Patent Description:
To meet the demand for wireless data traffic having increased since deployment of 4th generation (<NUM>) communication systems, efforts have been made to develop an improved 5th generation (<NUM>) or pre-<NUM> communication system. Therefore, the <NUM> or pre-<NUM> communication system is also called a 'beyond <NUM> Network' or a 'post long term evolution (LTE) system'.

The <NUM> communication system is considered to be implemented in higher frequency (millimeter (mm) Wave) bands, e.g., <NUM> gigahertz (GHz) bands, so as to accomplish higher data rates.

In the <NUM> system, Hybrid frequency shift keying (FSK) and quadrature amplitude modulation (FOAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed.

In a <NUM> system, a vehicle to everything (V2X) technology has been developed. In a V2X system in which a sidelink feedback channel exists between terminals, a method and an apparatus for processing a signal to effectively transmit and receive a sidelink feedback channel by a user equipment (UE) are being discussed.

In a discussion paper to<NPL>, different aspects concerning NR V2X were discussed in general.

In another discussion paper to <NPL>, various sidelink procedure aspects, including groupcast HARQ design, power control, transport of SL control information via Uu, Usage of L-<NUM> ID, and MIMO support for sidelink, were discussed in general.

In still another discussion paper to <NPL>" and referred to as R1-<NUM>, submitted to the 3GPP TSG RAN WG1 Ad-Hoc-Meeting <NUM>, which took place in Taipei, 21st - 25th January, <NUM>, a detailed procedure for the design of NR sidelink physical layer procedure was discussed in general.

In still another discussion paper to Lenovo and Motorola Mobility, entitled "Physical layer procedures in NR V2X" and referred to as R1-<NUM>, submitted to the 3GPP TSG RAN WG1 Meeting #<NUM>, which took place in Athens, Greece, 25th February - 1st March, <NUM>, different views on physical layer procedures, including the feedback mechanism in unicast communication and groupcast communication, were discussed in general.

In still another discussion paper to<NPL>, the design aspects on physical layer procedures in NR sidelink was discussed in general.

Accordingly, an aspect of the disclosure is to provide an apparatus and a method for effectively processing a signal of a sidelink feedback channel in a wireless communication system.

In accordance with an aspect of the disclosure, a method of operating a UE in a wireless communication system is provided. The method includes acquiring at least one of a source identification (ID), a destination ID, or a cell ID, generating Sidelink Feedback Control information (SFCI) to be transmitted through a sidelink feedback channel (Physical Sidelink Feedback Channel (PSFCH)), performing channel encoding and scrambling on the SFCI using at least one of the source ID, the destination ID, or the cell ID, and transmitting the SFCI through the PSFCH.

In accordance with another aspect of the disclosure, an apparatus of a UE in a wireless communication system is provided. The apparatus includes at least one transceiver, and at least one processor, wherein the at least one processor is configured to acquire at least one of a source ID, a destination ID, or a cell ID, generate Sidelink Feedback Control information (SFCI) to be transmitted through a sidelink feedback channel (Physical Sidelink Feedback Channel (PSFCH)), perform channel encoding and scrambling on the SFCI using at least one of the source ID, the destination ID, or the cell ID, and transmit the SFCI through the PSFCH.

Various embodiments provide an apparatus and a method for effectively processing a signal of a sidelink feedback channel in a wireless communication system.

The advantages and features of the disclosure and ways to achieve them will be apparent by making reference to embodiments as described below in conjunction with the accompanying drawings.

These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions stored in the computer usable or computer-readable memory produce an article of manufacture including instruction means that implement the function specified in the flowchart block or blocks. The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operations to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions that execute on the computer or other programmable apparatus provide operations for implementing the functions specified in the flowchart block or blocks.

As used herein, the "unit" refers to a software element or a hardware element, such as a Field Programmable Gate Array (FPGA) or an Application Specific Integrated Circuit (ASIC), which performs a predetermined function. However, the "unit" does not always have a meaning limited to software or hardware. The "unit" may be constructed either to be stored in an addressable storage medium or to execute one or more processors. Therefore, the "unit" includes, for example, software elements, object-oriented software elements, class elements or task elements, processes, functions, properties, procedures, sub-routines, segments of a program code, drivers, firmware, micro-codes, circuits, data, database, data structures, tables, arrays, and parameters. The elements and functions provided by the "unit" may be either combined into a smaller number of elements, or a "unit", or divided into a larger number of elements, or a "unit". Moreover, the elements and "units" or may be implemented to reproduce one or more central processing units (CPUs) within a device or a security multimedia card. Further, the "unit" in the embodiments may include one or more processors.

The detailed description of embodiments is made mainly based on a New Radio (NR) access network (or a new RAN) and packet core (a <NUM> system, a <NUM> core network, or a Next Generation (NG) core) which is a core network on the <NUM>th Generation (<NUM>) mobile communication standard specified by the 3rd Generation Partnership Project (3GPP) corresponding to a mobile communication standardization organization, but the main subject of the disclosure can be applied to other communication systems having a similar technical background with slight modification without departing from the scope of the disclosure, which can be determined by those skilled in the art.

In the <NUM> system, a Network Data Collection and Analysis Function (NWDAF) that is a network function for analyzing and providing data collected by a <NUM> network may be defined to support network automation. The NWDAF may collect information from the <NUM> network, store and analyze the information, and provide the result to an unspecified Network Function (NF), and the analysis result may be independently used by each NF.

For convenience of the description, the disclosure may use terms and names defined in a 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) standard, a <NUM> New Radio (NR) standard, or a similar system standard. However, the disclosure is not limited to the terms or names, and may be equally applied to systems complying with other standards.

Terms for identifying access nodes in the following description, terms referring to network entities, terms referring to messages, terms referring to interfaces between network entities, and terms referring to various pieces of identification information are used for convenience of description. Accordingly, the disclosure is not limited to the terms used in the disclosure, and other terms referring to entities having the equivalent technical meaning may be used.

In order to meet wireless data traffic demands that have increased after <NUM> communication system commercialization, efforts to develop an improved <NUM> communication system (New Radio (NR)) have been made. The <NUM> communication system has been designed to use resources in a mmWave band, for example, a frequency band of <NUM> in order to achieve a high data transmission rate. In the <NUM> communication system, technologies, such as beamforming, massive Multi-Input Multi-Output (MIMO), Full Dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and large-scale antennas are being discussed to mitigate propagation path loss in the mmWave band and increase the propagation transmission distance. In addition, unlike LTE, the <NUM> communication system supports various subcarrier spacings, such as <NUM> kilohertz (kHz), <NUM>, and <NUM> including <NUM>, and a physical control channel uses polar coding and a physical data channel uses Low Density Parity Check (LDPC) coding. Moreover, as a waveform for uplink transmission, not only Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing (DFT-S-OFDM) but also Cyclic Prefix-based Orthogonal Frequency Division Multiplexing (CP-OFDM) are used. While resources for Hybrid Automatic Repeat Request (HARQ) retransmission in units of Transport Blocks (TBs) are allocated in LTE, resources for HARQ retransmission based on a Code Block Group (CBG) including a plurality of Code Blocks (CBs) may be additionally allocated in <NUM>.

Further, technologies, such as an evolved small cell, an advanced small cell, a cloud Radio Access Network (cloud RAN), an ultra-dense network, Device to Device communication (D2D), a wireless backhaul, a vehicle to everything network (a V2X network), cooperative communication, Coordinated Multi-Points (CoMP), and reception interference cancellation have been developed to improve the system network in the <NUM> communication system.

Meanwhile, the Internet has evolved from a human-oriented connection network, in which humans generate and consume information, to the Internet of Things (IoT), in which distributed components, such as objects exchange and process information. An Internet of Everything (IoE) technology in which a big data processing technology through a connection with a cloud server or the like is combined with the IoT technology has emerged. In order to implement the IoT, research is being conducted on technical factors, such as a sensing technique, wired/wireless communication and network infrastructure, service interface technology, and security technology are required, and thus technologies, such as a sensor network, Machine to Machine (M2M), Machine Type Communication (MTC), and the like for a connection between objects. In an IoT environment, through collection and analysis of data generated in connected objects, an intelligent Internet technology (IT) service to create a new value for peoples' lives may be provided. The IoT may be applied to fields, such as those of a smart home, a smart building, a smart city, a smart car, a connected car, a smart grid, health care, a smart home appliance, or high-tech medical services through the convergence of the information technology (IT) and various industries.

