in the radio frame 400 , each of subframe #1 and subframe #6 may be a special subframe. For example, when the downlink-uplink switching period is 5 ms, the radio frame 400 may include two special subframes. Alternatively, when the downlink-uplink switching period is 10 ms, the radio frame 400 may include one special subframe. The special subframe may include a downlink pilot time slot (DwPTS), a guard period (GP), and an uplink pilot time slot (UpPTS).

The downlink pilot time slot may be regarded as a downlink interval and may be used for cell search of the UE, time and frequency synchronization acquisition, channel estimation, and the like. The guard period may be used to solve an uplink data transmission interference problem caused by downlink data reception delay. In addition, the guard period may include a time required for switching from the downlink data reception operation to the uplink data transmission operation. The uplink pilot time slot may be used for uplink channel estimation, time and frequency synchronization acquisition, and the like. Transmission of a physical random access channel (PRACH) or a sounding reference signal (SRS) may be performed in an uplink pilot time slot.

Lengths of the downlink pilot time slot, guard period, and uplink pilot time slot included in the special subframe may be variably adjusted as necessary. In addition, the number and position of each of the downlink subframe, the uplink subframe, and the special subframe included in the radio frame 400 may be changed as needed.

In a communication system, a transmission time interval (TTI) may be a basic time unit for transmitting encoded data through a physical layer. A short TTI may be used to support low latency requirements in a communication system. The length of the short TTI may be less than 1 ms. The existing TTI having a length of 1 ms may be referred to as a base TTI or a regular TTI. That is, the basic TTI may consist of one subframe. In order to support transmission in a basic TTI unit, a signal and a channel may be configured in a subframe unit. For example, a cell-specific reference signal (CRS), a physical downlink control channel (PDCCH), a physical downlink shared channel (PDSCH), a physical uplink control channel (PUCCH), a physical uplink shared channel (PUSCH), etc. exist for each subframe. can

On the other hand, a synchronization signal (eg, a primary synchronization signal (PSS), a secondary synchronization signal (SSS)) may exist every 5 subframes, and a physical broadcast channel (PBCH) may exist every 10 subframes. And radio frames can be distinguished by SFN, and SFN is a signal having a transmission period longer than one radio frame (eg, a paging signal, a reference signal for channel estimation, a signal indicating channel state information, etc.) can be used to define the transport of The period of the SFN may be 1024.

In the LTE system, the PBCH may be a physical layer channel used for transmission of system information (eg, a master information block (MIB)). The PBCH may be transmitted every 10 subframes. That is, the transmission period of the PBCH may be 10 ms, and the PBCH may be transmitted once in a radio frame. The same MIB may be transmitted during 4 consecutive radio frames, and after 4 consecutive radio frames, the MIB may be changed according to the situation of the LTE system. The transmission period of the same MIB may be referred to as "PBCH TTI", and the PBCH TTI may be 40 ms. That is, the MIB may be changed for each PBCH TTI.

The MIB may consist of 40 bits. Of the 40 bits constituting the MIB, 3 bits may be used to indicate a system band, 3 bits may be used to indicate PHICH (physical hybrid automatic repeat request (ARQ) indicator channel) related information, and 8 bits are It may be used to indicate the SFN, 10 bits may be set as a reserved bit, and 16 bits may be used for a cyclic redundancy check (CRC).

The SFN that distinguishes the radio frame may consist of a total of 10 bits (B9 to B0), and among the 10 bits, 8 bits (B9 to B2) of the most significant bit (MSB) may be indicated by the PBCH (ie, MIB). . The MSB 8 bits (B9 to B2) of the SFN indicated by the PBCH (ie, MIB) may be the same during four consecutive radio frames (ie, PBCH TTI). The least significant bit (LSB) 2 bits (B1 to B0) of the SFN may be changed during four consecutive radio frames (ie, PBCH TTI), and may not be explicitly indicated by the PBCH (ie, MIB). have. The LSB 2 bits (B1 to B0) of the SFN may be implicitly indicated by a scrambling sequence for the PBCH (hereinafter, referred to as a “PBCH scrambling sequence”).

A gold sequence generated by being initialized with a cell ID may be used as the PBCH scrambling sequence, and the PBCH scrambling sequence may be initialized every four consecutive radio frames (ie, PBCH TTI) according to mod(SFN,4). have. A PBCH transmitted in a radio frame corresponding to an SFN in which LBS 2 bits (B1 to B0) is set to “00” may be scrambled by a Gold sequence generated by initializing the cell ID. Thereafter, the gold sequences generated according to mod(SFN,4) are used for scrambling the PBCH transmitted in the radio frame in which the LBS 2 bits (B1 to B0) of the SFN are “01”, “10” and “11”. can

Therefore, the UE acquiring the cell ID in the initial cell search process uses the PBCH scrambling sequence in the decoding process of the PBCH (ie, the MIB) to the value of the LSB 2 bits (B1 to B0) of the SFN (e.g., "00", " 01", "10", "11") can be found implicitly. The UE uses the LBS 2 bits (B1 to B0) of the SFN identified based on the PBCH scrambling sequence and the MBS 8 bits (B9 to B2) of the SFN indicated by the PBCH (ie, MIB) to the SFN (ie, the SFN All bits (B9~B0)) can be checked.

Meanwhile, the communication system may support not only high transmission speed but also technical requirements for various service scenarios. For example, the communication system may support a high transmission rate (enhanced Mobile BroadBand; eMBB), a short transmission delay time (Ultra Reliable Low Latency Communication; URLLC), massive machine type communication (mMTC), and the like.

A subcarrier interval of a communication system (eg, an OFDM-based communication system) may be determined based on a carrier frequency offset (CFO) or the like. The CFO may be caused by a Doppler effect, a phase drift, etc., and may increase in proportion to an operating frequency. Accordingly, in order to prevent degradation of the communication system due to the CFO, the subcarrier spacing may increase in proportion to the operating frequency. On the other hand, as the subcarrier spacing increases, CP overhead may increase. Accordingly, the subcarrier interval may be set based on channel characteristics according to frequency bands, radio frequency (RF) characteristics, and the like.

The communication system may support numerology defined in Table 1 below.

For example, the subcarrier spacing of the communication system may be set to 15 kHz, 30 kHz, 60 kHz, or 120 kHz. The subcarrier spacing of the LTE system may be 15 kHz, and the subcarrier spacing in the NR system may be 1, 2, 4, or 8 times the existing subcarrier spacing of 15 kHz. When the subcarrier spacing is increased by an exponential multiple of 2 of the existing subcarrier spacing, the frame structure can be easily designed.

The communication system may support a wide frequency band (eg, several hundred MHz to several tens of GHz). Since diffraction and reflection characteristics of radio waves in a high frequency band are poor, propagation loss (eg, path loss, return loss, etc.) in a high frequency band may be larger than a propagation loss in a low frequency band. Accordingly, the cell coverage of the communication system supporting the high frequency band may be smaller than the cell coverage of the communication system supporting the low frequency band. To solve this problem, a beamforming method based on a plurality of antenna elements may be used to increase cell coverage in a communication system supporting a high frequency band.

The beamforming method may include a digital beamforming method, an analog beamforming method, a hybrid beamforming method, and the like. In a communication system using a digital beamforming method, a beamforming gain may be obtained using a plurality of RF paths based on a digital precoder or a codebook. In a communication system using an analog beamforming method, a beamforming gain may be obtained through an analog RF device (eg, a phase shifter, a power amplifier (PA), a variable gain amplifier (VGA), etc.) and an antenna array. can

Since expensive digital to analog converter (DAC) or analog to digital converter (ADC) and transceiver units corresponding to the number of antenna elements are required for the digital beamforming method, an antenna for increasing the beamforming gain Implementation complexity may be increased. In a communication system using an analog beamforming method, since a plurality of antenna elements are connected to one transceiver unit through a phase shifter, even when a beamforming gain is increased, the complexity of antenna implementation may not significantly increase. However, the beamforming performance of the communication system using the analog beamforming method may be lower than the beamforming performance of the communication system using the digital beamforming method. In addition, since the phase shifter is adjusted in the time domain in a communication system using the analog beamforming method, frequency resources may not be efficiently used. Therefore, a hybrid beamforming method that is a combination of a digital method and an analog method may be used.

When cell coverage is increased by using the beamforming method, a common control channel and a common signal (eg, a reference signal, a synchronization signal) for all terminals belonging to the cell coverage as well as a control channel and data channel of each terminal may also be transmitted based on a beamforming method. In this case, a common control channel and a common signal for all terminals belonging to cell coverage may be transmitted based on a beam sweeping scheme.

Also, in the NR system, a synchronization block/physical broadcast channel (SS/PBCH) block may be transmitted in a beam sweeping scheme. The SS/PBCH block may be configured with PSS, SSS, PBCH, and the like, and the PSS, SSS, and PBCH within the SS/PBCH block may be configured with a time division multiplexing (TDM) scheme. The SS/PBCH block may be referred to as an “SS/PBCH block”. One SS/PBCH block may be transmitted using N consecutive OFDM symbols. Here, N may be an integer of 4 or more. The base station may periodically transmit the SS/PBCH block, and the terminal may obtain frequency/time synchronization, cell ID, system information, and the like, based on the SS/PBCH block received from the base station. The SS/PBCH block may be transmitted as follows.

