KR20200041570A - Method and apparatus for harq feedback in nr v2x - Google Patents

Abstract

According to a specification of the present invention is a communication method of a terminal performing side-link communication with another terminal. The specification is a communication method of a terminal and the terminal. The communication method of the terminal comprises the steps of: receiving two or more side-link data channels from a different terminal; bundling or multiplexing some of the received side-link data channels to configure HARQ information; and transmitting the bundled or multiplexed HARQ information to the different terminal.

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 side link communication with other terminals in NR V2X, specifically a HARQ feedback method and an apparatus thereof.

There is a demand for large-scale data processing, high-speed data processing, and various service demands using wireless terminals in vehicles, industrial sites, and the like. As such, there is a demand for a technology for a high-speed and large-capacity communication system capable of processing large-scale data and various scenarios such as video, wireless data, and machine-type communication data beyond simply voice-oriented services.

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

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

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

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

One embodiment devised to solve the above-described problem is a communication method of a terminal performing side link communication with another terminal, receiving two or more side link data channels from another terminal, among the received side link data channels It provides a communication method of a terminal comprising a step of bundling or multiplexing to configure HARQ information and transmitting the bundled or multiplexed HARQ information to the other terminal.

Further, another embodiment is a terminal that performs side link communication with another terminal, and configures HARQ information by bundling or multiplexing some of the received side link data channels, a receiving unit receiving two or more side link data channels from the other terminal. It provides a terminal including a control unit and a transmitting unit for transmitting the 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 briefly showing a structure of an NR wireless communication system to which the present embodiment can be applied.
2 is a diagram for explaining a frame structure in an NR system to which the present embodiment can be applied.
3 is a diagram for describing a resource grid supported by a radio access technology to which the present embodiment can be applied.
4 is a diagram for describing a bandwidth part supported by a radio access technology to which the present embodiment can be applied.
5 exemplarily shows 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 view 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 the present embodiment can be applied.
9 is a view for explaining various scenarios for V2X communication.
10 shows an example of a terminal 1 (UE1), a terminal 2 (UE2) performing sidelink communication, and a sidelink resource pool used by them.
11 illustrates the type of V2X transmission resource pool.
12 illustrates a method for performing SPS activation (request), reactivation (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 illustrates a format of PSCCH associated with HARQ in NR V2X according to another embodiment.
18 shows an example of one of the PSCCH formats.
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 technology will be described in detail with reference to exemplary drawings. In adding reference numerals to the components of each drawing, the same components may have the same reference numerals as possible even though they are displayed on different drawings. In addition, in describing the technical idea, when it is determined that a detailed description of a related known configuration or function may obscure the gist of the technical idea, the detailed description may be omitted.

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

In addition, the terms and technical names used in the present specification are for describing specific embodiments, and the technical thought is 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 this technical idea belongs, unless otherwise defined. When the term is an incorrect technical term that does not accurately represent the technical idea, it should be understood as being replaced by a technical term that can be correctly understood by those skilled in the art. In addition, general terms used in the present specification should be interpreted as defined in the dictionary or in context before and after, and should not be interpreted as an excessively reduced meaning.

The wireless communication system in the present specification means 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 embodiments disclosed below can be applied to a wireless communication system using various wireless access technologies. For example, the present embodiments are code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), and single carrier frequency division multiple (SC-FDMA). access) and the like. CDMA may be implemented with a radio technology such as universal terrestrial radio access (UTRA) or CDMA2000. TDMA may be implemented with radio technologies such as global system for mobile communications (GSM) / general packet radio service (GPRS) / enhanced data rates for GSM evolution (EDGE). OFDMA can be implemented with wireless technologies such as the 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 a universal mobile telecommunications system (UMTS). 3rd generation partnership project (3GPP) long term evolution (LTE) is part of evolved UMTS (E-UMTS) using evolved-UMTS terrestrial radio access (E-UTRA), employing OFDMA in the downlink and SC in the uplink -Adopt FDMA. As described above, the present embodiments may be applied to a currently disclosed or commercialized wireless access technology, or may be applied to a wireless access technology currently being developed or to be developed in the future.

