Sidelink harq feedback control method and apparatus thereof

Abstract

The disclosure relates to a method and device for providing V2X services in a next generation radio access technology (new RAT). The embodiment provides a method and device for a terminal to control a sidelink HARQ feedback operation, the method comprising the steps of: receiving, from a transmitting terminal, a physical sidelink control channel (PSCCH) including first sidelink control information; receiving, from the transmitting terminal, a physical sidelink shared channel (PSSCH) including second sidelink control information; and based on the second sidelink control information, confirming broadcast type information and HARQ feedback transmission type information about sidelink data received from the transmitting terminal.

Description

Technical Field

[0001] This disclosure relates to a method and apparatus for providing V2X services in next-generation radio access technology (RAT). Background Technology

[0002] In vehicles and industrial settings, wireless terminals are required for high-volume, high-speed data processing and various business operations. As mentioned above, a high-speed, high-capacity communication system technology is needed to handle diverse scenarios and large volumes of data, such as video, wireless data, and machine-type communication data, not just simple voice-oriented services.

[0003] To this end, the ITU-R has published the requirements for adopting the IMT-2020 international standard and is studying next-generation wireless communication technologies that meet the requirements of IMT-2020.

[0004] In particular, 3GPP is simultaneously researching the LTE-advanced Pro Rel-15 / 16 standard and the new radio access technology (NR) standard to meet the requirements of IMT-2020, which is known as 5G technology, and plans to approve these two standards as next-generation wireless communication technologies.

[0005] 5G technology can be applied to autonomous vehicles. Therefore, 5G technology needs to be applied to vehicle-to-everything (V2X) communication, while autonomous driving requires high-speed transmission and reception, while ensuring high reliability for increased data.

[0006] In addition, to meet the driving scenarios of various autonomous vehicles, such as platooning, V2X communication is required to ensure multicast data transmission / reception as well as unicast data transmission / reception.

[0007] In particular, a HARQ operation technique is needed to ensure data transmission reliability while reducing system load in sidelink communication. Summary of the Invention

[0008] Technical issues

[0009] This embodiment can provide a method and device for sidelink communication using next-generation wireless access technology.

[0010] Technical solution

[0011] On one hand, this embodiment provides a method for HARQ feedback operation via a UE control side link. The method includes: receiving a physical sidelink control channel (PSCCH) including first sidelink control information from a transmitting UE; receiving a physical sidelink shared channel (PSSCH) including second sidelink control information from the transmitting UE; and identifying HARQ feedback transmission scheme information and broadcast type information of the sidelink data received from the transmitting UE based on the second sidelink control information.

[0012] On the other hand, this embodiment provides a UE for controlling sidelink HARQ feedback operation, including a receiver and a controller. The receiver receives a physical sidelink control channel (PSCCH) including first sidelink control information from the transmitting UE, and receives a physical sidelink shared channel (PSSCH) including second sidelink control information from the transmitting UE. The controller identifies HARQ feedback transmission scheme information and broadcast type information of the sidelink data received from the transmitting UE based on the second sidelink control information.

[0013] Beneficial effects

[0014] According to embodiments of the present invention, a method and apparatus for sidelink communication using next-generation wireless access technology can be provided. Attached Figure Description

[0015] Figure 1 This is a schematic view illustrating the structure of an NR wireless communication system to which this embodiment can be applied;

[0016] Figure 2 This is a view showing the frame structure in an NR system to which this embodiment can be applied;

[0017] Figure 3 This is a view showing a resource grid supported by the wireless access technology to which this embodiment can be applied;

[0018] Figure 4 This is a view showing the bandwidth portion supported by the wireless access technology to which this embodiment can be applied;

[0019] Figure 5 This is an exemplary view showing a synchronization signal block in a wireless access technology to which this embodiment can be applied;

[0020] Figure 6 This is a view illustrating the random access process in the wireless access technology to which this embodiment can be applied;

[0021] Figure 7This is a view showing the CORESET;

[0022] Figure 8 It is a view showing various scenarios used for V2X communication;

[0023] Figure 9 This is a view illustrating the operation of the UE according to an embodiment;

[0024] Figure 10 This is a view illustrating side link control information received via PSCCH according to an embodiment;

[0025] Figure 11 This is a view showing side link control information for a second format received via PSSCH according to an embodiment;

[0026] Figure 12 This is a view illustrating an operation for calculating distance information based on the location of the transmitting UE and the location of the UE, according to an embodiment;

[0027] Figure 13 This is a view illustrating operations for receiving location information about the transmitting UE according to an embodiment;

[0028] Figure 14 This is a view illustrating operations for receiving location information about the transmitting UE according to another embodiment;

[0029] Figure 15 This is a view illustrating operations for receiving location information about the transmitting UE according to another embodiment; and

[0030] Figure 16 This is a view showing the configuration of the UE according to an embodiment. Detailed Implementation

[0031] Embodiments of this disclosure are described in detail below with reference to the accompanying drawings. Throughout the specification and drawings, the same or substantially the same reference numerals are used to refer to the same or substantially the same elements. When it is determined that a detailed description of a known technique or function makes the subject matter of the invention unclear, a detailed description of the known technique or function may be omitted. The terms “comprising,” “having,” or “including” are used in this specification to specify the presence of stated features, areas, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, areas, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0032] Identifiers such as “first,” “second,” “A,” “B,” “(a),” and “(b)” may be used to describe components of the present invention. These identifiers are provided merely to distinguish one component from another, and the nature of the components is not limited by the order or sequence of the identifiers.

[0033] When describing the positional relationship between components, when two or more components are described as “connected,” “coupled,” or “linked,” the two or more components may be directly “connected,” “coupled,” or “linked,” or another component may be involved. Here, the other component may be included in one or more of the two or more components that are “connected,” “coupled,” or “linked” to each other.

[0034] Regarding components, methods of operation, or methods of manufacture, when A is referred to as “after,” “following,” “next,” or “before,” A and B may not be sequential with each other unless the terms “immediately” or “directly” are used when referring to them.

[0035] When a component is specified with a value or its corresponding information (e.g., level), that value or corresponding information can be interpreted to include tolerances that may be caused by various factors (e.g., process factors, internal or external influences, or noise).

[0036] In this disclosure, "wireless communication system" means a system that uses wireless resources to provide various communication services such as voice and data packets, and may include a UE, a base station, or a core network.

[0037] The embodiments disclosed below can be applied to wireless communication systems using various wireless access technologies. For example, these embodiments can be applied to various wireless access technologies, such as code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), or non-orthogonal multiple access (NOMA). Furthermore, wireless access technology can refer not only to a specific access technology but also to each generation of communication technologies established by various communication organizations, such as 3GPP, 3GPP2, Wi-Fi, Bluetooth, IEEE, and ITU. For example, CDMA can be implemented as a wireless technology, such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA can be implemented as GSM (Global System for Mobile Communications) / GPRS (General Packet Radio Service) / EDGE (Enhanced Data Rate Evolution of GSM). OFDMA can be implemented using wireless technologies such as 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 IEEE 802.16e-based systems. UTRA is part of UMTS (Universal Mobile Telecommunications System). 3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution) is part of E-UMTS (Evolved UMTS) using Evolved UMTS Terrestrial Radio Access (E-UTRA), and its downlink uses OFDMA while its uplink uses SC-FDMA. Therefore, embodiments of the present invention can be applied to currently disclosed or commercialized wireless access technologies, as well as wireless access technologies currently under development or to be developed in the future.

[0038] In this disclosure, "UE" is a general concept referring to a device that includes a wireless communication module communicating with a base station in a wireless communication system. It should be interpreted as including not only user equipment (UE) in technologies such as WCDMA, LTE, NR, HSPA, and IMT-2020 (5G or New Radio), but also mobile stations (MS), user terminals (UT), subscriber stations (SS), or wireless devices in GSM. Furthermore, depending on the type of use, the UE can be a user-portable device such as a smartphone, and in V2X communication systems, the UE can refer to a vehicle or a device within a vehicle that includes a wireless communication module. Additionally, in the case of machine-type communication systems, the UE can refer to an MTC terminal, M2M terminal, or URLLC terminal equipped with a communication module to perform machine-type communication.

[0039] In this disclosure, "base station" or "cell" refers to a terminal that communicates with the UE in terms of the network, and conceptually includes various coverage areas such as Node-B, Evolved Node-B (eNB), gNode-B (gNB), Low Power Node (LPN), Sector, Site, various types of antennas, Base Transceiver System (BTS), Access Point, Point (e.g., Transmit Point, Receive Point, or Transmit / Receive Point), Relay Node, Megacell, Macrocell, Microcell, Picocell, Femtocell, Remote Radio Head (RRH), Radio Unit (RU), or Small Cell. Furthermore, "cell" can refer to a cell that includes the bandwidth part (BWP) in the frequency domain. For example, "Serving Cell" can refer to the UE's active BWP.

[0040] Because a base station controls one or more of the various types of cells listed above, a base station can be interpreted in two ways. A base station can be 1) the device itself that provides a giant cell, macro cell, micro cell, pico cell, femtocell, or small cell associated with a wireless area, or 2) the wireless area itself. In 1), all devices that provide a predetermined wireless area and are controlled by the same entity, or that interact collaboratively to configure the wireless area, are referred to as base stations. Examples of base stations are transmitting / receiving points, transmitting points, or receiving points, depending on the scheme used to configure the wireless area. In 2), from the perspective of the UE or neighboring base stations, the wireless area itself that receives or transmits signals can be a base station.

[0041] In this disclosure, "cell" may refer to the coverage area of ​​a signal transmitted from a transmitting / receiving point, a component carrier having the coverage area of ​​a signal transmitted from a transmitting / receiving point (transmitting point or transmitting / receiving point), or the transmitting / receiving point itself.

[0042] Uplink (UL) refers to the process by which a UE sends data to / receives data from a base station, while downlink (DL) refers to the process by which a base station sends data to / receives data from the UE. A downlink can refer to communication or a communication path from multiple sending / receiving points to the UE, and an uplink can refer to communication or a communication path from the UE to multiple sending / receiving points. In this context, in the downlink, the transmitter can be part of multiple sending / receiving points, and the receiver can be part of the UE. Similarly, in the uplink, the transmitter can be part of the UE, and the receiver can be part of multiple sending / receiving points.

[0043] Uplink and downlink transmit / receive control information through control channels such as the Physical Downlink Control Channel (PDCCH) or the Physical Uplink Control Channel (PUCCH), and configure data channels such as the Physical Downlink Shared Channel (PDSCH) or the Physical Uplink Shared Channel (PUSCH) to transmit / receive data. In the following text, the context of transmitting / receiving signals through channels such as PUCCH, PUSCH, PDCCH, and PDSCH is expressed as "transmitting or receiving PUCCH, PUSCH, PDCCH, and PDSCH".

