KR20220057449A - Method for controlling sidelink communication and apparatus thereof - Google Patents

Abstract

The present disclosure relates to a method and device for providing a V2X service in a next-generation radio access technology (New RAT). In a method for a terminal to control sidelink communication, the method comprises: a step of receiving sidelink control information from a second terminal; a step of receiving first sidelink data according to scheduling of the sidelink control information; and a step of determining priorities when a time resource for transmitting first HARQ feedback information for the first sidelink data and a time resource for receiving second HARQ feedback information for second sidelink data transmitted by the terminal overlap at least in part.

Description

Sidelink communication control method and apparatus

The present disclosure relates to a method and apparatus for providing a V2X service in a next-generation radio access technology (New RAT).

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 demand 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 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 LTE-Advanced Pro Rel-15/16 standard and NR (New Radio Access Technology) standard in parallel to satisfy the IMT-2020 requirement, which is referred to as 5G technology, and the two standard technologies is planning to be approved as a next-generation wireless communication technology.

In 5G technology, it can be applied and utilized in autonomous vehicles. To this end, it is necessary to apply 5G technology to vehicle to everything (V2X), and high-speed transmission and reception is required while ensuring high reliability of increased data for autonomous driving.

In addition, in order to satisfy operation scenarios of various autonomous vehicles such as platooning, it is necessary to ensure not only unicast data transmission/reception using vehicle communication but also multicast data transmission/reception.

As such, when a plurality of terminals perform sidelink communication using various communication types, there is a risk of collision of radio resources for sidelink communication. In addition, due to the frequent performance of V2X communication, a case in which a collision occurs during transmission and reception of HARQ feedback may occur.

The present embodiments may provide a method and apparatus for performing sidelink communication using next-generation radio access technology.

In one aspect, the present embodiment provides a method for a terminal to control sidelink communication, the step of receiving sidelink control information (Sidelink Control Information) from a second terminal and a first sidelink according to scheduling of the sidelink control information A time resource for receiving data and transmitting the first HARQ feedback information for the first sidelink data and a time resource for receiving the second HARQ feedback information for the second sidelink data transmitted by the terminal are at least part of In the case of overlapping, there is provided a method comprising the step of determining a priority.

In another aspect, the present embodiment provides a method for a terminal to control sidelink communication, by receiving sidelink control information (Sidelink Control Information) from a second terminal and first sidelink data according to scheduling of the sidelink control information At least a part of the time resource for the receiving unit receiving and transmitting the first HARQ feedback information for the first sidelink data and the time resource for receiving the second HARQ feedback information for the second sidelink data transmitted by the terminal Provided is a terminal device including a control unit for determining a priority when overlapping.

According to the present embodiments, it is possible to provide a method and apparatus for performing sidelink communication using next-generation wireless access technology.

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 this embodiment can be applied.
7 is a diagram for explaining CORESET.
8 is a diagram for explaining various scenarios for V2X communication.
9 is a diagram for explaining an operation of a terminal according to an embodiment.
10 is a diagram for explaining an operation of a terminal according to another embodiment.
11 is a diagram for explaining a situation in which adjustment information is requested in a sidelink communication operation according to an embodiment.
12 is a diagram for explaining a periodic adjustment information transmission operation according to an embodiment.
13 is a diagram for explaining an operation of transmitting coordination information according to collision prediction according to another embodiment.
14 is a diagram for explaining a sidelink resource reselection operation using adjustment information according to another embodiment.
15 is a diagram for explaining a terminal configuration according to an embodiment.

Hereinafter, some embodiments of the present disclosure 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 embodiments, if it is determined that a detailed description of a related well-known configuration or function may obscure the gist of the present technical idea, the detailed description may be omitted. When "includes", "having", "consisting of", etc. mentioned in this specification are used, other parts may be added unless "only" is used. When a component is expressed in the singular, it may include a case in which the plural is included unless otherwise explicitly stated.

In addition, in describing the components of the present disclosure, 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.

In the description of the positional relationship of the components, when it is described that two or more components are "connected", "coupled" or "connected", two or more components are directly "connected", "coupled" or "connected" ", but it will be understood that two or more components and other components may be further "interposed" and "connected," "coupled," or "connected." Here, other components may be included in one or more of two or more components that are “connected”, “coupled” or “connected” to each other.

In the description of the temporal flow relationship related to the components, the operation method or the production method, for example, the temporal precedence relationship such as "after", "after", "after", "before", etc. Alternatively, when a flow precedence relationship is described, it may include a case where it is not continuous unless "immediately" or "directly" is used.

On the other hand, when numerical values or corresponding information (eg, level, etc.) for a component are mentioned, even if there is no separate explicit description, the numerical value or the corresponding information is based on various factors (eg, process factors, internal or external shock, Noise, etc.) may be interpreted as including an error range that may occur.

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, or 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) Alternatively, it may be applied to various various radio access technologies such as non-orthogonal multiple access (NOMA). In addition, the wireless access technology may mean not only a specific access technology, but also a communication technology for each generation established by various communication consultation organizations such as 3GPP, 3GPP2, WiFi, Bluetooth, IEEE, and ITU. For example, 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 datarates for GSM evolution (EDGE). OFDMA may be implemented with a radio 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-UMTSterrestrial radio access (E-UTRA), and employs OFDMA in the downlink and SC- FDMA is employed. 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, the terminal in the present specification is a comprehensive concept meaning a device including a wireless communication module that performs communication with a base station in a wireless communication system, WCDMA, LTE, NR, HSPA and IMT-2020 (5G or New Radio), etc. It should be interpreted as a concept including all of UE (User Equipment), MS (Mobile Station), UT (User Terminal), SS (Subscriber Station), wireless device, etc. in GSM. In addition, the terminal may be a user's 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 (Machine Type Communication) system, it may mean an MTC terminal, an M2M terminal, a URLLC terminal, etc. equipped with a communication module to perform machine type communication.

A base station or cell of 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 ), mega cell, macro cell, micro cell, pico cell, femto cell, RRH (Remote Radio Head), RU (Radio Unit), small cell (small cell), such as a variety of coverage areas. In addition, the cell may mean including a BWP (Bandwidth Part) in the frequency domain. For example, the serving cell may mean the Activation BWP of the UE.

In the various cells listed above, since there is a base station controlling one or more cells, 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 signals are received or transmitted from the point of view 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 the coverage of a signal transmitted from a transmission/reception point or a signal transmitted from a transmission/reception point (transmission point or transmission/reception point), and the transmission/reception point itself. can

The uplink (Uplink, UL, or uplink) refers to a method of transmitting and receiving data by the terminal to the base station, and the downlink (Downlink, DL, or downlink) refers to a method of transmitting and receiving data to the terminal by the base station do. Downlink may mean a communication or communication path from a multi-transmission/reception point to a terminal, and uplink may mean a communication or communication path from a 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. In addition, 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 the downlink transmit and receive control information through a control channel such as a Physical Downlink Control CHannel (PDCCH) and a Physical Uplink Control CHannel (PUCCH), 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 and 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'. do.

For clarity of explanation, the present technical idea will be mainly described below for the 3GPP LTE/LTE-A/NR (New RAT) communication system, but the present technical characteristics are not limited to the corresponding communication system.

In 3GPP, after research on 4G (4th-Generation) communication technology, 5G (5th-Generation) communication technology is developed to meet the requirements of ITU-R's next-generation wireless access technology. Specifically, 3GPP develops LTE-A pro, which improves LTE-Advanced technology to meet the requirements of ITU-R as a 5G communication technology, and a new NR communication technology separate from 4G communication technology. LTE-A pro and NR both refer to 5G communication technology. Hereinafter, 5G communication technology will be described focusing on NR unless a specific communication technology is specified.

In the NR operation scenario, various operation scenarios were defined by adding consideration to satellites, automobiles, and new verticals from 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 access, 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, in the NR system, various technological changes are presented in terms of flexibility in order to provide forward compatibility. The main technical features of NR 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. The gNB interconnects or gNBs and ng-eNBs are interconnected via an 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 the frequency band below 6 GHz (FR1, Frequency Range 1) and the frequency band 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 distinguish gNB or ng-eNB as needed.

