KR20210130119A - Method and apparatus for harq feedback in nr v2x - Google Patents

Abstract

The present specification relates to a communication method of a terminal performing sidelink communication with another terminal which comprises the following steps of: receiving two or more sidelink data channels from another terminal; bundling or multiplexing some of the received sidelink data channels to configure HARQ information; and transmitting the bundled or multiplexed HARQ information to another terminal. Disclosed are the communication method of the terminal and the terminal thereof.

Description

HARQ feedback method and apparatus in NR V2X {METHOD AND APPARATUS FOR HARQ FEEDBACK IN NR V2X}

The present disclosure relates to a communication method for performing sidelink communication with another terminal in NR V2X, specifically, a HARQ feedback method and an apparatus thereof.

The demand for large-capacity data processing, the demand for high-speed data processing, and the demand for various services using wireless terminals in vehicles and industrial sites are occurring. As described above, there is a need for a technology for a high-speed, large-capacity communication system capable of processing various scenarios and large-capacity data such as video, wireless data, and machine-type communication data beyond a simple voice-oriented service.

To this end, ITU-R discloses the requirements for adopting the IMT-2020 international standard, and research on next-generation wireless communication technology to meet the requirements of IMT-2020 is in progress.

In particular, 3GPP is conducting research on the LTE-Advanced Pro Rel-15/16 standard and the NR (New Radio Access Technology) standard in parallel to satisfy the IMT-2020 requirements referred to as 5G technology, and the two standard technologies to be approved as a next-generation wireless communication technology.

In particular, LTE V2X was developed, but NR V2X was not developed.

In the background described above, an embodiment intends to propose a HARQ-related procedure in NR V2X.

An embodiment devised to solve the above problem is a communication method of a terminal performing sidelink communication with another terminal, the step of receiving two or more sidelink data channels from another terminal, among the received sidelink data channels It provides a communication method of a terminal comprising the steps of configuring HARQ information by bundling or multiplexing a part, and transmitting the bundled or multiplexed HARQ information to the other terminal.

In addition, another embodiment is a terminal performing sidelink communication with another terminal, a receiver receiving two or more sidelink data channels from another terminal, and bundling or multiplexing some of the received sidelink data channels to configure HARQ information It provides a terminal including a controller and a transmitter for transmitting bundled or multiplexed HARQ information to the other terminal.

According to the present disclosure, HARQ ACK/NACK information may be transmitted in terms of data transmission stability in NR V2X, and overhead may be reduced when transmitting ACK/NACK information.

1 is a diagram schematically illustrating a structure of an NR wireless communication system to which this embodiment can be applied.
2 is a diagram for explaining a frame structure in an NR system to which this embodiment can be applied.
3 is a diagram for explaining a resource grid supported by a radio access technology to which this embodiment can be applied.
4 is a diagram for explaining a bandwidth part supported by a radio access technology to which the present embodiment can be applied.
5 is a diagram exemplarily illustrating a synchronization signal block in a radio access technology to which the present embodiment can be applied.
6 is a diagram for explaining a random access procedure in a radio access technology to which the present embodiment can be applied.
7 is a diagram for explaining CORESET.
8 is a diagram for explaining, for example, a DMRS structure for a conventional sidelink and a DMRS structure for a sidelink to which this embodiment can be applied.
9 is a diagram for explaining various scenarios for V2X communication.
10 shows an example of UE1 (UE1), UE2 (UE2) performing sidelink communication, and a sidelink resource pool used by them.
11 illustrates the type of V2X transmission resource pool.
12 shows a method for performing SPS activation (request), re-activation (re-request) and/or release, change triggered by the UE.
13 shows the SA period.
14 is a diagram for explaining a method of bundling and transmitting HARQ feedback information in NR V2X, according to an embodiment.
15 is a diagram for explaining a method of bundling and transmitting HARQ feedback information in NR V2X, according to another embodiment.
16 is a diagram for explaining a method of multiplexing and transmitting HARQ feedback information in NR V2X, according to another embodiment.
17 shows the format of PSCCH related to HARQ in NR V2X, according to another embodiment.
18 shows an example of one of the PSCCH formats.
FIG. 19 shows HARQ feedback information according to the phase difference of the PSCCH of FIG. 18 .
20 is a diagram showing the configuration of a base station 2000 according to another embodiment.
21 is a diagram showing the configuration of a user terminal 2100 according to another embodiment.

Hereinafter, some embodiments of the present technical idea will be described in detail with reference to exemplary drawings. In adding reference numerals to components of each drawing, the same components may have the same reference numerals as much as possible even though they are indicated in different drawings. In addition, in describing the present technical idea, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present technical idea, the detailed description may be omitted.

In addition, in describing the components of the present embodiments, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only for distinguishing the elements from other elements, and the essence, order, order, or number of the elements are not limited by the terms. When it is described that a component is “connected”, “coupled” or “connected” to another component, the component may be directly connected or connected to the other component, but other components may be interposed between each component. It will be understood that each component may be “interposed” or “connected”, “coupled” or “connected” through another component.

In addition, terms and technical names used in this specification are for describing specific embodiments, and technical ideas are not limited to the terms. The terms described below may be interpreted as meanings generally understood by those of ordinary skill in the technical field to which the present technical idea belongs, unless otherwise defined. When the term is an incorrect technical term that does not accurately express the present technical idea, it should be understood by being replaced with a technical term that can be correctly understood by those skilled in the art. In addition, the general terms used in this specification should be interpreted according to the definition in the dictionary or according to the context before and after, and should not be interpreted in an excessively reduced meaning.

A wireless communication system in the present specification refers to a system for providing various communication services such as voice and data packets using radio resources, and may include a terminal, a base station, and a core network.

The present embodiments disclosed below may be applied to a wireless communication system using various wireless access technologies. For example, the present embodiments are CDMA (code division multiple access), FDMA (frequency division multiple access), TDMA (time division multiple access), OFDMA (orthogonal frequency division multiple access), SC-FDMA (single carrier frequency division multiple) access) may be applied to various radio access technologies. CDMA may be implemented with a radio technology such as universal terrestrial radio access (UTRA) or CDMA2000. TDMA may be implemented with a radio technology such as global system for mobile communications (GSM)/general packet radio service (GPRS)/enhanced data rates for GSM evolution (EDGE). OFDMA may be implemented with a wireless technology such as Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, and evolved UTRA (E-UTRA). IEEE 802.16m is an evolution of IEEE 802.16e, and provides backward compatibility with a system based on IEEE 802.16e. UTRA is part of the universal mobile telecommunications system (UMTS). 3rd generation partnership project (3GPP) long term evolution (LTE) is a part of evolved UMTS (E-UMTS) that uses evolved-UMTS terrestrial radio access (E-UTRA), and employs OFDMA in downlink and SC in uplink - Adopt FDMA. As such, the present embodiments may be applied to currently disclosed or commercialized radio access technologies, or may be applied to radio access technologies currently under development or to be developed in the future.

On the other hand, in the present specification, a terminal is a generic concept meaning a device including a wireless communication module that performs communication with a base station in a wireless communication system, and is a UE in WCDMA, LTE, HSPA, and IMT-2020 (5G or New Radio). (User Equipment), of course, should be interpreted as a concept including all of MS (Mobile Station), UT (User Terminal), SS (Subscriber Station), wireless device, etc. in GSM. In addition, the terminal may be a user portable device such as a smart phone depending on the type of use, and in a V2X communication system may mean a vehicle, a device including a wireless communication module in the vehicle, and the like. In addition, in the case of a machine type communication system, it may mean an MTC terminal, an M2M terminal, etc. equipped with a communication module to perform machine type communication.