[0044] Although for clarity, the technical spirit is mainly focused on the 3GPP LTE / LTE-A / New RAT (NR) communication system, the technical features are not limited to this communication system.

[0045] Following its research on fourth-generation (4G) communication technology, 3GPP developed fifth-generation (5G) communication technology to meet the requirements of ITU-R's next-generation radio access technology. Specifically, 3GPP developed a new NR communication technology, separate from LTE-A pro and 4G communication technologies, as a 5G communication technology. This technology enhances LTE-Advanced to meet ITU-R requirements. Both LTE-A pro and NR refer to 5G communication technology. In the following text, unless otherwise specified, 5G communication technology will be described primarily within the context of NR.

[0046] In NR, the operation scenarios add considerations such as satellites, vehicles, and new verticals to the existing 4G LTE scenarios, defining various operation scenarios. From a service perspective, it supports the enhanced mobile broadband (eMBB) scenario, the massive machine type communication (mMTC) scenario with a high UE density but a wide deployment range that requires low data rates and asynchronous access, and the ultra-reliable low latency (URLLC) scenario that requires high responsiveness and reliability and can support high-speed mobility.

[0047] To meet such scenarios, NR discloses a wireless communication system that employs new waveform and frame structure technologies, low latency technologies, millimeter wave (mmWave) support technologies, and technologies that provide forward compatibility. In particular, the NR system proposes various technical changes in terms of flexibility to provide forward compatibility. The main technical features of NR are described below with reference to the accompanying drawings.

[0048] <Overview of NR System>

[0049] Figure 1 It is a view schematically showing the structure of the NR system to which the present embodiment can be applied.

[0050] Refer to Figure 1 , the NR system is divided into a 5G core network (5GC) and an NR-RAN part. The NG-RAN consists of gNBs and ng-eNBs, providing user plane (SDAP / PDCP / RLC / MAC / PHY) and user equipment (UE) control plane (RRC) protocol terminations. The gNBs or the gNBs and ng-eNBs are interconnected via the Xn interface. The gNBs and ng-eNBs are connected to the 5GC via the NG interface. The 5GC may include an access and mobility management function (AMF) (e.g., UE access and mobility control function) responsible for the control plane and a user plane function (UPF) responsible for user data control functions. NR supports both frequency bands below 6 GHz (frequency range 1 (FR1)) and frequency bands above 6 GHz (frequency range 2 (FR2)).

[0051] A gNB refers to a base station that provides NR user plane and control plane protocol terminations for UEs, and an ng-eNB refers to a base station that provides E-UTRA user plane and control plane protocol terminations for UEs. In the present disclosure, the base station should be understood to include gNBs and ng-eNBs, and when necessary, it is used to represent gNBs or ng-eNBs respectively.

[0052] <NR Waveform, Numerology, and Frame Structure>

[0053] NR uses the CP - OFDM waveform, with a cyclic prefix for downlink transmission and CP - OFDM or DFT - s - OFDM for uplink transmission. The OFDM technology is easily combined with multiple input multiple output (MIMO), and has the advantages of high frequency efficiency and the ability to use a low - complexity receiver.

[0054] At the same time, in NR, since the above three scenarios have different requirements for data rate, latency, and coverage, it is necessary to effectively meet the requirements of each scenario through the frequency bands that make up any NR system. For this purpose, a technique for effectively multiplexing radio resources based on multiple different numerologies has been proposed.

[0055] Specifically, the NR transmission numerology is determined based on the sub - carrier spacing and the cyclic prefix (CP), and as shown in Table 1 below, it changes exponentially, where the exponential value 2 is used as μ relative to 15 kHz.

[0056] [Table 1]

[0057] μ Subcarrier spacing Cyclic prefix Support data Support synchronization 0 15 ordinary yes yes 1 30 ordinary yes yes 2 60 Normal, Extended yes no 3 120 ordinary yes yes 4 240 ordinary no yes

[0058] As shown in Table 1 above, the NR numerology can be divided into five types according to the sub - carrier spacing. This is different from the sub - carrier spacing in LTE, a 4G communication technology, which is fixed at 15 kHz. Specifically, in NR, the sub - carrier spacing for data transmission is 15 kHz, 30 kHz, 60 kHz, and 120 kHz, and the sub - carrier spacing for synchronization signal transmission is 15 kHz, 30 kHz, 12 kHz, and 240 kHz. In addition, the extended CP is only applied to the 60 kHz sub - carrier spacing. At the same time, as the frame structure in NR, a frame with a length of 10 ms is defined, which is composed of 10 sub - frames with the same length of 1 ms. A frame can be divided into two half - frames of 5 ms, and each half - frame can include 5 sub - frames. In the case of a 15 kHz sub - carrier spacing, a sub - frame is composed of one time slot, and each time slot is composed of 14 OFDM symbols. Figure 2 It is a view showing the frame structure in the NR system to which this embodiment can be applied.

[0059] Reference Figure 2, in the case of a normal CP, a time slot is fixedly composed of 14 OFDM symbols, but the length of the time slot in the time domain can vary depending on the subcarrier spacing. For example, in the case of a parameter set with a 15 kHz subcarrier spacing, the time slot has the same length as the subframe, that is, a length of 1 ms. On the contrary, in the case of a parameter set with a 30 kHz subcarrier spacing, the time slot is composed of 14 OFDM symbols, but two time slots can be included in one subframe with a length of 0.5 ms. In other words, the subframe and the frame are defined to have a fixed length, the time slot is defined by the number of symbols, and the time length can vary according to the subcarrier spacing.

[0060] At the same time, NR defines the time slot as the basic unit for scheduling, and to reduce the transmission delay in the radio part, mini-slots (or sub-slot or non-slot based scheduling) are adopted. If a wider subcarrier spacing is used, the length of one time slot is shortened inversely, so that the transmission delay in the radio part can be reduced. Mini-slots are for efficiently supporting the URLLC scenario and can be scheduled in units of 2, 4, or 7 symbols.

[0061] In addition, different from LTE, NR defines the uplink and downlink resource allocation at the symbol level in a time slot. To reduce the HARQ delay, a time slot structure is defined that enables the HARQ ACK / NACK to be directly transmitted in the transmission time slot, and this time slot structure is called a self-contained structure in the description.

[0062] NR is designed to be able to support a total of 256 time slots, among which 62 time slot formats are used in 3GPP Rel-15. In addition, through various combinations of time slots, the common frame structure constituting the FDD or TDD frame is supported. For example, the time slot structure where all symbols of the time slot are configured as downlink, the time slot structure where all symbols are configured as uplink, and the time slot structure with a combination of downlink symbols and uplink symbols are supported. In addition, NR supports data transmission distributed and scheduled in one or more time slots. Therefore, the base station can use the slot format indicator (SFI) to notify the UE whether the time slot is a downlink time slot, an uplink time slot, or a flexible time slot. Through the SFI, the base station can indicate the time slot format by indicating the index of the table configured via UE-specific RRC signaling, and the base station can indicate it dynamically through downlink control information (DCI) or indicate it statically or semi-statically through RRC.

[0063] <NR Physical Resources>

[0064] Combined with the physical resources in NR, antenna ports, resource grids, resource elements, resource blocks, and bandwidth parts are considered.

[0065] Define antenna ports such that the channel carrying symbols on an antenna port can be inferred from the channel carrying another symbol on the same antenna port. If the macroscale characteristics of the channel carrying symbols on one antenna port can be inferred from the channels carrying symbols on different antenna ports, then the two antenna ports can be said to have a QC / QCL (quasi-co-location or quasi-co-position) relationship. Here, macroscale characteristics include one or more of delay spread, Doppler spread, frequency shift, average received power, and received timing.

[0066] Figure 3 This is a view showing a resource grid that can be supported by the wireless access technology of this embodiment.

[0067] refer to Figure 3 Since NR supports multiple parameter sets on the same carrier, the resource grid can exist according to each parameter set. Furthermore, the resource grid can exist based on antenna port, subcarrier spacing, or transmission direction.

[0068] A resource block consists of 12 subcarriers and is defined only in the frequency domain. Furthermore, a resource element consists of one OFDM symbol and one subcarrier. Therefore, as... Figure 3 As shown, the size of a resource block can vary depending on the subcarrier spacing. Furthermore, in NR, a "point A" is defined as the common reference point for the resource block grid, along with common resource blocks and virtual resource blocks.

[0069] Figure 4 This is a view showing the bandwidth portion supported by the wireless access technology to which this embodiment can be applied.

[0070] In NR, unlike LTE where the carrier bandwidth is fixed at 20MHz, a maximum carrier bandwidth ranging from 50MHz to 400MHz is set for each subcarrier interval. Therefore, it is not assumed that all UEs use all of these carrier bandwidths. Thus, in NR, as... Figure 4 As shown, a bandwidth portion (BWP) can be specified within the carrier bandwidth and used by the UE. Furthermore, a bandwidth portion is associated with a set of parameters and consists of a subset of consecutive common resource blocks, and can be dynamically activated over time. Up to four bandwidth portions can be configured in the UE for each of the uplink and downlink. Data is transmitted / received using the bandwidth portion activated at a given time.

[0071] In the case of paired spectrum, the uplink bandwidth portion and the downlink bandwidth portion are set independently. In the case of unpaired spectrum, the uplink bandwidth portion and the downlink bandwidth portion are set in pairs to share the center frequency to prevent unnecessary frequency readjustment between downlink operation and uplink operation.

[0072] <NR Initial Access>

[0073] In NR, the UE performs a cell search and a random access procedure to access the base station and perform communication.

[0074] Cell search is a process in which the UE synchronizes with the cell of the base station using the synchronization signal block (SSB) transmitted by the base station, obtains the physical layer cell ID, and obtains system information.

[0075] Figure 5 It is a view exemplarily showing the synchronization signal block in the radio access technology to which this embodiment can be applied.

[0076] Reference Figure 5 , the SSB consists of a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) each occupying 1 symbol and 127 subcarriers, and a PBCH spanning 3 OFDM symbols and 240 subcarriers.

[0077] The UE monitors and receives the SSB in the time domain and the frequency domain.

[0078] The SSB can be transmitted up to 64 times within 5 ms. Multiple SSBs are transmitted on different transmission beams within 5 ms, and the UE performs detection assuming that the SSB is transmitted every 20 ms period based on a specific beam used for transmission. The number of beams available for SSB transmission within 5 ms can increase as the frequency band increases. For example, up to 4 SSB beams can be transmitted below 3 GHz, up to 8 different beams can be used to transmit the SSB in the frequency band from 3 GHz to 6 GHz, and up to 64 different beams can be used to transmit the SSB in the frequency band of 6 GHz or higher.