Meanwhile, the terminal in the present specification is a comprehensive concept that refers to a device including a wireless communication module that performs communication with a base station in a wireless communication system. UEs in WCDMA, LTE, HSPA, and IMT-2020 (5G or New Radio) (User Equipment), of course, it should be interpreted as a concept including all of MS (Mobile Station), User Terminal (UT), Subscriber Station (SS), and wireless device 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 the V2X communication system, it may mean a vehicle, a device including a wireless communication module in the vehicle, or the like. Also, 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.

The base station or cell in the present specification refers to an end that communicates with a terminal in terms of a network, Node-B (Node-B), evolved Node-B (eNB), gNode-B (gNB), Low Power Node (LPN), Sector, site, various types of antennas, BTS (Base Transceiver System), access point, access point (e.g., transmission point, reception point, transmission / reception point), relay node (Relay Node) ), Mega cell, macro cell, micro cell, pico cell, femto cell, remote radio head (RRH), radio unit (RU), and small cell (small cell).

Since the various cells listed above have a base station that controls each cell, the base station can be interpreted in two ways. 1) a device that provides a mega cell, a macro cell, a micro cell, a pico cell, a femto cell, or a small cell in relation to the wireless area, or 2) the wireless area itself. In 1), all devices that provide a predetermined wireless area are controlled by the same entity or interact to configure the wireless area in a collaborative manner. Points, transmission / reception points, transmission points, reception points, and the like, according to a configuration method of a wireless area, are examples of base stations. In 2), the radio area itself, which receives or transmits a signal from the viewpoint of the user terminal or the neighboring base station, may be directed to the base station.

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

Uplink (Uplink, UL, or uplink) means a method of transmitting and receiving data to the base station by the terminal, downlink (Downlink, DL, or downlink) means a method of transmitting and receiving data to the terminal by the base station do. Downlink (downlink) may mean a communication or communication path from a multiple transmit and receive point to a terminal, and uplink (uplink) may mean a communication or communication path from a terminal to a multiple transmit and receive point. At this time, in the downlink, the transmitter may be a part of multiple transmission / reception points, and the receiver may be a part of the terminal. In addition, in the uplink, the transmitter may be a part of the terminal, and the receiver may be a part of multiple transmission / reception points.

In the uplink and downlink, control information is transmitted and received through control channels such as PDCCH (Physical Downlink Control CHannel), PUCCH (Physical Uplink Control CHannel), and PDSCH (Physical Downlink Shared CHannel), PUSCH (Physical Uplink Shared CHannel), etc. The same data channel is configured to transmit and receive data. Hereinafter, a situation in which signals are transmitted / received through channels such as PUCCH, PUSCH, PDCCH and PDSCH is also described in the form of 'transmit and receive PUCCH, PUSCH, PDCCH and PDSCH'.

In order to clarify the description, hereinafter, the technical idea is mainly focused on the 3GPP LTE / LTE-A / NR (New RAT) communication system, but the technical features are not limited thereto.

In 3GPP, after research on 4G (4th-Generation) communication technology, 5G (5th-Generation) communication technology is being conducted to meet the requirements of ITU-R's next-generation wireless access technology. Specifically, 3GPP is conducting research on new NR communication technologies that are separate from LTE-A pro and 4G communication technologies, which have improved LTE-Advanced technology to meet the requirements of ITU-R with 5G communication technology. LTE-A pro and NR are both expected to be submitted in 5G communication technology, but the following description will focus on NR for convenience of explanation.

The operating scenario in NR has defined various operating scenarios by adding considerations for satellite, automobile, and new verticals in the existing 4G LTE scenario, and has an eMBB (Enhanced Mobile Broadband) scenario and high terminal density in terms of service It is deployed in the range and supports the Massive Machine Communication (mmmTC) scenario, which requires low data rate and asynchronous connection, and the Ultra Reliability and Low Latency (URLLC) scenario, which 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, ultra-high-bandwidth (mmWave) support technology, and forward compatibility technology are applied. In particular, in the NR system, various technical changes are proposed in terms of flexibility in order to provide forward compatibility. Main technical features will be described below with reference to the drawings.