5 is a conceptual diagram illustrating a first embodiment of a method for transmitting an SS/PBCH block in a communication system.

Referring to FIG. 5 , one or more SS/PBCH blocks in an SS/PBCH block burst set may be transmitted in a beam sweeping scheme. A maximum of L SS/PBCH blocks may be transmitted in one SS/PBCH block burst set. L may be an integer of 2 or more, and may be defined in the 3GPP standard. L may vary according to the region of the system frequency. In the SS/PBCH block burst set, SS/PBCH blocks may be located contiguously or distributedly. Consecutive SS/PBCH blocks may be referred to as “SS/PBCH block bursts”. The SS/PBCH block burst set may be periodically repeated, and system information (eg, MIB) transmitted through the PBCH of SS/PBCH blocks within the SS/PBCH block burst set may be the same. SS/PBCH block index, SS/PBCH block burst index, OFDM symbol index, slot index, etc. may be explicitly or implicitly indicated by the PBCH.

6 is a conceptual diagram illustrating a first embodiment of an SS/PBCH block in a communication system.

Referring to FIG. 6 , the arrangement order in the SS/PBCH block may be “PSS → PBCH → SSS → PBCH”. In the SS/PBCH block, PSS, SSS, and PBCH may be configured in a TDM manner. In the symbol in which the SSS is located, the PBCH may be disposed in frequency resources higher than the SSS and frequency resources lower than the SSS. When the maximum number of SS/PBCH blocks is 8 in a frequency band of 6 GHz or less, the index of the SS/PBCH block is based on a demodulation reference signal (DMRS) used for demodulation of the PBCH (hereinafter referred to as "PBCH DMRS"). can be confirmed as When the maximum number of SS/PBCH blocks is 64 in a frequency band of 6 GHz or higher, 3 LSB bits among 6 bits indicating the index of the SS/PBCH block may be identified based on PBCH DMRS, and the remaining 3 MSB bits are PBCH pay It can be identified based on the load.

The maximum system bandwidth that can be supported in the NR system may be 400 MHz. The size of the maximum bandwidth supportable by the terminal may vary according to the capability of the terminal. Accordingly, the UE may perform an initial access procedure (eg, an initial connection procedure) by using some of the system bandwidths of the NR system supporting broadband. In order to support the access procedure of terminals supporting various sizes of bandwidth, the SS/PBCH block may be multiplexed on the frequency axis within the system bandwidth of the NR system supporting wideband. In this case, the SS/PBCH block may be transmitted as follows.

7 is a conceptual diagram illustrating a second embodiment of a method for transmitting an SS/PBCH block in a communication system.

Referring to FIG. 7 , a broadband component carrier (CC) may include a plurality of bandwidth parts (BWP). For example, a wideband CC may include 4 BWPs. The base station may transmit the SS/PBCH block in each of BWP #0 to 3 belonging to the broadband CC. The UE may receive an SS/PBCH block in one or more BWPs of BWP #0 to 3, and may perform an initial access procedure using the received SS/PBCH block.

After detecting the SS/PBCH block, the UE may acquire system information (eg, remaining minimum system information (RMSI)) and may perform a cell access procedure based on the system information. The RMSI may be transmitted through the PDSCH scheduled by the PDCCH. Configuration information of a control resource set (CORESET) in which a PDCCH including scheduling information of a PDSCH in which RMSI is transmitted is transmitted may be transmitted through a PBCH in an SS/PBCH block. A plurality of SS/PBCH blocks may be transmitted in the entire system band, and one or more SS/PBCH blocks among the plurality of SS/PBCH blocks may be an SS/PBCH block associated with an RMSI. The remaining SS/PBCH blocks may not be associated with RMSI. The SS/PBCH block associated with the RMSI may be defined as a "cell defining SS/PBCH block". The UE may perform a cell search procedure and an initial access procedure using a cell-defined SS/PBCH block. The SS/PBCH block not associated with the RMSI may be used for a synchronization procedure and/or a measurement procedure in the corresponding BWP. The BWP through which the SS/PBCH block is transmitted may be limited to one or more BWPs within a wide bandwidth.

RMSI is "Operation of acquiring configuration information of CORESET from SS/PBCH block (eg, PBCH) → Detecting operation of PDCCH based on configuration information of CORESET → Operation of acquiring scheduling information of PDSCH from PDCCH → RMSI through PDSCH may be obtained by performing an "operation of receiving The transmission resource of the PDCCH may be set by the configuration information of CORESET. The RMSI CORESET mapping pattern may be defined as follows. The RMSI CORESET may be a CORESET used for RMSI transmission/reception.

8A is a conceptual diagram illustrating RMSI CORESET mapping pattern #1 in a communication system, FIG. 8B is a conceptual diagram illustrating RMSI CORESET mapping pattern #2 in a communication system, and FIG. 8C illustrates RMSI CORESET mapping pattern #3 in a communication system It is a conceptual diagram.

8A to 8C , one RMSI CORESET mapping pattern among RMSI CORESET mapping patterns #1-3 may be used, and detailed setting according to one RMSI CORESET mapping pattern may be completed. In the RMSI CORESET mapping pattern #1, the SS/PBCH block, CORESET (eg, RMSI CORESET), and PDSCH (eg, RMSI PDSCH) may be configured in a TDM manner. The RMSI PDSCH may mean a PDSCH through which RMSI is transmitted. In RMSI CORESET mapping pattern #2, CORESET (eg, RMSI CORESET) and PDSCH (eg, RMSI PDSCH) may be configured in a TDM manner, and PDSCH (eg, RMSI PDSCH) is an SS/PBCH block and frequency division multiplexing (FDM). In RMSI CORESET mapping pattern #3, CORESET (eg, RMSI CORESET) and PDSCH (eg, RMSI PDSCH) may be set in a TDM manner, and CORESET (eg, RMSI CORESET) and PDSCH (eg, RMSI CORESET) For example, RMSI PDSCH) may be configured in an SS/PBCH block and FDM scheme.

Only RMSI CORESET mapping pattern #1 can be used in a frequency band of 6 GHz or less. All of the RMSI CORESET mapping patterns #1, #2, and #3 may be used in the frequency band above 6 GHz. The numerology of the SS/PBCH block may be different from that of "RMSI CORESET and RMSI PDSCH". Here, the nucleolar may be a subcarrier spacing. In the RMSI CORESET mapping pattern #1, any combination of neumonologies can be used. In RMSI CORESET mapping pattern #2, a combination of "SS/PBCH block, RMSI CORESET/PDSCH = 120kHz, 60kHz or 240kHz, 120kHz" may be used. In RMSI CORESET mapping pattern #3, a combination of "SS/PBCH block, RMSI CORESET/PDSCH = 120 kHz, 120 kHz" may be used.

One RMSI CORESET mapping pattern may be selected from among RMSI CORESET mapping patterns #1-3 according to a combination of the neumonology of the SS/PBCH block and the neumonology of the RMSI CORESET/PDSCH. The setting information of RMSI CORESET may include table A and table B. Table A shows the number of resource blocks (RBs) of RMSI CORESET, the number of symbols of RMSI CORESET, and RBs of SS/PBCH blocks (eg, start RBs or end RBs) and RBs of RMSI CORESETs (eg, start RBs). Alternatively, it may indicate an offset between the end RBs). Table B may indicate the number of search space sets per slot in each of the RMSI CORESET mapping patterns, the offset of the RMSI CORESET, and the OFDM symbol index. Table B may indicate information for setting a monitoring occasion of the RMSI PDCCH. Each of the tables A and B may consist of a plurality of tables. For example, Table A may include Tables 13-1 to 13-8 specified in TS 38.213, and Table B may include Tables 13-9 to Table 13-13 specified in TS 38.213. Each of Table A and Table B may have a size of 4 bits.

In the NR system, the PDSCH may be mapped to the time domain according to PDSCH mapping type A or B. PDSCH mapping types A and B may be defined as shown in Table 2 below.

Type A (ie, PDSCH mapping type A) may be slot-based transmission. When type A is used, the position of the start symbol of the PDSCH may be set to one of {0, 1, 2, 3}. When type A and normal CP are used, the number of symbols constituting the PDSCH (eg, the duration of the PDSCH) may be set to one of 3 to 14 within a symbol boundary. Type B (ie, PDSCH mapping type B) may be a non-slot-based transmission. When type B is used, the position of the start symbol of the PDSCH may be set to one of 0 to 12. When type B and normal CP are used, the number of symbols constituting the PDSCH (eg, the duration of the PDSCH) may be set to one of {2, 4, 7} within a symbol boundary. A DMRS (hereinafter, referred to as "PDSCH DMRS") for demodulation of a PDSCH (eg, data) may be determined based on an ID indicating a PDSCH mapping type (eg, type A or type B) and a length. The ID may be defined differently according to the PDSCH mapping type.

Meanwhile, NR-U (unlicensed) is being discussed at the NR standardization meeting. The NR-U system can increase network capacity by improving the utilization of limited frequency resources. The NR-U system may support operation in an unlicensed band (eg, unlicensed spectrum).