A base station or cell in the present specification refers to an end that communicates with a terminal in terms of a network, a Node-B (Node-B), an evolved Node-B (eNB), gNode-B (gNB), a Low Power Node (LPN), Sector, site, various types of antennas, base transceiver system (BTS), access point, point (eg, transmission point, reception point, transmission/reception point), relay node (Relay Node) ), mega cell, macro cell, micro cell, pico cell, femto cell, RRH (Remote Radio Head), RU (Radio Unit), and small cell (small cell), etc.

In the various cells listed above, since there is a base station controlling each cell, the base station can be interpreted in two meanings. 1) in relation to the radio area, it may be the device itself providing a mega cell, a macro cell, a micro cell, a pico cell, a femto cell, or a small cell, or 2) may indicate the radio area itself. In 1), the devices providing a predetermined radio area are controlled by the same entity, or all devices interacting to form a radio area cooperatively are directed to the base station. A point, a transmission/reception point, a transmission point, a reception point, etc. become an embodiment of a base station according to a configuration method of a wireless area. In 2), the radio area itself in which the signal is received or transmitted from the viewpoint of the user terminal or the neighboring base station may be indicated to the base station.

In the present specification, a cell is a component carrier having a coverage of a signal transmitted from a transmission/reception point or a coverage of a signal transmitted from a transmission/reception point, and the transmission/reception point itself. can

Uplink (Uplink, UL, or uplink) refers to a method of transmitting and receiving data by the terminal to and from the base station, and downlink (Downlink, DL, or downlink) refers to a method of transmitting and receiving data to and from the terminal by the base station do. A downlink may mean a communication or communication path from a multi-transmission/reception point to a terminal, and an uplink may mean a communication or communication path from the terminal to a multi-transmission/reception point. In this case, in the downlink, the transmitter may be a part of multiple transmission/reception points, and the receiver may be a part of the terminal. Also, in the uplink, the transmitter may be a part of the terminal, and the receiver may be a part of the multi-transmission/reception point.

The uplink and downlink transmit and receive control information through a control channel such as a Physical Downlink Control CHannel (PDCCH), a Physical Uplink Control CHannel (PUCCH), etc., and a Physical Downlink Shared CHannel (PDSCH), a Physical Uplink Shared CHannel (PUSCH), etc. Data is transmitted and received by configuring the same data channel. Hereinafter, a situation in which signals are transmitted/received through channels such as PUCCH, PUSCH, PDCCH and PDSCH may be expressed in the form of 'transmitting and receiving PUCCH, PUSCH, PDCCH and PDSCH'.

For clarity of explanation, the present technical idea is mainly described below for a 3GPP LTE/LTE-A/NR (New RAT) communication system, but the present technical features are not limited thereto.

After research on 4G (4th-Generation) communication technology, 3GPP is conducting research on 5G (5th-Generation) communication technology to meet the requirements of ITU-R's next-generation wireless access technology. Specifically, 3GPP is conducting research on LTE-A pro, which improved LTE-Advanced technology to meet the requirements of ITU-R as a 5G communication technology, and new NR communication technology separate from 4G communication technology. LTE-A pro and NR are both expected to be submitted as 5G communication technology, but hereinafter, for convenience of description, the present embodiments will be described focusing on NR.

In the NR operation scenario, various operation scenarios were defined by adding consideration of satellites, automobiles, and new verticals to the existing 4G LTE scenarios. It is deployed in a range and supports the mMTC (Massive Machine Communication) scenario that requires a low data rate and asynchronous connection, and the URLLC (Ultra Reliability and Low Latency) scenario that requires high responsiveness and reliability and supports high-speed mobility. .

To satisfy this scenario, NR discloses a wireless communication system to which a new waveform and frame structure technology, low latency technology, mmWave support technology, and forward compatible technology are applied. In particular, the NR system presents various technical changes in terms of flexibility to provide forward compatibility. The main technical features will be described with reference to the drawings below.

<Normal NR system>

1 is a diagram schematically illustrating a structure of an NR system to which this embodiment can be applied.

1, the NR system is divided into a 5G Core Network (5GC) and an NR-RAN part, and the NG-RAN controls the user plane (SDAP/PDCP/RLC/MAC/PHY) and UE (User Equipment) It consists of gNBs and ng-eNBs that provide planar (RRC) protocol termination. gNB interconnection or gNB and ng-eNB interconnect via Xn interface. gNB and ng-eNB are each connected to 5GC through the NG interface. 5GC may be configured to include an Access and Mobility Management Function (AMF) in charge of a control plane such as terminal access and mobility control functions, and a User Plane Function (UPF) in charge of a control function for user data. NR includes support for both frequency bands below 6 GHz (FR1, Frequency Range 1) and frequency bands above 6 GHz (FR2, Frequency Range 2).

gNB means a base station that provides NR user plane and control plane protocol termination to a terminal, and ng-eNB means a base station that provides E-UTRA user plane and control plane protocol termination to a terminal. The base station described in this specification should be understood as encompassing gNB and ng-eNB, and may be used as a meaning to refer to gNB or ng-eNB separately if necessary.

<NR Waveform, Pneumologic and Frame Structure>

In NR, a CP-OFDM waveform using a cyclic prefix is used for downlink transmission, and CP-OFDM or DFT-s-OFDM is used for uplink transmission. OFDM technology is easy to combine with MIMO (Multiple Input Multiple Output), and has advantages of using a low-complexity receiver with high frequency efficiency.

Meanwhile, in NR, since the requirements for data rate, delay rate, coverage, etc. are different for each of the three scenarios described above, it is necessary to efficiently satisfy the requirements for each scenario through the frequency band constituting an arbitrary NR system. . To this end, a technique for efficiently multiplexing a plurality of different numerology-based radio resources has been proposed.

값에 따라 지수적으로 변경된다. Specifically, the NR transmission numerology is determined based on sub-carrier spacing and cyclic prefix (CP), and is based on 15 kHz as shown in Table 1 below.

It changes exponentially according to the value.

Cyclic prefix Supported for data Supported for synch 0 15 Normal Yes Yes One 30 Normal Yes Yes 2 60 Normal, Extended Yes No 3 120 Normal Yes Yes 4 240 Normal No Yes

As shown in Table 1 above, the NR pneumatology can be divided into five types according to the subcarrier spacing. This is different from that the subcarrier interval of LTE, one of the 4G communication technologies, is fixed at 15 kHz. Specifically, subcarrier intervals used for data transmission in NR are 15, 30, 60, and 120 kHz, and subcarrier intervals used for synchronization signal transmission are 15, 30, 12, 240 kHz. In addition, the extended CP is applied only to the 60khz subcarrier interval.

On the other hand, as for the frame structure in NR, a frame having a length of 10 ms is defined, which is composed of 10 subframes having the same length of 1 ms. One frame can be divided into half frames of 5 ms, and each half frame includes 5 subframes. In the case of a 15 kHz subcarrier interval, one subframe consists of one slot, and each slot consists of 14 OFDM symbols.

2 is a diagram for explaining a frame structure in an NR system to which this embodiment can be applied.

Referring to FIG. 2 , a slot is fixedly composed of 14 OFDM symbols in the case of a normal CP, but the length of the slot may vary according to a subcarrier interval. For example, in the case of a numerology having a 15 kHz subcarrier interval, the slot is 1 ms in length and is composed of the same length as the subframe. On the other hand, in the case of numerology having a 30 kHz subcarrier interval, a slot consists of 14 OFDM symbols, but two slots may be included in one subframe with a length of 0.5 ms. That is, the subframe and the frame are defined to have a fixed time length, and the slot is defined by the number of symbols, so that the time length may vary according to the subcarrier interval.