Accordingly, various attempts to apply the <NUM> communication to the IoT network are made. For example, <NUM> communication technologies, such as a sensor network, Machine-to-Machine (M2M) communication, and Machine-Type Communication (MTC) are implemented using beamforming, MIMO, and array-antenna schemes. The application of a cloud RAN as big-data processing technology is an example of convergence of the <NUM> technology and the IoT technology. As described above, a plurality of services may be provided to a user in a communication system, and in order to provide the plurality of services to the user, a method of providing each service in the same time interval according to a characteristic thereof and an apparatus using the same are needed. Various services provided by the <NUM> communication system are being researched, and one thereof is a service that satisfies requirements of low latency and high reliability.

In the case of vehicle communication, standardization of LTE-based V2X has been competed in 3GPP Rel-<NUM> and Rel-<NUM> based on the Device-to-Device (D2D) communication structure, and research on the development of V2X based on <NUM> New Radio (NR) is currently conducted. In NR V2X, unicast communication, groupcast communication, multicast communication, and broadcast communication will be supported between UEs. Further, NR V2X aims at providing more evolved service, such as platooning, advanced driving, extended sensor, and remote driving, unlike LTE V2X aiming at transmitting and receiving basic safety information required for driving of vehicles.

The NR V2X transmission UE may transmit sidelink control information and data information to the NR V2X reception UE. The NR V2X reception UE receiving the same may transmit acknowledgement (ACK) or negative acknowledgement (NAKC) for the sidelink data information received by the NR V2X reception UE to the NR V2X transmission UE. The ACK/NACK information may be referred to as Sidelink Feedback Control Information (SFCI). The SFCI may be transmitted through a sidelink feedback channel (Physical Sidelink Feedback Channel (PSFCH)) of a physical layer.

Meanwhile, the NR V2X transmission UE may transmit a sidelink reference signal to allow the NR V2X reception UE to acquire information on a sidelink channel state. The sidelink reference signal may be a Demodulation Reference Signal (DMRS) used to estimate a channel by the NR V2X reception UE or a Channel State Information Reference Signal (CSI-RS) used to acquire channel state information. When the CSI-RS is used, the CSI-RS may be transmitted using frequency/time/code resources different from the DMRS. The NR V2X reception UE acquiring the sidelink channel state information through the DMRS or the CSI-RS transmitted by the NR V2X transmission UE may report the sidelink channel state information to the NR V2X transmission UE. At this time, the CSI reporting information may correspond to the above-described SFCI and may be transmitted through the sidelink feedback channel.

In another example, HARQ-ACK/NACK information and CSI reporting information may be multiplexed and simultaneously transmitted through a sidelink feedback channel.

Embodiments of the specification are proposed to support the above-described scenario and aims at providing a method and an apparatus for transmitting and receiving a sidelink feedback channel by an NR V2X UE.

<FIG> illustrates a wireless communication system according to an embodiment of the disclosure, <FIG> illustrates a wireless communication system according to an embodiment of the disclosure, <FIG> illustrates a wireless communication system according to an embodiment of the disclosure, and <FIG> illustrates a wireless communication system according to an embodiment of the disclosure. Specifically, <FIG>, <FIG> illustrate an example of a system for describing an embodiment.

Referring to <FIG>, <FIG>, base Stations (BSs) <NUM> and <NUM> are network infrastructure for providing wireless access to terminals <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. The BSs <NUM> and <NUM> have coverage area defined as a predetermined geographical region based on a distance to which a signal can be transmitted. The BS <NUM> or <NUM> may be referred to as "Access Point (AP)", "eNodeB (eNB)", "<NUM>th-Generation (<NUM>) node", "next generation NodeB (gNB)", "wireless point", "Transmission/ Reception Point (TRP)", "Road Side Unit (RSU)", or other terms having an equivalent technical meaning, as well as a "base station".

In the specification, each of the terminals <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> is a device used by a user and communicates with the BSs <NUM> and <NUM> through a radio channel. According to circumstances, at least one of the terminals <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> may be operated without any involvement of the user. For example, at least one of the terminals <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> may be a device that performs Machine-Type Communication (MTC), and may not be carried by the user. Each of the UEs <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> may be referred to as "user equipment", "mobile station", "subscriber station", "remote terminal", "wireless terminal", "user device", or other terms having the equivalent technical meaning, as well as a "terminal".

<FIG> illustrates a case in which all V2X terminals, that is, UE-<NUM><NUM> and UE-<NUM><NUM> are located within coverage area <NUM> of the BS <NUM>.

All the V2X terminals <NUM> and <NUM> may receive data and control information from the BS <NUM> through downlink (DL) or transmit data and control information to the BS through uplink (UL). The data and the control information may be data and control information for V2X communication. Alternatively, the data and the control information may be data and control information for general cellular communication. The V2X terminals may transmit and receive data and control information for V2X communication through a sidelink (SL).

<FIG> illustrates a case in which UE-<NUM><NUM> among the V2X terminals <NUM> and <NUM> is located within coverage area <NUM> of the BS <NUM> and UE-<NUM><NUM> is located outside the coverage area <NUM> of the BS <NUM>. The example of <FIG> may be an example related to partial coverage area.

UE-<NUM><NUM> located within the coverage area of the BS <NUM> may receive data and control information from the BS <NUM> through a downlink (DL) and transmit data and control information to the BS <NUM> through an uplink (UL).

UE-<NUM><NUM> located outside the coverage area <NUM> of the BS <NUM> cannot receive data or control information from the BS <NUM> through the downlink and cannot transmit data or control information to the BS <NUM> through the uplink.

UE-<NUM><NUM> may transmit/receive data and control information for V2X communication to/from UE-<NUM><NUM> through a sidelink.

<FIG> illustrates a case in which V2X terminals <NUM> and <NUM> are located outside the coverage area <NUM> of the BS <NUM>.

Accordingly, UE-<NUM><NUM> and UE-<NUM><NUM> cannot receive data or control information from the BS <NUM> through the downlink and cannot transmit data or control information to the BS <NUM> through the uplink.

UE-<NUM><NUM> and UE-<NUM><NUM> may transmit/receive data and control information for V2X communication through the sidelink.

<FIG> illustrates a scenario in which terminals <NUM> and <NUM> located in different cells <NUM> and <NUM> perform V2X communication. Specifically, <FIG> illustrates a state in which a V2X transmission UE and a V2X reception UE access different BSs, that is, an Radio Resource Control (RRC)-connected state, or a state in which the terminals camp on the BSs, that is, an RRC connection-released state (RRC idle state). UE-<NUM><NUM> may be the V2X transmission UE, and UE-<NUM><NUM> may be the V2X reception UE. Alternatively, UE-<NUM><NUM> may be the V2X reception UE, and UE-<NUM><NUM> may be the V2X transmission UE. UE-<NUM><NUM> may receive a V2X-dedicated System Information Block (SIB) from the BS <NUM> which UE-<NUM><NUM> accesses or on which UE-<NUM><NUM> camps, and UE-<NUM><NUM> may receive a V2X-dedicated SIB from the other BS <NUM> which UE-<NUM><NUM> accesses or on which UE-<NUM><NUM> camps. Information on the V2X-dedicated SIB received by UE-<NUM><NUM> and information on the V2X-dedicated SIB received by UE-<NUM><NUM> may be different from each other. Accordingly, for V2X communication between the terminals <NUM> and <NUM> located in different cells <NUM> and <NUM>, the information is required to be unified.

Although <FIG> illustrate the V2X system including two terminals (UE-<NUM> and UE-<NUM>) for convenience of description, the disclosure is not limited thereto. The downlink and uplink between the BS and the V2X UEs may be referred to as a Uu interface, and the sidelink between the V2X UEs may be referred to as a PC5 interface. Accordingly, the terms may be interchangeably used in the disclosure.

