KR20200127861A - Method and apparatus for transmitting and receiving feedback information in communication system - Google Patents

Abstract

Disclosed are a method and an apparatus for transmitting and receiving feedback information in a communication system. According to the present invention, an operation method of a first terminal comprises the steps of: receiving data from a second terminal through one or more subchannels; checking feedback resources mapped to the one or more subchannels; and transmitting a physical sidelink feedback channel (PSFCH) including feedback information about the data to the second terminal by using the feedback resources. Accordingly, the performance of the communication system may be improved.

Description

Method and apparatus for transmitting and receiving feedback information in a communication system {METHOD AND APPARATUS FOR TRANSMITTING AND RECEIVING FEEDBACK INFORMATION IN COMMUNICATION SYSTEM}

The present invention relates to a technology for transmitting and receiving feedback information in a communication system in a communication system, and more particularly, to a technology for transmitting and receiving hybrid automatic repeat request (HARQ) feedback information for groupcast communication.

In order to process rapidly increasing wireless data, a frequency band 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) (eg, 6 GHz A communication system (for example, a new radio (NR) communication system) using the above frequency band) is being considered. The NR system can support not only a frequency band of 6 GHz or higher but also a frequency band of 6 GHz or lower, and can support various communication services and scenarios compared to the LTE system. In addition, requirements of the NR system may include enhanced Mobile BroadBand (eMBB), Ultra Reliable Low Latency Communication (URLLC), and Massive Machine Type Communication (mMTC).

Sidelink communication may be performed in the NR system. In order to improve the performance of the sidelink communication, feedback information (eg, acknowledgment (ACK) or negative ACK (NACK)) for sidelink data may be transmitted. 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. Meanwhile, sidelink communication may be performed based on not only a unicast method but also a broadcast method or a groupcast method. When sidelink communication is performed based on a broadcast method or a groupcast method, a procedure for transmitting feedback information for this is 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.

In order to achieve the above object, a method of operating a first terminal according to a first embodiment of the present invention includes receiving data from a second terminal through one or more subchannels, and a feedback resource mapped to the one or more subchannels. And transmitting a PSFCH (physical sidelink feedback channel) including feedback information on the data to the second terminal by using the feedback resource, wherein the data is a groupcast method Is transmitted, and feedback information of a plurality of terminals for the data is multiplexed in the PSFCH.

According to the present invention, some time intervals of a symbol may be used for AGC operation, and the remaining time intervals of a corresponding symbol may be used for transmission of feedback information. That is, since the reception of the feedback information is performed after the reception power level is adjusted through the AGC operation, the reception performance of the feedback information can be improved. In addition, feedback information of a plurality of terminals may be multiplexed in one PSFCH. The feedback resource to which the feedback information is transmitted may be mapped to a resource (eg, a subchannel) to which sidelink data related to the corresponding feedback information is transmitted. Accordingly, feedback information of a plurality of terminals can be efficiently transmitted in sidelink groupcast communication. Therefore, the performance of the communication system can be improved.

1 is a conceptual diagram showing 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 showing a first embodiment of a type 1 frame structure.
4 is a conceptual diagram showing a first embodiment of a type 2 frame structure.
5 is a conceptual diagram showing a first embodiment of a resource grid of slots included in a subframe.
6 is a conceptual diagram illustrating a first embodiment of a method for transmitting an SS/PBCH block in a communication system.
7 is a conceptual diagram illustrating a first embodiment of an SS/PBCH block in a communication system.
8 is a conceptual diagram illustrating a second embodiment of a method of transmitting an SS/PBCH block in a communication system.
9A is a conceptual diagram illustrating RMSI CORESET mapping pattern #1 in a communication system.
9B is a conceptual diagram illustrating RMSI CORESET mapping pattern #2 in a communication system.
9C is a conceptual diagram illustrating an RMSI CORESET mapping pattern #3 in a communication system.
10 is a conceptual diagram illustrating a first embodiment of a method for mapping feedback information in a communication system.
11 is a conceptual diagram showing a first embodiment of a method for receiving feedback information in a communication system.
12 is a conceptual diagram illustrating a second embodiment of a method for mapping feedback information in a communication system.
13 is a conceptual diagram illustrating a third embodiment of a method for mapping feedback information in a communication system.
14 is a conceptual diagram illustrating a fourth embodiment of a method for mapping feedback information in a communication system.
15A is a conceptual diagram illustrating a fifth embodiment of a method for mapping feedback information in a communication system.
15B is a conceptual diagram showing a sixth embodiment of a method for mapping feedback information in a communication system.
16A is a conceptual diagram illustrating a first embodiment of a method for indicating PSFCH resources in a communication system.
16B is a conceptual diagram illustrating a second embodiment of a method for indicating PSFCH resources in a communication system.
17 is a conceptual diagram illustrating a third embodiment of a method for indicating PSFCH resources in a communication system.

In the present invention, various modifications may be made and various embodiments may be provided, and specific embodiments will be illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to a specific embodiment, it is to be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. These terms are used only for the purpose of distinguishing one component from another component. For example, without departing from the scope of the present invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. The term 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 it may be directly connected or connected to the other component, but other components may exist in the middle. Should be. On the other hand, when a component is referred to as being "directly connected" or "directly connected" to another component, it should be understood that there is no other component 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. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof, does not preclude in advance.

Unless otherwise defined, 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 the present invention belongs. Terms as defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and should not be interpreted as 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 an overall understanding, the same reference numerals are used for the same elements in the drawings, and duplicate descriptions for the same elements 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, the communication system may be used with the same meaning as a communication network.

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

Referring to FIG. 1, a communication system 100 includes 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 includes a core network (eg, a serving-gateway (S-GW), a packet data network (PDN)-gateway), and a mobility management entity (MME)). It may contain 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. It may include.

The plurality of communication nodes 110 to 130 may support communication protocols (eg, LTE communication protocol, LTE-A communication protocol, NR communication protocol, etc.) specified in the 3rd generation partnership project (3GPP) standard. The plurality of communication nodes 110 to 130 are code division multiple access (CDMA) technology, wideband CDMA (WCDMA) technology, time division multiple access (TDMA) technology, frequency division multiple access (FDMA) technology, orthogonal frequency division (OFDM) technology. 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, NOMA (Non-orthogonal Multiple Access) 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 transmission/reception device 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, and a storage device 260. Each of the components included in the communication node 200 may be connected by a bus 270 to perform communication with each other.

However, each of the components included in the communication node 200 may be connected through an individual interface or an individual bus centering on the processor 210 instead of the common bus 270. For example, the processor 210 may be connected to at least one of the memory 220, the transmission/reception device 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 with at least one of a volatile storage medium and a nonvolatile storage medium. For example, the memory 220 may be formed of 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, 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 within 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), evolved NodeB (eNB), gNB, advanced base station (ABS), and HR. -BS (high reliability-base station), BTS (base transceiver station), radio base station, radio transceiver, access point, access node, radio access station (RAS) ), 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, and 130-6 is a user equipment (UE), terminal equipment (TE), 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 terminal 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) Can be transferred to.

In addition, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 transmits MIMO (e.g., 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 , ProSe (proximity services)), Internet of Things (IoT) communication, dual connectivity (DC), etc. may be supported. Here, each of the plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 is a base station 110-1, 110-2, 110-3, 120-1 , 120-2) 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 scheme, and the fourth terminal 130-4 may transmit a signal to the fourth terminal 130-4 by the SU-MIMO scheme. 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 method, and the fourth terminal 130-4 And each of the fifth terminal 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 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. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 has terminals 130-1, 130-2, 130-3, and 130-4 belonging to their 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 can control D2D between the fourth terminal 130-4 and the fifth terminal 130-5. And, each of the fourth terminal 130-4 and the fifth terminal 130-5 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 can support three types of frame structures. The type 1 frame structure can be applied to a frequency division duplex (FDD) communication system, the type 2 frame structure can be applied to a time division duplex (TDD) communication system, and the type 3 frame structure is a communication system based on an unlicensed band (e.g. For example, it may be applied to a licensed assisted access (LAA) communication system.