On the other hand, NR defines a basic unit of scheduling as a slot, and also introduces a mini-slot (or a sub-slot or a non-slot based schedule) to reduce transmission delay in a radio section. When a wide subcarrier interval is used, the length of one slot is shortened in inverse proportion, so that transmission delay in a radio section can be reduced. The mini-slot (or sub-slot) is for efficient support of the URLLC scenario and can be scheduled in units of 2, 4, or 7 symbols.

Also, unlike LTE, NR defines uplink and downlink resource allocation at a symbol level within one slot. In order to reduce HARQ delay, a slot structure capable of transmitting HARQ ACK/NACK directly within a transmission slot is defined, and this slot structure is named as a self-contained structure and will be described.

NR is designed to support a total of 256 slot formats, of which 62 slot formats are used in Rel-15. In addition, a common frame structure constituting an FDD or TDD frame is supported through a combination of various slots. For example, a slot structure in which all symbols of a slot are set to downlink, a slot structure in which all symbols are set to uplink, and a slot structure in which downlink symbols and uplink symbols are combined are supported. In addition, NR supports that data transmission is scheduled to be distributed in one or more slots. Accordingly, the base station may inform the terminal whether the slot is a downlink slot, an uplink slot, or a flexible slot using a slot format indicator (SFI). The base station may indicate the slot format by indicating the index of the table configured through UE-specific RRC signaling using SFI, and may indicate dynamically through DCI (Downlink Control Information) or statically or semi-statically through RRC. may be

<NR Physical Resources>

In relation to a physical resource in NR, an antenna port, a resource grid, a resource element, a resource block, a bandwidth part, etc. are considered can be

An antenna port is defined such that a channel on which a symbol on an antenna port is carried can be inferred from a channel on which another symbol on the same antenna port is carried. When the large-scale property of a channel carrying a symbol on one antenna port can be inferred from a channel carrying a symbol on another antenna port, the two antenna ports are QC/QCL (quasi co-located or QC/QCL) quasi co-location). Here, the wide range characteristic includes one or more of delay spread, Doppler spread, frequency shift, average received power, and received timing.

3 is a diagram for explaining a resource grid supported by a radio access technology to which this embodiment can be applied.

Referring to FIG. 3 , in the resource grid, since NR supports a plurality of numerologies on the same carrier, a resource grid may exist according to each numerology. In addition, the resource grid may exist according to an antenna port, a subcarrier interval, and a transmission direction.

A resource block consists of 12 subcarriers, and is defined only in the frequency domain. In addition, a resource element is composed of one OFDM symbol and one subcarrier. Accordingly, as in FIG. 3 , the size of one resource block may vary according to the subcarrier interval. In addition, NR defines "Point A" serving as a common reference point for a resource block grid, a common resource block, a virtual resource block, and the like.

4 is a diagram for explaining a bandwidth part supported by a radio access technology to which the present embodiment can be applied.

In NR, unlike LTE in which the carrier bandwidth is fixed at 20Mhz, the maximum carrier bandwidth is set from 50Mhz to 400Mhz for each subcarrier interval. Therefore, it is not assumed that all terminals use all of these carrier bandwidths. Accordingly, in NR, as shown in FIG. 4 , a bandwidth part may be designated within the carrier bandwidth and used by the terminal. In addition, the bandwidth part is associated with one numerology and is composed of a subset of continuous common resource blocks, and may be dynamically activated according to time. A maximum of four bandwidth parts are configured in the terminal, respectively, in uplink and downlink, and data is transmitted/received using the activated bandwidth part at a given time.

In the case of a paired spectrum, the uplink and downlink bandwidth parts are set independently, and in the case of an unpaired spectrum, to prevent unnecessary frequency re-tunning between downlink and uplink operations For this purpose, the downlink and uplink bandwidth parts are set in pairs to share a center frequency.

<NR Initial Connection>

In NR, the terminal accesses the base station and performs a cell search and random access procedure in order to perform communication.

Cell search is a procedure in which the UE synchronizes the cell of the corresponding base station using a synchronization signal block (SSB) transmitted by the base station, obtains a physical layer cell ID, and obtains system information.

5 is a diagram exemplarily illustrating a synchronization signal block in a radio access technology to which the present embodiment can be applied.

5, the SSB consists of a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) occupying 1 symbol and 127 subcarriers, respectively, and a PBCH spanning 3 OFDM symbols and 240 subcarriers. .

The UE receives the SSB by monitoring the SSB in the time and frequency domains.

SSB can be transmitted up to 64 times in 5ms. A plurality of SSBs are transmitted using different transmission beams within 5 ms, and the UE performs detection on the assumption that SSBs are transmitted every 20 ms when viewed based on one specific beam used for transmission. The number of beams that can be used for SSB transmission within 5 ms time may increase as the frequency band increases. For example, up to 4 SSB beams can be transmitted in 3 GHz or less, and SSB can be transmitted using up to 8 different beams in a frequency band of 3 to 6 GHz and up to 64 different beams in a frequency band of 6 GHz or more.

Two SSBs are included in one slot, and the start symbol and the number of repetitions within the slot are determined according to the subcarrier interval as follows.

- Case A - 15 kHz subcarrier spacing: the first symbols of the candidate SS/PBCH blocks have indexes of {2, 8} + 14*n. For carrier frequencies smaller than or equal to 3 GHz, n=0, 1. For carrier frequencies larger than 3 GHz and smaller than or equal to 6 GHz, n=0, 1, 2, 3.

- Case B - 30 kHz subcarrier spacing: the first symbols of the candidate SS/PBCH blocks have indexes {4, 8, 16, 20} + 28*n. For carrier frequencies smaller than or equal to 3 GHz, n=0. For carrier frequencies larger than 3 GHz and smaller than or equal to 6 GHz, n=0, 1.

- Case C - 30 kHz subcarrier spacing: the first symbols of the candidate SS/PBCH blocks have indexes {2, 8} + 14*n. For carrier frequencies smaller than or equal to 3 GHz, n=0, 1. For carrier frequencies larger than 3 GHz and smaller than or equal to 6 GHz, n=0, 1, 2, 3.

- Case D - 120 kHz subcarrier spacing: the first symbols of the candidate SS/PBCH blocks have indexes {4, 8, 16, 20} + 28*n. For carrier frequencies larger than 6 GHz, n=0, 1, 2, 3, 5, 6, 7, 8, 10, 11, 12, 13, 15, 16, 17, 18.

- Case E - 240 kHz subcarrier spacing: the first symbols of the candidate SS/PBCH blocks have indexes {8, 12, 16, 20, 32, 36, 40, 44} + 56*n. For carrier frequencies larger than 6 GHz, n=0, 1, 2, 3, 5, 6, 7, 8.