In the NR-U system, the UE may determine whether a signal is transmitted from the corresponding base station based on a discovery reference signal (DRS) received from the base station in the same way as in the general NR system. In the NR-U system of the SA (Stand-Alone) mode, the UE may acquire synchronization and/or system information based on the DRS. In the NR-U system, DRS may be transmitted according to the regulations of the unlicensed band (eg, transmission band, transmission power, transmission time, etc.). For example, according to an Occupied Channel Bandwidth (OCB) regulation, a signal may be configured and/or transmitted to occupy 80% of a total channel bandwidth (eg, 20 MHz).

In the NR-U system, a communication node (eg, a base station, a terminal) may perform Listen Before Talk (LBT) before transmitting a signal and/or a channel for coexistence with other systems. The signal may be a synchronization signal, a reference signal (eg, DRS, DMRS, channel state information (CSI)-RS, phase tracking (PT)-RS, sounding reference signal (SRS)). The channel may be a downlink channel, an uplink channel, a sidelink channel, or the like. In embodiments a signal may mean “signal”, “channel”, or “signal and channel”. LBT may be an operation to check whether a signal is transmitted by another communication node. If it is determined by the LBT that there is no transmission signal (eg, when the LBT is successful), the communication node may transmit a signal in the unlicensed band. If it is determined by the LBT that the transmission signal exists (eg, when the LBT fails), the communication node may not be able to transmit a signal in the unlicensed band. The communication node may perform LBT according to various categories before transmission of the signal. The category of LBT may vary according to the type of transmission signal.

Meanwhile, NR V2X (vehicular to everything) communication technology is being discussed at the NR standardization conference. The NR V2X communication technology may be a technology that supports communication between vehicles, communication between vehicles and infrastructure, communication between vehicles and pedestrians, etc. based on a device to device (D2D) communication technology.

NR V2X communication (eg, sidelink communication) is to be performed according to three transmission schemes (eg, unicast scheme, broadcast scheme, groupcast scheme) can When the unicast method is used, the first terminal may transmit data (eg, sidelink data) to the second terminal. When the broadcast method is used, the first terminal may transmit data to all terminals. When the groupcast method is used, the first terminal may transmit data to a group (eg, a groupcast group) including a plurality of terminals.

When the unicast method is used, the second terminal may transmit feedback information (eg, acknowledgment (ACK) or negative ACK (NACK)) on data received from the first terminal to the first terminal. In the embodiments below, the feedback information may be referred to as a “feedback signal”, a “physical sidelink feedback channel (PSFCH) signal”, or the like. When the ACK is received from the second terminal, the first terminal may determine that data has been successfully received from the second terminal. When the NACK is received from the second terminal, the first terminal may determine that the second terminal has failed to receive data. In this case, the first terminal may transmit additional information to the second terminal based on a hybrid automatic repeat request (HARQ) scheme. Alternatively, the first terminal may improve the reception probability of data in the second terminal by retransmitting the same data to the second terminal.

When the broadcast method is used, a procedure for transmitting feedback information for data may not be performed. For example, the system information may be transmitted in a broadcast manner, and the terminal may not transmit feedback information on the system information to the base station. Therefore, the base station may not know whether the system information has been successfully received from the terminal. To solve this problem, the base station may periodically broadcast system information.

When the groupcast method is used, a procedure for transmitting feedback information for data may not be performed. For example, necessary information may be periodically transmitted in a groupcast method without a procedure for transmitting feedback information. However, the target and/or the number of terminals participating in communication based on the groupcast method are limited, and data transmitted in the groupcast method is data that must be received within a preset time (eg, data sensitive to delay). In this case, a procedure for transmitting feedback information may be required even in groupcast sidelink communication. The groupcast sidelink communication may mean sidelink communication performed in a groupcast method. When a procedure for transmitting feedback information is performed in groupcast sidelink communication, data can be transmitted and received efficiently and stably.

In addition, data reliability in the receiving terminal may be improved by appropriately adjusting the power of the transmitting terminal according to the transmission environment. Interference to other terminals can be mitigated by appropriately adjusting the power of the transmitting terminal. Energy efficiency can be improved by reducing unnecessary transmit power. The power control method may be classified into an open-loop power control method and a closed-loop power control method. In the open-loop power control method, the transmitting terminal may determine the transmit power in consideration of a set and measured environment, and the like. In the closed-loop power control scheme, the transmitting terminal may determine the transmit power based on a transmit power control (TPC) command received from the receiving terminal.

Predicting the received signal strength in the receiving terminal may be difficult due to various causes including a multipath fading channel, interference, and the like. Accordingly, the reception terminal may adjust the reception power level (eg, reception power range) by performing an automatic gain control (AGC) operation in order to prevent a quantization error of the reception signal and maintain appropriate reception power. In a communication system, a terminal may perform an AGC operation using a reference signal received from a base station. However, in sidelink communication (eg, V2X communication), the reference signal may not be transmitted from the base station. That is, in sidelink communication, communication between terminals may be performed without a base station. Therefore, it may be difficult to perform an AGC operation in sidelink communication. In sidelink communication, a transmitting terminal may first transmit a signal (eg, a reference signal) to a receiving terminal before transmission of data, and the receiving terminal may perform an AGC operation based on a signal received from the transmitting terminal, thereby receiving power range (eg, a received power level) may be adjusted. Thereafter, the transmitting terminal may transmit the sidelink data to the receiving terminal. The signal used for the AGC operation may be a duplicated signal for a signal to be transmitted later or a signal preset between terminals.

A time interval required for the AGC operation may be 15 μs. When the subcarrier interval is 15 kHz in the NR system, the time interval (eg, length) of one symbol (eg, OFDM symbol) may be 66.7 μs. When the subcarrier interval is 30 kHz in the NR system, the time interval of one symbol (eg, OFDM symbol) may be 33.3 μs. In the embodiments below, a symbol may mean an OFDM symbol. That is, the time interval of one symbol may be twice or more than the time interval required for the AGC operation.

For sidelink communication, it may be necessary to transmit a data channel for data transmission and a control channel including scheduling information for data resource allocation. In sidelink communication, the data channel may be a Physical Sidelink Shared CHannel (PSSCH), and the control channel may be a Physical Sidelink Control CHannel (PSCCH). The data channel and the control channel may be multiplexed in a resource domain (eg, a time and frequency resource domain).

9 is a conceptual diagram illustrating embodiments of a method for multiplexing a control channel and a data channel in sidelink communication.

Referring to FIG. 9 , sidelink communication may support option 1A, option 1B, option 2, and option 3. When option 1A and/or option 1B is supported, the control channel and data channel may be multiplexed in the time domain. If option 2 is supported, the control channel and data channel can be multiplexed in the frequency domain. If option 3 is supported, the control channel and data channel can be multiplexed in time and frequency domains. Sidelink communication can support option 3 natively.

In sidelink communication (eg, NR-V2X sidelink communication), a basic unit of resource configuration may be a subchannel. A subchannel may be defined by time and frequency resources. For example, a subchannel may be composed of a plurality of symbols (eg, OFDM symbols) in the time domain and may be composed of a plurality of resource blocks (RBs) in the frequency domain. A subchannel may be referred to as an RB set. In the subchannel, the data channel and the control channel can be multiplexed based on option 3.

In sidelink communication (eg, NR-V2X sidelink communication), transmission resources may be allocated based on mode 1 or mode 2. When mode 1 is used, the base station may allocate sidelink resources for data transmission to the transmitting terminal in a resource pool, and the transmitting terminal receives data using the sidelink resources allocated by the base station. It can be transmitted to the terminal. Here, the transmitting terminal may be a terminal transmitting data in sidelink communication, and the receiving terminal may be a terminal receiving data in the sidelink communication.

When mode 2 is used, the transmitting terminal may autonomously select a sidelink resource to be used for data transmission by performing a resource sensing operation and/or a resource selection operation within the resource pool. The base station may set a resource pool for mode 1 and a resource pool for mode 2 in the terminal(s). The resource pool for mode 1 may be set independently of the resource pool for mode 2. Alternatively, a common resource pool may be configured for mode 1 and mode 2.

Next, sidelink communication methods based on feedback in a communication system will be described. Even when a method (eg, transmission or reception of a signal) performed in a first communication node among communication nodes is described, a corresponding second communication node is a method (eg, a method corresponding to the method performed in the first communication node) For example, reception or transmission of a signal) may be performed. That is, when the operation of the transmitting terminal is described, the corresponding receiving terminal may perform an operation corresponding to the operation of the transmitting terminal. Conversely, when the operation of the receiving terminal is described, the corresponding transmitting terminal may perform an operation corresponding to the operation of the receiving terminal.

[How to select a feedback resource]

In order to improve the reception reliability of data in sidelink communication (eg, NR-V2X sidelink communication), the terminal (eg, the transmitting terminal) transmits data a preset number of times according to a preset procedure regardless of whether reception is successful or not. can be retransmitted. In this case, feedback indicating whether data reception is successful may not be transmitted.