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

Referring to FIG. 3, a radio frame 300 may include 10 subframes, and a 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 length T _{f of the} radio frame 300 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, 720,000 s (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. The resource block may be composed of a plurality of subcarriers in the frequency domain. The number of OFDM symbols constituting a slot may vary depending on the configuration of a cyclic prefix (CP). CP can be classified into a normal (normal) CP and an extended (extended) CP. When a normal CP is used, a slot may be composed of 7 OFDM symbols, and in this case, a subframe may be composed of 14 OFDM symbols. When the extended CP is used, a slot may consist of 6 OFDM symbols, and in this case, a subframe may consist of 12 OFDM symbols.

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

The lengths of each 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 location of each of the downlink subframes, the uplink subframes, and the special subframes included in the radio frame 400 may be changed as necessary.

5 is a conceptual diagram showing a first embodiment of a resource grid of slots included in a subframe.

5, a resource block of a slot included in a downlink subframe or an uplink subframe may be composed of 7 OFDM symbols in the time domain when a normal CP is used, and 12 subframes in the frequency domain. It can be composed of carriers. Each of the seven OFDM symbols may be referred to as symbol #0, symbol #1, symbol #2, symbol #3, symbol #4, symbol #5, symbol #6, and symbol #7. Each of the 12 subcarriers is subcarrier #0, subcarrier #1, subcarrier #2, subcarrier #3, subcarrier #4, subcarrier #5, subcarrier #6, subcarrier #7, subcarrier # It may be referred to as 8, subcarrier #9, subcarrier #10, and subcarrier #11. In this case, a resource composed of one OFDM symbol in the time domain and one subcarrier in the frequency domain may be referred to as a "resource element (RE)".

Next, methods of transmitting and receiving hybrid automatic repeat request (HARQ) feedback information in a communication system will be described. Even when a method performed in the first communication node (for example, transmission or reception of a signal) among communication nodes is described, the second communication node corresponding thereto is a method corresponding to the method performed in the first communication node (e.g. For example, signal reception or transmission) may be performed. That is, when the operation of the terminal is described, the corresponding base station may perform an operation corresponding to the operation of the terminal. Conversely, when the operation of the base station is described, the terminal corresponding thereto may perform an operation corresponding to the operation of the base station.

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 can be less than 1ms. 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 units of basic TTI, signals and channels may be set in units of subframes. 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. are present per subframe. I 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. In addition, radio frames can be classified as SFN, and the SFN is a signal with a transmission period longer than one radio frame (e.g., a paging signal, a reference signal for channel estimation, a signal indicating channel state information, etc.) Can be used to define the transmission of. The cycle of 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)). 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 can be composed of 40 bits. Of the 40 bits constituting the MIB, 3 bits may be used to indicate the system band, 3 bits may be used to indicate information related to a physical hybrid ARQ (automatic repeat request) indicator channel (PHICH), and 8 bits It may be used to indicate SFN, 10 bits may be set as reserved bits, and 16 bits may be used for cyclic redundancy check (CRC).

The SFN separating the radio frame may consist of a total of 10 bits (B9 to B0), and among the 10 bits, the MSB (most significant bit) 8 bits (B9 to B2) may be indicated by the PBCH (ie, MIB). . 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 LSB (least significant bit) 2 bits (B1 to B0) of the SFN may be changed during 4 consecutive radio frames (i.e., PBCH TTI), and may not be explicitly indicated by the PBCH (i.e., 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 "PBCH scrambling sequence").

A gold sequence generated by initializing a cell ID as a PBCH scrambling sequence may be used, and the PBCH scrambling sequence may be initialized every four consecutive radio frames (i.e., PBCH TTI) according to mod(SFN,4). have. The PBCH transmitted in the radio frame corresponding to the SFN in which the LBS 2-bit (B1 to B0) is set to "00" may be scrambled by a gold sequence generated by initializing a cell ID. Thereafter, the gold sequences generated according to mod(SFN,4) will be used to scramble PBCH transmitted in radio frames in which the SFN's LBS 2 bits (B1 to B0) are "01", "10" and "11". I can.

Therefore, the UE that acquires the cell ID in the initial cell search process uses the PBCH scrambling sequence in the decoding process of the PBCH (ie, MIB) to determine the value of the LSB 2 bits (B1 ~ B0) of the SFN (eg, "00", " 01", "10", "11") can be found implicitly. The UE uses the SFN (i.e., SFN) using 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 (i.e., MIB). All bits (B9~B0)) can be checked.

Meanwhile, the communication system can support technical requirements for various service scenarios as well as high transmission rates. 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)), and massive machine type communication (mMTC).

The subcarrier spacing of the communication system (eg, 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, phase drift, or the like, and may increase in proportion to the operating frequency. Therefore, in order to prevent performance degradation of the communication system by 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 spacing may be set based on a channel characteristic according to a frequency band and a radio frequency (RF) characteristic.

The communication system may support the 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 in 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 increases in units of an exponent of 2 of the existing subcarrier spacing, the frame structure can be easily designed.

The communication system can support a wide frequency band (eg, hundreds of MHz to tens of GHz). Since the 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 greater than that in a low frequency band. Accordingly, cell coverage of a communication system supporting a high frequency band may be smaller than that of a communication system supporting a low frequency band. In order 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 can be obtained through an analog RF device (e.g., a phase shifter, a power amplifier (PA), a variable gain amplifier (VGA)) and an antenna array. I can.

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

When the cell coverage is increased by the use of the beamforming method, a common control channel and a common signal (e.g., reference signal, synchronization signal) for all terminals belonging to the cell coverage as well as the control channel and data channel of each terminal It 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 method.

In addition, in the NR system, a synchronization block/physical broadcast channel (SS/PBCH) block may also be transmitted using a beam sweeping method. The SS/PBCH block may be composed of PSS, SSS, PBCH, and the like, and the PSS, SSS and PBCH may be composed of a time division multiplexing (TDM) method in the SS/PBCH block. 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 acquire 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.

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

Referring to FIG. 6, one or more SS/PBCH blocks in an SS/PBCH block burst set may be transmitted in a beam sweeping method. 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 3GPP standards. L may vary depending on the system frequency range. SS/PBCH blocks may be continuously or distributedly located in the SS/PBCH block burst set. Consecutive SS/PBCH blocks may be referred to as “SS/PBCH block burst”. 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.

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

Referring to FIG. 7, 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 scheme. In the symbol in which the SSS is located, the PBCH may be allocated to 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 DMRS (demodulation reference signal) (hereinafter referred to as "PBCH DMRS") used for demodulation of the PBCH. Can be identified as If the maximum number of SS/PBCH blocks is 64 in a frequency band of 6 GHz or higher, among 6 bits indicating the index of the SS/PBCH block, 3 bits of the LSB can be identified based on the PBCH DMRS, and the remaining 3 bits of the MSB are PBCH pages. Can be identified based on the load.

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

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

Referring to FIG. 8, a broadband component carrier (CC) may include a plurality of bandwidth parts (BWP). For example, a broadband CC may include 4 BWPs. The base station may transmit an SS/PBCH block in each of BWP #0 to 3 belonging to the broadband CC. The UE may receive an SS/PBCH block from 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 obtain system information (eg, RMSI (remaining minimum system information)) 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) through which a PDCCH including scheduling information of a PDSCH through which RMSI 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 SS/PBCH blocks associated with RMSI. The remaining SS/PBCH blocks may not be associated with RMSI. The SS/PBCH block associated with 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. An SS/PBCH block not associated with 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 "an operation of acquiring CORESET setting information from an SS/PBCH block (e.g., PBCH) → an operation of detecting a PDCCH based on the setting information of a CORESET → an operation of acquiring scheduling information of a PDSCH from the PDCCH → RMSI through the PDSCH It can be obtained by performing an operation of receiving ". The transmission resource of the PDCCH may be set by setting information of CORESET. The RMSI CORESET mapping pattern can be defined as follows. RMSI CORESET may be a CORESET used for transmission and reception of RMSI.