On the other hand, the SSB is not transmitted at the center frequency of the carrier bandwidth, unlike the SS of the conventional LTE. That is, the SSB may be transmitted in a place other than the center of the system band, and a plurality of SSBs may be transmitted in the frequency domain when wideband operation is supported. Accordingly, the UE monitors the SSB using a synchronization raster, which is a candidate frequency location for monitoring the SSB. The carrier raster and synchronization raster, which are the center frequency location information of the channel for initial access, are newly defined in NR, and the synchronization raster has a wider frequency interval than the carrier raster, so that it can support fast SSB search of the terminal. can

The UE may acquire the MIB through the PBCH of the SSB. MIB (Master Information Block) includes minimum information for the terminal to receive the remaining system information (RMSI, Remaining Minimum System Information) broadcast by the network. In addition, the PBCH includes information on the position of the first DM-RS symbol in the time domain, information for the UE to monitor SIB1 (eg, SIB1 neurology information, information related to SIB1 CORESET, search space information, PDCCH related parameter information, etc.), offset information between the common resource block and the SSB (the position of the absolute SSB in the carrier is transmitted through SIB1), and the like. Here, the SIB1 neurology information is equally applied to messages 2 and 4 of the random access procedure for accessing the base station after the UE completes the cell search procedure.

The aforementioned RMSI means SIB1 (System Information Block 1), and SIB1 is broadcast periodically (ex, 160 ms) in the cell. SIB1 includes information necessary for the UE to perform an initial random access procedure, and is periodically transmitted through the PDSCH. In order for the UE to receive SIB1, it must receive neurology information used for SIB1 transmission and CORESET (Control Resource Set) information used for scheduling SIB1 through the PBCH. The UE checks scheduling information for SIB1 by using SI-RNTI in CORESET, and acquires SIB1 on PDSCH according to the scheduling information. SIBs other than SIB1 may be transmitted periodically or may be transmitted according to the request of the terminal.

6 is a diagram for explaining a random access procedure in a radio access technology to which the present embodiment can be applied.

Referring to FIG. 6 , upon completion of cell search, the terminal transmits a random access preamble for random access to the base station. The random access preamble is transmitted through the PRACH. Specifically, the random access preamble is transmitted to the base station through a PRACH consisting of continuous radio resources in a specific slot that is periodically repeated. In general, when a UE initially accesses a cell, a contention-based random access procedure is performed, and when performing random access for beam failure recovery (BFR), a contention-free random access procedure is performed.

The terminal receives a random access response to the transmitted random access preamble. The random access response may include a random access preamble identifier (ID), a UL grant (uplink radio resource), a temporary C-RNTI (Temporary Cell - Radio Network Temporary Identifier), and a Time Alignment Command (TAC). Since one random access response may include random access response information for one or more terminals, the random access preamble identifier may be included to inform which terminal the included UL Grant, temporary C-RNTI, and TAC are valid. The random access preamble identifier may be an identifier for the random access preamble received by the base station. The TAC may be included as information for the UE to adjust uplink synchronization. The random access response may be indicated by a random access identifier on the PDCCH, that is, RA-RNTI (Random Access - Radio Network Temporary Identifier).

Upon receiving the valid random access response, the terminal processes information included in the random access response and performs scheduled transmission to the base station. For example, the UE applies the TAC and stores the temporary C-RNTI. In addition, data stored in the buffer of the terminal or newly generated data is transmitted to the base station by using the UL grant. In this case, information for identifying the terminal should be included.

Finally, the terminal receives a downlink message for contention resolution.

<NR CORESET>

The downlink control channel in NR is transmitted in a control resource set (CORESET) having a length of 1 to 3 symbols, and transmits up/down scheduling information, slot format index (SFI), transmit power control (TPC) information, etc. .

In this way, NR introduced the concept of CORESET in order to secure the flexibility of the system. CORESET (Control Resource Set) means a time-frequency resource for a downlink control signal. The UE may decode the control channel candidates by using one or more search spaces in the CORESET time-frequency resource. Quasi CoLocation (QCL) assumptions for each CORESET are set, and this is used for the purpose of notifying the characteristics of the analog beam direction in addition to the delay spread, Doppler spread, Doppler shift, and average delay, which are characteristics assumed by the conventional QCL.

7 is a diagram for explaining CORESET.

Referring to FIG. 7 , CORESET may exist in various forms within a carrier bandwidth within one slot, and CORESET may consist of up to three OFDM symbols in the time domain. In addition, CORESET is defined as a multiple of 6 resource blocks up to the carrier bandwidth in the frequency domain.

The first CORESET is indicated through the MIB as part of the initial bandwidth part configuration to receive additional configuration information and system information from the network. After establishing a connection with the base station, the terminal may receive and configure one or more pieces of CORESET information through RRC signaling.

<LTE side link>

In the existing LTE system, a radio channel and radio protocol design for direct communication between terminals (ie, sidelink) was made to provide direct communication between terminals and V2X (particularly V2V) service.

Regarding the sidelink, PSSS/SSSS, which is a synchronization signal for synchronization between a wireless sidelink transmitter and a receiver, and a Physical Sidelink Broadcasting Channel (PSBCH) for transmitting and receiving a sidelink MIB (Master Information Block) related thereto are defined, and also discovery information PSDCH (Physical Sidelink Discovery channel) for transmission and reception, PSCCH (Physical Sidelink Control Channel) for transmission and reception of SCI (Sidelink Control Information), and PSSCH (Physical Sidelink Shared Channel) for transmitting and receiving sidelink data were designed.

In addition, for radio resource allocation for the sidelink, the technology was developed by dividing it into mode 1 in which the base station allocates radio resources and mode 2 in which the terminal selects and allocates radio resources from a pool of radio resources. In addition, additional technological evolution was required in order to satisfy the V2X scenario in the LTE system.

In this environment, 3GPP derived 27 service scenarios related to vehicle recognition from Rel-14 and determined the main performance requirements according to road conditions. In addition, in the recent Rel-15, 25 more advanced service scenarios such as platooning, advanced driving, and long-distance vehicle sensors were derived and 6 performance requirements were determined.

In order to satisfy these performance requirements, a technology development for improving the performance of the sidelink technology developed based on the conventional D2D communication according to the requirements of V2X has been progressed. In particular, for application to C-V2X (Cellular-V2X), a technology for improving the physical layer design of a sidelink to be suitable for a high-speed environment, a resource allocation technology, and a synchronization technology can be selected as major research technologies.

The sidelink described below means a link used for D2D communication developed after 3GPP Rel-12 and V2X communication after Rel-14, and each channel term, synchronization term, resource term, etc. Regardless of the requirements of Rel-14, 15, they are described in the same terms. However, for convenience of understanding, the difference between sidelinks satisfying the V2X scenario requirements will be mainly described based on the sidelinks for D2D communication in Rel-12/13 as needed. Therefore, the terms related to sidelink described below are only used to describe D2D communication/V2X communication/C-V2X communication separately for comparison difference and convenience of understanding, and are not limitedly applied to a specific scenario.

<Sidelink Physical Layer Design>

For V2X communication, a demodulation reference signal (DMRS), which is a pilot signal, needs to be allocated more than D2D communication in order to improve channel estimation performance and frequency offset estimation performance.

8 is a diagram for explaining, for example, a DMRS structure for a conventional sidelink and a DMRS structure for a sidelink to which this embodiment can be applied.

Referring to FIG. 8 , two conventional (Rel-12/13) DMRSs are allocated per subframe of PSCCH, PSSCH, and PSBCH, and the interval between DMRSs is 0.5 ms. The C-V2X terminal uses the 6GHz center frequency band defined for sidelink transmission, and the vehicle terminal moves at 280km/h considering the relative speed. At this time, the correlation time becomes 0.277 ms, and since this value is shorter than the interval between reference signals of Rel-12/13, the channel estimation time is insufficient. To solve this problem, in the sidelink for V2X communication, the number of DMRSs per subframe was increased to 4 and the interval between reference signals was reduced to 0.214 ms, so that the physical layer design was changed to facilitate channel estimation even with rapid channel changes. .