In another embodiment, the receiving terminal may transmit feedback (eg, ACK or NACK) to the transmitting terminal according to whether data reception is successful, and the transmitting terminal may determine whether to retransmit data based on the feedback. When "mode 1 is used and an uplink resource for feedback (eg, PUCCH and/or PUSCH) is configured", the transmitting terminal provides feedback (eg, HARQ response, HARQ-ACK) of the receiving terminal before retransmission of data ) may be transmitted to the base station using the corresponding uplink resource. The transmitting terminal may transmit the feedback of the receiving terminal to the base station as it is. Alternatively, the transmitting terminal may generate feedback based on the feedback of the receiving terminal, and may transmit the generated feedback to the base station. The base station may receive the feedback of the receiving terminal from the transmitting terminal, and may configure a new sidelink resource to the transmitting terminal based on the feedback. The transmitting terminal may retransmit data to the receiving terminal by using the new sidelink resource. When "mode 1 is used and uplink resources for feedback are not configured", the transmitting terminal may retransmit data to the receiving terminal through a resource region pre-allocated by the base station.

When mode 2 is used, the transmitting terminal may directly select the sidelink resource without the intervention of the base station. In this case, the transmitting terminal may not transmit the feedback of the receiving terminal to the base station, and may determine whether to retransmit data based on the feedback of the receiving terminal. The feedback transmission operation and the feedback monitoring operation may be clearly distinguished and performed in a point-to-point manner between the receiving terminal and the transmitting terminal. In sidelink communication, a transmitting terminal may autonomously select a sidelink resource and/or a receiving terminal without the control of a base station, and may transmit data to a receiving terminal (eg, a selected receiving terminal) using the selected sidelink resource. . Accordingly, the feedback transmission time and the feedback reception time may overlap in a specific terminal. One receiving terminal may simultaneously transmit feedbacks to a plurality of transmitting terminals. One receiving terminal may receive a plurality of data from one transmitting terminal, and may simultaneously transmit feedbacks for the plurality of data.

개의 RB들이 PSFCH 자원 풀로 설정된 경우, 슬롯(예를 들어, 사이드링크 슬롯)당 서브채널의 개수가

이고, PSFCH 슬롯과 연계된 PSSCH 슬롯의 개수가

이면, i번째 슬롯과 j번째 서브채널에 대응되는 각 PSFCH 후보 자원(예를 들어, PSFCH 후보 자원 집합)은

개의 RB들로부터

사이의

개의 RB들로 정의될 수 있다.

이 정의될 수 있다.1-bit ACK/NACK information (eg, feedback) may be transmitted through a physical sidelink feedback channel (PSFCH) in the form of a sequence. A PSFCH candidate resource set may be set according to "the number of subchannels per slot" and "the number of PSSCH slots associated with a PSFCH slot". The PSFCH slot may be a slot in which the PSFCH is transmitted, and the PSSCH slot may be a slot in which the PSSCH is transmitted. For example, for PSFCH transmission

When RBs are configured as a PSFCH resource pool, the number of subchannels per slot (eg, sidelink slot) is

and the number of PSSCH slots associated with the PSFCH slot is

, each PSFCH candidate resource (eg, PSFCH candidate resource set) corresponding to the i-th slot and the j-th subchannel is

from RBs

between

may be defined as RBs.

This can be defined

의 배수인

개의 RB들을 단말에 설정할 수 있다. HARQ ACK/NACK 다중화가 가능한 PSFCH 자원들의 개수는

일 수 있다.

는 상위계층에 의해 설정되는 사이클릭 시프트 쌍(cyclic shift pair)들의 개수일 수 있다.

는 1, 2, 3, 및 6 중에서 하나의 값으로 설정될 수 있다. 사이클릭 시프트 쌍이 1로 설정된 경우, 하나의 RB 내에서 하나의 HARQ 응답(예를 들어, ACK 또는 NACK)이 다중화될 수 있다. 사이클릭 시프트 쌍이 6으로 설정된 경우, 하나의 RB 내에서 최대 6개의 HARQ 응답(예를 들어, ACK 또는 NACK)이 다중화될 수 있다.the base station

multiple of

RBs may be configured in the UE. The number of PSFCH resources capable of HARQ ACK/NACK multiplexing is

can be

may be the number of cyclic shift pairs set by a higher layer.

may be set to one of 1, 2, 3, and 6. When the cyclic shift pair is set to 1, one HARQ response (eg, ACK or NACK) may be multiplexed within one RB. When the cyclic shift pair is set to 6, a maximum of 6 HARQ responses (eg, ACK or NACK) may be multiplexed within one RB.

에 따라 결정될 수 있다. "

=1이고, PSSCH 전송을 위해 복수의 서브채널들이 사용된 경우", PSFCH 전송은 복수의 서브채널들 중에서 첫 번째 서브채널과 연계된

개의 RB들을 통해 가능할 수 있다.

인 경우, PSFCH 전송은 PSSCH 전송에 사용된 복수의 서브채널들과 연계된

개의 RB들을 통해 가능할 수 있다.

인 경우에 HARQ 응답의 다중화 개수는

=1인 경우에 다중화 개수에 비해

배일 수 있다. The number of multiplexes in the HARQ response is

can be determined according to "

= 1, and if a plurality of subchannels are used for PSSCH transmission, PSFCH transmission is associated with the first subchannel among the plurality of subchannels.

It may be possible through RBs.

If , PSFCH transmission is associated with a plurality of subchannels used for PSSCH transmission.

It may be possible through RBs.

In the case of , the number of multiplexes in the HARQ response is

=1 compared to the number of multiplexes

can be a boat

개의 PSFCH 자원들은 우선

개의 RB들내에서 RB 인덱스의 오름차순으로 인덱싱될 수 있고, 그 다음에

개의 사이클릭 시프트 쌍들 중에서 사이클릭 시프트 쌍 인덱스의 오름차순으로 인덱싱될 수 있다. 단말은 HARQ 응답이 전송될 PSFCH 자원의 인덱스를

로 결정할 수 있다. 이때, P_ID는 물리 계층 소스(source) ID(identifier)일 수 있다. P_ID는 SCI 포맷 0-2를 통해 시그널링될 수 있다. M_ID는 HARQ ACK/NACK 피드백 옵션에 따라 설정될 수 있다. 예를 들어, M_ID는 0으로 설정될 수 있다. 또는, M_ID는 상위계층 시그널링(예를 들어, 상위계층 메시지)에 의해 수신 단말 ID(예를 들어, 멤버 ID)로 설정될 수 있다.

PSFCH resources are prioritized

may be indexed in ascending order of the RB index within the RBs, and then

Among the cyclic shift pairs, they may be indexed in an ascending order of a cyclic shift pair index. The UE determines the index of the PSFCH resource to which the HARQ response is to be transmitted.

can be decided with In this case, P _ID may be a physical layer source ID (identifier). P _ID may be signaled through SCI format 0-2. M _ID may be configured according to the HARQ ACK/NACK feedback option. For example, M _ID may be set to 0. Alternatively, M _ID may be set as the receiving terminal ID (eg, member ID) by higher layer signaling (eg, higher layer message).

When groupcast feedback option 2 is used, all member terminals in the group (eg, all receiving terminals) transmit ACK/NACK information (eg, HARQ ACK) for data to the transmitting terminal through individual PSFCH resources. (eg, a groupcast transmitting terminal). The groupcast feedback option 2 may be used when the transmitting terminal is aware of all the receiving terminals in the group, and an individual member ID may be configured for each of all the receiving terminals in the group.

When the groupcast feedback option 2 is used, a method of setting a member ID to each of all receiving terminals in the group will be proposed. In groupcast communication, since all receiving terminals in a group receive the same PSCCH and PSSCH, it may not be possible to set a member ID through an individual control channel and/or data channel for each receiving terminal. Accordingly, the member ID of each of the receiving terminals in the group may be configured through MAC signaling (eg, MAC CE (control element)) and/or higher layer signaling (eg, system information, RRC message).

When groupcast feedback option 2 is used, the transmitting terminal can recognize all the receiving terminals (eg, all members) in the group, and the member ID is the terminal ID or terminal specific of each of all the receiving terminals in the group. It can be associated with an ID. The member ID may be signaled based on "association between the corresponding member ID and the terminal ID" or "the association between the corresponding member ID and the terminal-specific ID". The member ID may be different from the terminal ID or the terminal specific ID.

The terminal ID and/or the terminal specific ID may be set to have a preset bit. A terminal ID and/or a terminal specific ID may be set in each terminal. In order to prevent collision of PSFCH resources within a group (eg, a groupcast group), when the number of all members in the group is K, each member ID is one of "0, 1, ..., K-1". It can be set to a value. For example, "there are four members in the group (ie, K=4), and the terminal ID (UE _ID ) or terminal specific ID (UE _ID ) of each of the four members is A, B, C, D case", the transmitting terminal by associating "member ID and terminal ID" or "member ID and terminal specific ID" {(UE _ID = A, M _ID = 0), (UE _ID = B, M _ID = 1), (UE _ID =C, M _ID =2), (UE _ID =D, M _ID =3)} may be set. The transmitting terminal is {(UE _ID =A, M _ID =0), (UE _ID =B, M _ID =1), (UE _ID =C, M _ID =2), (UE _ID =D, M _ID =3) )} can be signaled to each member. Each member (eg, each receiving terminal) may obtain a member ID associated with a terminal ID or a terminal-specific ID. Each member may select a PSFCH resource based on the member ID, and may feed back ACK/NACK information to the transmitting terminal using the selected PSFCH resource.