9A is a conceptual diagram illustrating RMSI CORESET mapping pattern #1 in a communication system, FIG. 9B is a conceptual diagram illustrating RMSI CORESET mapping pattern #2 in a communication system, and FIG. 9C is a diagram illustrating RMSI CORESET mapping pattern #3 in a communication system. It is a conceptual diagram.

9A to 9C, one RMSI CORESET mapping pattern among RMSI CORESET mapping patterns #1-3 may be used, and detailed configuration 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 set in a TDM manner. The RMSI PDSCH may mean a PDSCH through which RMSI is transmitted. In RMSI CORESET mapping pattern #2, CORESET (e.g., RMSI CORESET) and PDSCH (e.g., RMSI PDSCH) may be set in a TDM scheme, and PDSCH (e.g., RMSI PDSCH) is an SS/PBCH block And frequency division multiplexing (FDM). In RMSI CORESET mapping pattern #3, CORESET (e.g., RMSI CORESET) and PDSCH (e.g., RMSI PDSCH) may be set in a TDM manner, and CORESET (e.g., RMSI CORESET) and PDSCH (e.g. For example, RMSI PDSCH) may be configured in an SS/PBCH block and an 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 a frequency band exceeding 6GHz. The numerology of the SS/PBCH block may be different from that of “RMSI CORESET and RMSI PDSCH”. Here, the neurology may be a subcarrier spacing. In the RMSI CORESET mapping pattern #1, a combination of all neurons can be used. In RMSI CORESET mapping pattern #2, a combination of "{SS/PBCH block, RMSI CORESET/PDSCH} = {120 kHz, 60 kHz} or {240 kHz, 120 kHz"} 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 numerology of the SS/PBCH block and the numerology of the RMSI CORESET/PDSCH. The configuration 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 (e.g., start RB or end RB) and RBs of RMSI CORESET (e.g., start RB Alternatively, it may represent an offset between the end RB). Table B may indicate the number of search space sets per slot in each of the RMSI CORESET mapping patterns, an offset of RMSI CORESET, and an OFDM symbol index. Table B may indicate information for setting a monitoring occasion of the RMSI PDCCH. Each of Table A and Table B may be composed 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.

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

NR V2X communication (e.g., sidelink communication) is performed according to three transmission methods (e.g., unicast method, broadcast method, groupcast method) I can. When the unicast method is used, the first terminal can transmit data (eg, sidelink data) to the second terminal. When the broadcast scheme is used, the first terminal can transmit data to all terminals. When the groupcast method is used, the first terminal may transmit data to a group (eg, a groupcast group) composed of 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 following embodiments, the feedback information may be referred to as a “feedback signal”, a “physcial sidelink feedback channel (PSFCH) signal”, or the like. When an 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 the HARQ scheme. Alternatively, the first terminal may improve the probability of receiving data from 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, system information may be transmitted in a broadcast manner, and the terminal may not transmit feedback information on system information to the base station. Therefore, the base station may not know whether the system information has been successfully received from the terminal. In order 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 transmission procedure of feedback information. However, the target and/or the number of terminals participating in communication based on the groupcast method is limited, and data transmitted by the groupcast method must be received within a preset time (for example, data sensitive to delay). In this case, a procedure for transmitting feedback information may also be required in groupcast sidelink communication. 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 efficiently and stably transmitted and received.

In addition, data reliability in the receiving terminal can 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 transmission power. The power control method can be classified into an open-loop power control method and a closed-loop power control method. In the open-loop power control scheme, the transmitting terminal may determine the transmission power in consideration of the set and measured environment. 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 and interference. Accordingly, the receiving terminal may adjust the received power level (eg, a receiving power range) by performing an automatic gain control (AGC) operation in order to prevent a quantization error of a received signal and maintain an appropriate received power. In the communication system, the terminal can perform the AGC operation using the reference signal received from the 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 the AGC operation in sidelink communication. In sidelink communication, a transmitting terminal may first transmit a signal (e.g., a reference signal) to a receiving terminal before transmitting data, and the receiving terminal performs an AGC operation based on a signal received from the transmitting terminal, thereby providing a range of received power. (For example, the received power level) can be adjusted. After that, the transmitting terminal can 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.

[Feedback Channel Design Method]

In the NR system, sidelink communication (eg, V2X communication) may be performed in a unicast method or a groupcast method. In this case, the receiving terminal may transmit feedback information (eg, ACK or NACK) according to a preset method according to whether data reception is successful. Feedback information may be transmitted through a specific channel (eg, PSFCH). In addition, a signal for the AGC operation of the receiving terminal may be additionally transmitted in sidelink communication. The signal for the AGC operation may be transmitted before the feedback information is transmitted. In the embodiments below, methods of designing a feedback channel (eg, PSFCH) suitable for transmission of feedback information in unicast sidelink communication or groupcast sidelink communication will be described. Unicast sidelink communication may mean sidelink communication performed in a unicast manner.

The receiving terminal may perform the AGC operation to adjust the received power range (eg, the received power level). A signal for the AGC operation (eg, a reference signal) may be transmitted before data (eg, sidelink data) is transmitted. The receiving terminal may receive a signal from the transmitting terminal and may perform an AGC operation based on the received signal, thereby performing a data receiving operation according to an appropriate received power level.

The time interval required for the AGC operation may be 15 µs. In the case where the subcarrier spacing is 15 kHz in the NR system, the time period (eg, length) of one symbol (eg, OFDM symbol) may be 66.7 μs. In an NR system, when the subcarrier interval is 30 kHz, the time interval of one symbol (eg, OFDM symbol) may be 33.3 μs. In the following embodiments, 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. Therefore, using an entire symbol for AGC operation may result in waste of radio resources. To solve this problem, some time intervals of a symbol may be used as a time interval for AGC operation, and the remaining time intervals of a symbol may be used as a time interval for transmission of feedback information.

When a comb-type mapping method is used, a signal (eg, a sequence) may be alternately mapped in units of one or more subcarriers in a frequency domain within one symbol. In this case, after the IFFT (inverse fast Fourier transform) operation is performed, the same signal may be repeated in the time domain. In the present invention, feedback information (e.g., a feedback signal) may be mapped to the frequency domain based on a comb-type mapping method, and the front region of the repetition pattern of feedback information in the time domain is used as a time interval for the AGC operation. The remaining area (eg, the rear area) may be used as a time period for transmitting and receiving feedback information.

10 is a conceptual diagram illustrating a first embodiment of a method for mapping feedback information in a communication system.

Referring to FIG. 10, feedback information (eg, a sequence) may be mapped in a frequency domain using a comb-type mapping method. In this case, the feedback information may be mapped to some subcarriers, and the remaining subcarriers may be empty resource elements (REs). An IFFT operation may be performed on feedback information mapped to the frequency domain. When the IFFT operation is completed, the feedback information (eg, PSFCH signal) may be repeated in the time domain (eg, a time interval of one symbol (eg, OFDM symbol)). A region in front of the time interval (eg, symbol duration) of one symbol may be used for AGC operation. For example, the terminal may adjust the received power level by performing an AGC operation based on a signal (eg, PSFCH signal) received in the front region of the symbol, and the rear of the corresponding symbol based on the adjusted received power level. Feedback information (eg, PSFCH signal) may be received in the region.