On the other hand, as one example of a method of selecting a DMRS symbol pattern, in the dedicated carrier, DMRS is allocated to OFDM symbols 2/5/8/11 in PSCCH/PSSCH, and DMRS in OFDM symbols 3/5/8/10 in PSBCH. allocate In the 2GHz band, the Rel-12/13 method with two DMRSs can be used as it is. That is, the number and pattern of DMRS transmission may be configured differently according to channels and carrier frequency bands.

In addition, the TDM (Time Division Multiplexing) method used in D2D uses the FDM (Frequency Division Multiplexing) method because it is not suitable for C-V2X in which a large number of vehicles are densely connected at the same time.

<Resource Allocation>

9 is a diagram for explaining various scenarios for V2X communication.

Referring to FIG. 9 , a V2X terminal (represented as a vehicle, but can be set in various ways such as a user terminal) may be located within the coverage of a base station (eNB or gNB or ng-eNB), or may be located outside the coverage of the base station. For example, communication may be performed between terminals within the coverage of a base station (UE N-1, UE G-1, UE X), and between terminals within coverage of a base station and terminals outside (eg, UE N-1, UE N-) 2) can also perform communication. Alternatively, communication may be performed between terminals (eg, UE G-1, UE G-2) outside the coverage of the base station.

In order for the corresponding terminal to perform communication using the sidelink in these various scenarios, allocation of radio resources for communication is required, and allocation of radio resources is largely divided into a base station handling allocation and a method in which the terminal itself selects and allocates.

Specifically, in D2D, there are a centralized method in which the base station intervenes in resource selection and management (Mode 1) and a distributed method in which the terminal randomly selects a preset resource (Mode 2) in D2D. Similar to D2D, in C-V2X, there are a method in which a base station intervenes in resource selection and management (Mode 3) and a method in which a vehicle directly selects a resource in V2X (Mode 4). In Mode 3, the base station schedules the SA (Scheduling Assignment) pool resource area and the DATA pool resource area allocated thereto to the transmitting terminal.

10 shows an example of UE1 (UE1) and UE2 (UE2) performing sidelink communication and a sidelink resource pool used by them.

Referring to FIG. 10 , the base station is denoted as an eNB, but as described above, it may be a gNB or an ng-eNB. In addition, although a mobile phone is illustrated as an example, the terminal may be variously applied to a vehicle, an infrastructure device, and the like.

In FIG. 10A , the transmitting terminal UE1 may select a resource unit corresponding to a specific resource from a resource pool indicating a set of a series of resources and transmit a sidelink signal using the resource unit. The receiving terminal UE2 may receive a resource pool configured to allow the UE1 to transmit a signal and detect a transmission signal of the corresponding terminal.

Here, the resource pool may be informed by the base station when the UE1 is in the connection range of the base station, and when the UE1 is outside the connection range of the base station, the resource pool may be notified by another terminal or may be determined as a predetermined resource. In general, a resource pool is composed of a plurality of resource units, and each terminal can select one or a plurality of resource units to use for its own sidelink signal transmission.

Referring to FIG. 10( b ), it can be seen that the total frequency resource is divided into NF and the total time resource is divided into NT, so that a total of NF * NT resource units are defined. Here, it can be said that the resource pool is repeated with an NT subframe cycle. In particular, one resource unit may appear periodically and repeatedly as shown.

Meanwhile, the resource pool may be subdivided into several types. First, it may be classified according to the contents of a sidelink signal transmitted from each resource pool. For example, the content of the sidelink signal may be divided, and a separate resource pool may be configured for each. As the content of the sidelink signal, there may be a scheduling assignment (SA), a sidelink data channel, and a discovery channel.

SA provides information such as the location of resources used by the transmitting terminal for transmission of the following sidelink data channel and information such as the modulation and coding scheme (MCS), MIMO transmission method, and timing advance (TA) required for demodulation of other data channels. It may be a signal including This signal may also be multiplexed and transmitted together with sidelink data on the same resource unit. In this case, the SA resource pool may mean a pool of resources in which SA is multiplexed with sidelink data and transmitted.

On the other hand, the FDM method applied to V2X communication can reduce the delay time in which the data resource is allocated after the SA resource allocation. For example, a non-adjacent method of separating a control channel resource and a data channel resource within one subframe in the time domain and an adjacent method of continuously allocating a control channel and a data channel within one subframe are considered.

On the other hand, when SA is multiplexed and transmitted together with sidelink data on the same resource unit, only a sidelink data channel of a type excluding SA information may be transmitted in the resource pool for the sidelink data channel. In other words, resource elements used to transmit SA information on individual resource units in the SA resource pool may still be used to transmit sidelink data in the sidelink data channel resource pool. The discovery channel may be a resource pool for a message in which a transmitting terminal transmits information such as its ID so that a neighboring terminal can discover itself. Even when the content of the sidelink signal is the same, different resource pools may be used according to the transmission/reception property of the sidelink signal.

For example, even in the same sidelink data channel or discovery message, the transmission timing determination method of the sidelink signal (for example, whether it is transmitted at the reception time of the synchronization reference signal or transmitted by applying a certain TA) or the resource allocation method (For example, whether the base station designates individual signal transmission resources to individual transmitting terminals or whether individual transmitting terminals independently select individual signal transmission resources within the pool), signal format (e.g., each sidelink signal is one sub It may be divided into different resource pools again according to the number of symbols occupied by a frame or the number of subframes used for transmission of one sidelink signal), signal strength from a base station, transmission power strength of a sidelink terminal, and the like.

V2X resource pool (Sensing and selection windows)

The V2X terminal may perform message (or channel) transmission on a predefined (or signaled) resource pool. Here, the resource pool may mean resource(s) defined in advance so that the UE performs a V2X operation (or may perform a V2X operation). In this case, the resource pool may be defined, for example, in terms of time-frequency. On the other hand, various types of V2X transmission resource pool may exist.

11 illustrates the type of V2X transmission resource pool.

Referring to Figure 11 (a), V2X transmission resource pool #A may be a resource pool that allows only (partial) sensing (sensing). The V2X transmission resource selected by (partial) sensing is semi-statically maintained at a certain period as shown in FIG. 11(a).

Referring to FIG. 11(b), the V2X transmission resource pool #Β may be a resource pool in which only random selection is allowed. In the V2X transmission resource pool #B, the UE does not perform (partial) sensing, and may randomly select a V2X transmission resource in a selection window.

Here, as an example, in a resource pool in which only random selection is allowed, unlike a resource pool in which only (partial) sensing is allowed, it may be set (/signaled) so that the selected resource is not semi-statically reserved. The base station may configure not to perform a sensing operation (based on scheduling allocation decoding/energy measurement) in order for the terminal to perform a V2X message transmission operation on the V2X transmission resource pool.

On the other hand, although not shown in FIG. 11, there may also exist a resource pool in which both (partial) sensing and random selection are possible. The base station may inform that it can select a V2X resource by one of (either of the partial sensing and the random selection) sensing and random selection.

V2X UL SPS

In general, UL transmission using SPS may cause a slight delay when a gap between the generation of user data and the configured SPS resource is large. Therefore, when SPS is used for delay-sensitive traffic such as V2X communication, the SPS scheduling interval should be small enough to support the delay requirement.

However, since the UE may not fully utilize the configured SPS resources, a smaller SPS scheduling interval may incur more overhead. Therefore, the gap between the user data generation and the configured SPS resource should be small and the SPS scheduling interval should be suitable to satisfy the delay requirement. Currently, there is no mechanism to support this functionality.