<NR system general>

1 is a diagram briefly showing the structure of an NR system to which the present embodiment can be applied.

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

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

<NR wave form, numerology 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 multiple input multiple output (MIMO), and has the advantage of being able to use a receiver of high complexity with high frequency efficiency.

Meanwhile, in the NR, the demands for data rate, delay rate, and coverage for each of the three scenarios described above are different from each other, so 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 multiple different numerology-based radio resources has been proposed.

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

It changes exponentially depending on 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 numerology can be divided into 5 types according to the subcarrier spacing. This is different from that in which the subcarrier spacing of LTE, which is one of 4G communication technologies, is fixed at 15khz. Specifically, the subcarrier interval used for data transmission in NR is 15, 30, 60, and 120 khz, and the subcarrier interval used for synchronization signal transmission is 15, 30, 12, and 240 khz. In addition, the extended CP applies only to the 60khz subcarrier spacing.

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

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

Referring to FIG. 2, the slot is fixedly composed of 14 OFDM symbols in the case of a normal CP, but the length of the slot may vary depending on the subcarrier interval. For example, in the case of a numerology with a 15 khz subcarrier spacing, the slot is 1 ms long and is configured to have the same length as the subframe. On the contrary, in the case of a neuromerlage having a 30 khz subcarrier spacing, a slot is composed of 14 OFDM symbols, but may have two slots in one subframe with a length of 0.5 ms. That is, the subframe and the frame are defined with 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.

Meanwhile, the NR defines a basic unit of scheduling as a slot, and also introduces a mini-slot (or sub-slot or non-slot based schedule) to reduce transmission delay in a radio section. If a wide subcarrier interval is used, the transmission delay in a radio section can be reduced because the length of one slot is inversely shortened. The mini-slot (or sub-slot) is for efficient support for URLLC scenarios and can be scheduled in units of 2, 4, and 7 symbols.

In addition, unlike LTE, uplink and downlink resource allocation is defined as a symbol level within one slot. In order to reduce HARQ delay, a slot structure capable of directly transmitting HARQ ACK / NACK within a transmission slot has been defined, and this slot structure is referred to as a self-contained structure.

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, the NR supports that data transmission is scheduled in one or more slots. Accordingly, the base station may inform the UE 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 a table configured through RRC signaling using SFI, and dynamically indicate through DCI (Downlink Control Information) or statically or quasi-statically through RRC. It might be.

<NR Physical Resources>

With regard to physical resources in the NR, antenna ports, resource grids, resource elements, resource blocks, bandwidth parts, etc. are considered. Can be.

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

3 is a diagram for describing a resource grid supported by a radio access technology to which the present embodiment can be applied.

Referring to FIG. 3, a resource grid may exist according to each neuromerging because the NR supports a plurality of neuromerging on the same carrier. In addition, the resource grid may exist according to the antenna port, subcarrier spacing, and transmission direction.

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

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

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

In the case of a paired spectrum, the uplink and downlink bandwidth parts are independently set, and in the case of an unpaired spectrum, unnecessary frequency re-tunning is prevented between downlink and uplink operation. For this, the bandwidth part of the downlink and the uplink is set in pairs so that the center frequency can be shared.

<NR initial connection>

In NR, a terminal accesses a base station and performs cell search and random access procedures to perform communication.

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

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

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

The terminal receives the SSB by monitoring the SSB in the time and frequency domain.

SSB can be transmitted up to 64 times in 5 ms. Multiple SSBs are transmitted with different transmission beams within 5 ms time, and the terminal performs detection by assuming that SSBs are transmitted every 20 ms period when viewed based on a specific one 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 below 3 GHz, and up to 8 SSBs can be transmitted using up to 8 different beams in the frequency band from 3 to 6 GHz and up to 64 in the frequency band above 6 GHz.