<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.

On the other hand, 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.

값이 2의 지수 값으로 사용되어 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.

The value is used as an exponent value of 2 to change exponentially.

subcarrier spacing 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 five types according to the subcarrier spacing. This is different from the fact 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 in the time domain may vary according to the subcarrier interval. For example, in the case of a numerology having a 15 kHz subcarrier interval, the slot is 1 ms long and is configured with the same length as the subframe. Contrary to this, 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.

Meanwhile, 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) in order 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 the HARQ delay, a slot structure capable of transmitting HARQ ACK/NACK directly within a transmission slot has been defined, and this slot structure will be described as a self-contained structure.

NR is designed to support a total of 256 slot formats, of which 62 slot formats are used in 3GPP 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 through RRC. It can also be ordered quasi-statically.

<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 do.

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 on which a symbol on one antenna port is carried can be inferred from a channel on which a symbol on another antenna port is carried, the two antenna ports are QC/QCL (quasi co-located or It can be said that there is a quasi co-location) relationship. 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 (BWP) 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. Up to 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 terminal synchronizes with 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.

Referring to FIG. 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.

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 that 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. Compared to the carrier raster, the synchronization raster has a wider frequency interval, so that the terminal can support fast SSB search. 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 some messages used in the random access procedure for accessing the base station after the UE completes the cell search procedure. For example, the neurology information of SIB1 may be applied to at least one of messages 1 to 4 for the random access procedure.

The aforementioned RMSI may mean System Information Block 1 (SIB1), and SIB1 is periodically broadcast (eg, 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 this 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 random access is performed 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 UEs, the random access preamble identifier may be included to inform which UE 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 CORESET (Control Resource Set) having a length of 1 to 3 symbols, and transmits uplink/downlink scheduling information, SFI (Slot Format Index), and TPC (Transmit Power Control) information. .

As such, in NR, the concept of CORESET was introduced 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 connection establishment with the base station, the terminal may receive and configure one or more pieces of CORESET information through RRC signaling.

In the present specification, frequencies, frames, subframes, resources, resource blocks, regions, bands, subbands, control channels, data channels, synchronization signals, various reference signals, various signals or various messages related to NR (New Radio) can be interpreted in various meanings used in the past or present or used in the future.

<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 (especially V2V) service.

Regarding the sidelink, S-PSS/S-SSS, 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 sidelink MIB (Master Information Block) related thereto have been defined. , In addition, PSDCH (Physical Sidelink Discovery channel) for transmission and reception of discovery information, 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 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 major 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, technology development has been carried out to improve the performance of the sidelink technology developed based on the conventional D2D communication according to the requirements of V2X. 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 may be understood as encompassing links used for D2D communication developed after 3GPP Rel-12, V2X communication after Rel-14, and NR V2X after Rel-15. In addition, each channel term, synchronization term, resource term, etc. will be described in the same terms regardless of D2D communication requirements, V2X Rel-14, 15 requirements. 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.

<Resource Allocation>

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

Referring to FIG. 8 , 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 a terminal within coverage of a base station and a terminal 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 the method of allocating resources by the UE in the sidelink, there are a method in which the base station intervenes in resource selection and management (Mode 1) and a method in which the UE directly selects resources (Mode 2). In Mode 1, the base station schedules the SA (Scheduling Assignment) pool resource area and the DATA pool resource area allocated thereto to the transmitting terminal.

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 the 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 be multiplexed together with sidelink data on the same resource unit and transmitted. 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 form 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 time of reception of the synchronization reference signal or transmitted by applying a certain TA) or resource allocation method (For example, whether the base station assigns individual signal transmission resources to individual transmitting terminals or whether individual transmitting terminals select individual signal transmission resources by themselves within the pool), signal format (e.g., each sidelink signal has one sub It may be divided into different resource pools again according to the number of symbols occupied in 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.

<Synchronous signal>

As described above, in the case of the sidelink 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. For this, it is important that the terminal located outside the base station coverage acquires synchronization.

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

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 priority information. For example, in determining its own transmission synchronization, the terminal preferentially selects a synchronization signal directly transmitted by the base station, and if it is located outside the coverage of the base station, preferentially synchronizes to the SLSS transmitted by the terminal within the coverage of the base station. it will match

On the other hand, a wireless terminal installed in a vehicle or a terminal installed in a vehicle has relatively less problems with battery consumption and can use satellite signals such as GPS for navigation purposes. can be used to Here, the satellite signal 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 synchronization signal (S-PSS, Sidelink Primary synchronization signal) and a secondary synchronization signal (S-SSS, Sidelink Secondary synchronization signal). The S-PSS may be a Zadoff-chu sequence (Zadoff-chu sequence) of a predetermined length or a structure similar/modified/repeated to PSS. Also, unlike DL PSS, other Zadoff Chu root indexes (eg, 26, 37) may be used. The S-SSS 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 S-SS (Sidelink Synchronization Signal) becomes the PSS/SSS.

Unlike PSS/SSS of DL, S-PSS/S-SSS follows the UL subcarrier mapping scheme. PSBCH (Physical Sidelink broadcast channel) is basic system information that the UE needs to know first before transmitting and receiving sidelink signals (eg, information related to S-SS, duplex mode (DM), TDD UL/DL configuration , resource pool related information, type of application related to S-SS, subframe offset, broadcast information, etc.) may be a transmission channel. The PSBCH may be transmitted on the same subframe as the S-SS or on a subsequent subframe. DMRS may be used for demodulation of PSBCH. The S-SS and PSBCH may be described by describing the S-SSB (Sidelink Synchronization Signal Block).

The SRN may be a node transmitting S-SS and PSBCH. The S-SS may be in the form of a specific sequence, and the PSBCH 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 S-SS 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 demand 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 PUCCH resources and feedback timing may be indicated by a timing indicator (PDSCH-to-HARQ feedback timing indicator).

In LTE V2X, separate HARQ ACK/NACK information is not transmitted in order to reduce system overhead, and for data transmission safety, the transmitting terminal can retransmit data once according to its selection. 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.

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, with respect to FR2 for 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.

Sidelink UL SPS

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

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.

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 reset message, or an RRC connection release message.

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

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

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

Meanwhile, when UL data to be transmitted from a higher layer exists at a specific time, the UE transmits an SPS request message to the base station again through, for example, MAC CE. The base station 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.

On the other hand, S-SS id_net is a set of S-SS 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}, {0, 1,. .. , 167}. In addition, S-SS id_oon is a set of S-SS IDs used when base station/out-of-coverage terminals transmit synchronization signals themselves, and may be {168, 169,..., 335}.

As described above, unlike the conventional signal transmission/reception between the base station and the terminal, in the sidelink communication between the terminals, resource allocation, time synchronization setting, and reference signal transmission are performed independently or according to interworking with the base station.

In particular, in the case of next-generation wireless access technology (including terms such as NR and 5G), a number of protocols between the base station and the terminal have been added/modified. Therefore, unlike the conventional V2X communication protocol based on LTE technology, it is necessary to newly develop various protocols even in the case of sidelink communication based on NR technology.

The present disclosure intends to propose operations such as synchronization signal reception, resource allocation, PSCCH, PSSCH, and DMRS configuration when a transmitting terminal and a receiving terminal perform sidelink communication. Each of the embodiments described below will be mainly described with respect to sidelink communication, but as described above, it may be equally applied to C-V2X and D2D communication.

According to the change in subcarrier spacing (SCS) of the OFDM communication system that is changed in NR, a change in the frame structure of the sidelink to be used for information transmission and reception in sidelink communication is also required.