Meanwhile, in the disclosure, the UE may be a vehicle supporting Vehicle-to-Vehicle (V2V) communication, a vehicle or a handset of a pedestrian, that is, a smartphone supporting Vehicle-to-Pedestrian (V2P) communication, a vehicle supporting Vehicle-to-Network (V2N) communication, or a vehicle supporting Vehicle-to-Infrastructure (V2I) communication. In the disclosure, the terminal may be a Road Side Unit (RSU) having a UE function, an RSU having a BS function, or an RSU having some of the BS function and some of the UE function.

In the disclosure, it is predefined that the BS is a BS supporting both the V2X communication and the general cellular communication or a BS supporting only the V2X communication. The BS may be a <NUM> BS (gNB), a <NUM> BS (eNB), or an RSU. Accordingly, unless specially mentioned, the BS and the RSU may be the same concept and thus interchangeably used.

<FIG> illustrates a wireless communication system according to an embodiment of the disclosure, and <FIG> illustrates a wireless communication system according to an embodiment of the disclosure. Specifically, <FIG> and <FIG> illustrate an example of a V2X communication method performed through a sidelink.

Referring to <FIG>, a transmission UE and a reception UE may communicate in one-to-one manner, which may be called unicast communication.

Referring to <FIG>, a transmission UE and a reception UE may communicate in a one-to-many manner, which may be called groupcast or multicast communication.

Referring to <FIG>, UE-<NUM><NUM>, UE-<NUM><NUM>, and UE-<NUM><NUM> form group A <NUM> to perform groupcast communication, and UE-<NUM><NUM>, UE-<NUM><NUM>, UE-<NUM><NUM>, and UE-<NUM><NUM> may form group B <NUM> to perform groupcast communication. Each UE may perform groupcast communication only within the group to which the UE belongs, and may perform unicast, groupcast, or broadcast communication with a terminal located within a different group. Although <FIG> illustrates that the two groups <NUM> and <NUM> are formed, the disclosure is not necessarily limited to the two groups.

Meanwhile, although not illustrated in <FIG> and <FIG>, the V2X UEs may perform broadcast communication. The broadcast communication is communication through which all V2X UEs receive data and control information transmitted by a V2X transmission UE through a sidelink. For example, when it is assumed that UE-<NUM><NUM> is a transmission UE for broadcast in <FIG>, all UEs, that is, UE-<NUM><NUM>, UE-<NUM><NUM>, UE-<NUM><NUM>, UE-<NUM><NUM>, UE-<NUM><NUM>, and UE-<NUM><NUM> may receive data and control information transmitted by UE-<NUM><NUM>.

<FIG> illustrates a configuration of a BS in a wireless communication system according to an embodiment of the disclosure. The configuration illustrated in <FIG> may be understood as the configuration of the BS <NUM> or <NUM>. The term "-unit" or "~er" used hereinafter may refer to the unit for processing at least one function or operation and may be implemented in hardware, software, or a combination of hardware and software.

Referring to <FIG>, the BS <NUM> or <NUM> includes a wireless communication unit <NUM>, a backhaul communication unit <NUM>, a storage unit <NUM>, and a controller <NUM>.

The wireless communication unit <NUM> performs functions for transmitting and receiving signals through a wireless channel. For example, the wireless communication unit <NUM> performs a function of conversion between a baseband signal and a bit stream according to a physical layer standard of the system. For example, in data transmission, the wireless communication unit <NUM> generates complex symbols by encoding and modulating a transmission bitstream. In data reception, the wireless communication unit <NUM> restores a reception bit stream by demodulating and decoding a baseband signal.

The wireless communication unit <NUM> up-converts a baseband signal into a RadioFrequency (RF) band signal and transmits the same through an antenna, and down-converts an RF band signal received through an antenna into a baseband signal. To this end, the wireless communication unit <NUM> may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a Digital-to-Analog Convertor (DAC), an Analog-to-Digital Convertor (ADC), and the like. Further, the wireless communication unit <NUM> may include a plurality of transmission/reception paths. In addition, the wireless communication unit <NUM> may include at least one antenna array consisting of a plurality of antenna elements.

On the hardware side, the wireless communication unit <NUM> may include a digital unit and an analog unit, and the analog unit may include a plurality of sub-units according to operation power, operation frequency, and the like. The digital unit may be implemented by, for example, a Digital Signal Processor (DSP).

The wireless communication unit <NUM> transmits and receives the signal as described above. Accordingly, all or some of the wireless communication unit <NUM> may be referred to as a "transmitter", a "receiver", or a "transceiver". In addition, the transmission and reception performed through a radio channel described in the following description may be understood to mean that the above-described processing is performed by the wireless communication unit <NUM>.

The backhaul communication unit <NUM> provides an interface for performing communication with other nodes within the network. That is, the backhaul communication unit <NUM> converts a bit stream transmitted from the base station to another node, for example, another access node, another base station, a higher node, or a core network, into a physical signal, and converts a physical signal received from another node into a bit stream.

The storage unit <NUM> stores data, such as a basic program, an application, or configuration information for the operation of the BS <NUM> or <NUM>. The storage unit <NUM> may be configured as volatile memory, nonvolatile memory, or a combination of volatile memory and nonvolatile memory. Further, the storage unit <NUM> provides stored data in response to a request from the controller <NUM>.

The controller <NUM> controls the overall operation of the BS <NUM> or <NUM>. For example, the controller <NUM> transmits and receives a signal through the wireless communication unit <NUM> or the backhaul communication unit <NUM>. Further, the controller <NUM> records data in the storage unit <NUM> and reads the recorded data. The controller <NUM> may perform the functions of a required protocol stack according to communication standards. According to another implementation, the protocol stack may be included in the wireless communication unit <NUM>. To this end, the controller <NUM> may include at least one processor. The controller <NUM> may be functionally connected to the wireless communication unit <NUM>, the backhaul communication unit <NUM>, and the storage unit <NUM> of the BS <NUM> or <NUM> and may be configured to perform the operation method of the BS <NUM> or <NUM> according to various embodiments.

<FIG> illustrates a configuration of a UE in a wireless communication system according to an embodiment of the disclosure. <FIG> may be understood as the configuration of the UE <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>. The term "-unit" or "~er" used hereinafter may refer to the unit for processing at least one function or operation and may be implemented in hardware, software, or a combination of hardware and software.

Referring to <FIG>, the UE <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> includes a communication unit <NUM>, a storage unit <NUM>, and a controller <NUM>.

The communication unit <NUM> performs functions for transmitting/receiving a signal through a wireless channel. For example, the communication unit <NUM> performs a function of conversion between a baseband signal and a bit stream according to a physical layer standard of the system. For example, in data transmission, the communication unit <NUM> generates complex symbols by encoding and modulating a transmission bit stream. In data reception, the communication unit <NUM> restores a reception bit stream by demodulating and decoding a baseband signal. Further, the communication unit <NUM> up-converts a baseband signal to an RF band signal, transmits the RF band signal through an antenna, and then down-converts the RF band signal received through the antenna to the baseband signal. For example, the communication unit <NUM> may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, and the like.

Further, the communication unit <NUM> may include a plurality of transmission/ reception paths. In addition, the communication unit <NUM> may include at least one antenna array consisting of a plurality of antenna elements. On the hardware side, the communication unit <NUM> may include a digital circuit and an analog circuit (for example, a radio frequency integrated circuit (RFIC)). The digital circuit and the analog circuit may be implemented as a single package. The communication unit <NUM> may include a plurality of RF chains. The communication unit <NUM> may perform beamforming.

In addition, the communication unit <NUM> may include a plurality of communication modules for supporting a plurality of different radio access technologies. For example, the different radio access technologies may include Bluetooth Low Energy (BLE), wireless fidelity (Wi-Fi), Wi-Fi Gigabyte (WiGig), and cellular network, for example, Long-Term Evolution (LTE) or <NUM> NR. Further, different frequency bands may include a Super High Frequency (SHF), for example, bands from <NUM> to <NUM> and an millimeter (mm) wave, for example, a band of <NUM>.

The communication unit <NUM> transmits and receives the signal as described above. Accordingly, all or some of the communication unit <NUM> may be referred to as a "transmitter", a "receiver", or a "transceiver". In addition, transmission and reception performed through a wireless channel, which is described in the following descriptions, may be understood to mean that the above-described processing is performed by the communication unit <NUM>.