11 is a conceptual diagram showing a first embodiment of a method for receiving feedback information in a communication system.

Referring to FIG. 11, the terminal may set an appropriate received power level by performing an AGC operation using a signal in the front region of the repetition pattern (eg, the front region of the symbol), and repeat based on the set received power level. A signal may be received in a region behind a pattern (eg, a region behind a symbol). The terminal may copy or duplicate a signal received in a region behind the repetition pattern, and may place a copied signal (eg, a duplicated signal or a repeated signal) in the front region of the repetition pattern. The signal located in the region behind the repeating pattern may be referred to as the original signal. The UE may reconstruct a sequence by performing an FFT operation on “the copied signal and the original signal”, and obtain feedback information from the restored sequence. In the frequency domain, the sequence (eg, feedback information) may be an orthogonal sequence (eg, a CAZAC sequence). In this case, the number of feedback information (eg, feedback signals) multiplexed in the same resource region may be proportional to the length of the sequence.

The size of the frequency resources required when the sequence of the same length and the comb-type mapping method are used is the size of the frequency resources required when the sequence mapping method (hereinafter referred to as "continuous mapping method") is used. It can be doubled. When the above-described method is applied when the symbol period for PSFCH transmission is limited, a separate symbol for AGC operation may not be required. In this case, time resources can be used efficiently.

Meanwhile, in order to increase the coverage of the feedback channel, the PSFCH may be transmitted using a plurality of symbols. A repetition pattern may be applied to each of a plurality of symbols in which the PSFCH is transmitted. As the number of symbols through which the PSFCH is transmitted increases, the number of repetition patterns may increase. In order to increase the number of multiplexable feedback signals (eg, feedback information), an orthogonal sequence may be used in the frequency domain, and an orthogonal cover code (OCC) may be applied in the time domain. In this case, the OCC can be applied to the remaining time intervals except for the time interval for the AGC operation in the repetition pattern.

For example, the feedback information may be mapped to the frequency domain by a comb-type mapping method, and after the IFFT operation, the PSFCH signal (eg, feedback information) may be repeated twice in a time interval of one symbol, This repetition pattern can be applied to two symbols. Accordingly, the PSFCH signal may be repeated four times in the time interval of two symbols. Here, one repetition pattern may mean one PSFCH signal. When one repetition pattern is set for the AGC operation, the number of multiplexable feedback signals may increase by applying OCC to the remaining three repetition patterns. When the number of repetition patterns other than the repetition pattern used for the AGC operation is an exponential multiple of 2, a Walsh code may be applied. When the number of repetition patterns other than the repetition pattern used for the AGC operation is an arbitrary number including an odd number, a discrete Fourier transform (DFT) code may be applied.

12 is a conceptual diagram illustrating a second embodiment of a method for mapping feedback information in a communication system.

Referring to FIG. 12, when a PSFCH signal is transmitted in a plurality of symbols, OCC may be applied in the time domain. In this case, the number of feedback signals that can be multiplexed in the PSFCH may increase. When the PSFCH signal is transmitted in two symbols, since two repetition patterns exist in one symbol, four repetition patterns may exist in two symbols. One of the four repeating patterns may be set as a time period for the AGC operation, and the number of multiplexable feedback signals may be increased by applying OCC to the remaining three repeating patterns. The AGC operation may be performed on an entire symbol rather than a partial time interval of one symbol according to a change in symbol length according to a subcarrier interval and a system environment. In this case, the OCC can be applied to two repeating patterns in the remaining one symbol. OCC can be applied as a time axis. Accordingly, the number of multiplexable feedback signals can be reduced.

Alternatively, the OCC may not be applied to two repeating patterns in the remaining one symbol. In this case, the number of multiplexable feedback signals may further decrease. Therefore, depending on the system environment, the operation of changing the number of symbols for PSFCH transmission, the operation of changing the time interval for the AGC operation, the operation of determining whether to apply OCC according to the above-described change operation, and the operation of changing the application length of OCC are performed. Can be. OCC can be applied in units of repeating patterns within a symbol. Alternatively, OCC may be applied in units of symbols. Information for setting of the above-described operations may be transmitted to the terminal through system information and/or a UE-specific RRC message.

In the above-described embodiments, when the comb-type mapping method is used, it has been described that the sequence is mapped at intervals of two subcarriers. However, in embodiments of the present invention, a comb-type mapping method in which a sequence is mapped according to an interval of an arbitrary number of subcarriers may also be applied. As the mapping interval of the sequence (eg, feedback information) increases, the number of repetition patterns may increase. Accordingly, the size of frequency resources required for transmission of a sequence of the same length may increase, and a time interval occupied by one repetition pattern within one symbol may decrease in inverse proportion.

In addition, the receiving terminal may receive all symbols having a repetition pattern and may perform an FFT operation on all symbols. In this case, the reception sequence (eg, feedback information) may be mapped only to some frequency resources (eg, subcarriers), and only interference and/or noise components may exist in the remaining frequency resources. Interference and/or noise components present in frequency resources to which feedback information is not mapped (eg, empty REs) may be used to determine a threshold for detection of a reception sequence mapped to the remaining frequency resources. .

In other embodiments, a continuous mapping scheme may be used instead of the comb-type mapping scheme in the frequency domain. When the continuous mapping scheme is used, a repetitive pattern may not be formed in the time domain. Therefore, some time periods of the symbol cannot be used for the AGC operation, and a separate symbol may be required for the AGC operation. When the number of multiplexable feedback information is the same, the size of frequency resources required when the continuous mapping method is used may be smaller than the size of frequency resources required when the comb-type mapping method is used. Therefore, when a continuous mapping scheme is used, resource efficiency in the frequency domain can be improved. Feedback information of a plurality of terminals may be multiplexed in one PSFCH. That is, one PSFCH may include feedback information of a plurality of terminals. Therefore, it may not be easy to change the location of a frequency resource through which feedback information (eg, PSFCH) is transmitted.

In a general data transmission procedure, data reception performance can be improved by transmitting general data through a frequency resource having a good channel state. However, in the transmission procedure of the PSFCH including feedback information of a plurality of terminals, since the channel state between the plurality of terminals may be different, even when the positions of frequency resources to which the feedback information is transmitted is changed in consideration of the channel state, the changed frequency It may not be easy to inform the locations of resources to a plurality of terminals. Therefore, it may be desirable to set positions of frequency resources to which feedback information (eg, PSFCH) is mapped to be fixed or semi-static. In the method proposed in the present invention, feedback information of a plurality of terminals may be multiplexed in the PSFCH, and the PSFCH may be repeated in the frequency domain. That is, the PSFCH may be distributed and arranged according to a preset interval in the frequency domain.

13 is a conceptual diagram illustrating a third embodiment of a method for mapping feedback information in a communication system.

Referring to FIG. 13, PSFCH (eg, feedback information) may be repeatedly distributed in the frequency domain. The PSFCH may be repeated several times (eg, 3 times) in the frequency domain. A symbol including feedback information may be mapped to each sequence (eg, by multiplying) to be mapped to the same frequency resource, and feedback information mapped to the same frequency resource may be repeatedly distributed and arranged in the frequency domain. Feedback information of a plurality of terminals may be multiplexed on the same resource, and multiplexed feedback information may be transmitted through the same resource. The terminal may map the feedback information to the sequence based on Equation 1 below.

In Equation 1, x _i (k) may be a mapping symbol in the k-th subcarrier in the PSFCH of the i-th terminal, α _i may be a symbol including feedback information of the i-th terminal, and s _i (k) is It may be a sequence in the k-th subcarrier of the i-th terminal. The length of the sequence may be N. In the embodiment shown in FIG. 13, N may be 12, and a sequence may be mapped to one resource block (RB). An embodiment of the present invention can be applied even when N has a different value instead of 12.