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

-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.

Meanwhile, 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 out of the center of the system band, and in the case of supporting broadband operation, a plurality of SSBs may be transmitted on the frequency domain. Accordingly, the terminal monitors the SSB using a synchronization raster, which is a candidate frequency location for monitoring the SSB. The carrier raster and the 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, and thus supports fast SSB search of the UE. You can.

The UE may acquire MIB through the PBCH of the SSB. The MIB (Master Information Block) includes minimum information for the UE to receive the remaining system information (RMSI, Remaining Minimum System Information) broadcast by the network. In addition, PBCH is information on the location of the first DM-RS symbol on the time domain, information for the UE to monitor SIB1 (for example, SIB1 neuromerging 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, SIB1 pneumatic information is equally applied to messages 2 and 4 of the random access procedure for accessing the base station after the terminal completes the cell search procedure.

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

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, when the cell search is completed, the UE transmits a random access preamble for random access to the base station. The random access preamble is transmitted through PRACH. Specifically, the random access preamble is transmitted to the base station through PRACH composed of continuous radio resources in a specific slot that is periodically repeated. Generally, a contention-based random access procedure is performed when the UE initially accesses a cell, and a non-competition-based random access procedure is performed when random access is performed for beam failure recovery (BFR).

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), UL grant (uplink radio resource), temporary C-RNTI (Temporary Cell-Radio Network Temporary Identifier) and TAC (Time Alignment Command). Since one random access response may include random access response information for one or more terminals, a 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, a Random Access-Radio Network Temporary Identifier (RA-RNTI).

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

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

<NR CORESET>

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

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

7 is a view 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 3 OFDM symbols in a time domain. In addition, CORESET is defined as a multiple of 6 resource blocks from the frequency domain to the carrier bandwidth.

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 UE may configure by receiving one or more CORESET information through RRC signaling.

<LTE Side Link>

In the existing LTE system, to provide direct communication between terminals and V2X (especially V2V) service, radio channel and radio protocol design for direct communication between terminals (i.e., side link) was made.

With respect to the sidelink, a PSSS / SSSS, which is a synchronization signal for synchronization between a wireless sidelink transmitting end and a receiving end, and a PSBCH (Physical Sidelink Broadcasting Channel) for transmitting and receiving a side link Master Information Block (MIB) have been defined, and also discovery information. A design for a physical sidelink discovery channel (PSCH) for transmission / reception, a physical sidelink control channel (PSCCH) for transmission and reception of Sidelink Control Information (SCI), and a physical sidelink shared channel (PSSCH) for transmission and reception of sidelink data was made.

In addition, for the allocation of radio resources for the sidelink, a technology has been developed that is divided 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 radio resource pool. In addition, additional technical evolution was required for the LTE system to satisfy the V2X scenario.

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

In order to satisfy these performance requirements, technology development has been conducted to improve the performance of the sidelink technology developed based on the conventional D2D communication according to the requirements of V2X. In particular, in order to apply to C-V2X (Cellular-V2X), a technique for improving the physical layer design of the side link to be suitable for a high-speed environment, resource allocation technology, and synchronization technology may be selected as the main research technology.

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

<Sidelink Physical Layer Design>

For V2X communication, in order to improve channel estimation performance and frequency offset estimation performance, a pilot signal DMRS (Demodulation Reference Signal) needs to be allocated more than D2D communication.

8 is a diagram for explaining, for example, a DMRS structure for a conventional sidelink and a DMRS structure for a sidelink to which the present 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 a 6 GHz center frequency band defined for sidelink transmission, and in the case of a vehicle terminal, moves at 280 km / h in consideration of the relative speed. At this time, the correlation time is 0.277 ms, and this value is shorter than the interval between the reference signals of Rel-12 / 13, so the channel estimation time is insufficient. To solve this problem, in the sidelink for V2X communication, the number of DMRSs per subframe is increased to 4 and the spacing between reference signals is reduced to 0.214 ms, so that the physical layer design is changed to facilitate channel estimation even with fast channel changes. .