12 illustrates a method for performing SPS activation (request), re-activation (re-request) and/or release, change triggered by the UE.

A UE may receive an SPS configuration for one or more specific logical channels. The UE may receive the SPS configuration for a specific logical channel through system information, an RRC connection establishment message, an RRC connection re-establishment message, or an RRC connection release message.

When data becomes available for a specific logical channel(s), the UE may request SPS activation to the eNB and then perform UL transmission using the configured SPS resource according to the SPS activation command received from the eNB. The UE may transmit an SPS activation request to the eNB through a physical uplink control channel (PUCCH), a control element (MAC CE), or an RRC message. That is, the UE may transmit the SPS activation request to the eNB using the control resource used to request the SPS activation. The control resource may be a PUCCH resource, a random access resource, or a new UL control channel resource. Also, the UE may send an SPS activation request to the eNB, eg, during RRC connection (re-) establishment, during handover, after handover, or in RRC_CONNECTED.

Since the UE actively requests SPS activation to the eNB when there is UL data to transmit, the gap between the generation of UL data and the configured SPS resource can be reduced.

Referring to FIG. 12 , the UE receives SPS configuration information including three SPS configurations from the eNB. If there is UL data to be transmitted from a higher layer, the UE transmits an SPS request message from the eNB through, for example, MAC CE. The eNB sends an acknowledgment message (Ack message) for one of the three SPS configurations. The UE transmits UL data in a specific resource according to the corresponding SPS configuration, for example, in a 1sec period.

Meanwhile, when UL data to be transmitted from a higher layer exists at a specific time point, the UE transmits an SPS request message from the eNB again, for example, through the MAC CE. The eNB sends an acknowledgment message (Ack message) for the other one of the three SPS configurations. The UE transmits UL data in a specific resource, for example, 100sec period according to the corresponding SPS configuration.

Transmission and reception of SA (Scheduling assignment)

Mode 1 UE may transmit SA (or sidelink control signal, SCI (Sidelink Control Information)) through the resource configured from the base station. The mode 2 terminal is configured with a resource to be used for sidelink transmission from the base station. Then, the SA can be transmitted by selecting a time frequency resource from the configured resource.

The SA period may be defined as shown in FIG. 13 . Referring to FIG. 13 , the first SA period may start in a subframe separated from a specific system frame by a predetermined offset (SAOffsetIndicator) indicated by higher layer signaling. Each SA period may include an SA resource pool and a subframe pool for sidelink data transmission.

The SA resource pool may include the last subframe of the subframes indicated to be transmitted in the subframe bitmap (saSubframeBitmap) from the first subframe of the SA period. As for the resource pool for sidelink data transmission, in the case of mode 1, a subframe used for actual data transmission may be determined by applying a time-resource pattern for transmission (T-RPT) or time-resource pattern (TRP). As shown, if the number of subframes included in the SA period excluding the SA resource pool is greater than the number of T-RPT bits, T-RPT may be repeatedly applied, and the lastly applied T-RPT is the number of remaining subframes. It can be applied after being truncated as much as possible.

<Synchronous signal>

As described above, in the case of a V2X communication terminal, it is highly likely to be located outside the base station coverage. Even in this case, communication using the sidelink must be performed. To this end, it is important that the terminal located outside the coverage of the base station acquires synchronization.

Hereinafter, based on the above description, a method for synchronizing time and frequency in communication between vehicles, in particular between vehicles, between vehicles and other terminals, and between vehicles and an infrastructure network, in sidelink communication will be described.

D2D communication uses a sidelink synchronization signal (SLSS), which is a synchronization signal transmitted from a base station for time synchronization between terminals. In C-V2X, a Global Navigation Satellite System (GNSS) may be additionally considered to improve synchronization performance. However, priority may be given to synchronization establishment or the base station may indicate information on priority. For example, in determining its own transmission synchronization, the terminal preferentially selects a synchronization signal directly transmitted by the base station. it will match

On the other hand, since a wireless terminal installed in a vehicle or a terminal installed in a vehicle has relatively less battery consumption and can use satellite signals such as GPS for navigation purposes, time or frequency synchronization between terminals is set for satellite signals. can be used to Here, the satellite signals may correspond to GNSS signals such as Global Navigation Satellite System (GLONAS), GALILEO, and BEIDOU in addition to the illustrated Global Positioning System (GPS).

Meanwhile, the sidelink synchronization signal may include a primary sidelink synchronization signal (PSSS) and a secondary sidelink synchronization signal (SSSS). The PSSS may be a Zadoff-chu sequence of a predetermined length or a structure similar/modified/repeated to the PSS. Also, unlike DL PSS, other Zadoff Chu root indexes (eg, 26, 37) may be used. The SSSS may be an M-sequence or a structure similar to/modified/repeated with the SSS. If the terminals synchronize from the base station, the SRN becomes the base station and the SLSS becomes the PSS/SSS.

Unlike PSS/SSS of DL, PSSS/SSSS follows UL subcarrier mapping scheme. PSSCH (Physical Sidelink Synchronization Channel) is the basic system information that the UE must know first before transmitting and receiving sidelink signals (eg, SLSS-related information, Duplex Mode, DM), TDD UL/DL configuration, resources Pool-related information, SLSS-related application type, subframe offset, broadcast information, etc.) may be transmitted through a channel. The PSSCH may be transmitted on the same subframe as the SLSS or on a subsequent subframe. DM-RS may be used for demodulation of PSSCH.

The SRN may be a node transmitting SLSS and PSSCH. The SLSS may be in the form of a specific sequence, and the PSSCH may be in the form of a sequence indicating specific information or a code word after undergoing predetermined channel coding. Here, the SRN may be a base station or a specific sidelink terminal. In the case of partial network coverage or out of network coverage, the UE may be the SRN.

In addition, if necessary, the SLSS may be relayed for sidelink communication with an out-of-coverage terminal, and may be relayed through multiple hops. In the following description, relaying the synchronization signal is a concept including not only relaying the synchronization signal of the base station directly, but also transmitting the sidelink synchronization signal in a separate format according to the synchronization signal reception time. In this way, the in-coverage terminal and the out-of-coverage terminal can directly communicate by relaying the sidelink synchronization signal.

<NR side link>

As described above, unlike V2X based on LTE system, there is a need for NR-based V2X technology to satisfy complex requirements such as autonomous driving.

In the case of NR V2X, NR frame structure, numerology, channel transmission/reception procedure, etc. are applied to enable flexible V2X service provision in more diverse environments. To this end, it is required to develop technologies such as a resource sharing technology between a base station and a terminal, a sidelink carrier aggregation (CA) technology, a partial sensing technology for a pedestrian terminal, and sTTI.

In NR V2X, it was decided to support unicast and groupcast as well as broadcast used in LTE V2X. At this time, it was decided to use the target group ID for groupcast and unicast, but whether to use the source ID was discussed later.

In addition, as it was decided to support HARQ for QOS, it was decided to include a HARQ process ID in the control information. In LTE HARQ, PUCCH for HARQ was transmitted 4 subframes after downlink transmission, but in NR HARQ, the feedback timing is, for example, in DCI format 1_0 or 1_1 PUCCH resource indicator (PUCCH resource indicator) or HARQ feedback for PDSCH A PUCCH resource and feedback timing may be indicated by a timing indicator (PDSCH-to-HARQ feedback timing indicator).