, 또는

으로 정의될 수 있다.When the PSFCH (eg, feedback information) is distributedly disposed in the frequency domain, the PSFCH may be distributedly disposed within a transmittable frequency range at equal intervals in order to obtain a maximum diversity gain. For example, when the number of RBs for PSFCH transmission is N _PSFCH , and the PSFCH is repeatedly distributed M times, the distance between the repeated PSFCHs (eg, repetition patterns) is N _PSFCH /M,

, or

Can be defined as

PSFCHs repeatedly distributed in the frequency domain may be referred to as “PSFCH groups”. The number of feedback information that can be multiplexed in one PSFCH may be limited according to the length of the sequence. For example, when the length (N) of the sequence is 12, up to 12 pieces of feedback information may be multiplexed in one PSFCH. Even when the length of the sequence (N) is 12, less than 12 pieces of feedback information may be multiplexed in one PSFCH to reduce interference between multiplexed feedback information. When a Zadoff-Chu (ZC) sequence is used, orthogonality between sequences may be guaranteed through a cyclic shift of the sequence. Accordingly, a plurality of feedback information may be multiplexed using different cyclic sequences (eg, cyclic shift) of the same sequence. In this case, when the cyclic sequence is applied by one sample in the sequence, if the length of the sequence is N, up to N pieces of feedback information may be multiplexed.

, 또는

개의 피드백 정보들이 다중화될 수 있다. Nc개의 샘플 간격을 보장하기 위해, 다중화 가능한 피드백 정보들의 최대 개수를

로 정의하는 것이 바람직할 수 있다.When the cyclic shift is applied at one sample interval, orthogonality between sequences may not be guaranteed according to the channel state. When the sample interval to which the cyclic shift is applied increases, orthogonality between sequences can be guaranteed even in a poor channel environment. When the cyclic shift is applied at two sample intervals, if the length of the sequence is N, up to N/2 pieces of feedback information may be multiplexed. When the cyclic shift is applied at Nc sample intervals, if the length of the sequence is N, then at most N/Nc,

, or

Feedback information may be multiplexed. In order to guarantee the Nc sample interval, the maximum number of multiplexable feedback information

It may be desirable to define as.

In the present invention, the maximum number of multiplexable feedback information can be adjusted by appropriately setting a sample interval to which a cyclic shift is applied according to a channel state. The base station may transmit configuration information of the cyclic shift (eg, a sample interval to which the cyclic shift is applied) to the terminal using system information and/or a UE-specific RRC message. The number of multiplexable feedback information may be determined based on a sequence length and a symbol interval to which a cyclic shift is applied. Accordingly, the number of feedback information that can be transmitted through one PSFCH group may also be determined. When the number of feedback information to be transmitted exceeds the number of feedback information that can be transmitted through one PSFCH group, a plurality of PSFCH groups may be defined, and the feedback information may be transmitted through a plurality of PSFCH groups.

14 is a conceptual diagram illustrating a fourth embodiment of a method for mapping feedback information in a communication system.

Referring to FIG. 14, a plurality of PSFCH groups (eg, PSFCH group #0, PSFCH group #1) may be configured, and feedback information may be transmitted through a plurality of PSFCH groups. When the number of feedback information to be transmitted exceeds the number of feedback information that can be transmitted through one PSFCH group (eg, PSFCH group #0), a new PSFCH group (eg, PSFCH group #1) is additionally It may be set, and feedback information may be transmitted through PSFCH groups #0 and #1. PSFCH group #1 may be repeatedly distributed in the frequency domain. In the frequency domain, PSFCH group #1 may be arranged at the same interval. A plurality of PSFCH groups may be set according to the number of feedback information required in the entire communication system. The base station may transmit the configuration information of the PSFCH group to the terminal using system information and/or a UE-specific RRC message.

The PSFCH may be a channel through which feedback information of a plurality of terminals is multiplexed. Accordingly, information on the time and frequency resources of the PSFCH can be shared by a plurality of terminals. In the present invention, the transmission region of the PSFCH may be limited to the last K symbol(s) in a slot (eg, a slot corresponding to a transmission time of the PSFCH). In the embodiments shown in FIGS. 13 and 14, K may be 1. Depending on the PSFCH structure, K may be set to a value exceeding 1.

When the last K symbol(s) of the slot are set as the transmission region of the PSFCH, interference between feedback information (or interference between feedback information and other signals) may be reduced even when multiplexed feedback information of a plurality of terminals is transmitted. I can. In this case, the frequency domain for PSFCH transmission is the entire system bandwidth, active BWP within the system bandwidth, or a bandwidth set for sidelink communication (e.g., V2X communication) within the system bandwidth in order to maximize the frequency diversity gain. For example, it may be desirable to be set to BWP). The bandwidth or BWP set for sidelink communication (eg, V2X communication) may be set to a resource pool (eg, the entire frequency domain in the resource pool). The K symbol(s) may be set for each transmission period of feedback information. When feedback information is transmitted for every L slot(s), the transmission region of the PSFCH may be set to the last K symbol(s) of the Lth slot in every transmission period. When a plurality of symbols are configured for PSFCH transmission, the repetition pattern of the PSFCH group can be applied to the time domain as well as the frequency domain. For example, PSFCH (eg, feedback information) may be repeatedly transmitted in a plurality of symbols.

15A is a conceptual diagram showing a fifth embodiment of a method for mapping feedback information in a communication system, and FIG. 15B is a conceptual diagram showing a sixth embodiment of a method for mapping feedback information in a communication system.

15A and 15B, the PSFCH may be transmitted according to a preset transmission period. The base station may transmit information indicating the transmission period of the PSFCH to the terminal using system information and/or a UE-specific RRC message. The last K symbols of the transmission period of the PSFCH may be configured as a common PSFCH resource region. In the embodiment shown in FIG. 15A, K may be 1. In the embodiment shown in FIG. 15B, K may be 3. In the common PSFCH resource region, the PSFCH (eg, feedback information) may be repeatedly distributed in time and frequency domains.

When a plurality of symbols are set as a common PSFCH resource region, the PSFCH group may be transmitted through a plurality of symbols. In this case, the transmission start time point of each of the PSFCH groups may be set differently. Through this, PSFCH groups may be evenly distributed among a plurality of symbols. The common PSFCH resource region may be fixed or semi-static. The base station may transmit configuration information of the common PSFCH resource region to the terminal using system information and/or a UE-specific RRC message. In the embodiments of the present invention, a guard period (GP) symbol for switching a transmission/reception operation is not mentioned, but when a GP symbol exists, the design method of the above-described feedback channel (eg, PSFCH) excludes the GP symbol. Can be applied to symbol(s). For example, when the GP symbol is located at the end of the slot, the last K symbol(s) in the corresponding slot may be composed of symbol(s) excluding the GP symbol.

[Feedback resource allocation method]

Feedback information of a plurality of terminals may be multiplexed in one PSFCH by multiplying by a specific sequence, and the multiplexed feedback information may be transmitted through one PSFCH. When a plurality of PSFCH groups are configured, the PSFCH resource may mean a PSFCH group and a specific sequence within the PSFCH group. For example, the PSFCH resource may include a PSFCH group index and a sequence index within a corresponding PSFCH group. It may be necessary to establish a mapping relationship between feedback information of a specific terminal and a PSFCH resource (eg, a PSFCH resource through which the corresponding feedback information is transmitted). In the present invention, a method of explicitly or implicitly setting a PSFCH resource through which feedback information of a specific terminal is transmitted will be proposed.