Alternatively, the member ID may be set by the base station that has set up the group instead of the transmitting terminal in the group. The base station may set up a group (eg, a groupcast group) consisting of a transmitting terminal and a receiving terminal(s) for groupcast communication. In the group setting procedure, the base station may set the member ID to each receiving terminal in the group. When the receiving terminals in the group have a terminal ID or a terminal-specific ID, the base station may set a member ID associated with the terminal ID or terminal-specific ID, and association information (eg, "terminal ID - member ID" or " UE-specific ID - member ID") may be signaled to the receiving UE.

When the receiving terminals in the group do not have the terminal ID or the terminal-specific ID, the base station may set the terminal ID or the terminal-specific ID to the receiving terminal so that it can be used for setting the PSFCH resource. The UE ID or UE-specific ID may be configured to include or indicate a member ID. Specifically, when the total number of members in the group is K, the member ID used for configuring PSFCH resources is set to one of "0, 1, ..., K-1" in order to prevent collision between PSFCH resources. can be Therefore, when some bit(s) of the UE ID or UE-specific ID are used as member IDs, the corresponding bit(s) may be set to indicate a corresponding value among “0, 1, …, K-1”. Some bits used as the member ID may be set as a part of a MSB (most significant bit) or a part of a least significant bit (LSB) of a terminal ID or a terminal specific ID.

Alternatively, the terminal ID or the terminal-specific ID is the terminal ID or the terminal-specific ID and the result of a modulo operation on K (eg, the total number of members in the group) is "0, 1, ... , K-1" may be set so that the corresponding value appears. For example, "when there are four members in the group (ie, K=4), and the terminal ID or terminal specific ID of each of the four members is A, B, C, D", the transmitting terminal is the terminal ID Alternatively, the terminal ID or the terminal-specific ID may be set so that the result of the terminal-specific ID and modulo operation for K is {A mod 4 = 0, B mod 4 = 1, C mod 4 = 2, D mod 4 = 3}. .

The UE may transmit the HARQ response based on the RB and the cyclic shift pair corresponding to the PSFCH resource index. When the HARQ response is NACK, the UE may transmit a sequence to which the determined cyclic shift pair is applied through the determined RB. When the HARQ response is ACK, the UE may transmit a sequence to which the "determined cyclic shift pair + 6" is applied through the determined RB. In embodiments, methods for determining the position of the RB through which the HARQ response is transmitted and the index of the cyclic shift pair from the PSFCH resource index will be described.

에 기초하여 PSFCH 자원을 결정할 수 있다. 데이터가 전송되는 PSSCH의 서브채널(들)과 연계된

개의 RB들로 구성된 PSFCH 후보 자원 내에서 RB 인덱스가 Y(

)인 경우,

가 정의될 수 있다.

개의 RB들 내에서 해당 RB의 위치는

일 수 있다. 해당 RB에서 사이클릭 시프트 쌍의 인덱스가 C인 경우,

가 정의될 수 있다. PSFCH 자원 인덱스 X, RB 인덱스 Y, 및 사이클릭 시프트 쌍의 인덱스 C가 정의되지 않는 경우, RB의 위치는 아래 수학식 1에 기초하여 정의될 수 있고, 사이클릭 시프트 쌍의 값(예를 들어, 인덱스)은 아래 수학식 2에 기초하여 정의될 수 있다.If the PSFCH resource index is X, the terminal

PSFCH resources may be determined based on . Associated with the subchannel(s) of the PSSCH through which data is transmitted

In the PSFCH candidate resource consisting of RBs, the RB index is Y (

), if

can be defined.

The position of the RB within the RBs is

can be If the index of the cyclic shift pair in the corresponding RB is C,

can be defined. When the PSFCH resource index X, the RB index Y, and the index C of the cyclic shift pair are not defined, the position of the RB may be defined based on Equation 1 below, and the value of the cyclic shift pair (eg, index) may be defined based on Equation 2 below.

[How to allocate feedback resources]

Code Block Group (CBG)-based transmission may be used for efficiency of transmission resources. In the TB (Transport Block)-based transmission scheme of the LTE system, one TB may be composed of a plurality of CBs (Code Blocks) according to the channel coding size limitation, and HARQ for one TB instead of the plurality of CBs A response may be sent. When one TB is configured with a plurality of CBs in the NR system, the plurality of CBs may be configured in a plurality of groups (eg, CBGs), and a HARQ response for one group may be transmitted. . Each group may include one or more CBs.

When the TB-based transmission scheme is used, the receiving terminal may transmit the HARQ response for the entire TB instead of each CB constituting the received TB. That is, one HARQ response may be transmitted per TB. When the HARQ response is NACK, a retransmission procedure for the entire TB including a plurality of CBs may be performed.

When the CBG-based transmission method is used, the receiving terminal may transmit a HARQ response for each CBG constituting the received TB (eg, data). The number of HARQ responses may be the same as the number of CBGs included in the corresponding TB. One CBG may include one or more CBs. When a NACK for some CBGs among a plurality of CBGs constituting data is received, the base station may perform a retransmission procedure for some CBGs. When a CBG-based transmission scheme is used, transmission resources can be efficiently used.

The CBG-based transmission method is efficient even in "a case where a part of data is preempted due to transmission of data having a high priority" and/or "when some data is not transmitted due to LBT in the NR-U system" can be used as In sidelink communication (eg, NR-V2X sidelink communication), not only a TB-based transmission method but also a CBG-based transmission method may be used.

In order to support the CBG-based transmission scheme, it may be necessary to improve the PSFCH through which the HARQ response (eg, ACK/NACK feedback information) is transmitted. For example, the PSFCH needs to be improved so that the HARQ response for each of the plurality of CBGs constituting the TB can be transmitted. For transmitting a plurality of HARQ responses simultaneously, PSFCH transmission methods will be proposed. To transmit multiple HARQ responses simultaneously, multiple PSFCHs may be used.

"When simultaneous transmission of a plurality of HARQ responses for TBs received from a plurality of terminals is required" or "When simultaneous transmission of a plurality of HARQ responses for a plurality of TBs received from one terminal is required", a plurality of PSFCHs may be available. The maximum number of transmittable PSFCHs (N _PSFCH ) may be configured by system information, UE-specific RRC signaling and/or control information. The maximum number of transmittable PSFCHs in consideration of the transmission power of the UE may be defined as _{M PSFCH.} In this case, the maximum number of transmittable PSFCHs may be a result _{of min(M PSFCH} , N _{PSFCH ). HARQ responses for min (M PSFCH} , N _PSFCH ) TBs having a high priority among a plurality of TBs may be transmitted through PSFCHs.

인 경우, 단말은

를 사용하여 PSFCH 자원 인덱스를 계산할 수 있고, PSFCH 자원 인덱스에 상응하는 PSFCH 자원을 사용하여 HARQ 응답을 전송할 수 있다. 여기서, C_index는 CBG 인덱스(0, …, M-1)일 수 있다.In order to support a CBG-based transmission scheme, an index of each of a plurality of CBGs in a TB may be additionally applied to the above-described PSFCH resource index. In this case, the terminal uses "the maximum number of CBGs per TB set by higher layer signaling (N)" and "the number of CBs calculated based on the TB (eg, TB to be actually transmitted) size (C)" Thus, the number (M) of CBGs can be calculated. For example, the UE may calculate the actual number of CBGs based on M=min(N, C). The UE may select a PSFCH resource for transmission of the HARQ response for each CBG by adding a CBG index (eg, 1, ..., M-1) based on the number of CBGs (M) to the PSFCH resource index. Here, the PSFCH resource may be implicitly selected. Specifically, the PSFCH resource index is

If , the terminal is

can be used to calculate a PSFCH resource index, and a HARQ response can be transmitted using a PSFCH resource corresponding to the PSFCH resource index. Here, C _index may be a CBG index (0, ..., M-1).

In a simultaneous transmission procedure of HARQ responses for a plurality of CBGs of each of a plurality of TBs, only min(M _PSFCH , N _PSFCH ) PSFCHs (eg, HARQ responses) may be transmittable simultaneously. SCI UE formats 0-1 (e.g., SCI format 1-A, Step 1 (1 ^st stage) SCI) on the basis of the priority (priority) of data from a plurality of high TB priority signaling through ranking _{TB may be selected, and min(M PSFCH} , N _PSFCH ) CBGs may be selected from among CBGs included in the selected TBs in an ascending order of the index. The UE may transmit a HARQ response for each of the selected CBGs through the PSFCH.

For example, transmission of a HARQ response for two TBs (eg, TB#0, TB#1) may be required, and the priority of TB#1 may be higher than that of TB#0, and , each of the TBs may include two CBGs (eg, CBG#0, CBG#1). If the maximum number of transmittable PSFCHs (eg, HARQ response) is 3, the UE includes HARQ responses for each of CBG#0 and CBG#1 included in TB#1 with high priority and TB#0 The HARQ response for the CBG#0 may be transmitted through the PSFCH. That is, the UE may transmit three HARQ responses through the PSFCH.

For another example, transmission of the HARQ response for two TBs (eg, TB#0, TB#1) may be required, and the priority of TB#0 may be higher than that of TB#1. and each of the TBs may include four CBGs (eg, CBG#0, CBG#1, CBG#2, CBG#3). If the maximum number of transmittable PSFCHs (eg, HARQ responses) is 3, the UE receives HARQ responses for each of CBG#0, CBG#1, and CBG#2 included in TB#0 having high priority. It can be transmitted through the PSFCH. That is, the UE may transmit three HARQ responses through the PSFCH.