The sidelink signal in this embodiment may use a CP-OFDM type waveform among the CP-OFDM type and the DFT-s-OFDM type. In addition, the sidelink may use the following subcarrier spacing (hereinafter, SCS). For example, in FR (frequecy range) 1 using a frequency band of less than 6 GHz, SCS of 15 kHz, 30 kHz, and 60 kHz is used. In FR 2, which uses a frequency band of 6 GHz or higher, 60 kHz and 120 kHz intervals are used, and the 60 kHz band can be mainly used.

In addition, the sidelink uses a cyclic prefix (CP) to prevent modulation that may occur in the wireless communication transmission/reception process, and the length may be set equal to the normal CP length of the NR Uu interface. If necessary, an extended CP may be applied.

As described above, sidelink communication can be performed based on the NR radio access technology. In addition, when considering a scenario for sidelink communication, there is a possibility that a plurality of terminals perform communication in a cluster within a certain range, such as when a plurality of vehicles perform group driving.

In this case, a problem in which radio resources for sidelink communication frequently collide may occur. In particular, unlike Mode 1, in which the base station allocates and schedules sidelink communication resources, in Mode 2, in which the terminal selects sidelink communication resources within a certain resource pool based on a sensing operation, resource collision and an adjustment procedure are required. can be

In addition, when sidelink communication is frequently used, a problem may occur in which transmission and reception of HARQ feedback information transmitted by a specific terminal and transmission/reception of HARQ feedback information received by a specific terminal overlap.

In this situation, an embodiment of a technique for adjusting HARQ feedback transmission/reception radio resources and a radio resource coordination technique for sidelink communication will be described below.

9 is a diagram for explaining an operation of a terminal according to an embodiment.

Referring to FIG. 9 , the terminal controlling sidelink communication may perform a step of receiving sidelink control information from the second terminal (S910).

For example, the sidelink control information may be received through a PSCCH and a PSSCH. The sidelink control information may include various information such as reserved radio resource information, scheduling information, and priority information in each field.

The terminal may perform the step of receiving the first sidelink data according to the scheduling of the sidelink control information (S920).

For example, upon receiving the sidelink control information, the terminal may receive sidelink data from a radio resource indicated by the sidelink control information. The sidelink data may be received through the PSSCH.

In general, when receiving sidelink data, the UE may generate and transmit HARQ feedback information for it. Alternatively, the UE may transmit HARQ feedback information only when specific feedback information occurs according to the HARQ feedback option. Alternatively, the UE may not transmit HARQ feedback information. Options related to transmission of various HARQ feedback information may be set in association with a transmission type.

When the terminal overlaps at least a part of a time resource for transmitting the first HARQ feedback information for the first sidelink data and the time resource for receiving the second HARQ feedback information for the second sidelink data transmitted by the terminal , a step of determining the priority may be performed (S930).

For example, the terminal may transmit the second sidelink data to the second terminal or another terminal. In this case, the second terminal or another terminal may be configured to transmit the second HARQ feedback for the second sidelink data transmitted by the terminal. Accordingly, the terminal needs to receive HARQ feedback for the sidelink data transmitted by the terminal at a specific time point. Meanwhile, the terminal may be configured to transmit the first HARQ feedback information for the first sidelink data received from the second terminal.

When a specific condition is satisfied, the first HARQ feedback transmission and the second HARQ feedback reception may occur in the same time period. Alternatively, a portion of the time resource for transmitting the first HARQ feedback and the time resource for receiving the second HARQ feedback may overlap.

Therefore, when the time resources of the first HARQ feedback transmission and the second HARQ feedback reception overlap, the UE needs to determine a priority so that any one operation is performed.

As an example, the terminal may determine the priority based on the transmission type of the first sidelink data and the second sidelink data. Here, the transmission type may be divided into a unicast type, a groupcast type, and a broadcast type. For example, when the first sidelink data is received in unicast and the second sidelink data is transmitted in groupcast, the terminal transmits the first HARQ feedback for the first sidelink data transmitted in the unicast type. You can decide to prioritize. Of course, the opposite is also possible.

As another example, the terminal may determine the priority based on a result of comparing the priority information of each of the first sidelink data and the second sidelink data. The UE may control so that HARQ feedback for data having a higher priority is processed preferentially. For example, the priority information may be determined by a priority field value included in sidelink control information associated with each of the first sidelink data and the second sidelink data. That is, the priority information is determined by the priority field value included in the sidelink control information, and the corresponding priority field value is applied to the sidelink data scheduled by the corresponding sidelink control information. The UE may check and compare values of the priority field associated with two sidelink data, respectively, and prioritize HARQ feedback information associated with sidelink data having a lower value.

The priority field value may be determined in consideration of various factors. For example, the priority field value may be determined based on the service type of the corresponding sidelink data. Alternatively, the priority field value may be determined based on the transmission types of the first sidelink data and the second sidelink data. As described above, the transmission type may be determined as any one of a unicast type, a groupcast type, and a broadcast type.

As another example, when the priority information of each of the first sidelink data and the second sidelink data indicates the same priority, the terminal includes the HARQ option type information of each of the first HARQ feedback information and the second HARQ feedback information, the side The priority may be determined based on any one of the format types of the link control channel.

For example, when set to the same priority field value, the terminal may determine the priority based on HARQ feedback option type information set in each sidelink data. For example, an option type configured to transmit HARQ only in the case of NACK may be determined to have a higher priority than an option type configured to provide feedback in the case of ACK/NACK.

Alternatively, when NACK is included in HARQ feedback information to be transmitted, it may be determined so that transmission takes precedence over reception of HARQ feedback information. Alternatively, the priority may be determined based on the transport channel format of the sidelink control information.

Through the above operation, the terminal can efficiently perform sidelink communication by operating without ambiguity even when transmission and reception of HARQ feedback information overlap.

Hereinafter, an operation of a terminal for adjusting the overlap of radio resources of sidelink communication other than HARQ feedback information will be described.

For example, the sidelink control information may further include sidelink reservation resource information. Through this, the terminal may obtain information on the sidelink radio resource to be used by the second terminal.

Before receiving the first sidelink data, the terminal determines whether to transmit the adjustment information and, when the transmission of the adjustment information is determined, includes any one of collision indication information, preference resource information, and non-preferred resource information to the second terminal It may further include the step of transmitting the adjustment information.

An operation for determining transmission of the adjustment information, information included in the adjustment information, and an operation taken when the second terminal receives the adjustment information will be described in more detail below with reference to the drawings. Hereinafter, except for steps S920 and S930 described above, description will be made. Of course, the excluded steps may also be connected and operated.

10 is a diagram for explaining an operation of a terminal according to another embodiment.

Referring to FIG. 10 , the terminal controlling the sidelink communication may perform a step of receiving sidelink control information including sidelink reservation resource information from the second terminal (S1010).

For example, when the terminal performs sidelink communication, the terminal may select a resource to be used from a specific radio resource pool. Alternatively, the terminal may use a specific radio resource as a radio resource for sidelink communication according to the scheduling of the base station. That is, as a method for the terminal to select a radio resource during sidelink communication, two methods of mode 1 scheduling by the base station and mode 2 in which the terminal selects itself within a specific pool may be used.

If the mode 2 method is used, the terminal may select a radio resource by using a sensing result value in the radio resource pool configured by the base station for each terminal. Accordingly, when a plurality of terminals perform sidelink communication, such as platooning, there is a possibility that radio resources selected by each terminal may collide.

To this end, the terminal transmits sidelink reservation resource information to use the selected radio resource. The sidelink reservation resource information may be transmitted while being included in the sidelink control information. The sidelink control information is transmitted through the PSCCH and the PSSCH. The above-described sidelink reservation resource information may be transmitted through at least one channel of a PSCCH and a PSSCH.

The terminal may receive the sidelink reservation resource information transmitted from the second terminal through at least one of the aforementioned PSCCH and PSSCH channels. The sidelink reservation resource information may include at least one piece of radio resource information.

The terminal may perform a step of determining whether to transmit the adjustment information (S1020).

For example, the terminal may determine whether it is necessary to transmit coordination information for preventing collision of radio resources.