The PSFCH resource may be explicitly indicated to a terminal to transmit feedback information. The PSFCH resource may include a feedback resource and/or an index of a feedback resource. The feedback resource and/or the index of the feedback resource may be indicated by one or more combinations of the PSFCH group index and the sequence index within the corresponding PSFCH group. The configuration information of the PSFCH resource may be included in sidelink control information (SCI) (eg, scheduling information) transmitted through a physical sidelink control channel (PSCCH). The UE can check the configuration information of the PSFCH resource by receiving the SCI, and can transmit the feedback information (eg, PSFCH) by using the PSFCH resource. Here, the PSFCH resource may be dynamically configured in every data transmission procedure. Alternatively, the configuration information of the PSFCH resource may be transmitted using a UE-specific RRC message. The UE may check the configuration information of the PSFCH resource by receiving the UE-specific RRC message, and may transmit feedback information (eg, PSFCH) using the PSFCH resource. Here, the PSFCH resource may be semi-statically configured.

The configuration information of the PSFCH resource may be implicitly indicated. For example, the PSFCH resource is a specific control channel element (CCE) index and/or a data channel (eg, PDSCH or PSSCH (physical sidelink shared channel)) constituting a control channel (eg, PDCCH or PSCCH). It may be implicitly indicated by a constituting specific resource block (RB) index. Accordingly, the UE may select a PSFCH resource based on a specific CCE index constituting the control channel and/or a specific RB index constituting the data channel, and may transmit feedback information using the PSFCH resource. In this case, the specific CCE index may be the lowest CCE index or the largest CCE index among CCE indexes for the corresponding control channel. The specific RB index may be the lowest RB index or the largest RB index among RB indexes for the corresponding data channel. Alternatively, the PSFCH resource may be implicitly set according to a specific index of a subchannel, which is a basic unit of sidelink resource allocation. In this case, the specific subchannel index may be the lowest subchannel index or the largest subchannel index among subchannel indexes for the sidelink.

16A is a conceptual diagram showing a first embodiment of a method for indicating PSFCH resources in a communication system, and FIG. 16B is a conceptual diagram showing a second embodiment of a method for indicating PSFCH resources in a communication system.

)는 아래 수학식 2에 기초하여 결정될 수 있고, PSFCH 그룹 내에서 시퀀스 인덱스(

)는 아래 수학식 3에 기초하여 결정될 수 있다.16A and 16B, PSFCH resources (eg, feedback resources) used for transmission of feedback information may be implicitly set according to a subchannel index. In the embodiment shown in FIG. 16A, the PSFCH resource may be implicitly set according to the subchannel index. When the number of feedback information to be transmitted exceeds the number of multiplexable feedback information in one PSFCH group (eg, PSFCH group #0), a new PSFCH group (eg, PSFCH group #1) is set. I can. The subchannel index may be defined as i _subch , and the number of multiplexable feedback information in one PSFCH group may be defined as M _PSFCH . In this case, the PSFCH group index according to the subchannel index (

) May be determined based on Equation 2 below, and the sequence index (

) May be determined based on Equation 3 below.

In the embodiment shown in FIG. 16B, data transmission may be performed through a plurality of subchannels. In this case, feedback information on data may be transmitted through a PSFCH resource (eg, a feedback resource) mapped to a subchannel having the lowest index among a plurality of subchannels to which the corresponding data is transmitted. When a PSFCH resource (eg, a feedback resource) is implicitly set based on a specific resource, the same PSFCH resource may always be used. For example, when a PSFCH resource mapped to the lowest subchannel index among a plurality of subchannel indices for data transmission is used for transmission of feedback information for corresponding data, it is mapped to a subchannel having index #0. The PSFCH resource can always be used for transmission of feedback information.

In a neighboring cell or in another case, the same subchannel may be used for data transmission, and a feedback resource (eg, PSFCH resource) accordingly may be implicitly set. In this case, since the feedback information is transmitted through the same feedback resource, interference may occur between transmissions of the feedback information. Accordingly, even when data is transmitted through the same subchannel in the present invention, by applying an additional offset, interference due to transmission of feedback information through an implicitly set feedback resource can be minimized. Here, the offset may be signaled using one or more of system information, a UE-specific RRC message, and control information for scheduling data transmission. The offset may be used to determine the PSFCH group index and/or the sequence index within the PSFCH group. The above-described offset may be a signaled value for other purposes. For example, the offset may be a source ID or a destination ID included in the control information. Alternatively, the offset may be a value transmitted through a UE-specific RRC message for generation of a DMRS sequence.

The feedback information may be set to be transmitted according to a preset transmission period. For example, the feedback information may be set to be transmitted every L slots. In this case, a feedback channel through which feedback information is transmitted (eg, PSFCH) may also be set to be transmitted every L slots. In consideration of a processing time for a data reception operation and a feedback information transmission operation, feedback information on data previously received through a plurality of slots may be transmitted through a corresponding feedback channel. In order to transmit feedback information on data received through a plurality of slots and to set a resource for transmission of feedback information, feedback information on data received through a plurality of slots are at the same time point (e.g., the same slot ), feedback information for data received through different slots may be configured to be mapped to different PSFCH groups. To this end, a slot index may be applied in a procedure for determining the PSFCH group index. For example, it may be possible to apply different PSFCH group indices through a modulo operation of the slot index.

)는 아래 수학식 4에 기초하여 결정될 수 있다.For example, when L is 4, the PSFCH may be transmitted every 4 slots, and feedback information on data received through 4 slots from a specific time before the transmission time of the PSFCH will be transmitted through the corresponding PSFCH. I can. In this case, feedback information for data received through the first slot among four slots may be transmitted through PSFCH groups #0, #4, #8, etc., and received through the second slot among four slots. Feedback information on the received data may be transmitted through PSFCH groups #1, #5, #9, etc., and feedback information on data received through the third slot among four slots is PSFCH groups #2, #6. , #10, etc., and feedback information for data received through the fourth slot among the four slots may be transmitted through PSFCH groups #3, #7, #11, and the like. That is, the PSFCH group index (

) May be determined based on Equation 4 below.

In order to map feedback information on data received through different slots to different PSFCH groups, different PSFCH resources must be set for each slot in which data is received, so resources may not be used efficiently. Therefore, even when feedback information for data received through a plurality of slots is transmitted at the same time, different PSFCH groups are not set for each slot in which data is received, and PSFCH resources are shared within the resource area of the entire PSFCH group. Can be. In this case, since feedback resources necessary for transmission of feedback information on data received through a plurality of slots need to be distinguished, a slot index may be applied to set the feedback resources.

)는 아래 수학식 5에 기초하여 결정될 수 있다.For example, if different PSFCH groups are not allocated for each slot, feedback resources for data received through subchannel #0 of the first slot and data received through subchannel #0 of the second slot Feedback resources may be mapped to the same PSFCH group. In this case, when determining the sequence index in the PSFCH group, feedback resources for data transmitted through different slots can be classified by additionally applying a slot index to the subchannel index. Sequence index within the PSFCH group (

) May be determined based on Equation 5 below.

When the sequence index in the PSFCH group is determined based on Equation 5, feedback resources for data transmitted through subchannels having the same index in different slots may be classified. When data is transmitted through a plurality of subchannels, only feedback resources mapped to a subchannel having a specific index (eg, the lowest index or the largest index) among the plurality of subchannels are feedback resources for the corresponding data. May be used, and a feedback resource adjacent to the corresponding feedback resource may not be used for actual transmission. Therefore, according to the above-described method, the feedback resource can be used efficiently.

Feedback information may be set to be transmitted every L slots so that no collision occurs between feedback resources mapped to different slots. In this case, the basic unit of data transmission may be set to L subchannels. When the basic unit of data transmission is set, feedback resources may be implicitly set without collision even when a slot index is additionally applied to a subchannel index. However, when the basic unit of data transmission increases, data transmission resources may not be used efficiently. When it is set that feedback information is transmitted for every L slots, the basic unit of data transmission may be set to K subchannel(s). K can be less than L. K may be set to an appropriate value according to the transmission resource of the feedback information and/or the transmission resource of the data. The base station may transmit K using one or more of system information, a UE-specific RRC message, and control information scheduling data transmission.