On the other hand, an example of a method of selecting a DMRS symbol pattern is that the PSCCH / PSSCH is assigned to the DMRS on the 2/5/8/11 OFDM symbol in the dedicated carrier, and the PSBCH is the DMRS on the 3/5/8/10 OFDM symbol. Assigns In the 2 GHz band, the Rel-12 / 13 method with two DMRSs can be used as it is. That is, the number and pattern of DMRS transmissions may be configured differently according to a channel and a carrier frequency band.

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

<Resource allocation>

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

Referring to FIG. 9, a V2X terminal (denoted as a vehicle, but can be variously set such as a user terminal) may be located within the base station (eNB or gNB or ng-eNB) coverage, or may be located outside the base station coverage. For example, communication may be performed between UEs in UE coverage (UE N-1, UE G-1, UE X), and between UEs in UE coverage and UEs (ex, 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 base station coverage.

In these various scenarios, in order to perform communication using a sidelink, a corresponding terminal requires allocation of radio resources for communication, and allocation of radio resources is largely divided into base station handling allocation and terminal selection.

Specifically, in D2D, a method of allocating a resource by a terminal includes a centralized method (Mode 1) in which a base station intervenes in resource selection and management and a distributed method (Mode 2) in which a terminal randomly selects a preset resource. Similar to D2D, C-V2X has 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 region and the DATA pool resource region allocated thereto.

10 shows an example of a terminal 1 (UE1), a terminal 2 (UE2) performing sidelink communication, and a sidelink resource pool used by them.

Referring to FIG. 10, the base station is designated as an eNB, but may be a gNB or ng-eNB as described above. In addition, the terminal is illustrated as a mobile phone by way of example, it can be applied to a variety of vehicles, infrastructure devices.

In FIG. 10 (a), the transmitting terminal UE1 may select a resource unit corresponding to a specific resource in a resource pool representing a set of a set of resources and transmit a sidelink signal using the resource unit. The receiving terminal UE2 may configure a resource pool through which UE1 can transmit signals and detect a transmission signal of the corresponding terminal.

Here, the resource pool may be notified by the base station when UE1 is in the connection range of the base station, or may be determined by a predetermined resource or notified by another terminal when the UE1 is outside the connection range of the base station. 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 and use it to transmit its own sidelink signal.

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

Meanwhile, resource pools can be subdivided into several types. First, it may be classified according to contents of sidelink signals transmitted from each resource pool. For example, the content of the sidelink signal can be classified, and a separate resource pool can 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.

The SA provides information such as a location of a resource used for transmission of a sidelink data channel followed by a transmitting terminal and a modulation and coding scheme (MCS) or MIMO transmission method, and a timing advance (TA) required for demodulation of other data channels. It may be a signal including. This signal may 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 transmitted by multiplexing SA with sidelink data.

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

Meanwhile, when SAs are multiplexed and transmitted together with sidelink data on the same resource unit, only a sidelink data channel in a form excluding SA information can be transmitted from 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 can 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 that allows a transmitting terminal to transmit information such as its own ID so that an adjacent terminal can discover itself. Even when the contents of the sidelink signal are the same, different resource pools may be used according to the transmission and reception attributes of the sidelink signal.

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

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 refer to a resource (s) defined in advance so that the terminal performs a V2X operation (or a V2X operation). In this case, the resource pool may be defined in terms of time-frequency. Meanwhile, various types of V2X transmission resource pools may exist.

11 illustrates the type of V2X transmission resource pool.

Referring to FIG. 11 (a), V2X transmission resource pool #A may be a resource pool in which only (partial) sensing is allowed. The V2X transmission resource selected by (partial) sensing is semi-statically maintained at a constant cycle as shown in FIG. 11 (a).