As an example, the terminal may determine that transmission of the adjustment information is necessary when the request information for requesting the adjustment information is received from the second terminal. The request information may be received while being included in the above-described sidelink control information. In this case, the adjustment information may include any one of preference resource information and non-preference resource information. Alternatively, the adjustment information may include both preference resource information and non-preference resource information.

As another example, the terminal adjusts when the radio resource indicated by the sidelink reservation resource information transmitted by the second terminal at least partially overlaps with the sidelink reservation resource information reserved by at least one other terminal that the terminal receives It may be determined that the transmission of information is necessary. For example, the terminal may receive sidelink reservation resource information transmitted by at least one other terminal as well as the second terminal. In this case, the terminal determines whether the reserved resources of the second terminal and the other terminal overlap by using the sidelink reservation resource information transmitted by the second terminal and the sidelink reservation resource information transmitted by the other terminal. When some or all overlap, the terminal may determine that it is necessary to transmit the adjustment information. In this case, the coordination information includes collision indication information indicating whether or not the collision occurrence of the sidelink reservation resource information transmitted by the second terminal occurs. Also, in this case, the adjustment information may not include the above-mentioned preference resource information and non-preferred resource information.

As another example, the terminal may use the comparison result between the sidelink reservation resource information transmitted by the second terminal and the sidelink radio resource already used by another terminal for communication. That is, when the reserved resource of the second terminal and the radio resource used by another terminal at least partially overlap, the terminal may determine to transmit the adjustment information.

In addition to this, the terminal may determine to periodically transmit the adjustment information according to a preset period. Alternatively, the terminal may determine to transmit the adjustment information when a preset event condition is satisfied.

When the transmission of the coordination information is determined, the terminal may perform a step of transmitting the coordination information including any one of the collision indication information, the preference resource information, and the non-preference resource information to the second terminal (S1030).

For example, the preference resource information may include information on radio resources that the terminal prefers to be used by the second terminal. The non-preferred resource information may include information on radio resources that the terminal expects not to be used by the second terminal.

For example, the preference resource information included in the adjustment information may include at least one radio resource selected based on sidelink reservation resource information reserved by at least one other terminal received by the terminal. For example, the terminal may select the preference resource information based on the sidelink reservation resource information of the other terminal when transmitting the preference resource information including the adjustment information. Specifically, the selected at least one radio resource included in the preference resource information is configured to exclude sidelink reservation resource information having an RSRP measurement value greater than a preset threshold among sidelink reservation resource information reserved by at least one other terminal. can be The terminal may measure RSRP for at least one radio resource included in the sidelink reservation resource information received from at least one other terminal, respectively. The terminal compares the RSRP value measured for each of at least one radio resource with a preset RSRP threshold. Thereafter, the terminal configures the preference resource information so that, among reserved resources of other terminals, the reserved resource exceeding the threshold is not included in the preference resource information. This is because, in the case of measuring the RSRP measurement value below a certain level, the possibility of collision with the use of the second terminal due to distance, blockage, etc. is low even if the radio resource used is overlapped with other terminals. In addition, when all other terminal reserved resources are excluded from the preference resource information, the above-described operation may be required because there is a high possibility that the preference resource information to be transmitted to the second terminal is substantially insufficient.

As another example, the non-preference resource information included in the adjustment information includes at least one radio resource determined based on the sidelink reservation resource information reserved by at least one other terminal received by the terminal and the RSRP measurement value measured by the terminal. can For example, the non-preferred resource information may be determined based on the RSRP measurement value for at least one radio resource included in the sidelink reservation resource information reserved by the other terminal. Similar to the preference resource information, for a reserved resource having an RSRP measurement value of a certain level or more, the terminal may include it in the non-preferred resource information. Alternatively, the terminal may include both a reserved resource reserved by another terminal and a radio resource having an RSRP measurement value of a predetermined level or higher measured by the terminal in the non-preferred resource information.

Meanwhile, the adjustment information may be included in the sidelink control information transmitted by the terminal. As described above, the adjustment information may be transmitted through at least one channel of the PSCCH and the PSSCH.

Meanwhile, the adjustment information may include different values according to the cause of the transmission decision of the adjustment information. For example, when the adjustment information is transmitted according to the reception of the request information of the second terminal or is transmitted through periodic transmission, the adjustment information includes at least one of preference resource information and non-preference resource information. Contrary to this, when the coordination information is transmitted when a collision of sidelink reservation resource information of the second terminal occurs or a collision is expected, the coordination information includes only collision indication information.

On the other hand, upon receiving the adjustment information, the second terminal selects or reselects a radio resource for sidelink communication by using it.

For example, the second terminal may select or reselect a sidelink resource by using at least one of the adjustment information and the sensing result resource information sensed in the sensing window. The sensing window means a time period for each terminal to select a radio resource for performing sidelink communication. Each terminal selects or reselects a specific radio resource in the resource pool by using the radio resource sensing result value sensed in the sensing window. Accordingly, when the adjustment information is received, the second terminal may select or reselect a radio resource by using at least one of preferred or non-preferred resource information included in the adjustment information and resource information selected as a result of sensing.

When the coordination information includes the collision indication information, the second terminal performs a radio resource reselection operation. In addition, when preference resource information and/or non-preferred resource information is included in the adjustment information, the second terminal performs radio resource selection or reselection operation in a different operation according to the included resource as follows.

For example, when preference resource information is included in the adjustment information, the second terminal may select or reselect a radio resource commonly included in the sensing result resource information and the preference resource information as a sidelink resource. For example, the second terminal may preferentially select or reselect a resource commonly included in the resource information as a result of sensing performed before receiving the adjustment information and the preference resource information included in the adjustment information. Alternatively, the second terminal may perform sensing for radio resource selection after receiving the adjustment information, and preferentially select or reselect a common resource of resource information and preference resource information as a result of the sensing.

As another example, when the preference resource information is included in the adjustment information, the second terminal may select or reselect a sidelink resource from among radio resources included in the preference resource information without considering the sensing result resource information. That is, the second terminal may select or reselect a sidelink resource only from radio resources included in the preference resource information, without using the resource information as a result of sensing sensed by itself.

As another example, when the non-preferred resource information is included in the adjustment information, the second terminal may select or reselect a sidelink resource from the sensing result resource information except for radio resources included in the non-preferred resource information. The second terminal may select or reselect a radio resource from the remaining sensing result resource information except when the radio resource included in the sensing result resource information sensed in the sensing window overlaps with the non-preferred resource information.

Through the operation of the above-mentioned terminal and the second terminal, it is possible to prevent problems due to collision of radio resources in sidelink communication.

Hereinafter, various embodiments for solving the aforementioned HARQ transmission/reception collision problem and radio resource use collision problem in Mode2 will be described. The embodiments described below may be performed by the aforementioned terminal.

First, when HARQ feedback transmission and reception overlap during vehicle-to-vehicle communication, a criterion for determining priority may be required. As described above, the priority may be determined in consideration of various factors. For example, the priority of the HARQ feedback may be determined in consideration of a cast type, a state of the transmitted HARQ feedback, a HARQ feedback option, a communication range requirement, and the like.

The terminal may receive sidelink data from another terminal or may transmit sidelink data to another terminal. In this case, HARQ feedback is transmitted with respect to the received data, and HARQ feedback is received with respect to the transmitted data. For each HARQ feedback, feedback information, a feedback offset, and a feedback radio resource may be variously determined according to various factors such as an option, a cast type, and a configuration.

Therefore, HARQ feedback transmission/reception of the terminal may overlap on time resources. In this case, the terminal cannot properly receive the received signal. Alternatively, the terminal may not be able to properly transmit a signal.

In order to solve this problem, the present disclosure intends to control the HARQ feedback transmission/reception process of the terminal by using priority information of sidelink data associated with HARQ feedback as described above.

For example, the UE may preferentially process HARQ feedback information for sidelink data having a high priority by using priority information of the transmitted or received sidelink data. For example, the priority information of sidelink data may be determined by a priority field value of sidelink control information associated with each data. The UE may compare the priority field value included in the sidelink control information to prioritize HARQ feedback for sidelink data with a small priority field value (high priority).