The storage unit <NUM> stores data, such as a basic program, an application, and configuration information for the operation of the UE <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>. The storage unit <NUM> may be configured as volatile memory, nonvolatile memory, or a combination of volatile memory and nonvolatile memory. Further, the storage unit <NUM> provides stored data in response to a request from the controller <NUM>.

The controller <NUM> controls the overall operation of the UE <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>. For example, the controller <NUM> transmits and receives a signal through the communication unit <NUM>. Further, the controller <NUM> records data in the storage unit <NUM> and reads the recorded data. The controller <NUM> may perform protocol stack functions required by the communication standards. To this end, the controller <NUM> may include at least one processor or microprocessor, or may play the part of the processor. Further, the part of the communication unit <NUM> or the controller <NUM> may be referred to as a Communication Processor (CP). The controller <NUM> may be functionally connected to the communication unit <NUM> and the storage unit <NUM> of the UE <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> and may be configured to perform the operation method of the UE <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> according to various embodiments.

<FIG> is a flowchart illustrating an operation of a UE in a wireless communication system according to an embodiment of the disclosure.

Referring to <FIG>, the UE acquires at least one of a transmitter ID (source identifier), a destination ID, and a cell ID in operation S401. The destination ID may be one of a unicast destination ID, a groupcast destination ID, and a broadcast destination ID. According to an embodiment of the disclosure, the UE may acquire information on the transmitter ID and the destination ID through a service search process performed in an application layer. According to an embodiment of the disclosure, when the UE and another UE, which performs V2X communication with the UE, are all in the coverage area of the same BS, the UE and the other UE may acquire a cell ID from the corresponding BS. According to an embodiment of the disclosure, when the UE and the other UE performing V2X communication with the UE are all outside the coverage area of the BS, the UE and the other UE may acquire a predefined cell ID or a preconfigured cell ID. The predefined cell ID or the preconfigured cell ID may be a specific cell ID which the UE and the other UE has already known before V2X communication. According to an embodiment of the disclosure, when the UE and the other UE performing V2X communication with the UE are within the coverage area of different BSs, the UE and the other UE may acquire predefined cell IDs or preconfigured cell IDs. At this time, information on the cell IDs of different BSs may be exchanged.

In operation S402, the UE generates Sidelink Feedback Control Information (SFCI) to be transmitted through a sidelink feedback channel (Physical Sidelink Feedback Channel (PSFCH)). According to an embodiment of the disclosure, the UE may generate an SFCI to be transmitted through a PSFCH by a configuration or an indication from the BS or another UE performing V2X communication with the UE. For example, the UE may receive a configuration or indication indicating whether only NACK information should be transmitted or each of ACK and NACK information should be transmitted.

In operation S403, the UE performs channel encoding and scrambling for the SFCI based on at least one of the transmitter ID, the destination ID, and the cell ID. According to an embodiment of the disclosure, a scrambling sequence generator used for scrambling may be initialized based on at least one of the transmitter ID, the destination ID, and the cell ID. According to an embodiment of the disclosure, the PSFCH may include one or more Orthogonal Frequency Division Multiplexing (OFDM) symbols. According to an embodiment of the disclosure, the PSFCH may have one or more formats, and respective formats may use different signal processing methods. According to an embodiment of the disclosure, the PSFCH may have one or more formats having different signal processing methods according to the number of bits of the SFCI, and may include one or more OFDM symbols. According to an embodiment of the disclosure, the PSFCH may alternately include an OFDM symbol in which a Demodulation Reference Signal (DMRS) exists and an OFDM symbol in which no DMRS exists. According to an embodiment of the disclosure, locations of Resource Elements (REs) for transmitting the DMRS are different in OFDM symbols included in the PSFCH.

In operation S404, the UE transmits the SFCI through the PSFCH. According to an embodiment of the disclosure, transmission of the SFCI may be performed through one of unicast, groupcast, and broadcast schemes. At this time, resources of the PSFCH may include not only resources distinguished in time or/and frequency domains but also resources distinguished using code, such as scrambling code or orthogonal cover code, and resources distinguished using different sequences and cyclic shift applied to the sequence.

<FIG> illustrates a UE protocol for V2X communication in a wireless communication system according to an embodiment of the disclosure. Specifically, <FIG> illustrates an example of the UE protocol for V2X communication according to various embodiments.

Although not illustrated in <FIG>, application layers of UE-A <NUM> and UE-B <NUM> may perform service discovery. The service discovery may include discovery indicating a V2X communication scheme, that is, a communication scheme to be performed by each UE among unicast, groupcast, and broadcast communication schemes.

Referring to <FIG>, it may be assumed that UE-A <NUM> and UE-B <NUM> recognize that the unicast communication scheme will be performed via a service discovery process performed on the application layers. NR V2X UEs may acquire information on a transmitter ID (source identifier) and a destination ID (identifier) for NR V2X communication through the service discovery process.

When the service discovery process is completed, a direct link setup procedure between UEs may be performed in PC5 signaling protocol layers illustrated in <FIG>. At this time, security setup information for direct communication between UEs may be exchanged.

When the direct link setup is completed, a PC5 RRC configuration procedure between UEs may be performed in the PC5 RRC layers of <FIG>. At this time, UE capability information of UE-A <NUM> and UE-B <NUM> may be exchanged, and Access Stratum (AS) layer parameter information for unicast communication may be exchanged.

When the PC5 Radio Resource Control (RRC) configuration procedure is completed, UE-A <NUM> and UE-B <NUM> may perform unicast communication.

Although the unicast communication is described as an example, the groupcast communication may be applied. For example, when UE-A <NUM>, UE-B <NUM>, and UE-C, which is not illustrated in <FIG>, perform groupcast communication, the service discovery, direct link setup, and PC5 RRC configuration procedures between UE-A <NUM> and UE-B <NUM> may be performed between UE-B <NUM> and UE-C and between UE-A <NUM> and UE-C.

<FIG> is a signal flowchart illustrating a V2X communication process in a wireless communication system according to an embodiment of the disclosure. Specifically, <FIG> illustrates an example of a V2X communication procedure according to an embodiment of the disclosure.

Referring to <FIG>, a BS <NUM> may configure a parameter for V2X communication in V2X UEs <NUM> and <NUM> through system information in operation S601. For example, the BS <NUM> may configure information on a resource pool through which V2X communication can be performed in its own cell. The resource pool may be referred to as a transmission resource pool for V2X transmission or a reception resource pool for V2X reception. The V2X UEs <NUM> and <NUM> may receive a configuration of information on one or more resource pools from the BS <NUM>. The BS <NUM> may configure unicast, groupcast, and broadcast communication to be performed in different resource pools through system information. For example, resource pool <NUM> may be used for unicast communication, resource pool <NUM> may be used for groupcast communication, and resource pool <NUM> may be used for broadcast communication. In another example, the BS <NUM> may configure unicast, groupcast, and broadcast communication to be performed within the same resource pool. The resource pool information configured by the BS <NUM> may include at least one piece of the following information.

Although the above-described information is included in the configuration of the resource pool for V2X communication, the disclosure is not limited thereto. For example, the information may be configured in the V2X transmission UE <NUM> or the V2X reception UE <NUM> independently from the configuration of the resource pool.

Referring to <FIG>, when the V2X transmission UE <NUM> has data to be transmitted to the V2X reception UE <NUM> in operation S602, the V2X transmission UE <NUM> may make a request for sidelink resources to be transmitted to the V2X reception UE <NUM> to the BS <NUM> through a Scheduling Request (SR) or/and a Buffer Status Report (BSR). The BS <NUM> receiving the BSR may identify that the V2X transmission UE <NUM> has data for sidelink transmission and determine resources required for sidelink transmission based on the BSR.