[0079] Two SSBs are included in one time slot, and the start symbol and repetition number within the time slot are determined according to the subcarrier spacing as follows.

[0080] Meanwhile, unlike the standard SS in conventional LTE, SSBs are not transmitted at the center frequency of the carrier bandwidth. In other words, SSBs can be transmitted even outside the center of the system frequency band, and multiple SSBs can be transmitted in the frequency domain when wideband operation is supported. Accordingly, the UE monitors SSBs through a synchronization raster, which is used to detect candidate frequency locations for SSBs. NR newly defines the carrier raster and synchronization raster, which are information about the center frequency location of the initial access channel. The synchronization raster has a wider frequency spacing than the carrier raster, enabling the UE to perform fast SSB searches.

[0081] The UE can obtain the MIB through the PBCH of the SSB. The master information block (MIB) includes the minimum information that enables the UE to receive the remaining system information (remaining minimum system information (RMSI)) broadcast by the network. In addition, the PBCH may include information about the position of the first DM-RS symbol in the time domain, information about the UE monitoring SIB1 (e.g., SIB1 parameter set information, information related to the SIB1 CORESET, search space information, parameter information related to the PDCCH, etc.), offset information between the common resource block and the SSB (the absolute position of the SSB within the carrier is transmitted via SIB1), etc. Here, the SIB1 parameter set information also applies to some messages used by the UE during the random access process after completing the cell search procedure to access the base station. For example, the parameter set information about SIB1 can be applied to at least one of messages 1 to 4 in the random access procedure.

[0082] The aforementioned RMSI can refer to System Information Block 1 (SIB1). SIB1 is broadcast periodically (e.g., every 160ms) within the cell. SIB1 includes information required by the UE to perform the initial random access procedure and is periodically transmitted via the PDSCH. To receive SIB1, the UE needs to receive parameter set information for SIB1 transmission and control resource set (CORESET) information for SIB1 scheduling via the PBCH. The UE uses the SI-RNTI in the CORESET to identify the SIB1 scheduling information and obtains the SIB1 on the PDSCH based on the scheduling information. Other SIBs besides SIB1 can be transmitted periodically and can be transmitted upon the UE's request.

[0083] Figure 6 This is a view illustrating the random access procedure in the wireless access technology to which this embodiment can be applied.

[0084] refer to Figure 6 If cell search is complete, the UE sends a random access preamble to the base station for random access. The random access preamble is sent via PRACH. Specifically, the random access preamble is sent to the base station via a PRACH consisting of continuous radio resources in a periodically repeating specific time slot. Generally, when the UE initially accesses a cell, a contention-based random access procedure is performed; when performing random access for beam failure recovery (BFR), a non-contention-based random access procedure is performed.

[0085] The UE receives a random access response in response to the transmitted random access preamble. The random access response may include a random access preamble identifier (ID), uplink radio resources (UL grant), cell-radio network temporary identifier (C-RNTI), and time alignment command (TAC). Since a random access response may include random access response information for one or more UEs, the random access preamble identifier may be included to indicate which UE the included UL grant, temporary C-RNTI, and TAC are valid for. The random access preamble identifier may be the identifier of 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 the random access identifier on the PDCCH, i.e., the random access-radio network temporary identifier (RA-RNTI).

[0086] Upon receiving a valid random access response, the UE processes the information included in the random access response and performs scheduled transmissions to the base station. For example, the UE applies a TAC and stores a temporary C-RNTI. Furthermore, the UE uses UL authorization to send data stored in the UE's buffer or newly generated data to the base station. In this case, information identifying the UE should be included.

[0087] Finally, the UE receives downlink messages for contention resolution.

[0088] <NR CORESET>

[0089] In NR, the downlink control channel is transmitted in a control resource set (CORESET) of 1 to 3 symbols in length, and transmits uplink / downlink scheduling information, slot format index (SFI), transmit power control (TPC) information, etc.

[0090] Therefore, NR introduced the concept of CORESET to ensure system flexibility. A control resource set (CORESET) refers to the time-frequency resources used for downlink control signals. The UE can use one or more search spaces within the CORESET time-frequency resources to decode candidate control channels. Quasi-co-location (QCL) assumptions are set for each CORESET to indicate characteristics of the simulated beam direction in addition to delay spread, Doppler spread, Doppler shift, and average delay (characteristics assumed by conventional QCL).

[0091] Figure 7 This is a view showing the CORESET.

[0092] refer to Figure 7 A CORESET can exist in various forms within the carrier bandwidth of a single time slot. In the time domain, a CORESET can consist of up to three OFDM symbols. Furthermore, in the frequency domain, a CORESET is defined as a multiple of six resource blocks (up to the carrier bandwidth).

[0093] The first CORESET is indicated via the MIB as part of the initial bandwidth portion configuration to allow the reception of additional configuration and system information from the network. After establishing a connection with the base station, the UE can receive and configure one or more CORESET messages via RRC signaling.

[0094] As used herein, frequency, frame, subframe, resource, resource block, region, band, subband, control channel, data channel, synchronization signal, various reference signals, various signals, and various messages related to New Radio (NR) may be interpreted according to different meanings currently in use or in the future.

[0095] Side link

[0096] In conventional LTE systems, radio channels and radio protocols are designed for direct communication between UEs (i.e., sidelinks) in order to enable direct communication between UEs and provide V2X (especially V2V) services.

[0097] Regarding sidelinks, S-PSS / S-SSS and the physical sidelink broadcasting channel (PSBCH) are defined. S-PSS / S-SSS is a synchronization signal used for synchronization between the wireless sidelink transmitter and receiver. PSBCH is used to send and receive the associated sidelink master information block (MIB). The physical sidelink discovery channel (PSDCH), the physical sidelink control channel (PSCCH) used for sending / receiving sidelink control information (SCI), and the physical sidelink shared channel (PSSCH) are designed.

[0098] In addition, to allocate radio resources to sidelinks, technologies were developed for Mode 1, where the base station allocates radio resources, and Mode 2, where the UE selects and allocates radio resources from the radio resource pool. Furthermore, LTE systems require additional technological evolution to meet the needs of V2X scenarios.

[0099] In this context, 3GPP derived 27 service scenarios related to vehicle identification in Rel-14 and determined the main performance requirements based on road conditions. Furthermore, in the more recent Rel-15, 25 more advanced service scenarios were derived, such as platooning, advanced driving, and long-range vehicle sensors, and six performance requirements were identified.

[0100] To meet these performance requirements, technologies are developed to enhance the performance of sidelink technologies based on conventional D2D communication to meet V2X requirements. In particular, for application in Cellular-V2X (C-V2X), technologies that enhance sidelink physical layer design to adapt to high-speed environments, resource allocation technologies, and synchronization technologies are selected as the main research technologies.

[0101] The sidelinks described below can be understood to include links used for D2D communication developed after 3GPP Rel-12, V2X communication after Rel-14, and NR V2X after Rel-15. Furthermore, regardless of D2D communication requirements and V2X Rel-14 and Rel-15 requirements, each channel terminology, synchronization terminology, and resource terminology is described using the same terminology. However, for ease of understanding, the differences between sidelinks meeting V2X scenario requirements and sidelinks used for D2D communication in Rel-12 / 13 will be described primarily where necessary. Therefore, for ease of understanding and comparison, the sidelink-related terminology described below is categorized only for D2D communication / V2X communication / C-V2X communication, and not limited to any specific scenario.

[0102] <Resource Allocation>

[0103] Figure 8 It is a view showing various scenarios used for V2X communication.

[0104] refer to Figure 8 V2X UEs (labeled as vehicles, but can be configured in various ways, e.g., UE) can be located within or outside the coverage area of ​​a base station (eNB, gNB, or ng-eNB). For example, communication can occur between UEs within the base station's coverage area (UE N-1, UE G-1, and UE X), or between UEs within the base station's coverage area and external UEs (e.g., UE N-1 and UE N-2). Alternatively, communication can occur between UEs outside the base station's coverage area (e.g., UE G-1 and UE G-2).

[0105] In these different scenarios, radio resources need to be allocated for communication so that the corresponding UE can use the side link to perform communication. The allocation of radio resources mainly includes allocation by the base station and selection and allocation by the UE itself.

[0106] Specifically, the schemes for allocating resources in the sidelink by the UE include a scheme in which the base station participates in resource selection and management (Scheme 1) and a scheme in which the UE selects resources on its own (Scheme 2). In Scheme 1, the base station schedules the scheduling assignment (SA) pool resource area and the DATA pool resource area allocated to it to the transmitting UE.

[0107] Furthermore, resource pools can be subdivided into several types. Firstly, resource pools can be partitioned based on the content of the sidelink signals transmitted within each pool. For example, the content of the sidelink signals can be partitioned, and a separate resource pool can be configured for each type. The content of the sidelink signals can include scheduling assignment (SA), sidelink data channels, and discovery channels.

[0108] SA can be a signal that includes information such as: the location of resources used by the transmitting UE in subsequent sidelink data channel transmissions, the modulation and coding scheme (MCS) or MIMO transmission scheme required to modulate other data channels, and timing advance (TA). This signal can be multiplexed and transmitted with sidelink data on the same resource element. In this case, the SA resource pool can refer to the resource pool where SA is multiplexed and transmitted with sidelink data.

[0109] Meanwhile, the FDM scheme applied to V2X communication can reduce the latency when allocating data resources after SA resource allocation. For example, consider a non-adjacent scheme that separates control channel resources and data channel resources in a subframe in the time domain, and an adjacent scheme that continuously allocates control channels and data channels in a subframe.

[0110] Simultaneously, when the SA is multiplexed and transmitted with sidelink data on the same resource element, only sidelink data channels other than SA information can be transmitted in the resource pool used for sidelink data channels. In other words, resource elements on each resource element in the SA resource pool that have already been used to transmit SA information can still be used to transmit sidelink data in the sidelink data channel resource pool. The discovery channel can be a resource pool used for messages to allow the transmitting UE to send its ID or such information that will be discovered by neighboring UEs. Even when the content of the sidelink signals is the same, different resource pools can be used based on the transmission / reception attributes of the sidelink signals.