Synchronization mechanism

NR V2X sidelink synchronization includes sidelink synchronization signal(s) and PSBCH, and the sidelink source may include a UE along with GNSS and gNB.

resource allocation

In NR V2X sidelink communication, at least two sidelink resource allocation modes, ie, mode 3 and mode 4, may be defined. In mode 3, the base station schedules sidelink resource(s) used by the terminal for sidelink transmission. In mode 4, the UE determines sidelink transmission resource(s) within the sidelink resources configured by the base station or preconfigured sidelink resources.

Mode 4 may cover the following resource allocation sub-modes. That is, the UE automatically selects a sidelink resource for transmission, helps the sidelink resource selection for other UE(s), is configured with a configured grant for sidelink transmission, or a sidelink of another UE(s) Transmissions can be scheduled.

NR preemtion

In the case of a terminal that is critical to delay, such as a URLLC terminal, even a data resource already allocated to another eMBB terminal or the like may be preempted to use the data resource. In addition, information on which area of the data resource is occupied may be indicated to the terminal through the group common DCI.

Uu interface based sidelink resource allocation/configuration

The NR Uu may allocate NR sidelink resources for a shared licensed carrier and/or a dedicated NR sidelink carrier between the Uu and the NR sidelink. In this case, resource allocation may support dynamic resource allocation and activation/deactivation-based resource allocation. Activation/deactivation-based resource allocation may reuse SPS allocation or NR grant free type-2.

In the following description, SLSS id_net is a set of SLSS IDs used by terminals selecting a synchronization signal of a base station as a synchronization reference among physical layer SLSS IDs {0, 1, 335}, and may be {0, 1, , 167}. . In addition, SLSS id_oon is a set of SLSS IDs used when base stations/out-of-coverage terminals transmit synchronization signals themselves, and may be {168, 169, , 335}.

In the following descriptions, as examples of satellite signals, GNSS and GPS are mainly used, but other satellite signals may be substituted. In addition, in the following description, V (vehicle)-UE may be a vehicle, and P (pedestrian)-UE may be a terminal moving on foot or a terminal moving by cycle. In addition, in the following description, the GPS timing sets a frame/subframe boundary based on an absolute time reference of a time acquired when GPS is received (eg, Coordinated Universal Time or GPS time (UTC)), and some or all of the subframes. It may mean that is set as a subframe for sidelink signal transmission.

Example

14 is a diagram for explaining a method of bundling and transmitting HARQ feedback information in NR V2X, according to an embodiment.

Referring to FIG. 14 , in LTE V2X, separate HARQ ACK/NACK information is not transmitted in order to reduce system overhead, and the transmitting terminal can retransmit data once according to selection for data transmission safety. However, NR V2X may transmit HARQ ACK/NACK information in terms of data transmission stability, and in this case, overhead may be reduced by bundling and transmitting the corresponding information.

That is, when the transmitting terminal UE1 transmits three pieces of data to the receiving terminal UE2 and the receiving terminal generates HARQ ACK/NACK information for it, it may be bundled and transmitted through the PSCCH. Although it has been described that the HARA ACK/NACK is transmitted through the PSCCH in the drawing, it may be transmitted through a separate channel or another channel, and bundled HARQ information may consist of 3 bits or less.

Meanwhile, in FR1 for the frequency domain below 3 GHz, 15 kHz, 30 kHz, 60 kHz, and 120 kHz were discussed as candidates for SCS (subcarrier spacing). In addition, for FR2 in the frequency region exceeding 3 GHz, 30 kHz, 60 kHz, 120 kHz, and 240 kHz as subcarrier spacing (SCS) were decided to be discussed as candidates. For NR V2X, a mini-slot (eg, 2/4/7 symbol) smaller than 14 symbols may be supported as a minimum scheduling unit.

As a candidate group for RS, DM-RS, PT-RS, CSI-RS, SRS, and AGC training signals were to be discussed.

The multiplexing of the PSSCH associated with the PSCCH will discuss the following four options as shown in FIG. 14 . Option 2 is similar to multiplexing of PSCCH and PSSCH in LTE V2X.

15 is a diagram for explaining a method of bundling and transmitting HARQ feedback information in NR V2X, according to another embodiment.

15A illustrates inter-CBG bundling within a TB of codebook groups (CBGs) within one transport block (TB).

In NR, codebooks included in one transport block may be divided into one or more codebook groups, and HARQ may be performed in units of codebook groups. In (a) of FIG. 15 , each of the codebook groups CBG0 and CBG1 includes one or more codebooks.

As a method of bundling and transmitting HARQ feedback information in NR V2X, bundling between codebook groups (CBGs) within a transport block (TB) can be performed (inter-CBG bundling within a TB). have.

For example, as shown in FIG. 14 , one codebook group (CBG) consists of three codebooks, and as shown in FIG. 15A , one transport block TB has 2 It may be composed of codebook groups CBG0 and CBG1.

Therefore, when bundling (inter-CBG bundling within a TB) is performed between codebook groups (CBGs) within one transport block (TB), the terminal transmits a total of 6 bits of HARQ information to the base station. and the base station may receive this HARQ information.

FIG. 15B illustrates inter-TB bundling per CBG index between transport blocks (TBs) per CBG index. As shown in FIG. 15B , bundling may be performed between CBGs having the same CBG indices included in two transport blocks TB0 and TB1.

For example, as shown in FIG. 14 , one codebook group (CBG) consists of three codebooks, and as shown in FIG. 15B , one transport block TB has 2 It may be composed of codebook groups CBG0 and CBG1.

Therefore, when bundling (inter-TB bundling per CBG index) is performed between transport blocks (TBs) per CBG index, the terminal transmits a total of 6 bits of HARQ information to the base station, and the base station can receive this HARQ information. have.

FIG. 15(c) shows inter-CBG bundling within a TB of codebook groups (CBGs) within one transport block (TB) shown in FIG. 15(a) and It is a combination of inter-TB bundling per CBG index, shown in (b) of FIG. 15 , between transport blocks (TBs) per CBG index.

16 is a diagram for explaining a method of multiplexing and transmitting HARQ feedback information in NR V2X, according to another embodiment.

Referring to FIG. 16, NR V2X can reduce overhead by multiplexing and transmitting HARQ ACK/NACK information in terms of data transmission stability.

That is, when the transmitting terminal UE1 transmits four pieces of data to the receiving terminal UE2 and the receiving terminal generates HARQ ACK/NACK information for it, it may be multiplexed through the PSCCH and transmitted. Although it has been described that the HARA ACK/NACK is transmitted through the PSCCH in the drawing, it may be transmitted through a separate channel or another channel. The multiplexed HARQ information may have its value set based on a codebook, and may be transmitted, for example, through a PSCCH.

The HARQ codebook may be a semi-static HARQ-ACK codebook set by higher layer signaling or a dynamic HARQ ACK codebook that is dynamically set by being included in a specific field in the PSCCH. . On the other hand, the HARQ codebook may be fixed without being changed in NR V2X as a fixed HARQ-ACK codebook.

As a method for multiplexing and transmitting HARQ feedback information in NR V2X according to another embodiment, similarly to that shown in FIG. 15 (a), codebook groups within one transport block (TB) Multiplexing between (codebook groups, CBGs) and multiplexing between transport blocks (TBs) per CBG index similarly to that shown in (b) of FIG. 15, similar to that shown in FIG. 15 (c), their It can be multiplexed by combination.

Although HARQ feedback by CBG-based bundling or multiplexing has been described in the above embodiments, it may be HARQ feedback by TB-based bundling or multiplexing. In addition, HAQR feedback may be performed by selecting one of HARQ feedback by CBG-based bundling or multiplexing and HARQ feedback by TB-based bundling or multiplexing.