The BS <NUM> may transmit a sidelink scheduling grant including at least one piece of resource information for Sidelink Control Information (SCI) transmission, resource information for sidelink data transmission, and resource information for sidelink feedback information to the V2X transmission UE <NUM> in operation S604. The sidelink scheduling grant is information for granting dynamic scheduling in the sidelink and may be Downlink Control Information (DCI) transmitted through a Physical Downlink Control Channel (PDCCH). The sidelink scheduling grant may include information indicating a bandwidth part (BWP) in which sidelink transmission is performed, a Carrier Indicator Field (CIF) for sidelink transmission, or a carrier frequency indicator when the BS <NUM> is an NR BS, and may include only a CIF when the BS is an LTE BS. Further, the sidelink scheduling grant may further include feedback information of the sidelink data, that is, resource allocation-related information of the PSFCH in which ACK/NACK information is transmitted. When the sidelink transmission corresponds to groupcast, the resource allocation information may include information for allocating a plurality of PSFCH resources to a plurality of UEs within a group. The resource allocation-related information of the feedback information may be information indicating at least one of a plurality of feedback information resource candidate sets configured through higher-layer signaling.

The V2X transmission UE <NUM> receiving the sidelink scheduling grant transmits SCI for scheduling sidelink data according to the sidelink scheduling grant to the V2X reception UE <NUM> through a Physical Sidelink Control Channel (PSCCH) and transmits the sidelink data through a Physical Sidelink Shared Channel (PSSCH) in operation S605. The SCI may include at least one of resource allocation information used for sidelink data transmission, Modulation and Coding Scheme (MCS) information applied to sidelink data, group destination ID information, transmitter ID (source ID) information, unicast destination ID information, power control information for controlling sidelink power, Timing Advance (TA) information, DMRS configuration information for sidelink transmission, packet-repeated transmission-related information, for example, information on the number of packet-repeated transmissions, information on resource allocation when packets are repeatedly transmitted, a Redundancy Version (RV), and an HARQ process ID. The SCI may further include feedback information for sidelink data, that is, information indicating resources through which ACK/NACK information is transmitted.

The V2X reception UE <NUM> receiving the SCI receives sidelink data. Thereafter, the V2X reception UE <NUM> transmits ACK/NACK information indicating whether decoding of the sidelink data is succeeded or failed to the V2X transmission UE <NUM> through a Physical Sidelink Feedback Channel (PSFCH) in operation S606. Transmission of sidelink feedback information may be applied to unicast transmission or groupcast transmission, but the case of broadcast transmission is not excluded. When sidelink transmission corresponds to groupcast transmission, respective UEs receiving groupcast data may transmit feedback information through different PSFCH resources. Alternatively, respective UEs receiving groupcast data may transmit feedback information through the same PSFCH resources, in which case only NACK information may be fed back. For example, the UE receiving data does not perform feedback in the case of ACK. At this time, PSFCH resources may include not only resources distinguished in time or/and frequency domains but also resources distinguished using code, such as scrambling code or orthogonal cover code, and resources distinguished using different sequences and cyclic shift applied to the sequence.

<FIG> illustrates a scenario in which the V2X transmission UE <NUM> configures an uplink connection with the BS <NUM>, that is, an RRC-connected state and both the V2X transmission UE <NUM> and the V2X reception UE <NUM> exist within the coverage area of the BS <NUM>. Although not illustrated in <FIG>, when the V2X transmission UE <NUM> has not configured the uplink connection with the BS <NUM>, that is, in an RRC-idle state, the V2X transmission UE <NUM> may perform a random access procedure for configuring the uplink connection with the BS <NUM>. Although not illustrated in <FIG>, the V2X reception UE <NUM> may receive in advance the configuration of information for V2X communication in the scenario in which the V2X transmission UE <NUM> exists within the coverage area of the BS <NUM> and the V2X reception UE <NUM> exists outside the coverage area of the BS <NUM>. Meanwhile, the V2X transmission UE <NUM> may receive the configuration of information for V2X communication from the BS <NUM> as illustrated in <FIG>. When both the V2X transmission UE <NUM> and the V2X reception UE <NUM> exist outside the coverage area of the BS <NUM>, the V2X transmission UE <NUM> and the V2X reception UE <NUM> may receive in advance and use the configuration of information of V2X communication. At this time, receiving in advance the configuration may be interpreted as using a value included in the UE when the UE is released. Alternatively, it may mean the most recently acquired information when the V2X transmission UE <NUM> or the V2X reception UE <NUM> has accessed the BS <NUM> and previously acquired the information on V2X communication through an RRC configuration or has acquired the information on V2X communication through system information of the BS <NUM>.

Although not illustrated in <FIG>, it may be assumed that the V2X transmission UE <NUM> completes the service discovery, the direct link setup procedure, and the PC5 RRC configuration with the V2X reception UE <NUM> through the procedure illustrated in <FIG> before transmitting the SR/BSR to the BS <NUM>.

<FIG> illustrates a process in which a V2X UE transmits a sidelink feedback channel in a wireless communication system according to an embodiment of the disclosure. Specifically, <FIG> illustrates an example of a signal processing method by which the V2X UE transmits a sidelink feedback channel according to an embodiment.

Referring to <FIG>, the NR V2X reception UE may acquire parameters for sidelink feedback channel transmission through at least one of the following methods in operation S701.

In operation S702, the NR V2X reception UE may generate SFCI information transmitted through the PSFCH by a configuration or an indication of the BS or the NR V2X transmission UE.

In operation S703, the NR V2X reception UE may encode a channel using the SFCI information generated in operation S702, that is, a bit sequence. At this time, different channel encoding schemes may be applied according to the length of the generated bit sequence.

In operation S704, the NR V2X reception UE may scramble the bit sequence acquired through the channel encoding in operation S703.

In Equation <NUM>, the scrambling sequence c(i) is a pseudo-random sequence and may correspond to a gold sequence having a length of <NUM>. A scrambling sequence generator of c(i) used in Equation <NUM> may be initialized by Equation <NUM>.

In Equation <NUM>, there may be various combinations depending on α,β,γ, A, and B, and α,β,γ, A, and B may be determined by at least one of a transmitter ID (source ID), a destination ID, and a cell ID. It may be assumed that the transmission ID (source ID) includes [s] bits, the destination ID includes [d] bits, and the cell ID includes [c] bits. When both the NR V2X transmission UE and reception UE exist in the coverage area of the same BS, the NR V2X transmission UE and reception UE may acquire a cell ID used in Equation <NUM> from the corresponding BS. In another example, the NR V2X transmission UE and reception UE may always use the fixed cell ID for Equation <NUM>. For example, the cell ID = <NUM> or the cell ID = <NUM>. Meanwhile, the NR V2X transmission UE may acquire destination ID information of the UE which the NR V2X transmission UE desires to transmit from higher layer, for example, an application layer or an L2 layer through at least one of the service discovery process, the direct link setup process, or the PC5 RRC configuration process for unicast or groupcast communication as described with reference to <FIG>. Further, the NR V2X transmission UE may acquire information on the transmitter ID (source ID) of the NR V2X transmission UE from a higher layer thereof. Equation <NUM> may include the case in which both A and B are <NUM> and one of A and B is <NUM>. In Equation <NUM>, β may be influenced by γ, and α may be influenced by B and β. For example, as described above, when the cell ID = <NUM> is used as γ, γ may become <NUM> through binary conversion. In this case, β=<NUM>. When it is assumed that B = <NUM>, α= <NUM>. However, this is only an example, but is not limited thereto. For example, similar to the example, β= <NUM> even though the cell ID = <NUM> is used as γ.

The NR V2X transmission UE may transmit information on a transmitter ID (source ID) or a destination ID, used by the NR V2X transmission UE, to the NR V2X reception UE through at least one of the following methods.

(<NUM>-<NUM>) The V2X reception UE acquiring information on the transmitter ID (source ID) and the destination ID transmitted through SCI of the PSCCH may determine whether the destination ID included in the SCI corresponds to the V2X reception UE itself. When the destination ID corresponds to the V2X reception UE itself, that is, when the destination ID transmitted by the V2X transmission UE is the same as the destination ID received form a higher layer of the V2X reception UE, the V2X reception UE may decode the PSSCH through resource allocation information of the PSSCH included in the SCI. When the V2X reception UE successfully decodes the PSSCH, the V2X reception UE may transmit ACK information to the V2X transmission UE through the PSFCH. When the V2X reception UE fails in decoding the PSSCH, the V2X reception UE may transmit NACK information to the V2X transmission UE through the PSFCH. The PSFCH may be scrambled through initialization of the scrambling sequence generator as shown in Equation <NUM> based on at least one of the transmitter ID (source ID), the destination ID, and the cell ID acquired by the V2X UE through method <NUM>) and the above-described method.