[0111] For example, regardless of sidelink data channels or discovery messages, they can be divided into different resource pools based on the following: sidelink signal transmission timing determination scheme (e.g., whether to send when receiving a synchronization reference signal or when a pre-defined TA is applied), resource allocation scheme (e.g., whether the base station assigns transmission resources for each signal to the UE or each transmitting UE selects transmission resources for each signal itself), signal format (e.g., the number of symbols occupied by each sidelink signal in a subframe or the number of subframes used to transmit a sidelink signal), signal strength from the base station, or transmission power strength of the sidelink UE.

[0112] Synchronization Signal

[0113] As mentioned above, the UE using sidelink communication is likely located outside the base station's coverage area. Even in this case, communication using the sidelink should still be performed. Therefore, it is important to address the issue of obtaining synchronization through a UE located outside the base station's coverage area.

[0114] Based on the above description, a method for time and frequency synchronization in side-link communication, particularly between vehicles, between a vehicle and another UE, and between a vehicle and an infrastructure network, is described.

[0115] D2D communication uses a sidelink synchronization signal (SLSS), which is a synchronization signal sent from the base station for time synchronization between UEs. In C-V2X, a satellite system (Global Navigation Satellite System, GNSS) can be additionally considered to enhance synchronization performance. However, priority can be assigned to synchronization establishment, or the base station can indicate priority information. For example, the UE may first select the synchronization signal directly sent by the base station to determine the UE's transmission synchronization; if the UE is located at the edge of the base station's coverage area, then synchronization is preferentially performed using the SLSS sent by UEs within the base station's coverage area.

[0116] Meanwhile, wireless UEs installed in vehicles are relatively less susceptible to battery drain issues and can use satellite signals such as GPS for navigation purposes. Therefore, time and frequency synchronization between UEs can be established using satellite signals. Here, in addition to the example Global Positioning System (GPS), the satellite signal can also be GNSS signals, such as Global Navigation Satellite System (GLONASS), GALILEO, and BEIDOU.

[0117] Simultaneously, the sidelink synchronization signal can include a sidelink primary synchronization signal (S-PSS) and a sidelink secondary synchronization signal (S-SSS). The S-PSS can have a Zadoff-chu sequence of predetermined length or a similar / modified / repeated structure of the PSS. Furthermore, unlike the DL PSS, other Zadoff-chu root indices (e.g., 26 and 37) can be used. The S-SSS can have a similar / modified / repeated structure of the SSS or M sequence. If the UE synchronizes from the base station, the SRN becomes the base station, and the sidelink synchronization signal (S-SS) becomes the PSS / SSS.

[0118] Different from DL PSS / SSS, S-PSS / S-SSS follows the UL subcarrier mapping scheme. The physical sidelink broadcast channel (PSBCH) can be a channel on which basic system information that the UE first needs to know before transmitting and receiving sidelink signals (e.g., information related to S-SS, duplex mode (DM), TDD UL / DL configuration, resource pool related information, application type related to S-SS, subframe offset, broadcast information, etc.) is transmitted. The PSBCH can be transmitted on the same subframe as the S-SS or on a subsequent subframe. DMRS can be used for the demodulation of the PSBCH. The S-SS and PSBCH can be referred to as the sidelink synchronization signal block (S-SSB).

[0119] The SRN can be a node that transmits the S-SS and PSBCH. The S-SS can have a specific sequence form. The PSBCH can have the form of a sequence indicating specific information or a codeword经过预定信道编码的码字的形式。在此,SRN可以是基站或特定的侧链路UE。在部分网络覆盖或网络覆盖外的情况下,UE可成为SRN。

[0120] In addition, the S-SS can be relayed as needed for sidelink communication with UEs outside the coverage area and can be relayed through multiple hops. In the following description, the relayed synchronization signal is a concept that includes not only the synchronization signal of the direct relay base station but also the sidelink synchronization signal transmitted in a separate format according to the synchronization signal reception time. Since the sidelink synchronization signal is relayed in this way, UEs within the coverage area and UEs outside the coverage area can communicate directly.

[0121] <NR Sidelink>

[0122] As described above, different from V2X based on the LTE system, NR-based V2X technology is required to meet complex requirements such as autonomous driving.

[0123] NR V2X aims to flexibly provide V2X services in more diverse environments by applying the frame structure, parameter set, and channel transmission and reception processes of NR. For this purpose, technologies such as resource sharing technology between the base station and the UE, sidelink carrier aggregation (CA) technology, partial sensing technology for pedestrian UEs, and sTTI need to be developed.

[0124] It should be noted that there is an unclear expression "经过预定信道编码的码字的形式" in the original text, which is translated as "经过预定信道编码的码字的形式" in a literal way for the time. You may need to check and correct it according to the accurate content.NR V2X is confirmed to support unicast and multicast, as well as broadcast used in LTE V2X. In this case, for multicast and unicast, the target group ID is determined to be used, but whether the source ID is used will be discussed later.

[0125] Furthermore, since HARQ for QoS is supported, the control information is determined to also include the HARQ process ID. In LTE HARQ, the PUCCH for HARQ is transmitted four subframes after the downlink transmission. However, in NR HARQ, the PUCCH resource and feedback timing can be indicated by, for example, the PUCCH resource indicator or the PDSCH-to-HARQ feedback timing indicator in DCI format 1_0 or 1_1.

[0126] In LTE V2X, separate HARQ ACK / NACK messages are not sent to reduce system overhead, and for data transmission stability, the transmitting UE is determined to retransmit data once, depending on its choice. However, NR V2X can send HARQ ACK / NACK messages based on data transmission stability; in this case, the messages are bundled and sent, reducing overhead.

[0127] In other words, the sending UE UE1 can send three data to the receiving UE UE2. If the receiving UE generates HARQACK / NACK information in response, this information can be bundled and sent via PSCCH.

[0128] Meanwhile, in FR1 (frequency domain below 3 GHz), 15 kHz, 30 kHz, 60 kHz, and 120 kHz were identified and discussed as candidate subcarrier spacing (SCS). Furthermore, for FR2 (frequency domain above 3 GHz), 30 kHz, 60 kHz, 120 kHz, and 240 kHz were identified and discussed as candidate subcarrier spacing (SCS). NR V2X can support micro-slots of less than 14 symbols (e.g., 2 / 4 / 7 symbols) as the minimum scheduling unit.

[0129] As RS candidates, DM-RS, PT-RS, CSI-RS, SRS, and AGC training signals were identified and discussed.

[0130] Side Link UL SPS

[0131] Generally, when there is a large gap between the user data generation and the configured SPS resources, UL transmission using SPS may result in some latency. Therefore, when SPS is used for latency-sensitive traffic (such as sidelink communication), the SPS scheduling interval should be small enough to support latency requirements.

[0132] However, smaller SPS scheduling intervals can lead to higher overhead because the UE may not fully utilize the configured SPS resources. Therefore, the gap between user data generation and the configured SPS resources should be small, and the SPS scheduling interval should be suitable for meeting latency requirements. Currently, there is no mechanism supporting this feature.

[0133] The UE can receive SPS configurations for one or more specific logical channels. The UE can receive SPS configurations for specific logical channels through system information, RRC connection establishment messages, RRC connection reconfiguration messages, or RRC connection release messages.

[0134] When data is available for a specific logical channel, the UE can request the base station to activate SPS, and then perform UL transmission using the configured SPS resources according to the SPS activation command received from the base station. The UE can send the SPS activation request to the base station via the Physical Uplink Control Channel (PUCCH), MAC control element (CE), or RRC message. In other words, the UE can use control resources for requesting SPS activation to send the SPS activation request to the base station. This control resource can be PUCCH resources, random access resources, or new UL control channel resources. Furthermore, the UE can send the SPS activation request to the base station, for example, during RRC connection (re)establishment, handover, after handover, or in RRC_CONNECTED.

[0135] Since the UE actively requests SPS activation from the base station when there is UL data to be transmitted, the gap between the generation of UL data and the configured SPS resources can be reduced.

[0136] For example, the UE receives SPS configuration information from the base station, including three SPS configurations. If there is UL data to be transmitted at the upper layer, the UE sends an SPS request message to the base station, for example, via MAC CE. The base station sends an Ack message for one of the three SPS configurations. Depending on the corresponding SPS configuration, the UE transmits the UL data using specific resources (e.g., within a 1-second period).

[0137] Meanwhile, if there is UL data to be transmitted at the upper layer at a specific time, the UE will, for example, send an SPS request message to the base station again via MAC CE. The base station sends an Ack message for another of the three SPS configurations. The UE then transmits the UL data using specific resources (e.g., within a 100-second period) according to the corresponding SPS configuration.

[0138] Meanwhile, S-SS id_net is a set of S-SS IDs used by a UE that selects the base station's synchronization signal as a synchronization reference from the physical layer SLSS IDs {0,1,...,335}, and can be {0,1,...,167}. Furthermore, S-SS id_oon is a set of S-SS IDs used by a UE outside the base station / coverage area when transmitting its own synchronization signal, and can be {168,169,...,335}.

[0139] As mentioned above, unlike the conventional signal transmission and reception between the base station and the UE, sidelink communication between UEs performs resource allocation, time synchronization settings, and reference signal transmission independently or in conjunction with the base station.

[0140] In particular, under next-generation radio access technologies (including terms such as NR and 5G), many protocols between base stations and UEs have been added or modified. Therefore, unlike conventional V2X communication protocols based on LTE technology, sidelink communication based on NR technology also requires the development of various protocols.

[0141] This disclosure describes operations such as PSCCH, PSSCH, or DMRS configuration, resource allocation, and synchronization signal reception when a transmitting UE and a receiving UE perform sidelink communication. Each of the following embodiments focuses on sidelink communication, but can also be applied to C-V2X and D2D communication as described above.

[0142] Since the subcarrier spacing (SCS) of an OFDM communication system varies in NR, the frame structure of the sidelink used for information transmission and reception in sidelink communication also needs to be changed.

[0143] In this embodiment, the sidelink signal can use CP-OFDM type waveforms of both CP-OFDM and DFT-s-OFDM types. Furthermore, the sidelink can use the following subcarrier spacings (hereinafter referred to as "SCS"). For example, in frequency range (FR)1 using a frequency band less than 6 GHz, SCSs of 15 kHz, 30 kHz, and 60 kHz are used; in this case, the 60 kHz spacing, exhibiting optimal performance, can be set as standby. In FR2 using a frequency band of 6 GHz or higher, spacings of 60 kHz and 120 kHz are used, and the 60 kHz band can be primarily used.

[0144] In addition, the sidelink uses a cyclic prefix (CP) to prevent modulation that may occur during wireless communication transmission / reception, and its length can be set to be equal to the length of the normal CP of the NR Uu interface. Extended CPs can be applied if necessary.

[0145] In this case, considering efficiency, it is necessary to set up sidelink synchronization signals, resource allocation, and the structure of each sidelink channel.

