WO2024035189A1

WO2024035189A1 - Apparatus and method for transmitting and receiving sidelink based on unlicensed band in wireless communication system

Info

Publication number: WO2024035189A1
Application number: PCT/KR2023/011899
Authority: WO
Inventors: 박성진; 신철규; 류현석; 최승훈
Original assignee: 삼성전자 주식회사
Priority date: 2022-08-11
Filing date: 2023-08-11
Publication date: 2024-02-15
Also published as: KR20240022281A

Abstract

The present disclosure relates to 5G or 6G communication systems for supporting higher data rates. A method performed by a first terminal in a wireless communication system may comprise the steps of: receiving, from a base station, resource information of an unlicensed band for sidelink communication with a second terminal; identifying, with respect to the resource information of the unlicensed band, that a channel access procedure for at least one of transmission of PSCCH, transmission of PSSCH, or reception of PSFCH has failed; and transmitting, to the base station, information indicating failure of the channel access procedure.

Description

Apparatus and method for transmitting and receiving sidelink based on unlicensed band in wireless communication system

This disclosure relates to a wireless communication system (or mobile communication system), and specifically relates to an apparatus and method for controlling congestion in a wireless communication system (or mobile communication system).

5G mobile communication technology defines a wide frequency band to enable fast transmission speeds and new services, including sub-6 GHz ("Sub 6GHz") bands such as 3.5 GHz, as well as millimeter wave (mm) bands such as 28 GHz and 39 GHz. It is also possible to implement it in the ultra-high frequency band ("Above 6GHz") called Wave. In addition, in the case of 6G mobile communication technology, which is called the system of Beyond 5G, Terra is working to achieve a transmission speed that is 50 times faster than 5G mobile communication technology and an ultra-low delay time that is reduced to one-tenth. Implementation in Terahertz (THz) bands (e.g., 3 terahertz bands at 95 GHz) is being considered.

In the early days of 5G mobile communication technology, there were concerns about ultra-wideband services (enhanced Mobile BroadBand, eMBB), ultra-reliable low-latency communications (URLLC), and massive machine-type communications (mMTC). With the goal of satisfying service support and performance requirements, efficient use of ultra-high frequency resources, including beamforming and massive array multiple input/output (Massive MIMO) to alleviate radio wave path loss in ultra-high frequency bands and increase radio transmission distance. Various numerology support (multiple subcarrier interval operation, etc.) and dynamic operation of slot format, initial access technology to support multi-beam transmission and broadband, definition and operation of BWP (Band-Width Part), large capacity New channel coding methods such as LDPC (Low Density Parity Check) codes for data transmission and Polar Code for highly reliable transmission of control information, L2 pre-processing, and dedicated services specialized for specific services. Standardization of network slicing, etc., which provides networks, has been carried out.

Currently, discussions are underway to improve and enhance the initial 5G mobile communication technology, considering the services that 5G mobile communication technology was intended to support, based on the vehicle's own location and status information. V2X (Vehicle-to-Everything) to help autonomous vehicles make driving decisions and increase user convenience, and NR-U (New Radio Unlicensed), which aims to operate a system that meets various regulatory requirements in unlicensed bands. ), NR terminal low power consumption technology (UE Power Saving), Non-Terrestrial Network (NTN), which is direct terminal-satellite communication to secure coverage in areas where communication with the terrestrial network is impossible, positioning, etc. Physical layer standardization for technology is in progress.

In addition, IAB (IAB) provides a node for expanding the network service area by integrating intelligent factories (Industrial Internet of Things, IIoT) to support new services through linkage and convergence with other industries, and wireless backhaul links and access links. Integrated Access and Backhaul, Mobility Enhancement including Conditional Handover and DAPS (Dual Active Protocol Stack) handover, and 2-step Random Access (2-step RACH for simplification of random access procedures) Standardization in the field of wireless interface architecture/protocol for technologies such as NR) is also in progress, and 5G baseline for incorporating Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technology Standardization in the field of system architecture/services for architecture (e.g., Service based Architecture, Service based Interface) and Mobile Edge Computing (MEC), which provides services based on the location of the terminal, is also in progress.

When this 5G mobile communication system is commercialized, an explosive increase in connected devices will be connected to the communication network. Accordingly, it is expected that strengthening the functions and performance of the 5G mobile communication system and integrated operation of connected devices will be necessary. To this end, eXtended Reality (XR) and Artificial Intelligence are designed to efficiently support Augmented Reality (AR), Virtual Reality (VR), and Mixed Reality (MR). , AI) and machine learning (ML), new research will be conducted on 5G performance improvement and complexity reduction, AI service support, metaverse service support, and drone communication.

In addition, the development of these 5G mobile communication systems includes new waveforms, full dimensional MIMO (FD-MIMO), and array antennas to ensure coverage in the terahertz band of 6G mobile communication technology. , multi-antenna transmission technology such as Large Scale Antenna, metamaterial-based lens and antenna to improve coverage of terahertz band signals, high-dimensional spatial multiplexing technology using OAM (Orbital Angular Momentum), RIS ( In addition to Reconfigurable Intelligent Surface technology, Full Duplex technology, satellite, and AI (Artificial Intelligence) to improve the frequency efficiency of 6G mobile communication technology and system network are utilized from the design stage and end-to-end. -to-End) Development of AI-based communication technology that realizes system optimization by internalizing AI support functions, and next-generation distributed computing technology that realizes services of complexity beyond the limits of terminal computing capabilities by utilizing ultra-high-performance communication and computing resources. It could be the basis for .