(<NUM>-<NUM>) When the destination ID transmitted through the SCI does not correspond to the V2X reception UE in the above example, the V2X reception UE may delete the corresponding SCI from its own buffer and may not decode the PSSCH.

(<NUM>-<NUM>) The remaining bits of the destination ID may be transmitted through a MAC header transmitted through the PSSCH or a MAC PDU. For example, MSB or LSB [d1] bits of the [d] bits of the destination ID may be transmitted through the PSCCH, and the remaining [d2] bits may be transmitted through the MAC header transmitted through the PSSCH or the MAC PDU ([d1] + [d2] = [d]).

(<NUM>-<NUM>) The V2X reception UE acquiring information on the transmitter ID (source ID) and the destination ID transmitted through SCI of the PSCCH may determine whether the [d1] bits of the destination ID included in the SCI corresponds to the V2X reception UE itself. When the destination ID corresponds to the V2X reception UE itself, the V2X reception UE may decode the PSSCH through resource allocation information of the PSSCH included in the SCI. When the V2X reception UE successfully decodes the PSSCH, the V2X reception UE may generate the destination ID of [d] bits through the remaining bits of the destination ID transmitted through the PSSCH, that is, [d1] bits and [d2] bits of destination ID received through the SCI. The V2X reception UE may compare the generated destination ID with the destination ID received from a higher layer of the V2X reception UE and finally identify whether the corresponding PSSCH is sidelink data to be received by the V2X reception UE. When it is recognized that the corresponding PSSCH is sidelink data to be received by the V2X reception UE through the final identification, the V2X reception UE may transfer the decoding result to the higher layer. When it is recognized that the corresponding PSSCH is not sidelink data to be received by the V2X reception UE through the final identification, the V2X reception UE may delete the decoding result from its own buffer without transferring the same to the higher layer.

(<NUM>-<NUM>) Meanwhile, the V2X reception UE successfully decoding the PSSCH and identifying that the corresponding PSSCH is sidelink data to be received by the V2X reception UE may transmit ACK information to the V2X transmission UE through the PSFCH. When the V2X reception UE fails in decoding the PSSCH, the V2X reception UE may transmit NACK information to the V2X transmission UE through the PSFCH. At this time, the V2X reception UE may initialize the scrambling sequence generator and perform scrambling as shown in Equation <NUM> based on at least one of the transmitter ID (source ID), the destination ID, and the cell ID acquired through method <NUM>) and the above-described method.

(<NUM>-<NUM>) The remaining bits of the transmitter ID may be transmitted through a Medium Access Control (MAC) header transmitted through the PSSCH or a MAC Protocol Data Unit (PDU). For example, most significant bits (MSB) or least significant bits (LSB) [s1] bits of the [s] bits of the transmitter ID (source ID) may be transmitted through the PSCCH, and the remaining [s2] bits may be transmitted through the MAC header transmitted through the PSSCH or the MAC PDU ([s1] + [s2] = [s]).

(<NUM>) Method <NUM>) some of the bits of the transmitter ID (source ID) and some of the bits of the destination ID are transmitted through the PSCCH. The remaining bits of the transmitter ID (source ID) and the destination ID may be transmitted through a MAC header transmitted through the PSSCH or a MAC PDU.

(<NUM>-<NUM>) The remaining bits of the transmitter ID may be transmitted through a MAC header transmitted through the PSSCH or a MAC PDU. For example, MSB or LSB [s1] bits of the [s] bits of the transmitter ID (source ID) may be transmitted through the PSCCH, and the remaining [s2] bits may be transmitted through the Medium Access Control (MAC) header transmitted through the PSSCH or the MAC Protocol Data Unit (PDU) ([s1] + [s2] = [s]).

(<NUM>-<NUM>) The remaining bits of the destination ID may be transmitted the MAC header transmitted through the PSSCH or the MAC PDU. For example, MSB or LSB [d1] bits of the [d] bits of the destination ID may be transmitted through the PSCCH, and the remaining [d2] bits may be transmitted through the MAC header transmitted through the PSSCH or the MAC PDU ([d1] + [d2] = [d]).

(<NUM>-<NUM>) The V2X reception UE acquiring information on the transmitter ID (source ID) and the destination ID transmitted through SCI of the PSCCH may determine whether the [d1] bits of the destination ID included in the SCI corresponds to the V2X reception UE itself. When the destination ID corresponds to the V2X reception UE itself, the V2X reception UE may decode the PSSCH through resource allocation information of the PSSCH included in the SCI. When the V2X reception UE successfully decodes the PSSCH, the V2X reception UE may generate the destination ID of [d] bits through the remaining bits of the destination ID transmitted through the PSSCH (that is, [d2] bits) and [d1] bits of destination ID received through the SCI. The V2X reception UE may compare the generated destination ID with the destination ID received from a higher layer of the V2X reception UE and finally identify whether the corresponding PSSCH is sidelink data to be received by the V2X reception UE. When it is recognized that the corresponding PSSCH is sidelink data to be received by the V2X reception UE through the final identification, the V2X reception UE may transfer the decoding result to the higher layer. When it is recognized that the corresponding PSSCH is not sidelink data to be received by the V2X reception UE through the final identification, the V2X reception UE may delete the decoding result from its own buffer without transferring the same to the higher layer.

In operation S705, the scrambled sequence may be quadrature phase shift keying (QPSK)-modulated.

In operation S706, the QPSK-modulated symbols may be mapped to frequency resources (resource element (RE)) which are physical resources of the PSFCH. At this time, a Demodulation Reference Signal (DMRS) may be added to the PSFCH, and the QPSK-modulated symbols may be mapped to the remaining frequency resources except for the frequency resources of the PSFCH in which the DMRS is transmitted.

Although not illustrated in <FIG>, after operation S706, OFDM symbols may be generated through Inverse Fast Fourier Transform (IFFT), a Cyclic Prefix (CP) may be added to the OFDM symbols, and the OFDM symbols may be transmitted through an antenna.

Although the above example has been described based on unicast communication in which the number of NR V2X reception UEs is one, the disclosure may also be applied to groupcast communication in which the number of NR V2X reception UEs is two or more.

Referring to <FIG>, in operation S801, the NR V2X reception UE may acquire parameters for sidelink feedback channel transmission through at least one of the methods described in operation S701 of <FIG>. Information on the parameters for sidelink feedback channel transmission may include at least one piece of the PSFCH-related information described in <FIG>, the PSFCH-related information described in operation S701 of <FIG>, and the following information.

In operation S802, the NR V2X reception UE may generate SFCI information transmitted through the PSFCH by a configuration or an indication of the BS or the NR V2X transmission UE.

In operation S803, the sequence may be generated using the SFCI information generated in operation S802 and one of the methods described in operation S801.

In operation S804, the generated sequence may be mapped to frequency resources (resource element (RE)) which are physical resources of the PSFCH. Unlike operation S706 of <FIG>, no DMRS may be added.

Although not illustrated in <FIG>, after operation S804, OFDM symbols may be generated through Inverse Fast Fourier Transform (IFFT), a Cyclic Prefix (CP) may be added to the OFDM symbols, and the OFDM symbols may be transmitted through an antenna.

<FIG> illustrates a process in which a V2X UE transmits a sidelink feedback channel in a wireless communication system according to an embodiment of the disclosure. Specifically, <FIG> illustrates another example of the signal processing method by which the V2X UE transmits the sidelink feedback channel according to an embodiment.

Referring to <FIG>, in operation S901, the NR V2X reception UE may acquire parameters for sidelink feedback channel transmission through at least one of the methods described in operation S701 of <FIG>. Information on the parameters for sidelink feedback channel transmission may include at least one piece of the PSFCH-related information described in <FIG>, the PSFCH-related information described in operation S701 of <FIG>, and the PSFCH-related information described in operation S801 of <FIG>.

In operation S902, the NR V2X reception UE may generate SFCI information transmitted through the PSFCH by a configuration or an indication of the BS or the NR V2X transmission UE. At this time, as described in operation S702 of <FIG>, whether only NACK information should be transmitted or ACK information and NACK information should be separately transmitted may be configured or indicated.

In operation S903, binary phase shift keying (BPSK) or QPSK modulation may be performed using the SFCI information generated in operation S902.