[0146] First, when the UE performs sidelink communication, it is proposed to include the DMRS configuration in the transmitted PSSCH.

[0147] The transmitting UE may perform the following steps: receive a resource information set from the base station, including information about one or more sidelink resources and one or more DMRS mode information.

[0148] In the case of sidelink communication, two resource allocation methods can be configured. For example, in method 1, the UE requests sidelink radio resource allocation from the base station and performs sidelink communication using the sidelink radio resources allocated by the base station. In method 2, the base station can pre-allocate a resource information set for the sidelink UE, which contains information about one or more sidelink radio resources. The UE selects a sidelink radio resource from the allocated resource information set and performs sidelink communication.

[0149] Resource information sets and one or more DMRS mode information can be received via higher-layer signaling. For example, a transmitting UE or a receiving UE located within the base station's coverage area can receive a resource information set containing one or more sidelink resources to be used for sidelink communication via RRC signaling. Furthermore, the transmitting UE and / or the receiving UE can receive one or more DMRS mode information for sidelink communication from the base station. Since the transmitting and receiving UEs receive the same information, resource information sets and DMRS mode information can be configured in each UE.

[0150] Simultaneously, one or more DMRS mode information entries can be mapped to each resource information set or sidelink resource. For example, when the base station indicates a first resource information set including one or more resource information entries and a second resource information set including one or more resource information entries, a first DMRS mode information entry for the first resource information set and a second DMRS mode information entry for the second resource information set can be mapped and indicated to the resource information sets. Alternatively, DMRS mode information can be mapped and indicated for each sidelink resource included in a resource information set. Alternatively, DMRS mode information can be mapped and indicated for each subset of sidelink resources included in two or more subsets of sidelink resources in a resource information set. Alternatively, two or more resource information sets can be grouped, and DMRS mode information can be mapped and indicated for each group. Sidelink resources and DMRS modes can be mapped and indicated in various other forms. The transmitting UE configures the received resource information set and DMRS mode in the UE.

[0151] The transmitting UE can perform the following steps based on a resource information set: selecting a sidelink resource for sidelink communication. If sidelink communication is triggered, the transmitting UE selects a specific sidelink resource from the configured resource information set. Various methods can be implemented to enable the UE to select a specific sidelink resource for sidelink communication from the resource information set. For example, the transmitting UE can select a specific sidelink resource based on the priority allocated to multiple sidelink resources. Alternatively, the UE can sense whether a resource is being used by multiple sidelink resources and select a sidelink resource with a sensing result value lower than a reference value. In other words, the transmitting UE can sense unused or infrequently used sidelink resources and select a sidelink resource that is yet to be used by the transmitting UE.

[0152] The transmitting UE can perform the step of selecting a specific DMRS mode from one or more DMRS mode information based on a selected sidelink resource. For example, when the transmitting UE selects a sidelink resource, it can select the DMRS mode to be mapped and configured to the selected sidelink resource. Alternatively, the transmitting UE can select the DMRS mode based on characteristic information about the selected sidelink resource.

[0153] For example, the selected specific DMRS mode can be determined based on the following information: persistent symbol information about the sidelink resources selected for Physical Sidelink Shared Channel (PSSCH) transmission, information about the number of symbols allocated at the Physical Sidelink Control Channel (PSCCH), and information about the number of DMRS symbols included in the PSSCH. Specifically, when selecting PSSCH sidelink resources for transmitting sidelink data, the persistent symbol information constituting the corresponding PSSCH sidelink resources, the number of PSCCH symbols allocated in the time slots at the PSSCH transmission, and the number of DMRS symbols can be determined. In this case, the position of the symbols at the DMRS to be transmitted can be determined based on pre-configuration information in tabular form, depending on the combination of conditions. For example, the information about the number of symbols allocated at the PSCCH can be set to 2 or 3, and the information about the number of DMRS symbols included in the PSSCH can be set to 2, 3, or 4. In other words, each component can be determined within the above-mentioned range for each sidelink resource.

[0154] The transmitting UE can perform the following steps: transmit the PSCCH and PSSCH in a time slot using the selected sidelink resources, and transmit DMRS in specific symbols of the PSSCH based on a specific DMRS mode. For example, if the sidelink resources used for sidelink data transmission are determined, the transmitting UE can transmit the PSCCH and PSSCH in a time slot. The DMRS mode information included in the PSSCH can be indicated to the receiving UE through the sidelink control information (SCI) included in the PSCCH.

[0155] For example, specific DMRS mode information applied to the PSSCH can be indicated by the DMRS mode field of the sidelink control information included in the PSCCH. The DMRS mode field can be included in the first SCI and can be determined to be any value from 1 to 5 bits. Alternatively, the bit value of the DMRS mode field can be determined based on the number of DMRS mode information entries transmitted by the base station. The SCI format including the DMRS mode indication field is SCI 0_1.

[0156] The receiving UE can receive sidelink data from the PSSCH sidelink resources indicated by the PSCCH, and can use the DMRS mode indication field to identify the DMRS symbols allocated in the PSSCH area.

[0157] Simultaneously, when configuring the mode table for DMRS symbol allocation in both the transmitting and receiving UEs, the DMRS mode information included in the DMRS mode indication field can include information indicating the number of DMRS assigned to the PSSCH. In other words, since the number of persistent symbols on the PSSCH and the number of symbols set to the PSCCH can be identified through other fields of the SCI, the receiving UE can use the table used to identify the number of DMRS to recognize information about the symbols (to which DMRS are assigned). In this case, the DMRS indication field can be concatenated to 2 bits.

[0158] Through the above operations, the transmitting UE can dynamically configure and transmit the DMRS mode, and the receiving UE can recognize the dynamically configured DMRS mode and thus receive the PSSCH.

[0159] Next, the operation of sending and receiving synchronization signals when the application performs sidelink communication based on the base station's synchronization configuration is described.

[0160] In sidelink communication, unlike the Uu interface, the allocated frequency band may be relatively narrow, and there may be more information to be transmitted through the broadcast channel. Furthermore, time-slot-based synchronization signal transmission is required.

[0161] Therefore, in this disclosure, a sidelink synchronization block is proposed that is different from the synchronization block in the Uu interface.

[0162] The UE can perform the step of receiving sidelink synchronization block (SSB) configuration information, wherein the SSB configuration information includes synchronization information for sidelink communication.

[0163] For example, the sidelink synchronization signal block configuration information may include at least one of the following: subcarrier index information in the frequency domain in which the sidelink synchronization signal block is transmitted, information about the number of sidelink synchronization signal blocks transmitted within a sidelink synchronization signal period, offset information from the start of the sidelink synchronization signal period to the first sidelink synchronization signal block monitoring time slot, and interval information between sidelink synchronization signal block monitoring time slots. For example, the sidelink synchronization signal period may be set to 16 frames and set to 160 ms. As another example, the sidelink synchronization signal period may be set to a multiple of 16.

[0164] For example, the number of sidelink synchronization signal blocks can be set within different ranges, depending on the subcarrier spacing set in the frequency band transmitting the sidelink synchronization signal blocks. As shown in Table 1, the subcarrier spacing in the frequency band can be set to 15kHz, 30kHz, 60kHz, 120kHz, or 240kHz. Specifically, when the subcarrier spacing is 15kHz, the number of sidelink synchronization signal blocks is set to 1 or 2. Alternatively, when the subcarrier spacing is 30kHz, the number of sidelink synchronization signal blocks is set to one of 1, 2, or 4. Alternatively, when the subcarrier spacing is 60kHz, the number of sidelink synchronization signal blocks is set to one of 1, 2, 4, or 8. Alternatively, when the subcarrier spacing is 120kHz, the number of sidelink synchronization signal blocks is set to one of 1, 2, 4, 8, 16, 32, or 64. Meanwhile, in the case of FR2, even when the subcarrier spacing is set to 60kHz, the number of sidelink synchronization signal blocks can be set to one of 1, 2, 4, 8, 16, and 32.

[0165] The UE can perform the step of monitoring the monitoring time slots of the sidelink synchronization signal block, where the monitoring time slots are configured based on the sidelink synchronization signal block configuration information. For example, the UE monitors a specific time slot within the sidelink synchronization signal period based on the sidelink synchronization signal block configuration information.

[0166] For example, when 16 frames are set as the sidelink synchronization signal period, the UE identifies the interval from the start time slot of the sidelink synchronization signal period to the first sidelink synchronization signal block monitoring time slot in the synchronization signal period based on offset information. Furthermore, the UE uses interval information to identify the interval from the first sidelink synchronization signal block monitoring time slot to the second sidelink synchronization signal block monitoring time slot. Similarly, the UE uses interval information to identify the interval from the second sidelink synchronization signal block monitoring time slot to the third sidelink synchronization signal block monitoring time slot. Additionally, the UE identifies the number of all sidelink synchronization signal block monitoring time slots allocated within the sidelink synchronization signal period based on information about the number of sidelink synchronization signal blocks. Therefore, the UE uses sidelink synchronization signal block configuration information to identify and monitor the index (position) of the monitoring time slot within the sidelink synchronization signal period.

[0167] The UE can perform the step of receiving a sidelink synchronization signal block in a sidelink synchronization signal block monitoring time slot. For example, the UE uses the aforementioned sidelink synchronization signal block configuration information to receive a sidelink synchronization signal block in a monitoring time slot. A sidelink synchronization signal block consists of a sidelink primary synchronization signal (S-PSS), a sidelink secondary synchronization signal (S-SSS), and a physical sidelink broadcast channel (PSBCH). The S-PSS, S-SSS, and PSBCH can be allocated to N consecutive symbols within the sidelink synchronization signal block monitoring time slot.

[0168] For example, a sidelink synchronization block can be configured by assigning it to N consecutive symbols within a time slot. In this case, the sidelink synchronization block can be connected to two S-PSS, two S-SSS, and N-4 PSBCH symbols. For instance, a sidelink synchronization block can allocate a PSBCH at symbol index 0, S-PSS at symbol indices 1 and 2, S-SSS at symbol indices 3 and 4, and PSBCH at symbol indices 5 to N-1 within the sidelink synchronization block monitoring time slot. In this case, N is 13 when the sidelink synchronization block monitoring time slot is a normal cyclic prefix (CP), and N is 11 when the sidelink synchronization block monitoring time slot is an extended cyclic prefix (CP). In other words, when a time slot consists of 14 or 12 symbols, S-PSS, S-SSS, and PSBCH (excluding the last symbol) can be allocated to form a sidelink synchronization block. As another example, a sidelink synchronization block can consist of 132 subcarriers.