Referring to FIG. 11 (b), V2X transmission resource pool # Β may be a resource pool where only random selection is allowed. In the V2X transmission resource pool #B, the UE may randomly select the V2X transmission resource in the selection window without performing (partial) sensing.

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, the selected resource may be set (/ signaling) so that it is not semi-reserved. The base station may be configured so that the terminal does not perform a sensing operation (based on scheduling allocation decoding / energy measurement) to perform a V2X message transmission operation on the V2X transmission resource pool.

Meanwhile, although not shown in FIG. 11, a resource pool capable of both (partial) sensing and random selection may exist. The base station may inform that V2X resources can be selected by either of the partial sensing and the random selection.

V2X UL SPS

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

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

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

The UE may receive SPS configuration for one or more specific logical channels. The UE may receive SPS configuration for a specific logical channel through system information, an RRC connection setup message, an RRC connection reset message, or an RRC connection release message.

When data is available for a specific logical channel (s), the UE may request the 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), MAC control element (CE), or RRC message. That is, the UE may transmit an SPS activation request to the eNB using a control resource used to request SPS activation. The control resource may be a PUCCH resource, a random access resource, or a new UL control channel resource. In addition, the UE may send an SPS activation request to the eNB, for example, during RRC connection (re-) establishment, during handover, after handover, or from RRC_CONNECTED.

Since the UE actively requests SPS activation to the eNB when there is UL data to be transmitted, the gap between the generation of UL data and the configured SPS resource may 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 in the upper layer, the UE transmits an SPS request message through the MAC CE, for example, from the eNB. The eNB sends an acknowledgment message for one of the three SPS configurations. The UE transmits UL data in a specific resource, for example, 1 sec period, according to the corresponding SPS configuration.

On the other hand, if there is UL data to be transmitted from a higher layer at a specific time, the UE transmits an SPS request message again through the MAC CE, for example, from the eNB. The eNB sends an acknowledgment message for the other of the three SPS configurations. The UE transmits UL data at a specific resource, for example, 100 sec period, according to the corresponding SPS configuration.

Sending and receiving SA (Scheduling assignment)

The mode 1 UE may transmit SA (or sidelink control signal, Sidelink Control Information (SCI)) through resources configured from the base station. The mode 2 terminal is configured (resourced) of resources to be used for sidelink transmission from the base station. Then, the SA may 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 by a predetermined offset (SAOffsetIndicator) indicated by higher layer signaling from a specific system frame. 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 among the subframes indicated as SA being transmitted in the subframe bitmap (saSubframeBitmap) from the first subframe of the SA period. In 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 or a time-resource pattern (TRP). As illustrated, when the number of subframes included in the SA period excluding the SA resource pool is greater than the number of T-RPT bits, the T-RPT may be repeatedly applied, and the last applied T-RPT is the number of remaining subframes. As long as it is truncated, it can be applied.

<Sync 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 a side link should be performed. For this, it is important that a terminal located outside the base station coverage acquires synchronization.

Hereinafter, based on the above description, a method for obtaining time and frequency synchronization in side link communication, particularly in communication between a vehicle, a vehicle and another terminal, and a vehicle and an infrastructure network will be described.

D2D communication used SLSS (Sidelink Synchronization Signal), a synchronization signal transmitted from a base station, for time synchronization between terminals. In the C-V2X, a global navigation satellite system (GNSS) may be additionally considered to improve synchronization performance. However, priority may be given to establishment of synchronization or the base station may indicate information on priority. For example, the UE first selects a synchronization signal that the base station directly transmits in determining its transmission synchronization, and if it is located outside the base station coverage, preferentially synchronizes to the SLSS transmitted by the UE inside the base station coverage. To match.

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

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 / deformed / repeated with the PSS. Also, unlike the DL PSS, other Zadoff weight root indexes (eg, 26 and 37) may be used. The SSSS may be an M-sequence or a structure similar / modified / repeatable to the SSS or the like. If the terminals synchronize with the base station, the SRN becomes the base station, and the SLSS becomes the PSS / SSS.