As another example, the terminal may determine the priority based on the transmission type of the transmitted or received sidelink data. When sidelink data is received in unicast and sidelink data is transmitted in groupcast, the terminal may prioritize HARQ feedback reception based on a preset priority for each transmission type. Of course, the opposite is also possible.

As another example, the UE may determine a priority based on a HARQ option configured in association with transmission/reception sidelink data, whether NACK information is included in HARQ feedback, a HARQ feedback transmission format, and the like.

The content of determining the priority using the cast type will be described as an example. In the same or similar form, each of the factors described above may be considered and priorities may be determined.

When the cast types of the HARQ feedback to be transmitted and the HARQ feedback to be received are both unicast

The HARQ feedback to be transmitted and the HARQ feedback to be received in the overlapping time period of the UE may be set to the same transmission type. In this case, even if it is set to determine the priority based on the transmission type, since it is the same transmission type, additional criteria must be provided.

In this case, the UE may perform reception of a Physical Sidelink Feedback Channel (PSFCH) including HARQ feedback before transmission of the PSFCH. That is, when the cast types of the HARQ feedback to be transmitted and the HARQ feedback to be received are both unicast, the UE may be configured to first receive the HARQ feedback.

This is because the HARQ feedback transmission can be controlled by the UE, but the HARQ feedback reception needs to be prioritized high in that other UEs cannot check whether the UE has received the HARQ feedback.

When the cast type of the HARQ feedback to be transmitted and the HARQ feedback to be received are different from each other

In the case of unicast, it is mainly used for applications such as sensor sharing and see through, and in the case of groupcast, it is used for applications such as platooning. In this case, since platooning requires less delay time compared to sensor sharing, the PSFCH can be preferentially allocated to the HARQ feedback used for groupcast.

That is, the UE may preferentially process HARQ feedback for the case of groupcast, which is more critical to delay.

Even when the priority is determined by comparing the priority field values of the sidelink control information, the priority field value may be set so that groupcast has a lower value (higher priority) than unicast.

Accordingly, if transmission of HARQ feedback used for groupcast and reception of HARQ feedback used for unicast are both required, the user terminal may determine transmission of PSFCH with priority.

Conversely, when the reception of HARQ feedback used for groupcast and transmission of HARQ feedback used for unicast are required together, the user terminal may determine the reception of the PSFCH as a priority.

When the HARQ feedback to be transmitted and the HARQ to be received are both groupcast

As an example, the UE may determine the priority of transmission and reception of the PSFCH according to whether the HARQ feedback to be transmitted is ACK or NACK.

When the terminal successfully receives the sidelink data, the terminal does not need to receive the same data again. That is, when the HARQ feedback to be transmitted by the terminal is ACK, there is no need to receive the TB retransmission, but when the HARQ feedback is NACK, the TB must be received again by sending a NACK to another vehicle.

In this case, if the HARQ feedback to be transmitted by the terminal is NACK, as shown in Table 2, the terminal may be configured to give priority to transmission of the PSFCH. That is, if the HARQ feedback to be transmitted is NACK, the UE may transmit the HARQ feedback prior to reception of the PSFCH from another UE.

If the feedback of the HARQ to be transmitted by the terminal is ACK, the terminal may be configured to give priority to reception of the PSFCH. That is, since the data channel has already been effectively transmitted, the reception of the PSFCH from another terminal, which is more urgent, may be preferentially performed.

HARQ Tx HARQ Rx Priority NACK - HARQ Tx ACK - HARQ Rx

As another example, the UE may be configured to determine the priority of transmission and reception of the PSFCH according to the HARQ feedback option.

In vehicle-to-vehicle communication, the groupcast HARQ feedback option is divided into NACK only (option1) and ACK/NACK (option2). In the case of the NACK only option, the main purpose is to reduce the delay time by reducing the HARQ feedback signal. Therefore, it is more critical to the delay in the case of option 1.

In this case, the UE may be configured to preferentially allocate the PSFCH to the HARQ feedback having the NACK only option rather than the HARQ feedback having the ACK/NACK option as shown in Table 3. That is, if the option of the HARQ feedback to be transmitted is NACK only, the UE may transmit the HARQ feedback prior to reception of the PSFCH from another UE.

If the option of HARQ feedback to be received by the terminal is NACK only, the terminal may be configured to give priority to reception of the PSFCH.

HARQ Tx HARQ Rx Priority Groupcast option 1 Groupcast option 2 HARQ Tx Groupcast option 2 Groupcast option 1 HARQ Rx

As another example, the UE may be configured to determine the priority of transmission and reception of the PSFCH according to the communicable distance when using the ^2nd SCI Format-B.

Sidelink control information (SCI) used in sidelink communication may be transmitted in two steps as ^1st SCI and ^2nd SCI. In this case, ^2nd SCI may be divided into SCI format 2-A and SCI format 2-B.

SCI format 2-A is used for decoding PSSCH, and HARQ operation when ACK or NACK is included in HARQ-ACK information, when only NACK is included in HARQ-ACK information, or when there is no feedback of HARQ-ACK information. can

SCI format 2-A may include information such as HARQ process number, New data indicator, Redundancy version, Source ID, Destination ID, HARQ feedback enabled/disabled indicator, Cast type indicator, CSI request, and the like.

In addition, SCI format 2-B is used for decoding the PSSCH, and when only NACK is included in HARQ-ACK information or there is no feedback on HARQ-ACK information, it can be used together with HARQ operation.

SCI format 2-B may include information such as HARQ process number, New data indicator, Redundancy version, Source ID, Destination ID, HARQ feedback enabled/disabled indicator, Zone ID, Communication range requirement, and the like.

As shown in Table 4, the UE may be configured to give priority to HARQ feedback for a data channel using SCI format 2-B in ^2nd SCI over HARQ feedback for a data channel using SCI format 2-A. That is, regardless of transmission and reception of HARQ feedback, the case of SCI format 2-B may be performed preferentially when the case of SCI format 2-A.

HARQ Tx HARQ Rx Priority ^2nd SCI Format-A ^2nd SCI Format-B HARQ Rx ^2nd SCI Format-B ^2nd SCI Format-A HARQ Tx ^2nd SCI Format-B ^2nd SCI Format-B The shorter the communication distance, the more PSFCH priority is allocated.

For example, when the ^2nd SCI Format of the HARQ feedback to be transmitted is SCI format 2-B and the ^2nd SCI Format of the HARQ feedback to be received is SCI format 2-A, the UE is configured to give priority to the transmission of the PSFCH can be Similarly, when the ^2nd SCI Format of the HARQ feedback to be transmitted is SCI format 2-A and the ^2nd SCI Format of the HARQ feedback to be received is SCI format 2-B, the UE may be configured to give priority to the reception of the PSFCH. there is.

If the ^2nd SCI format of the HARQ feedback to be transmitted and received is both SCI format 2-B, the terminal may give priority based on the communication range with the target terminal. That is, the terminal may determine that a shorter delay time is required as the communication distance is shorter, and may preferentially allocate the PSFCH to the terminal in the shorter communication distance.

Accordingly, when both transmission and reception of HARQ feedback use SCI format 2-B, the UE may first perform HARQ feedback processing for a UE having a shorter communication distance to each target UE.

In addition, the priority may be determined based on various information described with reference to FIG. 9 . Hereinafter, an embodiment of preventing radio resource collision using coordination information described with reference to FIG. 10 will be described.

3GPP Rel-17 supports mode 2 of vehicle-to-vehicle direct communication (PC5) in 5G V2X. In Mode 1, the base station adjusts resource allocation to each vehicle so that resource collision may not occur. However, in mode 2, each vehicle allocates (selects) a resource, and a collision in which the allocated resource overlaps may occur. To prevent this, as described above, a sub-mode in which one vehicle assists resource selection of another vehicle may be required. That is, an inter-UE coordination protocol for adjusting resource allocation by sharing allocated resource information between vehicles is required. In this background, the present embodiments propose a specific user-to-user coordination protocol procedure, message, information, and the like.