[0169] Furthermore, HARQ operations can even be performed in sidelink communication. However, frequent HARQ operations in sidelink communication may lead to resource aggregation and increased system load. Additionally, HARQ operations may not execute smoothly due to limitations such as the UE's transmission power. Therefore, in sidelink communication, various operations can be controlled and executed based on a HARQ feedback transmission scheme.

[0170] Therefore, the UE needs to receive information about the HARQ feedback transmission scheme from the sending UE.

[0171] Figure 9 This is a view used to describe the operation of the UE according to an embodiment.

[0172] refer to Figure 9 The UE performing the control side link HARQ feedback operation executes the step (S910) of receiving the physical side link control channel (PSCCH) including the first side link control information from the sending UE.

[0173] For example, a UE receives a PSCCH sent by a transmitting UE. The PSCCH may include first side link control information. The side link control information can be divided into first side link control information included in the PSCCH and second side link control information included in the PSSCH.

[0174] For example, the first-side link control information may include at least one of the following: PSSCH scheduling information, DMRS mode information, information indicating the format of the second-side link control information, modulation and coding scheme information, and PSFCH overhead indication information.

[0175] For example, the first side link control information may include information in a 2-bit field indicating the format of the second side link control information. The format of the second side link control information can be divided into two types based on the information indicating the format of the second side link control information.

[0176] The second-side link control information format can provide the same or different HARQ feedback transmission schemes. In other words, the HARQ feedback transmission scheme can be divided based on the information indicating the format of the second-side link control information.

[0177] For example, when the information indicating the format of the second-side link control information indicates the first format, it can be determined that the HARQ feedback transmission scheme is one of the three. As another example, when the information indicating the format of the second-side link control information indicates the second format, it can be determined that the HARQ feedback transmission scheme is one of the two.

[0178] For example, when the information indicating the format of the second sidelink control information indicates the first format, the HARQ feedback transmission scheme can support any of the following schemes: a first scheme that sends HARQ feedback including ACK or NACK information depending on whether sidelink data is received; a second scheme that sends HARQ feedback only when the sidelink data reception is determined to be NACK; and a third scheme that does not send HARQ feedback for sidelink data.

[0179] When the information indicating the format of the second sidelink control information indicates the second format, the HARQ feedback transmission scheme can support any of the following schemes: a second scheme that sends HARQ feedback only when the reception of sidelink data is determined to be NACK, and a third scheme that does not send HARQ feedback for sidelink data.

[0180] The UE performs the step (S920) of receiving the Physical Side Link Shared Channel (PSSCH) including the second side link control information from the transmitting UE.

[0181] For example, the UE can receive the second side link control information via PSSCH based on the scheduling information of the first side link control information. As described above, the second side link control information can be determined to be one of two formats and is determined by the following information: the format of the second side link control information that indicates the first side link control information.

[0182] For example, second-side link control information may include HARQ process number, new data indication information, redundancy version, source ID, destination ID, and HARQ feedback activation information. Furthermore, depending on the format of the second-side link control information, it may include at least one of the following: broadcast type information, CSI request indication information, area ID, and communication range request information.

[0183] For example, when the second-side link control information is in the first format, it may include broadcast type information and CSI request indication information. As another example, when the second-side link control information is in the second format, it may include area ID information and communication range request information.

[0184] Additionally, PSSCH can also include sidechain data information.

[0185] The UE performs the step of identifying broadcast type information and HARQ feedback transmission scheme information about the side link data received from the transmitting UE based on the second side link control information (S930).

[0186] As described above, various HARQ feedback transmission schemes can be supported in sidelink communication. For example, the following schemes can be supported: a first scheme that sends HARQ feedback including ACK or NACK information based on whether sidelink data is received; a second scheme that sends HARQ feedback only when the reception of sidelink data is determined to be NACK; and a third scheme that does not send HARQ feedback for sidelink data.

[0187] Based on the second sidelink control information, the UE can identify the HARQ feedback transmission scheme information from the sidelink data received by the sending UE via PSSCH.

[0188] For example, the broadcast type field included in the second-side link control information can consist of 2 bits and can include a value indicating one of broadcast, multicast, and unicast.

[0189] In addition, the broadcast type field can include multiple values ​​indicating multicast. These multiple values ​​can be differentiated based on HARQ feedback transmission scheme information.

[0190] For example, one of the values ​​indicating multicast can indicate a HARQ feedback transmission scheme for sending HARQ feedback including ACK or NACK information, depending on whether sidelink data is received. As another example, another of the values ​​indicating multicast can indicate a HARQ feedback transmission scheme for sending HARQ feedback only when the reception of sidelink data is determined to be NACK.

[0191] In other words, the UE can simultaneously identify the broadcast type information and HARQ transmission scheme information of the sidelink data by recognizing the value of the broadcast type field in the second sidelink control information. To this end, different values ​​can be assigned to the 2-bit broadcast type field based on the broadcast type; in the case of multicast, at least two values ​​are assigned. Each of the two assigned values ​​indicates the multicast type but is configured to simultaneously indicate different HARQ transmission schemes.

[0192] Therefore, the sending UE can indicate information about the HARQ feedback transmission scheme to the receiving UE without generating additional fields and incurring system load during sidelink communication.

[0193] The following describes an embodiment of this HARQ feedback transmission scheme in more detail. To perform the HARQ feedback operation described above according to this disclosure, it is necessary to understand the sidelink communication type. V2X communication types may include unicast types that perform one-to-one communication and multicast or broadcast types that perform one-to-many communication.

[0194] As described above, the transmitting UE can indicate the broadcast type via the second side link control information (second SCI).

[0195] At the same time, for HARQ operations, the use of HARQ feedback (enabled, disabled), communication scheme (multicast, unicast, broadcast, etc.) and HARQ feedback transmission scheme (no feedback, ACK or NACK, NACK only) should be classified or specified.

[0196] Therefore, the transmitting UE needs to send information to the receiving UE regarding whether HARQ feedback is used and the HARQ feedback transmission scheme. However, transmitting all information using a separate field may increase the system load on control information, potentially reducing radio resources available for sidelink data transmission.

[0197] To address this problem, this disclosure proposes a method for transmitting information related to various types of HARQ operations.

[0198] For example, the first side link control information (first SCI) may include information indicating HARQ operation.

[0199] For example, a 2-bit format indicating the second side link control information can be used in the first SCI. Different supported HARQ feedback transmission schemes can be set according to each format. Therefore, candidates for HARQ feedback transmission schemes can be indicated based on the format of the second side link control information.

[0200] Alternatively, two bits can be used in the first SCI to indicate whether HARQ feedback is used and the HARQ feedback scheme. For example, see Table 2, where HARQ disabled indicates no feedback. When HARQ is enabled, the first bit can indicate the feedback scheme, and the second bit can indicate the communication scheme. In cases where unicast has less information than multicast, either ACK or NACK feedback can be indicated.

[0201] [Table 2]

[0202] First SCI 00 Do not use HARQ feedback 01 Using HARQ feedback, using only HARQ NACK information, multicast 10 Use HARQ feedback, using HARQ ACK or NACK messages, unicast. 11 Use HARQ feedback, use HARQ ACK or NACK messages, multicast.

[0203] For example, a two-digit field of the second side link control information (second SCI) can be used to indicate HARQ operation.

[0204] For example, the 2-bit broadcast type field of the second SCI can be used to indicate the broadcast type and HARQ feedback transmission scheme information. For instance, referring to Table 3, the four values ​​of the broadcast type field of the second SCI can be used to distinguish between broadcast, multicast, and unicast. In the case of multicast, different values ​​can be assigned to schemes that send HARQ feedback information with both HARQ ACK and NACK and schemes that send HARQ feedback information only with HARQ NACK.

[0205] [Table 3]

[0206]

[0207] Therefore, information about HARQ operations can be transmitted without adding additional control information bits.

[0208] For example, information instructing HARQ operations can be transmitted via the first SCI and the second SCI.

[0209] For example, information about HARQ feedback transmission scheme candidates corresponding to each format can be transmitted by indicating the format of the second side link control information of the first SCI, and HARQ operation can be indicated by HARQ feedback transmission scheme information in the broadcast type field or information about whether HARQ feedback is used in the second SCI.

[0210] In addition, HARQ operations can be indicated by any combination of the above embodiments.

[0211] Furthermore, as mentioned above, the second-side link control information can be divided into two or more formats and set. The HARQ operation based on the broadcast type field included in the second-side link control information has been described above. The UE HARQ operation when the second-side link control information includes area ID information in a second format is described below.

[0212] The description will focus on the operation of the UE. Omissions may be made where necessary, and the same applies to the foregoing descriptions below.

[0213] A UE performing a control-side link HARQ feedback operation can perform the following steps: receive multicast sidelink data from the sending UE via the Physical Sidelink Shared Channel (PSSCH).

[0214] In the case of multicast communication, the PSCCH may include scheduling information for PSSCH radio resources, wherein the PSSCH radio resources include sidelink multicast data. The UE receives the PSSCH including multicast sidelink data based on the sidelink control information included in the PSCCH.

[0215] The UE can perform the following steps: determine whether to send HARQ feedback information about multicast sidelink data based on the location information of the sending UE.

[0216] For example, location information about the sending UE can be included in the sidelink control information (SCI) received via the PSSCH, and may also include area ID information about the sending UE. The sidelink control information received via the PSSCH can refer to second sidelink control information (second SCI). In other words, the sidelink control information received via the PSSCH differs from the sidelink control information received via the physical sidelink control channel (PSCCH), which includes scheduling information for multicast sidelink data. For example, the SCI received via the PSSCH may include HARQ process ID information, new data indication information, redundancy version information, sending UE ID information, receiving UE ID information, CSI request information, area ID information, and communication range request information.

[0217] Simultaneously, the UE can receive geographic location information mapped to each region ID from the base station via higher-layer signaling. The UE can then use the geographic location information for each region ID and the region ID information about the sending UE received from the base station to obtain location information about the sending UE.

[0218] Meanwhile, HARQ feedback information can be determined based on the location of the sending UE, the distance information calculated from the UE's location, and whether the multicast side link data decoding was successful.

[0219] For example, HARQ feedback information can be sent only when the decoding of multicast side link data fails and the distance information is at or below a preset threshold, and the HARQ feedback information may include HARQ-NACK information.

[0220] For example, if the distance information is a preset threshold or greater, the HARQ feedback information, including HARQ-ACK or HARQ-NACK information, can be sent based on whether the multicast side link data decoding is successful.

[0221] For example, when the multicast link data is successfully decoded, regardless of the distance information, it can be determined not to send HARQ feedback information.