Unlike DL's PSS / SSS, PSSS / SSSS follows UL subcarrier mapping. PSSCH (Physical Sidelink synchronization channel) is the basic system information that the UE needs to first know before transmitting / receiving the sidelink signal (for example, information related to SLSS, Duplex Mode (DM), TDD UL / DL configuration, resource Pool-related information, SLSS-related application type, subframe offset, broadcast information, etc.) may be a transmitted channel. The PSSCH can be transmitted on the same subframe as SLSS or on a subsequent subframe. DM-RS can be used for demodulation of PSSCH.

The SRN may be a node that transmits SLSS and PSSCH. SLSS may be in the form of a specific sequence, and PSSCH may be in the form of a sequence indicating specific information or in the form of a code word after a 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 terminal may be an SRN.

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

<NR side link>

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

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

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

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

Synchronization mechanism

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

Resource allocation

In NR V2X sidelink communication, at least two sidelink resource allocation modes may be defined, mode 3 and mode 4. In mode 3, the base station schedules sidelink resource (s) used by the terminal for sidelink transmission. In mode 4, the terminal determines sidelink transmission resource (s) in sidelink resources configured by the base station or in 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 to select a sidelink resource for other UE (s), is configured as a configured grant for sidelink transmission, or sidelinks of other terminal (s) Transmissions can be scheduled.

NR preemtion

In the case of a terminal critical to delay, such as a URLLC terminal, data resources may be used by preempting even data resources already allocated to other eMBB terminals. In addition, information on which region of the data resource is preempted through the group common DCI may be indicated to the terminal.

Side link resource allocation / configuration based on Uu interface

The NR Uu may allocate NR sidelink resources for a shared licensed carrier and / or a dedicated NR sidelink carrier between Uu and the NR sidelink. At this time, the resource allocation can support dynamic resource allocation and activation / deactivation based resource allocation. The resource allocation based on activation / deactivation 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 that select 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 terminals outside the base station / coverage transmit synchronization signals themselves, and may be {168, 169,, 335}.

The following descriptions are examples of satellite signals, mainly GNSS and GPS, but may be replaced with other satellite signals. 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 on a cycle. In addition, in the following description, GPS timing sets a frame / subframe boundary based on an absolute time based on a time (eg, Coordinated Universal Time or GPS time) obtained when receiving GPS, and some or all of the subframes are set. 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 to reduce system overhead, and for data transmission safety, a transmitting terminal can retransmit data once according to selection. However, NR V2X can transmit HARQ ACK / NACK information in terms of data transmission stability, and in this case, overhead can 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 this, it can be bundled and transmitted through the PSCCH. In the figure, although HARA ACK / NACK is transmitted through the PSCCH, it may be transmitted through a separate channel or another channel, and the bundled HARQ information may be composed of 3 bits or less.

On the other hand, in the frequency domain of 3 GHz or less, 15 kHz, 30 kHz, 60 kHz, and 120 kHz were discussed as candidate groups in subcarrier spacing (SCS). In addition, 30 kHz, 60 kHz, 120 kHz, and 240 kHz as subcarrier spacing (SCS) for FR2 in a frequency range exceeding 3 GHz will be discussed as candidate groups. In the NR V2X, a mini slot smaller than 14 symbols (for example, 2/4/7 symbols) may be supported as a minimum scheduling unit.

As candidates for RS, DM-RS, PT-RS, CSI-RS, SRS, and AGC training signals were 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 the 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.

FIG. 15A illustrates inter-CBG bundling within a TB within 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 FIG. 15A, the codebook groups CBG0 and CBG1 each include one or more codebooks.

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

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

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

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

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

Accordingly, when inter-TB bundling per CBG index is performed per transport block (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 the HARQ information. have.

15 (c) shows inter-CBG bundling within a TB and codebook groups (CBGs) within one transport block (TB) shown in FIG. 15 (a). 15B, inter-TB bundling per CBG index is combined.