In operation S904, the BPSK or QPSK-modulated SFCI information in operation S903 may be sequence-modulated using at least one of the following methods.

In operation S905, the generated sequence may be mapped to frequency resources (resource element (RE)) which are physical resources of the PSFCH. Unlike operation S706 of <FIG>, no DMRS may be added.

Although not illustrated in <FIG>, after operation S905, OFDM symbols may be generated through Inverse Fast Fourier Transform (IFFT), a Cyclic Prefix (CP) may be added to the OFDM symbols, and the OFDM symbols may be transmitted through an antenna.

Although the above example has been described based on unicast communication in which the number of NR V2X reception UEs is one, the disclosure may be applied to groupcast communication in which the number of NR V2X reception UEs is two or more.

<FIG> illustrates sidelink resources through which a V2X UE performs V2X communication in a wireless communication system according to an embodiment of the disclosure. <FIG> illustrates an example of sidelink resources through which the V2X UE performs V2X communication according to an embodiment.

Referring to <FIG>, sidelink resources <NUM> may include K symbols <NUM> in the time axis and M Resource Blocks (RBs) <NUM> in the frequency axis. One resource block <NUM> may consist of <NUM> subcarriers. K symbols <NUM> may be consecutive in the time axis physically or logically. When the K symbols are consecutive logically, the K symbols are non-consecutive physically. Similarly, M resource blocks <NUM> may be consecutive in the frequency axis physically or logically. When the K symbols are consecutive logically, the K symbols are non-consecutive physically.

Although not illustrated in <FIG>, the V2X transmission UE may use some or all of the sidelink resources <NUM> of <FIG> to transmit sidelink control information or data information. The V2X reception UE may use some or all of the sidelink resources <NUM> of <FIG> to receive sidelink control information or data information.

In another example, the V2X reception UE may use some or all of the sidelink resources <NUM> of <FIG> to transmit sidelink feedback information to the V2X transmission UE. In <FIG>, K and M may be the same or may vary depending on the time point at which sidelink control information or data information is transmitted. For example, K and M at the time point of T1 at which the V2X transmission UE transmits sidelink control information or sidelink data information may be the same as or different from K and M at the time point of T2 at which sidelink control information or sidelink data information is transmitted.

Similarly, referring to <FIG>, K and M may be the same or may vary depending on the time point at which the V2X reception UE receives sidelink control information or data information. For example, K and M at the time point of T1 at which the V2X reception UE receives sidelink control information or sidelink data information may be the same as or different from K and M at the time point of T2 at which sidelink control information or sidelink data information is received.

Referring to <FIG>, K and M may be the same or may vary depending on the time point at which the V2X reception UE transmits sidelink feedback information to the V2X transmission UE. For example, K and M at the time point of T1 at which the V2X reception UE transmits sidelink feedback information to the V2X transmission UE may be the same as or different from K and M at the time point of T2 at which the sidelink feedback information is transmitted to the V2X transmission UE.

<FIG> illustrates a multiplexing scheme of a sidelink control channel, a sidelink data channel, and a sidelink feedback channel within sidelink resources in a wireless communication system according to an embodiment of the disclosure. Specifically, <FIG> illustrates an example of a multiplexing scheme of a sidelink control channel, a sidelink data channel, and a sidelink feedback channel within sidelink resources according to an embodiment.

Referring to <FIG>, a sidelink control channel (Physical Sidelink Control Channel (PSCCH)) <NUM> and a sidelink data channel (Physical Sidelink Shared Channel (PSSCH)) <NUM> may be multiplexed in the time axis and the frequency axis. For example, Time Division Multiplexing (TDM) and Frequency Division Multiplexing (FDM) are shown.

The PSCCH <NUM> and the PSSCH <NUM> may include the different numbers of resource blocks in the frequency axis. For example, in the frequency axis, the PSCCH <NUM> may include N1 frequency blocks <NUM> and the PSSCH <NUM> may include M frequency blocks <NUM>. N1 may be smaller than M (N1 < M). However, the case in which the PSCCH <NUM> and the PSSCH <NUM> have the same number of resource blocks (M RBs) in the frequency axis is not excluded. The PSCCH <NUM> and the PSSCH <NUM> may be frequency-division-multiplexed in K1 symbols <NUM> of the time axis, and only the PSSCH may be transmitted in the remaining K2 symbols <NUM> without transmission of the PSCCH. For example, the PSCCH <NUM> may include N1 frequency blocks <NUM> in the frequency axis and K1 symbols <NUM> in the time axis. The PSSCH <NUM> may include N2 blocks <NUM> during the length of K1 symbols <NUM>, and the PSSCH <NUM> and the PSCCH <NUM> may be frequency-divided. The PSSCH may include M frequency blocks <NUM> during the length of K2 symbols <NUM> without frequency-division with the PSCCH <NUM>. A sum of N2 and N1 may be the same as or different from M.

Although <FIG> illustrates that N1 frequency blocks <NUM> included in the PSCCH <NUM> and the PSSCH <NUM> including (M-N2) frequency blocks are physically successively located, they are not physically successive. For example, they may be logically consecutive, but physically non-consecutive. Meanwhile, K1 and K2 may be the same as or different from each other. When K1 and K2 are different from each other, K1 > K2 or K1 < K2. The V2X transmission UE may insert time/frequency allocation information of the PSCCH <NUM> into sidelink control information transmitted through the PSCCH <NUM> and transmit the sidelink control information. V2X reception UE may receive and decode the PSCCH <NUM>, acquire time/frequency allocation information of the PSSCH <NUM>, and then decode the PSSCH <NUM>. Although <FIG> illustrates that the PSSCH <NUM> including K2 symbols is physically continuous to K1 symbols <NUM> included in the PSCCH <NUM>, the PSSCH <NUM> may not be physically consecutive. For example, they may be logically consecutive, but physically non-consecutive.

<FIG> illustrates the case in which a sidelink feedback channel (Physical Sidelink Feedback Channel (PSFCH)) exists within sidelink resources including K symbols <NUM>. In this case, the sidelink resources may include K1 symbols <NUM> of the PSCCH <NUM>, K2 symbols <NUM> of the PSSCH <NUM> ((K1 <NUM> + K2 <NUM>) symbols of the PSSCH <NUM> when only symbols which are not frequency-division-multiplexed with the PSCCH <NUM> and when FDM with the PSCCH <NUM> is considered), guard symbols #<NUM><NUM>, the PSFCH <NUM>, K symbols <NUM>, and guard symbols #<NUM><NUM>. For example, K1 <NUM> + K2 <NUM> + guard symbols #<NUM><NUM> + K2 <NUM> + guard symbols #<NUM><NUM> = K <NUM>. At this time, guard symbols #<NUM><NUM> and guard symbols #<NUM><NUM> may be one or more OFDM symbols. The guard symbols #<NUM><NUM> may be required for conversion between transmission and reception when the V2X transmission UE transmits the PSCCH <NUM> and the PSSCH <NUM> and receives the PSFCH <NUM>. On the other hand, a gap <NUM> of guard symbols #<NUM><NUM> may be required for conversion between reception and transmission when the V2X reception UE receives the PSCCH <NUM> and the PSSCH <NUM> and transmit the PSFCH <NUM>. Similarly, a gap <NUM> of guard symbols #<NUM><NUM> may be required for conversion between and reception and transmission when the V2X transmission UE receives the PSFCH <NUM> from the V2X reception UE and transmits the PSCCH <NUM> and the PSSCH <NUM> in the next sidelink resources. On the other hands, the gap <NUM> of guard symbols #<NUM><NUM> may be required for conversion between and transmission and reception when the V2X reception UE transmits the PSFCH <NUM> to the V2X transmission UE and receives the PSCCH <NUM> and the PSSCH <NUM> in the next sidelink resources.

Meanwhile, although not illustrated in <FIG>, one of guard symbols #<NUM><NUM> and guard symbols #<NUM><NUM> may be <NUM>. For example, when the V2X transmission UE receives the PSFCH <NUM> and receives the PSCCH <NUM> and the PSSCH <NUM> from another UE in the next sidelink resources, there is no need of conversion between reception and transmission, and thus the number of guard symbols #<NUM><NUM> may be <NUM>. The disclosure does not exclude the case in which at least one of K1 <NUM>, K2 <NUM>, and K3 <NUM> is <NUM>.