[0222] For example, if decoding of multicast side link data fails, distance information can be used to determine whether to send HARQ feedback information.

[0223] The aforementioned HARQ feedback information transmission can be performed only when the sidelink HARQ feedback operation is activated. In other words, the sidelink HARQ feedback operation can be activated or deactivated, and whether it is activated can be determined by an indication from the transmitting UE or base station. Furthermore, the aforementioned threshold can be included in the sidelink control information received via PSSCH (e.g., communication range request information) or can be configured in the UE by the base station.

[0224] At the same time, when it is determined that HARQ feedback information will be transmitted, the UE can perform the step of sending HARQ feedback information.

[0225] For example, when it is determined to transmit HARQ feedback information, the UE can send HARQ feedback information for multicast sidelink data. This reduces unnecessary sidelink system load and provides the effect of performing HARQ feedback operations based on the distance information between the sending UE and other UEs.

[0226] Figure 10 This is a view showing side link control information received via PSCCH according to an embodiment.

[0227] refer to Figure 10 Sidelink control information can be sent via PSCCH and PSSCH. The sidelink control information sent via PSCCH may include, for example, PSSCH scheduling information and is represented as the first SCI.

[0228] For example, the first SCI includes a priority field for priority, a frequency resource allocation field for PSSCH, and a time resource allocation field. Furthermore, in the case of resource reservation, it includes resource reservation period information. Additionally, the first SCI may include the aforementioned DMRS mode indication field. Furthermore, the first SCI may include a format field for indicating the second SCI format, a β offset indication field, a field indicating the number of DMRS ports, and a field indicating the modulation and coding scheme. The frequency and resource reservation period fields can be set to variable sizes, and the DMRS mode and second SCI format fields can be fixed or set to variable. The receiving UE can receive... Figure 10 The first SCI identifies DMRS mode information, PSSCH scheduling information, and the second SCI format information.

[0229] Figure 11 This is a view showing side link control information received via PSSCH according to an embodiment.

[0230] refer to Figure 11The second SCI received via PSSCH may include a K-bit field containing HARQ process ID information. Additionally, the second SCI may include a 1-bit new data indication field, indicating whether the PSSCH data is retransmitted or initial transmission data. Furthermore, the second SCI may include a 2-bit redundancy version field for the HARQ process. Additionally, the second SCI may include a source ID field, which includes identification information about the sending UE sending the PSSCH, and this field consists of 8 bits. Furthermore, the second SCI may include a 16-bit destination ID field, which includes destination identification information about the PSSCH. Furthermore, the second SCI may include at least one of a 1-bit CSI request field and a 4-bit communication range request field. Additionally, it may include an N-bit area ID field, which includes location information about the aforementioned sending UE.

[0231] In the following description, various embodiments for calculating distance information between transmitting UEs are described with reference to the accompanying drawings.

[0232] Figure 12 This is a view illustrating the operation of calculating distance information based on the location of the transmitting UE and the location of the UE, according to an embodiment.

[0233] refer to Figure 12 The transmitting UE (Tx UE) may not consider the location of the receiving UE (Rx UE). In this case, the transmitting UE can transmit an SCI that includes location information obtained from GNSS or a base station. The receiving UE can extract location information about the transmitting UE from the received SCI information. For example, location information about the transmitting UE can be transmitted by sending identification information that divides the geographical location into area types.

[0234] For example, if the identifier information regarding the geographic location information of the sending UE is 1111 and the identifier information regarding the geographic location information of the receiving UE is 1110, then the sending UE can send an SCI including 4-bit area ID information (indicating 1111).

[0235] For example, if the transmitting UE knows the location of the receiving end, the transmitting UE can include its relative location information with the receiving UE in the SCI and send it to the receiving UE. In this case, n bits are used for the relative location information of the transmitting UE, and the SCI can also include resolution information of the location information. Figure 12 An example using 4 bits and a resolution of 10m*10m is shown. In this scenario, the transmitting UE can send an SCI that includes relative position information of 1110 and resolution information of 1110.

[0236] For example, when GNSS information is not used, the receiving UE can consider sidelink path loss and transmission signal strength to calculate the distance between the sending UE and the receiving UE, and compare it with the communication request range to determine whether to send HARQ feedback.

[0237] The CQI, PMI, or RI, which indicate channel status, exhibit characteristics that vary according to the degree of fading. Fading refers to the phenomenon where two or more radio waves on different paths interfere with each other, causing irregular changes in signal amplitude and phase over time. In particular, small-scale fading is caused by the combination of multiple multipath reflections resulting from the influence of surrounding structures, and is characterized by rapid changes over a short period of time. The degree of fading is directly related to the path loss coefficient under NLOS conditions, which is also closely related to the measured CQI, PMI, and RI. Therefore, after estimating the path loss coefficient from CQI, PMI, or RI, a more accurate distance can be calculated using RSRP and the strength of the transmitted reference signal. The relationship between the distance between the transmitter and receiver, the received signal strength (RSRP), the transmitted signal strength, and the path loss coefficient can be determined by a preset formula.

[0238] Figure 13 This is a view illustrating operations for receiving location information about the transmitting UE according to an embodiment.

[0239] refer to Figure 13 The transmitting UE can send location information about itself based on the region ID. In this case, the geographic location information corresponding to the region ID can be pre-configured in a table format by the transmitting and receiving UEs.

[0240] For example, area IDs can be configured in tabular form using geometric regions. These tabular area IDs can be pre-stored by both the transmitting and receiving UEs. When the receiving UE receives the area ID, it can identify the geographic location information about the transmitting UE. Since the geographic location information about the receiving UE can be estimated using the receiving UE's GNSS or base station reference signals, the receiving UE can calculate the distance between the transmitting and receiving UEs if it knows the geographic location information about the transmitting UE.

[0241] At the same time, each region and its corresponding ID can be predefined as a rectangular region, such as Figure 13 As shown. If the location of the transmitting vehicle obtained via GPS is within one of the predefined areas, the transmitting UE determines the ID corresponding to that area as the transmitting UE's area ID. The determined area ID is included in the SCI and transmitted, and can therefore be used to determine whether the receiving UE should provide HARQ feedback.

[0242] Figure 14This is a view illustrating operations for receiving location information about the transmitting UE according to another embodiment.

[0243] refer to Figure 14 The area ID can be determined based on the communication range of the base station. In this case, each UE 1800 has a base station-based area ID. If UE 1800 forms an RRC connection with gNB4 and is performing communication, the area ID of UE 1800 can be determined to be area ID #4 corresponding to gNB4. In other words, an area ID can be assigned to each base station. In this case, the UE can send an SCI that includes information indicating area ID #4.

[0244] Figure 15 This is a view illustrating operations for receiving location information about the transmitting UE according to another embodiment.

[0245] refer to Figure 15 Each region and its corresponding region ID can be predefined as a non-uniform region. At the upper layer, the size of each region can be determined based on the region and positioning accuracy, taking into account the density of UEs. Information about the region IDs of UEs located within a specific range or in cells of one or more specific base stations can be pre-configured in each UE. If UE 1900 belongs to a specific region, the corresponding vehicle can include the region ID in its SCI and send that region ID. For example, if UE 1900 is located in region #5, then UE 1900 includes information indicating #5 in its SCI and sends that information.

[0246] Simultaneously, the region ID and communication range can be included in the second-stage SCI as K bits and 4 bits, respectively. As mentioned above, the region ID information can be used to calculate the distance between TX and RX, and the communication range can be used as a threshold for HARQ feedback transmission based on the distance between TX and RX.

[0247] The receiving UE uses its location and the sending UE's area ID to calculate TX-RX distance information. The calculated TX-RX distance information can be compared with the communication range and used to determine HARQ feedback. For example, if the TX-RX distance calculated by the receiving UE in a multicast scenario is greater than the communication range, the corresponding UE does not send an ACK or NACK according to HARQ operation. Conversely, in the opposite case, the corresponding UE sends an ACK or NACK. In other words, if the distance information between TX and RX is calculated using the area ID and the receiving UE's location, it can be ultimately determined whether to send a HARQ feedback signal by comparing it with communication range information that can be included in the SCI. The communication range information has been described as being included in the SCI. However, by predefining a specific table, the communication range information may only include indication values ​​used to identify and indicate the corresponding table. Alternatively, the communication range information can be shared by the UEs via higher-layer signaling. In other words, the base station can send communication range information to each UE and can determine whether to perform HARQ feedback operation based on the communication range information at a predetermined time or up to the occurrence of a predetermined event.

[0248] As described above, information indicating various types of HARQ operation schemes (HARQ transmission schemes) can be transmitted to the receiving UE in various forms according to various types of HARQ operation schemes. The above-described schemes using broadcast type indication and schemes using area ID can be combined. Alternatively, each of the above schemes can be applied individually according to different second-side link control information formats.

[0249] The UE device capable of performing the above embodiments will be described again below.

[0250] Figure 16 This is a view showing the configuration of the UE according to an embodiment.

[0251] refer to Figure 16 The UE 1600, which controls the sidelink HARQ feedback operation, may include a receiver 1630 and a controller 1610. The receiver 1630 receives a physical sidelink control channel (PSCCH) including first sidelink control information from the transmitting UE and a physical sidelink shared channel (PSSCH) including second sidelink control information from the transmitting UE. The controller 1610 identifies the HARQ feedback transmission scheme information and broadcast type information of the sidelink data received from the transmitting UE based on the second sidelink control information.

[0252] For example, side link control information can be divided into first side link control information included in PSCCH and second side link control information included in PSSCH.

[0253] For example, the first-side link control information may include at least one of the following: PSSCH scheduling information, DMRS mode information, information indicating the format of the second-side link control information, modulation and coding scheme information, and PSFCH overhead indication information.

[0254] For example, the first side link control information may include information in a 2-bit field indicating the format of the second side link control information. The format of the second side link control information can be divided into two types based on the information indicating the format of the second side link control information.

[0255] The second-side link control information format can provide the same or different HARQ feedback transmission schemes. In other words, the HARQ feedback transmission scheme can be divided based on the information indicating the format of the second-side link control information.

[0256] For example, when the information indicating the format of the second-side link control information indicates the first format, it can be determined that the HARQ feedback transmission scheme is one of the three. As another example, when the information indicating the format of the second-side link control information indicates the second format, it can be determined that the HARQ feedback transmission scheme is one of the two.

[0257] For example, when the information indicating the format of the second sidelink control information indicates the first format, the HARQ feedback transmission scheme can support any of the following schemes: a first scheme that sends HARQ feedback including ACK or NACK information depending on whether sidelink data is received; a second scheme that sends HARQ feedback only when the sidelink data reception is determined to be NACK; and a third scheme that does not send HARQ feedback for sidelink data.