When determining the priority between CBGs included in the same TB, the CBG priority may be determined based on the HARQ response (eg, ACK/NACK information) instead of the ascending order of the CBG index. Alternatively, in order to determine the CBG priority, the CBG index and the HARQ response may be used together. Specifically, the priority of ACK may be higher than that of NACK.

Since the retransmission procedure for the CBG associated with the ACK is not performed when the ACK is transmitted, the efficiency of resource use may be improved. On the other hand, when the NACK is transmitted, a retransmission procedure for the CBG associated with the NACK may be performed. If the NACK cannot be transmitted, the transmitting terminal may perform a retransmission procedure for the corresponding CBG because it has not received the HARQ response. In both "NACK is successfully transmitted" and "NACK is not transmitted", a retransmission procedure for CBG may be performed. That is, setting the priority of the NACK higher than the priority of the ACK may not help to improve the efficiency of resource use. Therefore, when determining the priority between CBGs within the same TB, the UE sets the priority of the CBG (eg, successfully received CBG) associated with the ACK to the priority of the CBG (eg, CBG that has failed to receive) related to the NACK. It can be judged to be higher than the priority.

For example, transmission of a HARQ response for two TBs (eg, TB#0, TB#1) may be required, and the priority of TB#1 may be higher than that of TB#0, and , each of the TBs may include two CBGs (eg, CBG#0, CBG#1), and reception of CBG#0 included in TB#0 may fail, and included in TB#0 Reception of CBG#1 may be successful. When the maximum number of transmittable PSFCHs (eg, HARQ responses) is 3, the UE includes HARQ responses for each of CBG#0 and CBG#1 included in TB#1 having high priority and TB#0 A HARQ response for the CBG#1 (eg, a CBG that has been successfully received) may be transmitted through the PSFCH. That is, the UE may transmit three HARQ responses through the PSFCH.

When "reception of all CBGs included in the same TB is successful" or "reception of all CBGs included in the same TB fails", the UE may not be able to select a CBG according to the priority of ACK/NACK. In this case, the UE may select the CBG according to the ascending order of the CBG index. Alternatively, the UE may arbitrarily select a CBG.

Alternatively, the number of CBGs may be limited to the maximum number of transmittable (eg, simultaneous transmitable) PSFCHs. When the CBG-based transmission scheme is used, the UE uses the “maximum number of CBGs per TB set by higher layer signaling (N)” and “the number of CBs calculated based on the TB size (C)” of CBG The number (ie, M=min(N, C)) can be calculated. Here, N may be set to the maximum number of transmittable (eg, simultaneous transmitable) PSFCHs.

As another method for transmitting a plurality of HARQ responses for a plurality of CBGs, a new PSFCH format capable of transmitting a plurality of HARQ responses (or one or more HARQ responses) (hereinafter referred to as "PSFCH format 1") This can be set. PSFCH format 1 may be similar to NR PUCCH format 2. The UE may perform a channel coding operation and a modulation operation for a plurality of HARQ responses to a plurality of CBGs, and may transmit a result of the above-described operations through PSFCH format 1. The transmission resource of the PSFCH format 1 may be the same as the transmission resource of the existing PSFCH (hereinafter, referred to as "PSFCH format 0"). That is, PSFCH format 1 and PSFCH format 0 may share the same resource region. Alternatively, the transmission resource of PSFCH format 1 may be configured independently of the transmission resource of PSFCH format 0. In this case, the transmission resource of PSFCH format 1 may not overlap with the transmission resource of PSFCH format 0.

When PSFCH format 1 and PSFCH format 0 share the same resource region, transmission resources of PSFCH format 1 may be allocated (eg, indicated) in the same manner as PSFCH format 0. For example, PSFCH format 1 may be implicitly allocated (eg, indicated) based on an index of a PSCCH slot, an index of a PSSCH slot, and/or a subchannel index. In this case, the TX ID and/or RX ID used for setting the transmission resource of PSFCH format 0 may not be applied.

When the resource of PSFCH format 1 is indicated by a slot index and/or subchannel index used for data transmission, PSFCH format 1 may be configured in a form similar to PUCCH format 2. For example, the UE may perform a channel coding operation and a modulation operation for the HARQ response, and map the results of the above operations and reference signals (eg, PSFCH RS, PSFCH DMRS) to the resources of PSFCH format 1. can The number of RBs for PSFCH format 1 may be fixed in advance to a specific value. Alternatively, the number of RBs for PSFCH format 1 is higher layer signaling (eg, system information, RRC message), MAC signaling (eg, MAC CE), and/or PHY signaling (eg, SCI). can be set by

=1인 경우에 PSCCH 전송을 위해 사용된 첫 번째 서브채널과 연계된

개의 RB들로 설정될 수 있다.

=

인 경우, "PSSCH 전송을 위해 사용된

개의 서브채널들"과 "각 서브채널에 해당하는

개의 RB들"의 곱인

개의 RB들이 설정될 수 있다.For multiplexing of PSFCH format 1 and PSFCH format 0, the number of RBs for PSFCH format 1 is

= 1, associated with the first subchannel used for PSCCH transmission

RBs may be set.

=

If , "Used for PSSCH transmission

subchannels" and "corresponding to each subchannel

RBs" is the product of

RBs may be configured.

If a resource area and a resource area of the first format PSFCH PSFCH format 0 is set differently from each other, the resource PSFCH format 1 may be indicated by the first stage SCI and / or the step ^{2 1 (2 nd stage) SCI} . The resource of PSFCH format 1 may be allocated in advance by higher layer signaling (eg, system information, RRC signaling). Candidate resources of PSFCH format 1 may be configured by higher layer signaling, and the first step SCI and/or the second step SCI may indicate one resource for PSFCH format 1 among candidate resources of PSFCH format 1. .

Alternatively, the resource of PSFCH format 1 may be implicitly allocated (eg, indicated) by a slot index and/or a subchannel index used for data transmission in a separate resource region. That is, resources of PSFCH format 1 may be allocated in the same or similar manner as PSFCH format 0. Even when PSFCH format 1 is transmitted in a separate resource region, the structure and/or number of RBs of the corresponding PSFCH format 1 is the structure and/or number of RBs of PSFCH format 1 when PSFCH formats 0 and 1 share the same resource region. can be the same as

FIG. 10A is a conceptual diagram illustrating a first embodiment of a PSFCH resource allocation method, and FIG. 10B is a conceptual diagram illustrating a second embodiment of a PSFCH resource allocation method.

In the embodiment shown in FIG. 10A , a common resource region for PSFCH format 0 and PSFCH format 1 may be configured, and each resource of PSFCH format 0 and PSFCH format 1 is allocated by an implicit method (eg, an indication ) can be In the embodiment shown in FIG. 10B , a resource region for PSFCH format 0 and a resource region for PSFCH format 1 may be configured independently. A separate PSFCH resource region may be configured. That is, the resource region for PSFCH format 0 may be different from the resource region for PSFCH format 1. The resource of PSFCH format 1 may be explicitly configured (eg, allocated or indicated) by at least one of an RRC message and an SCI.

When PSFCH formats 0 and 1 exist, a method for selecting the PSFCH format (eg, PSFCH format 0 or 1) to be transmitted by the UE may be required. For example, a UE supporting a CBG-based transmission scheme may transmit implicitly indicated PSFCH format 1. Alternatively, the indicator included in the SCI (eg, the first stage SCI and/or the second stage SCI) may indicate the PSFCH format (eg, PSFCH format 0 or 1) used by the UE. Alternatively, the UE may select PSFCH format 1 according to a method of indicating one resource for PSFCH format 1 through an indicator included in SCI (eg, first step SCI and/or second step SCI). . In this case, "when there is no corresponding indicator in SCI" or "when the corresponding indicator indicates a specific value", the UE may select PSFCH format 0. Alternatively, a threshold that is a criterion for selecting the PSFCH format may be preset, and the terminal may use PSFCH format 1 when the number of HARQ responses exceeds the threshold, and the number of HARQ responses is the threshold. In the following cases, PSFCH format 0 may be used. The above-described threshold may be indicated by at least one of higher layer signaling, MAC signaling, and PHY signaling.

When a CBG-based transmission scheme is used, PSFCH format 1 may include a HARQ response for a CBG successfully received in a previous transmission procedure, and the HARQ response may be set to ACK. When reception of some CBGs is successful in the previous transmission procedure, a retransmission procedure for the remaining CBGs may be performed. Even in the case of transmitting HARQ responses for the remaining CBGs except for CBGs successfully received in the retransmission procedure, the corresponding HARQ responses may include HARQ responses for all CBGs. Accordingly, the ambiguity of the HARQ response can be resolved, and the transmission complexity of the HARQ response can be reduced.