11 is a diagram for explaining a situation in which adjustment information is requested in a sidelink communication operation according to an embodiment.

Referring to FIG. 11 , in sidelink communication, a plurality of terminals may transmit/receive data. As in the 1100 situation, UE1 and UE2 may perform sidelink communication using mode 2. In this case, UE1 and UE2 are out of a sensing range for radio resource selection, respectively, and may select the same radio resource. From the viewpoints of UE1 and UE2, there is no collision in radio resource selection and data transmission, respectively. However, UE3 may receive data from UE1 and UE2. In this case, since the UE3 receives sidelink data through the same radio resource, a resource collision problem occurs. As such, in order to solve the hidden node problem, an inter-terminal coordination procedure may be required.

In case of 1110, UE1 may transmit sidelink data to UE3. UE3 may also transmit sidelink data to UE2. In this case, when UE1 and UE3 select the same sidelink radio resource, there is a problem in that UE3 cannot receive data transmitted by UE1 due to collision. As such, in order to solve the half-duplex problem, an inter-terminal coordination procedure may be required.

As described above, the present disclosure proposes a method of inducing selection or reselection of radio resources by transmitting adjustment information to solve this problem. The coordination information may be transmitted through unicast communication (PC5-RRC), and may also be transmitted through a broadcast or groupcast method if necessary.

When the coordination information is used, various problems such as continuous resource collision, hidden node problem, and half-duplex problem can be solved.

For example, the terminal may acquire radio resource information used or to be used by another terminal through sidelink control information (SCI). The terminal generates adjustment information by using the obtained radio resource information of another terminal. The generated adjustment information is transmitted to the terminal that has transmitted the SCI. Alternatively, the terminal may select a radio resource to be used in consideration of radio resource information of another terminal.

The coordination information generated by the terminal may include any one of collision indication information, preference resource information, and non-preferred resource information. Preferred resource information or non-preferred resource information is determined by the terminal, and may each include one or more resources. Accordingly, the terminal directly determines the resource set to configure preferred resource information or non-preferred resource information. The collision indication information includes information for indicating when a collision of a reserved resource reserved by another terminal occurs or a collision is predicted.

The configured adjustment information may be transmitted to another terminal or a terminal that has transmitted the SCI. Although a unicast communication method is considered as the delivery method, it may be transmitted in a broadcast or groupcast method. In addition, various embodiments may be formed in the operation of the terminal receiving the transmission timing and the corresponding adjustment information.

First, an embodiment related to a transmission operation of adjustment information will be described.

12 is a diagram for explaining a periodic adjustment information transmission operation according to an embodiment.

Referring to FIG. 12 , the second terminal 1101 may transmit sidelink resource information for sidelink data transmission through SCI ( S1210 ). The sidelink resource information may include sidelink reservation resource information to be used by the second terminal. The sidelink resource information may be included in at least one of a sidelink control channel (PSCCH) and a sidelink data channel (PSSCH). In the case of SCI, it may be transmitted through a sidelink control channel and may also be transmitted through a sidelink data channel.

The terminal 1102 may check the sidelink resource information of the second terminal 1101 by monitoring the SCI. Also, the terminal 1102 can monitor and confirm sidelink resource information from other terminals.

The terminal 1102 may periodically transmit adjustment information. In this case, the terminal 1102 checks whether the transmission period of the adjustment information has arrived (S1215). When the transmission period for the adjustment information arrives, the terminal 1102 may transmit the adjustment information (S1220). In this case, the adjustment information is transmitted to the second terminal 1101 through a unicast communication method. Alternatively, the adjustment information may be transmitted to another terminal through multicast or broadcast. The coordination information is transmitted through at least one of a PSCCH and a PSSCH. In addition, as described above, the adjustment information includes preference resource information or non-preferred resource information.

The second terminal 1101 performs an operation of reselecting a sidelink resource by using at least one of the received adjustment information and a sensing result value sensed by itself (S1225). When the sidelink resource is reselected, the second terminal 1101 may perform an operation classified according to whether preference resource information or non-preference resource information is included in the adjustment information.

For example, when the preference resource information is included, the second terminal 1101 may select a common resource from among the preference resource information and a resource selected as a result of sensing as a sidelink resource.

As another example, when the preference resource information is included, the second terminal 1101 may select a sidelink resource from the preference resource information using only the preference resource information. In this case, a resource having the highest sensing result value in the preference resource information may be selected.

As another example, when the non-preferred resource information is included, the second terminal 1101 may select a sidelink resource by excluding a resource common to the selected resource and the non-preferred resource information as a sensing result.

13 is a diagram for explaining an operation of transmitting coordination information according to collision prediction according to another embodiment.

Referring to FIG. 13 , unlike FIG. 12 , adjustment information may be transmitted when a specific situation occurs, rather than being transmitted periodically.

The second terminal 1101 may transmit sidelink resource information for sidelink data transmission through SCI (S1310). The sidelink resource information may include sidelink reservation resource information that the second terminal 1101 intends to use. The sidelink resource information may be included in at least one of a sidelink control channel (PSCCH) and a sidelink data channel (PSSCH). In the case of SCI, it may be transmitted through a sidelink control channel and may also be transmitted through a sidelink data channel.

The terminal 1102 may check the sidelink resource information of the second terminal 1101 by monitoring the SCI. Also, the terminal 1102 can monitor and confirm sidelink resource information from other terminals.

The terminal 1102 compares the sidelink resource information of the second terminal 1101 with the sidelink resource information of another terminal to determine whether a collision occurs or a collision is predicted (S1315).

If a collision occurs or is predicted, the terminal 1102 transmits coordination information (S1320). In this case, adjustment information may be transmitted only when resources collide more than a preset ratio or number. Alternatively, if even one resource collides or is expected to collide, coordination information may be transmitted. Alternatively, coordination information may be transmitted only when all resources collide or collision is expected. The coordination information is transmitted through at least one of a PSCCH and a PSSCH. Also, as described above, the coordination information may include collision indication information.

The second terminal 1101 performs an operation of reselecting a sidelink resource by using at least one of the received adjustment information and a sensing result value sensed by itself (S1325). The second terminal 1101 may perform a sensing operation for radio resource reselection when the collision indication information included in the coordination information indicates a collision.

Alternatively, when preference resource information is included in the adjustment information, the second terminal 1101 may select a common resource from among the preference resource information and a resource selected as a result of sensing as a sidelink resource.

As another example, when preference resource information is included in the adjustment information, the second terminal 1101 may select a sidelink resource from within the preference resource information using only the preference resource information. In this case, a resource having the highest sensing result value in the preference resource information may be selected.

As another example, when non-preferred resource information is included in the adjustment information, the second terminal 1101 may select a sidelink resource by excluding a resource common to the selected resource and the non-preferred resource information as a sensing result.

14 is a diagram for explaining a sidelink resource reselection operation using adjustment information according to another embodiment.

Referring to FIG. 14 , the second terminal 1101 may transmit sidelink resource information for sidelink data transmission through SCI ( S1410 ). The sidelink resource information may include sidelink reservation resource information to be used by the second terminal. The sidelink resource information may be included in at least one of a sidelink control channel (PSCCH) and a sidelink data channel (PSSCH). In the case of SCI, it may be transmitted through a sidelink control channel and may also be transmitted through a sidelink data channel.

The terminal 1102 may check the sidelink resource information of the second terminal 1101 by monitoring the SCI. Also, the terminal 1102 can monitor and confirm sidelink resource information from other terminals.

The terminal 1102 may transmit the adjustment information to the second terminal 1101 (S1420). The transmission of coordination information may be caused by a periodic cause as described above, or may be caused by occurrence of an event such as collision prediction. Alternatively, it may be generated by various factors as described with reference to FIG. 10 . The coordination information is transmitted through at least one of a PSCCH and a PSSCH. In addition, as described above, the coordination information includes collision indication information, preferred resource information, or non-preferred resource information.