[0258] When the information indicating the format of the second sidelink control information indicates the second format, the HARQ feedback transmission scheme can support any of the following schemes: a second scheme that sends HARQ feedback only when the reception of sidelink data is determined to be NACK, and a third scheme that does not send HARQ feedback for sidelink data.

[0259] Receiver 1630 can receive second side link control information via PSSCH based on the scheduling information of the first side link control information. As described above, the second side link control information can be determined to be one of two formats, and is determined by information indicating the format of the second side link control information that indicates the first side link control information.

[0260] For example, second-side link control information may include HARQ process number, new data indication information, redundancy version, source ID, destination ID, and HARQ feedback activation information. Furthermore, depending on the format of the second-side link control information, it may include at least one of the following: broadcast type information, CSI request indication information, area ID, and communication range request information.

[0261] For example, when the second sidelink control information is in the first format, it may include broadcast type information and CSI request indication information. As another example, when the second sidelink control information is in the second format, it may include area ID information and communication range request information. Additionally, the PSSCH may also include sidelink data information.

[0262] As described above, various HARQ feedback transmission schemes can be supported in sidelink communication. For example, the following schemes can be supported: a first scheme, which sends HARQ feedback including ACK or NACK information based on whether sidelink data is received; a second scheme, which sends HARQ feedback only when the reception of sidelink data is determined to be NACK; and a third scheme, which does not send HARQ feedback for sidelink data.

[0263] The controller 1610 can identify the transmission scheme information based on the second side link control information and the HARQ feedback of the side link data received from the transmitting UE via PSSCH.

[0264] For example, the broadcast type field included in the second-side link control information can consist of 2 bits and can include a value indicating one of broadcast, multicast, and unicast. Furthermore, the broadcast type field can include multiple values ​​indicating multicast. Here, these multiple values ​​indicating multicast can be determined based on HARQ feedback transmission scheme information.

[0265] For example, one of the values ​​indicating multicast can indicate a HARQ feedback transmission scheme that sends HARQ feedback including ACK or NACK information, depending on whether sidelink data is received. As another example, another of the values ​​indicating multicast can indicate a HARQ feedback transmission scheme that sends HARQ feedback only when the reception of sidelink data is determined to be NACK.

[0266] In other words, the controller 1610 can simultaneously identify the broadcast type information and HARQ transmission scheme information of the sidelink data by recognizing the value of the broadcast type field in the second sidelink control information. To this end, different values ​​can be assigned to the two-bit broadcast type field based on the broadcast type; in the case of multicast, at least two values ​​are assigned. Each of the two assigned values ​​indicates the multicast type but is configured to simultaneously indicate different HARQ transmission schemes.

[0267] In addition, the controller 1610 can control the operation of the UE 1600 required to perform the above embodiments.

[0268] In addition, transmitter 1620 and receiver 1630 transmit / receive signals, data and messages with base station and another UE through corresponding channels.

[0269] The above embodiments can be supported by the standard documents disclosed in IEEE 802, 3GPP, and 3GPP2 as wireless access systems. In other words, the above standard documents can support steps, components, and parts not described for the purpose of clarifying the technical spirit of the embodiments. Furthermore, all terms disclosed in this disclosure can be described by the above-disclosed standard documents.

[0270] The above-described embodiment can be implemented by various means. For example, this embodiment can be implemented by various methods, such as hardware, firmware, software, or combinations thereof.

[0271] When implemented in hardware, the method according to this embodiment can be implemented, for example, by one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), processors, controllers, microcontrollers, or microprocessors.

[0272] When implemented in firmware or hardware, the method according to this embodiment can be implemented in the form of a device, process, or function that performs the above-described functions or operations. Software code can be stored in a storage unit and driven by a processor. The storage unit can be located inside or outside the processor to exchange data with the processor in various known ways.

[0273] The terms mentioned above, such as "system," "processor," "controller," "component," "module," "interface," "model," or "unit," generally refer to computer-related physical hardware, combinations of hardware and software, software, or software in execution. For example, a component can be, but is not limited to, a processor-driven process, a processor, a controller, a control processor, an entity, an execution thread, a program, and / or a computer. For example, an application program executed by a controller or processor, and the controller or processor itself, can both be components. One or more components may reside in a process and / or execution thread, and components may be located in one device (e.g., a system, a computing device, etc.) or distributed across two or more devices.

[0274] The above embodiments are merely examples, and those skilled in the art will understand that various modifications can be made thereto without departing from the scope of the invention. Accordingly, the embodiments described herein are provided for illustrative purposes only and are not intended to limit the scope of the invention. It should be understood that the scope of the invention is not limited by these embodiments. The scope of the invention should be interpreted by the appended claims, and all technical spirit within the equivalent scope thereof should be interpreted as falling within the scope of the invention.

[0275] Cross-reference to related applications

[0276] This patent application claims priority to Korean patent applications filed with the Korean Intellectual Property Office on August 7, 2020 and August 4, 2021, respectively, under 35U.SC119(a), the entire disclosure of which is incorporated herein by reference. This patent application also claims priority to other applications filed in other countries, the entire disclosure of which is also incorporated herein by reference.

Claims

1. A method for HARQ feedback operation via a terminal control side link, the method comprising: Receive the physical side link control channel (PSCCH) including the first side link control information from the transmitting terminal. Receive the Physical Side Link Shared Channel (PSSCH) including second side link control information from the transmitting terminal. and The HARQ feedback transmission scheme information and broadcast type information of the side link data received from the transmitting terminal are identified based on the second side link control information. In this context, both the HARQ feedback transmission scheme information and the broadcast type information of the sidelink data are indicated by the broadcast type field included in the second sidelink control information. The broadcast type field consists of two bits and includes a value indicating broadcast, a second value indicating unicast, and... The broadcast type field further includes multiple values ​​indicating multicast, wherein the multiple values ​​indicating multicast are divided according to the HARQ feedback transmission scheme information.

2. The method of claim 1, wherein the plurality of values ​​indicating the multicast includes at least one value corresponding to a first HARQ feedback transmission scheme and at least another value corresponding to a second HARQ feedback transmission scheme.

3. The method according to claim 2, wherein the first HARQ feedback transmission scheme corresponds to an ACK / NACK-based feedback scheme, and the second HARQ feedback transmission scheme corresponds to a NACK-only feedback scheme.

4. The method of claim 1, wherein the terminal determines whether to send sidelink HARQ feedback based on the broadcast type field included in the second sidelink control information.

5. The method of claim 1, wherein any one of the plurality of values ​​indicating the multicast indicates: a HARQ feedback transmission scheme for sending HARQ feedback including ACK or NACK information, depending on whether the sidelink data is received, and wherein another of the plurality of values ​​indicating the multicast indicates: a HARQ feedback transmission scheme for sending the HARQ feedback only when the reception of the sidelink data is determined to be NACK.

6. The method of claim 1, wherein the first side link control information includes information in a 2-bit field indicating the format of the second side link control information, and wherein the HARQ feedback transmission scheme is identified based on the information indicating the format of the second side link control information.

7. The method according to claim 6, wherein the format of the second side link control information is divided into two types, wherein when the information indicating the format of the second side link control information indicates a first format, the HARQ feedback transmission scheme is determined to be any one of three types, and when the information indicating the format of the second side link control information indicates a second format, the HARQ feedback transmission scheme is determined to be any one of two types.

8. The method of claim 7, wherein when the first format is indicated, the HARQ feedback transmission scheme is any one of the following: a first scheme that sends HARQ feedback including ACK or NACK information depending on whether the sidelink data is received; a second scheme that sends HARQ feedback only when the reception of the sidelink data is determined to be NACK; and a third scheme that does not send HARQ feedback for the sidelink data, wherein when the second format is indicated, the HARQ feedback transmission scheme is one of the following: a second scheme that sends HARQ feedback only when the reception of the sidelink data is determined to be NACK; or a third scheme that does not send HARQ feedback for the sidelink data.

9. A terminal for control-side link HARQ feedback operation, comprising: The receiver receives a physical side link control channel (PSCCH) including first side link control information from the transmitting terminal, and a physical side link shared channel (PSSCH) including second side link control information from the transmitting terminal. and The controller identifies the HARQ feedback transmission scheme information and broadcast type information of the sidelink data received from the transmitting terminal based on the second sidelink control information; In this context, both the HARQ feedback transmission scheme information and the broadcast type information of the sidelink data are indicated by the broadcast type field included in the second sidelink control information. The broadcast type field consists of two bits and includes a value indicating broadcast, a second value indicating unicast, and... The broadcast type field further includes multiple values ​​indicating multicast, wherein the multiple values ​​indicating multicast are divided according to the HARQ feedback transmission scheme information.

10. The terminal of claim 9, wherein the plurality of values ​​indicating the multicast includes at least one value corresponding to a first HARQ feedback transmission scheme and at least another value corresponding to a second HARQ feedback transmission scheme.

11. The terminal according to claim 10, wherein the first HARQ feedback transmission scheme corresponds to an ACK / NACK-based feedback scheme, and the second HARQ feedback transmission scheme corresponds to a NACK-only feedback scheme.

12. The terminal of claim 9, wherein any one of the plurality of values ​​indicating the multicast indicates: sending a HARQ feedback transmission scheme including ACK or NACK information based on whether the sidelink data is received, and wherein another of the plurality of values ​​indicating the multicast indicates: sending the HARQ feedback transmission scheme only when the reception of the sidelink data is determined to be NACK.

13. The terminal of claim 9, wherein the first side link control information includes information in a 2-bit field indicating the format of the second side link control information, and wherein the HARQ feedback transmission scheme is identified based on the information indicating the format of the second side link control information.

14. The terminal according to claim 13, wherein the format of the second side link control information is divided into two types, wherein when the information indicating the format of the second side link control information indicates a first format, the HARQ feedback transmission scheme is determined to be any one of three types, and when the information indicating the format of the second side link control information indicates a second format, the HARQ feedback transmission scheme is determined to be any one of two types.

15. The terminal of claim 14, wherein when the first format is indicated, the HARQ feedback transmission scheme is any of the following: a first scheme that sends HARQ feedback including ACK or NACK information depending on whether the sidelink data is used; a second scheme that sends HARQ feedback only when the reception of the sidelink data is determined to be NACK; and a third scheme that does not send HARQ feedback for the sidelink data, wherein when the second format is indicated, the HARQ feedback transmission scheme is one of the following: a second scheme that sends HARQ feedback only when the reception of the sidelink data is determined to be NACK; or a third scheme that does not send HARQ feedback for the sidelink data.

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