When HARQ responses for CBGs of each of a plurality of TBs are simultaneously transmitted, one PSFCH format 1 may be transmitted by multiplexing the HARQ responses. The HARQ response to the CBG of a TB having a high priority may be preferentially mapped to a resource of PSFCH format 1. That is, the HARQ response to the CBG of the TB having a high priority may be preferentially transmitted through the PSFCH format 1. Here, a PSFCH resource (eg, a resource of PSFCH format 1) may correspond to a TB having the highest priority among TBs. When the priorities between the TBs are the same, the TBs may be mapped to the PSFCH in an ascending order of transmission resources. For example, if the index of the resource in which TB#0 is transmitted is 0, and the index of the resource in which TB#1 is transmitted is 1, TB#0 may be mapped to the PSFCH first, and then TB#1 to the PSFCH can be mapped to

The index of the transmission resource of the TB may be a resource pool index, a subchannel index, or a slot index. Alternatively, other parameter(s) used for transmission of PSCCH and/or PSSCH may be used to determine the priority of TBs. Alternatively, the HARQ response for the TB having the largest size or the TB having the smallest size among TBs may be transmitted through the PSFCH resource. When transmission is limited to HARQ responses for CBGs of each of a plurality of TBs, HARQ responses between TBs may not be multiplexed. In this case, PSFCH format 1 may be transmitted through a PSFCH resource corresponding to each TB. Accordingly, a plurality of PSFCH formats 1 may be transmitted. The number of transmittable PSFCH format 1 may be limited for reasons such as limitation of the transmission power of the terminal. In this case, PSFCH format 1 corresponding to a TB having a high priority may be transmitted preferentially. When the TBs have the same priority, a limited number of PSFCH format 1s may be transmitted by sequentially applying the above-described criteria.

As another method for transmitting a plurality of HARQ responses for a plurality of CBGs, one of various combinations for a plurality of HARQ responses may be selected, and the selected one combination may be transmitted through a PSFCH. That is, a channel selection method may be applied. Combinations of a plurality of HARQ responses for a plurality of CBGs may be mapped one-to-one with “combinations of a plurality of PSFCH resources corresponding to a plurality of CBGs and cyclic shift values of the PSFCH”. When a PSFCH having a specific cyclic shift value is received in a specific PSFCH resource, a combination of a plurality of HARQ responses mapped to "a specific PSFCH resource and a specific cyclic shift value" according to the above-described mapping relationship may be confirmed.

For example, a TB may include four CBGs (eg, CBG#0, CBG#1, CBG#2, CBG#3), and the HARQ response for CBG#0 may be ACK, The HARQ response for each of CBG#1, CBG#2, and CBG#3 may be NACK. In this case, the UE may transmit a PSFCH (eg, HARQ response) having “cyclic shift = 0” in the PSFCH resource corresponding to CBG#0. Alternatively, the HARQ response to each of CBG#0 and CBG#1 may be ACK, and the HARQ response to each of CBG#2 and CBG#3 may be NACK. The UE may transmit a PSFCH (eg, HARQ response) having “cyclic shift = 6” in the PSFCH resource corresponding to CBG#0.

That is, combinations of HARQ responses may be set as many as the number of combinations of PSFCH resources and cyclic shift values. Since a specific PSFCH resource and a specific cyclic shift value are used according to a combination of HARQ responses for CBGs, transmission efficiency of the PSFCH can be improved. When transmitting HARQ responses for CBGs of each of a plurality of TBs, one PSFCH may be transmitted for each TB. Thus, HARQ responses for CBGs of many TBs may be transmitted. When one PSFCH resource includes a plurality of RBs, a plurality of RBs as well as a "PSFCH resource and cyclic shift value" are additionally considered, so that the number of possible combinations may increase.

[Resource allocation method for sidelink transmission based on feedback]

In sidelink communication (eg, NR-V2X sidelink communication), resource allocation may be performed according to mode 1 or mode 2. When mode 1 is used, the base station may allocate sidelink resources for data transmission to the transmitting terminal within a preset resource pool, and the transmitting terminal uses the sidelink resources allocated by the base station to transmit data to the receiving terminal. can be transmitted When mode 2 is used, the transmitting terminal may autonomously select a sidelink resource by performing a resource sensing operation and/or a resource selection operation within a preset resource pool, and using the selected sidelink resource to transmit data to the receiving terminal can be transmitted

When scheduling information for resources allocated in mode 1 and mode 2 is transmitted, scheduling information for subsequent retransmission data (or initial transmission data for another TB) as well as scheduling information for current data may be transmitted together. . In the resource scheduling information for the current data and the resource scheduling information for the subsequent retransmission data, the location of time and frequency may be arbitrarily selected. However, the size of the subchannel within the slot cannot be changed.

When a TB-based transmission scheme is used, a retransmission procedure for the TB may be performed as a NACK for the initial transmission TB occurs. In this case, since TBs of the same size are retransmitted, there is no need to change the size of the subchannel. When a CBG-based transmission scheme is used, a retransmission procedure for some CBGs may be performed according to the occurrence of NACK for some CBGs included in the initial transmission TB. In this case, since only some CBGs in the TB are retransmitted, the size of the subchannel required for the retransmission procedure may be smaller than the size of the subchannel required for the previous initial transmission procedure. When "a CBG-based transmission method is used and scheduling information for initial transmission and scheduling information for retransmission are set together", methods of allocating retransmission resources will be described.

When mode 2 is used, the transmitting terminal may select a transmission resource of data. Accordingly, the transmitting terminal performs a resource (re) sensing operation and/or a resource (re) selection operation based on the HARQ response, thereby subchannel(s) for retransmission CBGs (eg, subchannels having a small size, small number of subchannels), and retransmission CBGs may be transmitted through the selected subchannel(s). In this case, the location of time and/or frequency resources for retransmission may be changeable. When mode 1 is used, the transmitting terminal may report the HARQ response of the receiving terminal to the base station before retransmission of CBGs. In this case, the base station may allocate retransmission resources for CBGs to the transmitting terminal based on the HARQ response of the receiving terminal, and the transmitting terminal may retransmit the CBGs to the receiving terminal using the retransmission resource allocated by the base station. .

However, when mode 1 is used, retransmission of some CBGs may be required before reporting the HARQ response of the receiving terminal to the base station. In this case, the transmitting terminal may retransmit some CBGs using a resource pre-allocated by the base station. In particular, for retransmission of some CBGs, methods for efficiently using a resource pre-allocated by a base station will be described.

When mode 1 is used, the transmitting terminal may not be able to arbitrarily change the resources pre-allocated by the base station. In this case, the transmitting terminal may change the existing MCS (eg, MCS index, MCS level) to a new MCS for retransmission of some CBGs, and using the new MCS, the entire subchannel(s) allocated by the base station Through this, some CBGs may be retransmitted. Here, the MCS may be changed so that some CBGs can occupy the entire subchannel(s). For example, the modulation order of the new MCS (eg, the changed MCS) may be lower than that of the existing MCS, and the coding rate of the new MCS may be lower than that of the existing MCS. When the above-described scheme is used, the resource allocated by the base station can be used as it is, and since a low MCS is used, the reception success probability of CBGs can be improved. When a low MCS is used, since a Channel Busy Ratio (CBR) is reduced, resource usage efficiency may be improved. The changed MCS information may be signaled through control information (eg, SCI) for retransmission CBGs.

Alternatively, the transmitting terminal may retransmit some CBGs using some of the pre-allocated retransmission resources. Some resources used for retransmission may be set according to a preset rule in pre-allocated retransmission resources. Specifically, the transmitting terminal may select resources in an ascending order of the subchannel index, and may perform retransmission using the selected resource. The PSCCH (eg, the first stage SCI) may be transmitted through the subchannel(s) having the lowest index among the allocated resources. Therefore, in order to facilitate monitoring of the PSCCH, a method of selecting resources in an ascending order of subchannel indexes may be appropriate.

Alternatively, the transmitting terminal may select the resources in descending order of the subchannel index, and may perform retransmission using the selected resource. The resource selection method (eg, ascending or descending order of subchannel indexes) may be configured (eg, indicated) by higher layer signaling, MAC signaling, and/or PHY signaling.

Alternatively, the transmitting terminal may arbitrarily select a specific resource from preset resources. In this case, some of the preset resources may be used for retransmission, and the remaining resources may not be used. Since the remaining resources are resources pre-allocated by the base station, other terminals cannot use the remaining resources, but the remaining resources are not used for transmission, so interference to other terminals can be reduced. A shared resource pool may be established for mode 1 and mode 2. In this case, since the terminal supporting mode 2 may use the remaining resources in the shared resource pool by performing a resource sensing operation and/or a resource selection operation, resource use efficiency may be improved.

The number, size and/or location of the changed subchannel(s) for the retransmitted CBGs may be indicated by control information (eg, SCI) for the retransmitted CBGs, and the control information may include any of all CBGs in the TB. Whether CBGs are retransmitted may be indicated by a bitmap. That is, the transmitting terminal may transmit control information (eg, SCI) including a bitmap indicating some retransmitted CBGs among all CBGs. Corresponding control information may be transmitted before retransmission of some CBGs. In the retransmission procedure, the method of changing the MCS and the method of changing the subchannel size (eg, the number of subchannels) may be simultaneously applied.

When mode 1 is used, the terminal may report the HARQ response for sidelink transmission to the base station. When a dynamic grant is used in sidelink communication, the maximum number of retransmissions between terminals may be set by the base station. When a configured grant is used in sidelink communication, the maximum number of retransmissions may be set for each configuration grant. In addition, the maximum number of retransmissions may be set for each priority.