Alternatively, the feedback resource may be implicitly set based on specific resource information without applying a slot index. In addition to this, feedback resources can be distinguished between slots by applying unique information of each terminal. Feedback resources different between slots may be implicitly set by applying an offset to specific resource information. The base station may transmit the offset using one or more of system information, a UE-specific RRC message, and control information for scheduling data transmission. The offset may be used to determine the PSFCH group index and/or the sequence index within the PSFCH group. The offset may be a signaled value for other purposes. For example, the offset may be a source ID or a destination ID included in the control information. Alternatively, the offset may be a value transmitted through a UE-specific RRC message to generate a DMRS sequence.

Alternatively, the feedback information may be transmitted according to a preset transmission period. In this case, all subchannel indices may be set differently within a transmission period, and a feedback resource may be implicitly set based on this.

17 is a conceptual diagram illustrating a third embodiment of a method for indicating PSFCH resources in a communication system.

Referring to FIG. 17, a common PSFCH resource region may be configured for every four slots, and feedback information may be repeatedly distributed and arranged in a common PSFCH resource region. Since the PSFCH is transmitted every four slots, indices of subchannels belonging to the four slots (eg, a data area of four slots) may be numbered differently without distinction between slots. That is, the indexes of the subchannels may be set differently in four slots instead of one slot. The feedback resource may be implicitly indicated based on the subchannel index set as described above. In this case, in order to set the feedback resource, the slot index may not be considered.

In the embodiment shown in FIG. 17, the subchannel index is numbered preferentially in the frequency domain, but the subchannel index may be numbered preferentially in the time domain. In addition, in the embodiment illustrated in FIG. 17, the time interval of one subchannel is illustrated as one slot, but the time interval of one subchannel may be a subslot smaller than that of the slot. When one slot includes a plurality of subslots, a plurality of subchannels may be set in one slot. A time interval required for a demodulation operation, a decoding operation, and the like may exist between the transmission time of data and the transmission time of feedback information on the corresponding data. In the embodiments, a slot is used as a term indicating a specific time unit, but terms other than the slot may be used to indicate a specific time unit.

Meanwhile, in the NR system, sidelink communication (eg, V2X communication) may be performed in a unicast method or a groupcast method. The UE may transmit ACK or NACK depending on whether data is received. A method of transmitting feedback information in unicast sidelink communication may be different from a method of transmitting feedback information in groupcast sidelink communication. In unicast sidelink communication, the relationship between the transmitting terminal and the receiving terminal may be a one-to-one correspondence, and the receiving terminal transmits feedback information (eg, ACK or NACK) according to whether or not data is received. Can be transferred to.

In groupcast sidelink communication, a group (eg, groupcast group) including one transmitting terminal and a plurality of receiving terminals may be set. The relationship between one transmitting terminal and a plurality of receiving terminals may be a one-to-many correspondence relationship. A plurality of receiving terminals belonging to the same group may transmit feedback information according to whether data is received to one transmitting terminal. In groupcast sidelink communication, a feedback transmission scheme can be applied in various ways. A plurality of receiving terminals belonging to the same group may transmit NACK using the same feedback resource only when data reception fails. This operation may be referred to as "option 1". Alternatively, a plurality of receiving terminals belonging to the same group may transmit ACK or NACK using different feedback resources depending on whether data is received. This operation may be referred to as "option 2". Whether to apply option 1 or option 2 may be determined according to system settings. In groupcast sidelink communication, the base station may transmit system information including information indicating a feedback scheme (eg, option 1 or option 2), a UE-specific RRC message, and/or control information to the terminal.

Unicast sidelink communication can coexist with groupcast sidelink communication. Therefore, various feedback methods according to various communication methods can coexist. Accordingly, in the present invention, when various feedback methods according to various communication methods coexist, methods of allocating feedback resources are proposed. When unicast sidelink communication and groupcast sidelink communication coexist, three cases may be defined according to a feedback method.

Case 1 may be a case in which option 1 is used in unicast sidelink communication and groupcast sidelink communication. Case 2 may be a case in which option 2 is used in unicast sidelink communication and groupcast sidelink communication. Case 3 may be a case in which options 1 and 2 are used in unicast sidelink communication and groupcast sidelink communication.

In the unicast sidelink communication according to case 1, only one feedback resource may be required for a feedback operation between a transmitting terminal and a receiving terminal. In the groupcast sidelink communication according to case 1, only one feedback resource may be required for a feedback operation between one transmitting terminal and a plurality of receiving terminals. Here, the feedback resource may be implicitly set based on a specific index of a resource (eg, a subchannel) through which data is transmitted, an ID of a transmitting terminal, and/or an ID of a receiving terminal. Alternatively, the feedback information may be explicitly set by control information including scheduling information. Therefore, feedback resources can coexist in the unicast sidelink communication and the groupcast sidelink communication according to Case 1. In case 1, a common feedback resource region for unicast sidelink communication and groupcast sidelink communication may be set, and the feedback resource may be set implicitly or explicitly regardless of the feedback method.

When Option 2 is used in unicast sidelink communication and groupcast sidelink communication according to case 2, it may be difficult to share feedback resources. When a plurality of feedback resources for groupcast sidelink communication are configured in the same feedback resource area, feedback resources for groupcast sidelink communication may collide with feedback resources for unicast sidelink communication. Accordingly, the feedback resource region for unicast sidelink communication according to case 2 may be set to be classified according to the feedback resource region for groupcast sidelink communication according to case 2 and option 1. Time domains or frequency domains to which different feedback resource domains belong may be different. In addition, PSFCH groups to which different feedback resource regions belong may be different.

In case 3, the feedback resource may be set according to the combination of cases 1 and 2 described above. The feedback resource region for unicast sidelink communication may be set to be the same as the feedback resource region for groupcast sidelink communication according to option 1. In this case, the feedback resource region may be shared in unicast sidelink communication and groupcast sidelink communication. The feedback resource region for unicast sidelink communication may be set differently from the feedback resource region for groupcast sidelink communication according to option 2. In this case, each of the time domain and the frequency domain of the feedback resource domain for unicast sidelink communication may be separated from the time domain and the frequency domain of the feedback resource domain for groupcast sidelink communication. In addition, the PSFCH group to which the feedback resource region for unicast sidelink communication belongs may be distinguished from the PSFCH group to which the feedback resource region for groupcast sidelink communication belongs. The above-described embodiments can be applied not only when only one feedback information is transmitted per TB (transport block), but also when feedback information of each of a plurality of code block groups (CBGs) constituting one TB is transmitted.

When option 2 is used in groupcast sidelink communication, a method of individually setting feedback resources for each of a plurality of terminals belonging to a group may be required. For example, the feedback resource is resource information (e.g., subchannel index) or specific information (e.g., group ID, transmitting terminal ID (e.g., source ID)), receiving terminal ID (e.g., destination ID)), a plurality of terminals belonging to the group may have the same information. Therefore, it may be difficult to set a feedback resource for each of a plurality of terminals belonging to a group. When option 2 is used in groupcast sidelink communication, a separate feedback resource area for groupcast sidelink communication may be set based on information representing the group, and information of each of a plurality of terminals belonging to the group Different feedback resources may be set in the corresponding feedback resource area based on the.

Each of the time domain, frequency domain, and PSFCH group of the feedback resource domain for groupcast sidelink communication according to option 2 can be distinguished from the time domain, frequency domain, and PSFCH group of the feedback resource domain for unicast sidelink communication. have. In addition, each of the time domain, the frequency domain, and the PSFCH group of the feedback resource domain for groupcast sidelink communication according to option 2 are the time domain, the frequency domain, and the feedback resource domain for groupcast sidelink communication according to option 1 It can be distinguished from the PSFCH group.