Although <FIG> illustrates that the size of frequency resource blocks of the PSFCH <NUM> is the same as the PSSCH <NUM> (that is, M RBs), the size of resource blocks of the PSFCH <NUM> in the frequency axis may be the same as or different from the size of resource blocks of the PSCCH <NUM> and the PSSCH <NUM>. The V2X reception UE may decode the PSSCH <NUM>, insert the result, that is, ACK/NACK information into the PSFCH <NUM>, and transmit the ACK/NACK information to the V2X transmission UE.

<FIG> illustrates a structure of a sidelink feedback channel in a wireless communication system according to an embodiment of the disclosure. Specifically, <FIG> illustrates an example of a structure of a sidelink feedback channel according to an embodiment.

Referring to <FIG>, the sidelink feedback channel (PSFCH) may be used to transmit SFCI information generated by the procedure of <FIG>. Although <FIG> illustrates that DMRS overhead is <NUM>/<NUM>, that is, <NUM> REs are used as DMRSs <NUM> in <NUM> Resource Elements (REs) <NUM>, the disclosure is not limited thereto. For example, when DMRS overhead is <NUM>/<NUM>, that is, when <NUM> REs are used as DMRSs <NUM> in <NUM> Resource Elements (REs) <NUM>, the DMRSs <NUM> may be mapped to RE index nos. <NUM>, <NUM>, and <NUM> (or <NUM>, <NUM>, and <NUM>), and SFCI may be mapped to the remaining RE indexes.

Although <FIG> illustrates the structure of the PSFCH in one RB including <NUM> REs <NUM>, the structure may be equally applied to the PSFCH including two or more RBs. For example, when it is assumed that two RBs correspond to the size of PSFCH frequency resources transmitted by one V2X reception UE, the DMRSs may be mapped to RE indexes <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>, and SFCI may be mapped to the remaining RE indexes.

When the PSFCH transmitted by one V2X reception UE includes two or more OFDM symbols in the time axis, the PSFCH <NUM> including <NUM> OFDM symbol may be repeated. For example, when the PSFCH includes two OFDM symbols as indicated by reference numeral <NUM> or when the PSFCH includes three OFDM symbols as indicated by reference numeral <NUM>, the PFSCH <NUM> including <NUM> OFDM symbol may be repeated as illustrated in <FIG>. Although not illustrated in <FIG>, expansion of the structure of the PSFCH including four or more OFDM symbols is possible based on such principle.

The PSFCH illustrated in <FIG> may be mapped to K3 symbols within the sidelink resources of <FIG>. Meanwhile, when SFCI information generated through the method of <FIG> is transmitted through the PSFCH, the SFCI information may be mapped to all REs of the PSFCH without any RE used for DMRS transmission in <FIG>. However, in this case, there is no DMRS, and thus channel estimation performance of the V2X transmission UE receiving the PSFCH may deteriorate. Accordingly, as illustrated in <FIG>, the SFCI information generated through the method of <FIG> may be mapped to only the remaining REs other than the REs used for DMRS transmission as illustrated in <FIG>.

Although <FIG> illustrates that the DMRSs <NUM> exist in the same REs <NUM> in the frequency axis even though the number of OFDM symbols increase, the disclosure is not limited thereto. For example, when the PSFCH <NUM> includes two OFDM symbols, the location of the DMRS RE in the second OFDM symbol may be different from the location of the DMRS RE existing in the first OFDM symbol. Similarly, when the PSFCH <NUM> includes three OFDM symbols, the location of the DMRS RE in each OFDM symbol may be different from each other. In another example, when the PSFCH <NUM> includes three or more OFDM symbols, the location of the DMSR RE in two or more OFDM symbols may be the same as each other.

<FIG> illustrates a structure of a sidelink feedback channel in a wireless communication system according to an embodiment of the disclosure. Specifically, <FIG> illustrates another example of the structure of the sidelink feedback channel according to an embodiment.

Referring to <FIG>, the sidelink feedback channel (PSFCH) may be used to transmit SFCI information generated by the procedure of <FIG>. Although <FIG> illustrates that DMRS overhead is <NUM>/<NUM>, that is, <NUM> REs are used as DMRSs <NUM> in <NUM> Resource Elements (REs) <NUM>, the disclosure is not limited thereto. For example, when DMRS overhead is <NUM>/<NUM>, that is, when <NUM> REs are used as DMRSs <NUM> in <NUM> Resource Elements (REs) <NUM>, the DMRSs may be mapped to RE index nos. <NUM>, <NUM>, and <NUM> (or <NUM>, <NUM>, and <NUM>), and SFCI may be mapped to the remaining RE indexes.

Although <FIG> illustrates the structure of the PSFCH <NUM> in one RB including <NUM> REs, the structure may be equally applied to the PSFCH <NUM> including two or more RBs. For example, when it is assumed that two RBs correspond to the size of PSFCH frequency resources transmitted by one V2X reception UE, the DMRSs may be mapped to RE indexes <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>, and SFCI may be mapped to the remaining RE indexes. Although not illustrated in <FIG>, expansion of the structure of the PSFCH including four or more OFDM symbols is possible based on such principle.

When the PSFCH transmitted by one V2X reception UE includes two or more OFDM symbols in the time axis, the PSFCH including <NUM> OFDM symbol is repeated in <FIG>. However, in <FIG>, the DMRS may exist only in an odd-numbered OFDM symbol but may not exist in an even-numbered OFDM symbol. For example, in <FIG>, the DMRS may exist only in first and third OFDM symbols but may not exist in a second OFDM symbol. Accordingly, in <FIG>, the PSFCH may alternately include an OFDM symbol in which the DMRS exists and an OFDM symbol in which no DMRS exists.

The PSFCH illustrated in <FIG> may be mapped to K3 symbols within the sidelink resources of <FIG>. Meanwhile, when SFCI information generated through the method of <FIG> is transmitted through the PSFCH, the SFCI information may be mapped to all REs of the PSFCH without the DMRS <NUM> in <FIG>. However, in this case, there is no DMRS, and thus channel estimation performance of the V2X transmission UE receiving the PSFCH may deteriorate. Accordingly, as illustrated in <FIG>, the SFCI information generated through the method of <FIG> may be mapped to only the remaining REs other than the REs used for transmission of the DMRS <NUM> as illustrated in <FIG>.

Although <FIG> illustrates that the DMRSs exist in the same REs in the frequency axis even though the number of OFDM symbols increase, the disclosure is not limited thereto. For example, when the PSFCH <NUM> includes three OFDM symbols, the location of the DMRS RE in the third OFDM symbol may be different from the location of the DMRS RE existing in the first OFDM symbol. Similarly, when the PSFCH includes four or more OFDM symbols, the location of the DMRS RE in each OFDM symbol in which the DMRS exists may be different from each other. In another example, when the PSFCH includes four or more OFDM symbols, the location of the DMSR RE in the OFDM symbols in which two or more DMRS exist may be the same as each other.

In addition, the programs may be stored in an attachable storage device which may access the electronic device through communication networks, such as the Internet, Intranet, Local Area Network (LAN), Wide LAN (WLAN), and Storage Area Network (SAN) or a combination thereof.

Claim 1:
A method performed by a first user equipment, UE, (<NUM>) for vehicle-to-everything, V2X, in a wireless communication system, the method comprising:
receiving (S601), from a base station, BS (<NUM>), configuration information for a sidelink, the configuration information comprising a resource pool;
transmitting (S605), to a second UE (<NUM>), sidelink control information, SCI, for scheduling a physical sidelink shared channel, PSSCH, based on the configuration information;
transmitting, to the second UE, a sidelink data on the PSSCH based on the SCI; and
receiving (S606), from the second UE, hybrid automatic repeat request-acknowledgement, HARQ-ACK, information for the sidelink data on a physical sidelink feedback channel, PSFCH,
wherein the SCI includes information on a resource assignment, information on a demodulation reference signal, and information on a modulation and coding scheme, MCS, and
wherein the configuration information includes a time gap between the PSFCH and the PSSCH, and wherein the time gap between the PSFCH and the PSSCH is in a unit of slots.