The UE may report the HARQ response for the data to the base station after retransmitting data as many times as the maximum number of retransmissions. Since the maximum number of retransmissions is set by the base station when the dynamic grant is used, the terminal may report the HARQ response for data to the base station according to the scheduling information of the base station regardless of the number of (re)transmissions. When the configuration grant is used, the terminal may report the HARQ response for the data to the base station after retransmitting data by the maximum number of retransmissions. In order to support this operation, the terminal may know the number of (re)transmissions.

"When a half-duplex problem in which the transmission time and the reception time overlap at the time of data transmission" or "selective transmission is required by intra-UE prioritization", the terminal transmits the actual data (re)transmission may not be possible. A method may be needed to determine whether to include this situation in the number of retransmissions. For example, even when (re)transmission of actual data is not performed at the time of (re)transmission of data, this situation may be included in the number of retransmissions. Specifically, the terminal may increase the number of retransmissions regardless of whether the actual data is (re)transmitted at the time of (re)transmission of data. In sidelink communication, it may be difficult for a base station to know a data transmission/reception situation between terminals. Therefore, it may be difficult for the base station to confirm whether data scheduled by the configuration grant is actually (re)transmitted.

Since the base station knows the resources configured by the configuration grant, it can be predicted that (re)transmission of data according to the configuration grant is performed as many times as the maximum number of retransmissions after a specific time point. Therefore, since the base station can predict the reporting time of the HARQ response according to the configuration grant, it can prepare for receiving the HARQ response from the terminal. The terminal may increase the number of retransmissions even when actual data is not (re)transmitted at the (re)transmission time of the data in order to transmit the HARQ response expected by the base station at the preset time. The terminal may report the HARQ response to the base station when the maximum number of retransmissions is reached.

Alternatively, when (re)transmission of actual data does not occur at the time of (re)transmission of data, the terminal may not increase the number of retransmissions. The maximum number of retransmissions may be a value set in advance to ensure stable data reception in consideration of the priority of data. Therefore, even when (re)transmission of actual data does not occur, if this situation is included in the number of retransmissions, the number of (re)transmission of actual data may be smaller than the maximum number of retransmissions. In this case, reliable reception of data may be difficult. Therefore, when (re)transmission of actual data does not occur for stable data reception, this situation may not be included in the number of retransmissions. That is, only when (re)transmission of actual data occurs, the terminal may increase the number of retransmissions. Accordingly, only when the number of (re)transmissions of the actual data reaches the maximum number of retransmissions, the terminal may report the HARQ information to the base station. Accordingly, stable data reception performance can be guaranteed.

After the transmitting terminal retransmits the sidelink data by the maximum number of retransmissions, the transmitting terminal may report the HARQ response (eg, HARQ-ACK information) for the corresponding data to the base station. When there is an SL HARQ response received through the PSFCH, the transmitting terminal may perform a reporting operation based on the corresponding SL HARQ response.

An SL HARQ response may not be received through the PSFCH. For example, an SL HARQ response may not be received due to a priority between transmission and reception. In this case, the information that the transmitting terminal needs to report to the base station may be unclear. When a transmitting terminal that retransmits sidelink data for the maximum number of retransmissions reports an SL HARQ response to the corresponding sidelink data to the base station, the transmitting terminal always reports an ACK to the base station if there is no SL HARQ response obtained from the receiving terminal have. The ACK may always be transmitted regardless of whether data is successfully received, and the base station may determine that the retransmission operation has been completed for the maximum number of retransmissions based on the ACK.

Alternatively, when a transmitting terminal that retransmits sidelink data for the maximum number of retransmissions reports an SL HARQ response to the corresponding sidelink data to the base station, the transmitting terminal always receives a NACK if there is no SL HARQ response obtained from the receiving terminal It may also report to the base station. According to this operation, stable reception of data may be possible.

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

Examples of computer-readable media include hardware devices specially configured to store and carry out program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine language codes such as those generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as at least one software module to perform the operations of the present invention, and vice versa.

Although it has been described with reference to the above embodiments, it will be understood by those skilled in the art that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. will be able

Claims (20)

As a method of operating a receiving terminal in sidelink communication,
receiving one or more transport blocks (TBs) from a transmitting terminal;
generating hybrid automatic repeat request (HARQ) responses for code block groups (CBGs) included in each of the one or more TBs;
selecting one or more HARQ responses from among the HARQ responses based on priority; and
and transmitting the one or more HARQ responses to the transmitting terminal through a physical sidelink feedback channel (PSFCH) resource. The method according to claim 1,
The PSFCH resource is determined based on a CBG index associated with each of the one or more HARQ responses. The method according to claim 1,
The priority is the priority of the TB, and when a plurality of TBs are received from the transmitting terminal, HARQ responses to CBGs included in a TB having a high priority among the plurality of TBs are preferentially selected, receiving How the terminal operates. The method according to claim 1,
The priority is a priority of the CBG, and the HARQ response to the CBG having a low index among the CBGs is preferentially selected. The method according to claim 1,
The priority is a priority of a HARQ response, and a HARQ response indicating ACK (acknowledgement) is preferentially selected from among the HARQ responses. The method according to claim 1,
PSFCH format 1 for transmission of the one or more HARQ responses is configured, and the PSFCH resource is a resource for the PSFCH format 1. 7. The method of claim 6,
The PSFCH format 1 shares the same resource region as PSFCH format 0 for transmission of one HARQ response, and the transmission resource of the PSFCH format 1 is indicated in the same manner as the transmission resource of the PSFCH format 0. Operation of a receiving terminal Way. 7. The method of claim 6,
The resource region of the PSFCH format 1 is set independently of the resource region of the PSFCH format 0 for transmission of one HARQ response, and the resource region of the PSFCH format 1 is a higher layer message and/or sidelink control information (SCI). Indicated, the method of operation of the receiving terminal. The method according to claim 1,
When PSFCH format 0 and PSFCH format 1 are configured, a PSFCH format used for transmission of the one or more HARQ responses is selected according to a preset rule. As a method of operating a transmitting terminal in sidelink communication,
transmitting one or more transport blocks (TBs) to a receiving terminal through n subchannels;
One or more HARQ responses selected based on a priority among hybrid automatic repeat request (HARQ) responses to code block groups (CBGs) included in each of the one or more TBs through a physical sidelink feedback channel (PSFCH) resource. Receiving from a receiving terminal; and
When retransmission of some CBGs among all CBGs included in the one or more TBs is required, retransmitting the partial CBGs to the receiving terminal through m subchannels,
Each of n and m is a natural number, the operating method of the transmitting terminal. 11. The method of claim 10,
Where n is greater than m, a subchannel having a lower index is preferentially selected from among the n subchannels, and the m subchannels selected from the n subchannels are used for retransmission of some CBGs. , the method of operation of the transmitting terminal. 11. The method of claim 10,
A first modulation and coding scheme (MCS) is used for transmission of the one or more TBs, a second MCS is used for retransmission of the some CBGs, and a coding rate according to the second MCS is a coding rate according to the first MCS. lower, and the modulation order according to the second MCS is lower than the modulation order according to the first MCS. 11. The method of claim 10,
The priority is the priority of the TB, and when a plurality of TBs are transmitted, HARQ responses to CBGs included in a TB having a high priority among the plurality of TBs are preferentially selected, a method of operating a transmitting terminal . 11. The method of claim 10,
The priority is the priority of the CBG, and the HARQ response to the CBG having a low index among the CBGs is preferentially selected. 11. The method of claim 10,
The priority is a priority of the HARQ response, and the HARQ response indicating ACK (acknowledgement) is preferentially selected from among the HARQ responses. 11. The method of claim 10,
The method of operation of the transmitting terminal,
Further comprising the step of transmitting a bitmap indicating the retransmitted some of the CBGs among all the CBGs, the operating method of the transmitting terminal. As a receiving terminal in sidelink communication,
processor;
a memory in electronic communication with the processor; and
Including instructions stored in the memory,
When the instructions are executed by the processor, the instructions cause the receiving terminal to
receiving one or more transport blocks (TBs) from a transmitting terminal;
generate hybrid automatic repeat request (HARQ) responses for code block groups (CBGs) included in each of the one or more TBs;
select one or more HARQ responses from among the HARQ responses based on priority; and
and cause transmitting the one or more HARQ responses to the transmitting terminal on a physical sidelink feedback channel (PSFCH) resource. 18. The method of claim 17,
The PSFCH resource is determined based on a CBG index associated with each of the one or more HARQ responses. 18. The method of claim 17,
PSFCH format 1 for transmission of the one or more HARQ responses is configured, the PSFCH format 1 shares the same resource region as PSFCH format 0 for transmission of one HARQ response, and the transmission resource of the PSFCH format 1 is the PSFCH Receiving terminal, which is indicated in the same way as the transmission resource of format 0. 18. The method of claim 17,
PSFCH format 1 for transmission of the one or more HARQ responses is configured, and a resource region of PSFCH format 1 is configured independently of a resource region of PSFCH format 0 for transmission of one HARQ response, and the resource of PSFCH format 1 The region is indicated by a higher layer message and/or sidelink control information (SCI), the receiving terminal.

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