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 data to the receiving terminal UE2 and the receiving terminal generates HARQ ACK / NACK information for this, it can be multiplexed and transmitted through the PSCCH. In the figure, HARA ACK / NACK is transmitted through the PSCCH, but may be transmitted through a separate channel or another channel. The multiplexed HARQ information is set based on a codebook, and may be transmitted through PSCCH, for example.

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

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

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

17 illustrates a format of PSCCH associated with HARQ in NR V2X according to another embodiment.

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

The first field (Hybrid-ARQ process number field) indicates a device related to the Hybrid-ARQ process used for soft combining. The first field may have a bit number of 2 log values of the number of hybrid-ARQ processes, for example, 3 bits when the number of hybrid-ARQ processes is 8.

The second field (Downlink assignment index field) indicates a dynamic HARQ codebook when using a 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 way as NR DCI format 1-0.

The 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 PSCCH associated with HARQ in NR V2X may not include a second field (Downlink assignment index field) as shown in FIG. 17 (c). That is, in NR V2X, since a fixed HARQ codebook is used in the HARQ procedure or only a semi-static HARQ codebook is used, a dynamic HARQ procedure may not be performed.

According to another embodiment, the format of PSCCH associated with HARQ in NR V2X may not include a third field (HARQ feedback timing field) as shown in FIG. 17 (c). 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 associated with 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 FIG. 17 (d). It may not. This can simplify the HARQ procedure in NR V2X.

18 shows an example of one of the PSCCH formats.

Referring to FIG. 18, a PSCCH or another sidelink control channel including information related to HARQ in NR V2X may be configured in the same format as one of NR PUCCH formats. For example, the PSCCH or other sidelink control channel may be transmitted through resources 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. At this time, each sidelink control channel resource set may include two or more side link control channel resources. One of the site link control channel resources may be set as the resource of the last symbol of the corresponding slot.

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

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, respectively) A) can be distinguished. At this time, the feedback pair according to each phase difference may be determined by the HARQ codebook described above.

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

Referring to FIG. 20, the base station 1000 according to another embodiment includes a control unit 1010, a transmission unit 1020, and a reception unit 1030.

The control unit 1010 controls the operation of the overall base station 1000 according to the HARQ-related procedure in the NR V2X necessary to perform the above-described present invention.

The transmitting unit 1020 and the receiving unit 1030 are used to transmit and receive signals, messages, and data necessary to perform the present invention described above.

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 reception unit 1110, a control unit 1120, and a transmission unit 1130. The user terminal 1100 according to another embodiment may be the first terminal UE1 and the second terminal UE2 shown in FIG. 10 and the like.

The reception unit 1110 receives downlink control information, data, and messages from a 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 the NR V2X required to perform the present invention described above.

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

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

In the case of implementation by firmware or software, the method according to embodiments of the present invention may be implemented in the form of an apparatus, procedure, or function that performs the functions or operations described above. The software code can be stored in a memory unit and driven by a processor. The memory unit is located inside or outside the processor, and can exchange data with the processor by various known means.

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

In addition, the terms "system", "processor", "controller", "component", "module", "interface", "model" and "unit" described above generally refer to computer-related entity hardware, hardware and software. It can mean a combination, software or running software. For example, the components described above may be, but are not limited to, processes, processors, controllers, control processors, entities, threads of execution, programs and / or computers driven by a processor. For example, both an application running on a controller or processor and a controller or processor can be a component. One or more components can be in a process and / or thread of execution, and the components can be located on one system or deployed to more than one system.

The above description and the accompanying drawings are merely illustrative of the technical idea of the present invention, and those having ordinary skill in the art will combine, separate, and replace configurations without departing from the essential characteristics of the present technology. Various modifications and variations such as changes will be possible. Therefore, the embodiments disclosed in the present specification are not intended to limit the technical spirit, but to explain, and the scope of the technical spirit is not limited by these embodiments. The scope of protection of this technical spirit should be interpreted by the claims, and all technical spirits within the equivalent scope should be interpreted as being included in the scope of the present specification.

Claims (6)

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

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