The second terminal 1101 performs an operation of reselecting a sidelink resource by using at least one of the received adjustment information and a sensing result value sensed by itself (S1430). When the sidelink resource is reselected, the second terminal 1101 may perform an operation classified according to whether preference resource information or non-preference resource information is included in the adjustment information.

For example, when the preference resource information is included, the second terminal 1101 may select a common resource from among the preference resource information and a resource selected as a result of sensing as a sidelink resource.

As another example, when the preference resource information is included, the second terminal 1101 may select a sidelink resource from the preference resource information using only the preference resource information. In this case, a resource having the highest sensing result value in the preference resource information may be selected.

As another example, when the non-preferred resource information is included, the second terminal 1101 may select a sidelink resource by excluding a resource common to the selected resource and the non-preferred resource information as a sensing result.

The second terminal 1101 reselects the sidelink resource, and transmits sidelink control information indicating this again to the terminal 1102 (S1440). Through this operation, the terminal 1102 can prevent the problem as described in FIG. 10 from occurring.

In addition, such an operation may be equally applied when the second terminal 1101 operates as the terminal 1102 and communicates with other terminals.

Activation or deactivation of the operation related to the transmission of the above-described adjustment information may be instructed by the base station. In this case, the terminal may or may not perform the adjustment information transmission operation according to the activation and deactivation instructions.

Hereinafter, the configuration of the terminal described above will be described once again with reference to the drawings.

15 is a diagram for explaining a terminal configuration according to an embodiment.

15 , a terminal 1500 controlling sidelink communication receives sidelink control information from a second terminal, and receives first sidelink data according to scheduling of the sidelink control information. At least part of the time resource for transmitting the receiver 1530 and the first HARQ feedback information for the first sidelink data and the time resource for receiving the second HARQ feedback information for the second sidelink data transmitted by the terminal In the case of overlapping, a control unit 1510 for determining a priority may be included.

In addition, the terminal 1500 for controlling the sidelink communication determines whether to transmit the adjustment information with the receiver 1530 that receives the sidelink control information including the sidelink reservation resource information from the second terminal. When it is determined to transmit the control unit 1510 and the adjustment information, the second terminal may include a transmitter 1520 for transmitting the adjustment information including any one of collision indication information, preference resource information, and non-preference resource information.

For example, the sidelink control information may be received through a PSCCH and a PSSCH. The sidelink control information may include various information such as reserved radio resource information, scheduling information, and priority information in each field.

When receiving the sidelink control information, the receiver 1530 may receive sidelink data from a radio resource indicated by the sidelink control information. The sidelink data may be received through the PSSCH.

When the time resources of the first HARQ feedback transmission and the second HARQ feedback reception overlap, the control unit 1510 needs to determine a priority so that any one operation is performed.

As an example, the controller 1510 may determine the priority based on the transmission type of the first sidelink data and the second sidelink data. Here, the transmission type may be divided into a unicast type, a groupcast type, and a broadcast type. For example, when the first sidelink data is received in unicast and the second sidelink data is transmitted in groupcast, the control unit 1510 first HARQ for the first sidelink data transmitted in the unicast type It may be decided to give priority to feedback transmission. Of course, the opposite is also possible.

As another example, the controller 1510 may determine a priority based on a result of comparing the priority information of the first sidelink data and the second sidelink data, respectively. The controller 1510 may control HARQ feedback for data having a higher priority to be preferentially processed. For example, the priority information may be determined by a priority field value included in sidelink control information associated with each of the first sidelink data and the second sidelink data. That is, the priority information is determined by the priority field value included in the sidelink control information, and the corresponding priority field value is applied to the sidelink data scheduled by the corresponding sidelink control information. The controller 1510 may check and compare values of the priority field associated with the two sidelink data, respectively, and prioritize HARQ feedback information associated with the sidelink data having a lower value.

The priority field value may be determined in consideration of various factors. For example, the priority field value may be determined based on the service type of the corresponding sidelink data. Alternatively, the priority field value may be determined based on the transmission types of the first sidelink data and the second sidelink data.

As another example, when the priority information of each of the first sidelink data and the second sidelink data indicates the same priority, the controller 1510 controls the HARQ option type of each of the first HARQ feedback information and the second HARQ feedback information The priority may be determined based on any one of the information, the type of information included in the first HARQ feedback, and the format of the sidelink control information.

For example, when set to the same priority field value, the controller 1510 may determine the priority based on HARQ feedback option type information set in each sidelink data. For example, an option type configured to transmit HARQ only in the case of NACK may be determined to have a higher priority than an option type configured to provide feedback in the case of ACK/NACK.

Alternatively, when NACK is included in HARQ feedback information to be transmitted, it may be determined so that transmission takes precedence over reception of HARQ feedback information. Alternatively, the priority may be determined based on the transport channel format of the sidelink control information.

Meanwhile, the sidelink reservation resource information may be transmitted while being included in the sidelink control information.

The receiving unit 1530 may receive the sidelink reservation resource information transmitted from the second terminal through at least one of the aforementioned PSCCH and PSSCH channels. The sidelink reservation resource information may include at least one piece of radio resource information.

The controller 1510 may determine whether it is necessary to transmit adjustment information for preventing collision of radio resources.

For example, the controller 1510 may determine that transmission of the adjustment information is necessary when the request information for requesting the adjustment information is received from the second terminal. The request information may be received while being included in the above-described sidelink control information. In this case, the adjustment information may include at least one of preference resource information and non-preference resource information.

As another example, the control unit 1510 may be configured such that the radio resource indicated by the sidelink reservation resource information transmitted by the second terminal overlaps at least partially with the sidelink reservation resource information reserved by at least one other terminal that the terminal receives. In this case, it may be determined that the transmission of the adjustment information is necessary. In this case, the coordination information may include collision indication information.

For example, the receiver 1530 may receive sidelink reservation resource information transmitted by at least one other terminal as well as the second terminal. In this case, the controller 1510 determines whether the reserved resources of the second terminal and the other terminal overlap by using the sidelink reservation resource information transmitted from the second terminal and the sidelink reservation resource information transmitted from the other terminal. When some or all of them overlap, the controller 1410 may determine that it is necessary to transmit the adjustment information.

As another example, the controller 1510 may use the comparison result between the sidelink reservation resource information transmitted by the second terminal and the sidelink radio resource already used by another terminal for communication. That is, when the reserved resource of the second terminal and the radio resource used by another terminal at least partially overlap, the terminal may determine to transmit the adjustment information.

In addition, the controller 1510 may determine to periodically transmit the adjustment information according to a preset period. Alternatively, the controller 1510 may determine to transmit the adjustment information when a preset event condition is satisfied.

Meanwhile, the preference resource information may include information on a radio resource that the terminal prefers to be used by the second terminal. The non-preferred resource information may include information on radio resources that the terminal expects not to be used by the second terminal.

For example, the preference resource information included in the adjustment information may include at least one radio resource selected based on sidelink reservation resource information reserved by at least one other terminal received by the terminal. For example, when the control information includes the preference resource information and transmits it, the control unit 1510 may select the preference resource information based on sidelink reservation resource information of another terminal. Specifically, the selected at least one radio resource included in the preference resource information is configured to exclude sidelink reservation resource information having an RSRP measurement value greater than a preset threshold among sidelink reservation resource information reserved by at least one other terminal. can be The control unit 1510 may measure RSRP for at least one radio resource included in the sidelink reservation resource information received from at least one other terminal, respectively. The control unit 1510 compares the RSRP value measured for each of at least one radio resource with a preset RSRP threshold value. Thereafter, the control unit 1410 configures the preference resource information so that the reserved resource exceeding the threshold value among reserved resources of other terminals is not included in the preference resource information.