In order to allocate different feedback resources to a plurality of terminals belonging to a group, the feedback resource area for groupcast sidelink communication according to option 2 is information representing the group (e.g., subchannel index, group ID, transmission Terminal ID and receiving terminal ID), and feedback resources in the corresponding feedback resource area may be set differently based on information of each of a plurality of terminals belonging to the group. Here, the information of each of the plurality of terminals belonging to the group may be individually signaled to each of the receiving terminals in a setup procedure for groupcast sidelink communication between the transmitting terminal and the receiving terminal. Information of each of the plurality of terminals belonging to the group may be an offset that distinguishes different terminals within the feedback resource region.

Alternatively, a result value may be obtained by substituting a unique identifier (e.g., a terminal ID) of each of the receiving terminals into a specific function (hashing function) for randomization, and the feedback resource is the result value. It can be set based on. The signaling resources and complexity required for this method may be reduced compared to the signaling resources and complexity required for the method of individually signaling the offset, but when this method is used, feedback resources between a plurality of terminals belonging to the group collide. can do.

Alternatively, a separate feedback resource area for groupcast sidelink communication according to option 2 may not be set, and a feedback resource area for unicast sidelink communication or groupcast sidelink communication according to option 1 is option 2 It can be shared for groupcast sidelink communication according to. As in the above-described embodiments, a feedback resource (eg, a feedback resource region) may be implicitly set based on specific information, and additionally, a feedback resource is included in unique information of each of a plurality of terminals belonging to the group. It may be set to be distinguished on the basis of. Different feedback resources may be implicitly set by applying an offset to specific information. The offset may be transmitted using one or more of system information, a UE-specific RRC message, and control information scheduling data transmission. The offset may be used to determine the PSFCH group index and/or the sequence index within the PSFCH group. The offset may be a signaled value for other purposes. For example, the offset may be a source ID or a destination ID included in the control information. Alternatively, the offset may be a value transmitted through a UE-specific RRC message for generation of a DMRS sequence.

When option 2 is used in groupcast sidelink communication, each of a plurality of terminals belonging to the group may transmit feedback information. A plurality of receiving terminals belonging to the group may receive the same data from the transmitting terminal. It may be advantageous for a particular receiving terminal that has not received data to receive data again from another receiving terminal that has successfully received the data instead of the transmitting terminal. Accordingly, in the present invention, a feedback method for retransmitting data between a plurality of receiving terminals belonging to a group is proposed. When option 2 is used in groupcast sidelink communication, each of a plurality of receiving terminals belonging to the group may transmit feedback information on data. Accordingly, a specific receiving terminal belonging to the group can check whether data has been successfully received from another receiving terminal based on the feedback information.

Even if a plurality of receiving terminals belonging to a group use different feedback resources, if feedback information is transmitted at the same time, receiving terminals other than the transmitting terminal in the group may not be able to obtain the feedback information transmitted by other receiving terminals. . Accordingly, a plurality of receiving terminals belonging to a group may be classified into a plurality of subgroups according to a specific criterion, and transmission times of feedback information of each of the plurality of subgroups may be set differently. For example, receiving terminal #1 belonging to subgroup #1 may transmit feedback information at transmission time #1, and receiving terminal #2 belonging to subgroup #2 may transmit feedback information at transmission time #2. Transmission time #1 may be set differently from transmission time #2.

When the transmission time of feedback information between subgroups is set differently, UE #1 belonging to subgroup #1 can transmit an ACK to the transmitting UE at transmission time #1 when data reception is successful, and transmission time #2 In order to obtain feedback information of terminal #2 belonging to subgroup #2, a monitoring operation may be performed. If the feedback information of terminal #2 belonging to subgroup #2 is NACK, the terminal to retransmit data to terminal #2 (for example, the transmitting terminal or terminal #1) is "distance between the transmitting terminal and terminal #2 and/ Alternatively, it may be determined based on a comparison result between the channel state" and "the distance and/or the channel state between the terminal #1 and the terminal #2". When the "distance between the transmitting terminal and the terminal #2" is shorter than the "distance between the terminal #1 and the terminal #2", the transmitting terminal may retransmit data to the terminal #2. That is, the transmitting terminal may be determined as a terminal to retransmit data to terminal #2. Alternatively, if the "channel state between the transmitting terminal and the terminal #2" is worse than the "channel state between the terminal #1 and the terminal #2", the terminal #1 may retransmit data to the terminal #2. That is, terminal #1 may be determined as a terminal to retransmit data to terminal #2. By performing the above-described operation, data reception performance in terminal #2 can be improved.

Other parameter(s) capable of determining data reception performance as well as distance and channel state may be used as a criterion for determining a terminal performing data retransmission. Criteria (eg, parameters) used to determine a terminal that performs data retransmission may be set in advance. Or, the criterion (e.g., parameter) used to determine the terminal performing data retransmission is to be transmitted using one or more of system information, UE-specific RRC message, and control information for scheduling data transmission. I can.

When the transmission timing of the feedback information is set differently for each subgroup, the transmission timing of the subgroup having a relatively high data reception probability (for example, transmission timing #1 of subgroup #1) is relatively low according to a specific criterion. It is preferable to set the transmission time point prior to the transmission time point of the subgroup having the data reception probability (eg, the transmission time point #2 of the subgroup #2). Transmission times of the feedback information may be different symbols or different slots. Alternatively, transmission times of the feedback information may be expressed in different time units.

Among the terminals belonging to subgroup #1, the terminal(s) performing the operation of monitoring feedback information and retransmitting data of the terminals belonging to subgroup #2 are not required to receive previous data or all terminals that have successfully received previous data. Among all successful terminals, it may be limited to a specific terminal(s). Terminal(s) that perform a monitoring operation of feedback information of a terminal belonging to another subgroup and an operation of retransmitting data may be preset. Alternatively, the terminal(s) that perform the monitoring operation of the feedback information of the terminal belonging to the other subgroup and the retransmission operation of data may be set in the groupcast sidelink communication setting procedure. Alternatively, the information of the terminal(s) performing the monitoring operation of the feedback information of the terminal belonging to the other subgroup and the retransmission of data is at least one of system information, a UE-specific RRC message, and control information for scheduling data transmission. Can be transmitted using

In addition, the criteria (e.g., parameters) used to classify subgroups are the distance between terminals, channel quality information (e.g., RSRP (reference signal received power)), and the probability of data reception success (e.g. , Accumulated reception success probability), and the like. In addition, not only the above-described criteria but also other criteria (eg, other parameters) capable of determining data reception performance may be used to classify the subgroups. The criteria (eg, parameters) used to classify the subgroups may be transmitted using one or more of system information, UE-specific RRC messages, and control information for scheduling data transmission. In the above-described embodiments, two subgroups, two transmission times for feedback information, and an operation of monitoring feedback information for one terminal per subgroup and an operation of retransmitting data have been described. It can be applied to subgroups, a plurality of transmission times for feedback information, and a plurality of terminals for each subgroup.

The methods according to the present invention may be implemented in the form of program instructions that can be executed through various computer means and recorded 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 usable to those skilled in computer software.

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

Although described with reference to the above embodiments, those skilled in the art will understand that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention described in the following claims. I will be able to.

Claims (1)

As a method of operating a first terminal in sidelink communication,
Receiving data from a second terminal through one or more subchannels;
Checking a feedback resource mapped to the one or more subchannels; And
And transmitting a physical sidelink feedback channel (PSFCH) including feedback information for the data to the second terminal using the feedback resource,
The data is transmitted in a groupcast method, and feedback information of a plurality of terminals for the data is multiplexed in the PSFCH.

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