17 shows a format of a PSCCH related to HARQ in NR V2X, according to another embodiment.

In Figure 17 (a), according to another embodiment, the format of the PSCCH related to HARQ in NR V2X is a first field (Hybrid-ARQ process number field) and a second field (Downlink assignment index field), the third It may include a field (HARQ feedback timing field).

A first field (Hybrid-ARQ process number field) informs a device related to a Hybrid-ARQ process used for soft combining. The first field may have the number of bits of the logarithmic value of 2 of the number of Hybrid-ARQ processes, for example, the number of 3 bits when the number of Hybrid-ARQ processes is 8.

A second field (Downlink assignment index field) indicates the dynamic HARQ codebook when using the dynamic HARQ codebook. The second field may be 0, 2, or 4 bits. For example, the second field may use 2 bits in the same manner as in the NR DCI format 1-0.

A third field (HARQ feedback timing field) provides information on when the HARQ ACK should be transmitted based on the reception of the PSSCH.

According to another embodiment, the format of the PSCCH related to HARQ in NR V2X may not include a second field (Downlink assignment index field) as shown in (c) of FIG. 17 . That is, in NR V2X, the dynamic HARQ procedure may not be performed because a fixed HARQ codebook is used or only a semi-static HARQ codebook is used in the HARQ procedure.

According to another embodiment, the format of the PSCCH related to HARQ in NR V2X may not include a third field (HARQ feedback timing field) as shown in FIG. 17C . That is, the HARQ ACK may be transmitted after a fixed time point, for example, 4 slots based on the reception of the PSCCH.

According to another embodiment, the format of the PSCCH related to HARQ in NR V2X does not include a second field (Downlink assignment index field) and a third field (HARQ feedback timing field) as shown in (d) of FIG. may not be This can simplify the HARQ procedure in NR V2X.

18 shows an example of one of the PSCCH formats.

Referring to FIG. 18 , the PSCCH or other sidelink control channel including information related to HARQ in NR V2X may be configured in the same format as one of the NR PUCCH formats. For example, the PSCCH or other sidelink control channel may be transmitted through a resource located in one subcarrier in the last symbol of the corresponding slot. If one or more bandwidth parts are used as a sidelink physical channel, a specific bandwidth part may include two or more sidelink control channel resource sets. In this case, each sidelink control channel resource set may include two or more sidelink control channel resources. One of the site link control channel resources may be set as the resource of the last symbol of the aforementioned slot.

As shown in FIG. 18 , the PSCCH may be configured by multiplying a base sequence by a phase rotation.

FIG. 19 shows HARQ feedback information according to the phase difference of the PSCCH of FIG. 18 .

18 and 19 , when the PSCCH is configured by multiplying a base sequence by a phase rotation, the interval between the phase differences is set to 90 degrees, so that 2-bit HARQ feedback can be performed.

For example, as shown in FIG. 19, the phase difference is divided into 0 degrees, 90 degrees, 180 degrees and 270 degrees, and (N, A), (N, N), (A, N), (A, A) can be distinguished. In this case, the feedback pair according to each phase difference may be determined by the above-described HARQ codebook.

20 is a diagram showing the configuration of the base station 1000 according to another embodiment.

Referring to FIG. 20 , the base station 1000 according to another embodiment includes a controller 1010 , a transmitter 1020 , and a receiver 1030 .

The controller 1010 controls the overall operation of the base station 1000 according to the HARQ-related procedure in NR V2X necessary for carrying out the above-described present invention.

The transmitter 1020 and the receiver 1030 are used to transmit/receive signals, messages, and data necessary for carrying out the present invention to and from the terminal.

21 is a diagram showing the configuration of a user terminal 1100 according to another embodiment.

Referring to FIG. 21 , the user terminal 1100 according to another embodiment includes a receiver 1110 , a controller 1120 , and a transmitter 1130 . The user terminal 1100 according to another embodiment may be a first terminal UE1 and a second terminal UE2 illustrated in FIG. 10 and the like.

The receiver 1110 receives downlink control information, data, and a message from the base station through a corresponding channel.

In addition, the control unit 1120 controls the overall operation of the user terminal 1100 according to the HARQ-related procedure in NR V2X necessary to perform the above-described present invention.

The transmitter 1130 transmits uplink control information, data, and a message to the base station through a corresponding channel.

The above-described embodiments of the present invention may be implemented through various means. For example, embodiments of the present invention may be implemented by hardware, firmware, software, or a combination thereof.

In case of implementation by hardware, the method according to embodiments of the present invention may include one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), and Programmable Logic Devices (PLDs). , FPGAs (Field Programmable Gate Arrays), processors, controllers, microcontrollers, microprocessors, and the like.

In the case of implementation by firmware or software, the method according to the embodiments of the present invention may be implemented in the form of an apparatus, procedure, or function for performing the functions or operations described above. The software code may be stored in the memory unit and driven by the processor. The memory unit may be located inside or outside the processor, and may transmit and receive data to and from the processor by various known means.

The above-described embodiments may be supported by standard documents disclosed in at least one of IEEE 802, 3GPP, and 3GPP2, which are wireless access systems. That is, steps, configurations, and parts not described in order to clearly reveal the present technical idea among the present embodiments may be supported by the aforementioned standard documents. In addition, all terms disclosed in this specification can be described by the standard documents disclosed above.

In addition, the terms "system", "processor", "controller", "component", "module", "interface", "model", "unit", etc. as described above generally refer to computer-related entities hardware, hardware and software. may mean a combination, software, or software in execution. For example, the aforementioned components may be, but are not limited to, a process run by a processor, a processor, a controller, a controlling processor, an object, a thread of execution, a program, and/or a computer. For example, both an application running on a controller or processor and a controller or processor can be a component. One or more components may reside within a process and/or thread of execution, and components may reside on one machine or be distributed across two or more machines.

The above description and the accompanying drawings are merely illustrative of the present technical idea, and those of ordinary skill in the art may combine, separate, substitute and Various modifications and variations such as changes are possible. Therefore, the embodiments disclosed in the present specification are not intended to limit the present technical idea but to explain, and the scope of the present technical idea is not limited by these embodiments. The scope of protection of the present technical idea should be interpreted by the claims, and all technical ideas within the equivalent range should be interpreted as being included in the scope of the present specification.

Claims (6)

As a communication method of a terminal performing sidelink communication with another terminal,
receiving two or more sidelink data channels from the other terminal;
bundling or multiplexing some of the received side link data channels to configure HARQ information; and
A communication method of a terminal comprising transmitting bundled or multiplexed HARQ information to the other terminal. According to claim 1,
Further comprising the step of receiving a side link control channel from the other terminal,
The sidelink control channel is a communication method of a terminal including HARQ related information including a HARQ process number. According to claim 1,
In the step of configuring the HARQ information, a communication method of a terminal to configure HARQ information by bundling or multiplexing some of the sidelink data channels based on a codebook group or a transport block. As a terminal performing sidelink communication with another terminal,
a receiver for receiving two or more sidelink data channels from the other terminal;
a controller configured to configure HARQ information by bundling or multiplexing some of the received sidelink data channels; and
A terminal comprising a transmitter for transmitting bundled or multiplexed HARQ information to the other terminal. 5. The method of claim 4,
The receiving unit additionally receives a side link control channel from the other terminal,
The side link control channel is a terminal including HARQ related information including a HARQ process number. 6. The method of claim 5,
The control unit configures HARQ information by bundling or multiplexing some of the sidelink data channels based on a codebook group or a transport block.

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