As another example, the non-preference resource information included in the adjustment information includes at least one radio resource determined based on the sidelink reservation resource information reserved by at least one other terminal received by the terminal and the RSRP measurement value measured by the terminal. can For example, the non-preferred resource information may be determined based on the RSRP measurement value for at least one radio resource included in the sidelink reservation resource information reserved by the other terminal. Similar to the preference resource information, for a reserved resource having a RSRP measurement value of a certain level or more, the controller 1410 may include it in the non-preferred resource information. Alternatively, the controller 1510 may include both a reserved resource reserved by another terminal and a radio resource having an RSRP measurement value of a predetermined level or higher measured by the terminal in the non-preferred resource information.

Meanwhile, the transmitter 1520 may transmit the sidelink control information by including the adjustment information. As described above, the adjustment information may be transmitted through at least one channel of the PSCCH and the PSSCH. Alternatively, the coordination information may be transmitted in a broadcast or groupcast manner.

Meanwhile, the adjustment information may include different values according to the cause of the transmission decision of the adjustment information. For example, when the adjustment information is transmitted according to the reception of the request information of the second terminal or is transmitted through periodic transmission, the adjustment information includes at least one of preference resource information and non-preference resource information. Contrary to this, when the coordination information is transmitted when a collision of sidelink reservation resource information of the second terminal occurs or a collision is expected, the coordination information includes only collision indication information.

On the other hand, upon receiving the adjustment information, the second terminal selects or reselects a radio resource for sidelink communication by using it.

For example, when preference resource information is included in the adjustment information, the second terminal may select or reselect a radio resource commonly included in the sensing result resource information and the preference resource information as a sidelink resource. For example, the second terminal may preferentially select or reselect a resource commonly included in the resource information as a result of sensing performed before receiving the adjustment information and the preference resource information included in the adjustment information. Alternatively, the second terminal may perform sensing for radio resource selection after receiving the adjustment information, and preferentially select or reselect a common resource of resource information and preference resource information as a result of the sensing.

As another example, when the preference resource information is included in the adjustment information, the second terminal may select or reselect a sidelink resource from among radio resources included in the preference resource information without considering the sensing result resource information. That is, the second terminal may select or reselect a sidelink resource only from radio resources included in the preference resource information, without using the resource information as a result of sensing sensed by itself.

As another example, when the non-preferred resource information is included in the adjustment information, the second terminal may select or reselect a sidelink resource from the sensing result resource information except for radio resources included in the non-preferred resource information. The second terminal may select or reselect a radio resource from the remaining sensing result resource information except when the radio resource included in the sensing result resource information sensed in the sensing window overlaps with the non-preferred resource information.

As another example, when the collision indication information is included in the coordination information and the collision indication information indicates a collision, the second terminal may reselect the radio resource using the sensing result resource information sensed in the sensing window.

In addition to this, the controller 1510 may control the operation of the terminal 1400 required to perform the above-described embodiments.

In addition, the transmitter 1520 and the receiver 1530 transmit and receive signals, data, and messages to and from the base station and other terminals through a corresponding channel.

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 above-described standard documents. In addition, all terms disclosed in this specification can be described by the standard documents disclosed above.

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

In the case of implementation by hardware, the method according to the present embodiments may include one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), FPGAs (Field Programmable Gate Arrays), may be implemented by a processor, a controller, a microcontroller or a microprocessor.

In the case of implementation by firmware or software, the method according to the present embodiments may be implemented in the form of an apparatus, procedure, or function that performs 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/receive data to and from the processor by various well-known means.

Also, as described above, terms such as "system", "processor", "controller", "component", "module", "interface", "model", or "unit" generally refer to computer-related entities hardware, hardware and software. may mean a combination of, software, or running software. For example, the aforementioned component may be, but is 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 the components may be located on one device (eg, a system, computing device, etc.) or distributed across two or more devices.

The above description is merely illustrative of the technical spirit of the present disclosure, and various modifications and variations will be possible without departing from the essential characteristics of the present disclosure by those skilled in the art to which the present disclosure pertains. In addition, the present embodiments are not intended to limit the technical spirit of the present disclosure, but to explain, and thus the scope of the present technical spirit is not limited by these embodiments. The protection scope of the present disclosure should be construed by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present disclosure.

Claims (15)

A method for a terminal to control sidelink communication, the method comprising:
Receiving sidelink control information (Sidelink Control Information) from a second terminal;
receiving first sidelink data according to the scheduling of the sidelink control information; and
When the time resource for transmitting the first HARQ feedback information for the first sidelink data and the time resource for receiving the second HARQ feedback information for the second sidelink data transmitted by the terminal at least partially overlap , determining the priority. The method of claim 1,
The step of determining the priority is
The method of claim 1, wherein the determination is made based on a transmission type of the first sidelink data and the second sidelink data. The method of claim 1,
The step of determining the priority is
The method according to claim 1, wherein the determination is made based on a result of comparing the priority information of each of the first sidelink data and the second sidelink data. 4. The method of claim 3,
The priority information is
The method of claim 1, characterized in that it is determined by a priority field value included in sidelink control information associated with each of the first sidelink data and the second sidelink data. 6. The method of claim 5,
The priority field value is
It is determined based on a transmission type of the first sidelink data and the second sidelink data,
The transmission type is any one of a unicast type, a groupcast type, and a broadcast type. 4. The method of claim 3,
The step of determining the priority is
When priority information of each of the first sidelink data and the second sidelink data indicates the same priority,
Determination of priority based on any one of HARQ option type information of each of the first HARQ feedback information and the second HARQ feedback information, an information type included in the first HARQ feedback, and a format type of a sidelink control channel How to characterize. The method of claim 1,
The sidelink control information is
Further including sidelink reservation resource information,
Prior to receiving the first sidelink data,
determining whether to transmit adjustment information; and
When transmission of the adjustment information is determined, the method further comprising the step of transmitting the adjustment information including any one of collision indication information, preference resource information, and non-preference resource information to the second terminal. 8. The method of claim 7,
The step of determining whether to transmit the adjustment information includes:
When the request information requesting transmission of the adjustment information is received from the second terminal, it is determined to transmit the adjustment information,
The adjustment information is
The method characterized in that it includes any one of the preference resource information and the non-preferred resource information. 8. The method of claim 7,
The step of determining whether to transmit the adjustment information includes:
When the radio resource indicated by the sidelink reservation resource information transmitted by the second terminal overlaps at least partially with the sidelink reservation resource information reserved by at least one other terminal received by the terminal, the adjustment information decided to send
The adjustment information is
and the collision indication information indicating whether a collision occurs in the sidelink reservation resource information transmitted by the second terminal. 8. The method of claim 7,
The preference resource information included in the adjustment information is,
and at least one radio resource selected based on sidelink reservation resource information reserved by at least one other terminal received by the terminal. 8. The method of claim 7,
Non-preferred resource information included in the adjustment information,
The method, characterized in that it includes at least one radio resource determined based on sidelink reservation resource information reserved by at least one other terminal received by the terminal and an RSRP measurement value measured by the terminal. A method for a terminal to control sidelink communication, the method comprising:
a receiving unit for receiving sidelink control information from a second terminal and receiving first sidelink data according to scheduling of the sidelink control information; and
When the time resource for transmitting the first HARQ feedback information for the first sidelink data and the time resource for receiving the second HARQ feedback information for the second sidelink data transmitted by the terminal at least partially overlap , a terminal comprising a control unit for determining a priority. 13. The method of claim 12,
The control unit is
The terminal determines the priority based on a transmission type of the first sidelink data and the second sidelink data. 13. The method of claim 12,
The control unit is
The terminal determines the priority based on a result of comparing the priority information of each of the first sidelink data and the second sidelink data. 13. The method of claim 12,
The sidelink control information is
Further including sidelink reservation resource information,
Prior to receiving the first sidelink data,
The control unit determines whether to transmit the adjustment information,
When transmission of the adjustment information is determined, the terminal further comprises a transmitter for transmitting the adjustment information including any one of collision indication information, preference resource information, and non-preference resource information to the second terminal.

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