As wireless communication systems develop, various technologies such as sidelink-based communication (for example, vehicle-to-everything, V2X) can be supported, and there is a need for a method to smoothly provide such side communication. This is increasing.

Based on the above-described discussion, this disclosure proposes a method for controlling congestion when sidelink communication or V2X communication is provided in a wireless communication system.

According to one embodiment, a method performed by a first terminal in a wireless communication system includes receiving, from a base station, resource information of an unlicensed band for sidelink communication with a second terminal; Regarding, identifying that the channel access procedure for at least one of transmission of a physical sidelink control channel (PSCCH), transmission of a physical sidelink shared channel (PSSCH), or reception of a physical sidelink feedback channel (PSFCH) has failed. and transmitting information indicating failure of the channel access procedure to the base station.

According to one embodiment, in a wireless communication system, a first terminal includes a transceiver and a controller coupled to the transceiver, and the controller receives resource information of an unlicensed band for sidelink communication with a second terminal from a base station, , For the resource information in the unlicensed band, a channel access procedure for at least one of transmission of a physical sidelink control channel (PSCCH), transmission of a physical sidelink shared channel (PSSCH), or reception of a physical sidelink feedback channel (PSFCH) is performed. It may be configured to identify failure and transmit information indicating failure of the channel access procedure to the base station.

According to one embodiment, a method performed by a base station in a wireless communication system includes transmitting, to a first terminal, resource information of an unlicensed band for sidelink communication with a second terminal, and transmitting, from the first terminal, the unlicensed band. Regarding the resource information in the band, indicating that the channel access procedure for at least one of transmission of a physical sidelink control channel (PSCCH), transmission of a physical sidelink shared channel (PSSCH), or reception of a physical sidelink feedback channel (PSFCH) has failed. It may include the step of receiving information.

According to one embodiment, in a wireless communication system, a base station includes a transceiver and a controller coupled to the transceiver, and the controller transmits resource information in an unlicensed band for sidelink communication with a second terminal to a first terminal, , From the first terminal, with respect to the resource information in the unlicensed band, at least one of transmission of a physical sidelink control channel (PSCCH), transmission of a physical sidelink shared channel (PSSCH), or reception of a physical sidelink feedback channel (PSFCH) It can be set to receive information indicating that the channel access procedure for has failed.

According to various embodiments proposed in this disclosure, stable V2X communication can be performed through congestion control in sidelink (SL) communication.

The effects that can be obtained from the present disclosure are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the description below. will be.

FIG. 1A illustrates examples of scenarios for sidelink communication in a wireless communication system according to various embodiments of the present disclosure.

FIG. 1B illustrates examples of scenarios for sidelink communication in a wireless communication system according to various embodiments of the present disclosure.

FIG. 1C illustrates examples of scenarios for sidelink communication in a wireless communication system according to various embodiments of the present disclosure.

1D illustrates examples of scenarios for sidelink communication in a wireless communication system according to various embodiments of the present disclosure.

FIG. 2A shows examples of transmission methods of sidelink communication in a wireless communication system according to various embodiments of the present disclosure.

FIG. 2B shows examples of transmission methods of sidelink communication in a wireless communication system according to various embodiments of the present disclosure.

FIG. 3 illustrates an example of a sidelink resource pool in a wireless communication system according to various embodiments of the present disclosure.

FIG. 4 illustrates an example of a signal flow for allocating transmission resources of a sidelink in a wireless communication system according to various embodiments of the present disclosure.

FIG. 5 illustrates another example of a signal flow for allocating transmission resources of a sidelink in a wireless communication system according to various embodiments of the present disclosure.

FIG. 6 shows an example of a channel structure of a slot used for sidelink communication in a wireless communication system according to various embodiments of the present disclosure.

FIG. 7A shows a first example of the distribution of a feedback channel in a wireless communication system according to various embodiments of the present disclosure.

FIG. 7B shows a second example of the distribution of a feedback channel in a wireless communication system according to various embodiments of the present disclosure.

FIG. 8 shows an example of signal flow for measuring and reporting sidelink channel status in a wireless communication system according to various embodiments of the present disclosure.

FIG. 9 illustrates an example of a signal flow for measuring and transmitting a channel busy ratio (CBR) in a wireless communication system according to various embodiments of the present disclosure.

FIG. 10 illustrates an example for setting a channel occupancy ratio (CR) limit and transmission parameter range in a wireless communication system according to various embodiments of the present disclosure.

FIG. 11 illustrates an example for setting a CR limit and feedback parameter range in a wireless communication system according to various embodiments of the present disclosure.

FIG. 12 is a diagram illustrating an example of a channel access procedure in an unlicensed band in a wireless communication system according to various embodiments of the present disclosure.

Figure 13 is a diagram explaining a channel sensing method in which a terminal reports to a base station according to an embodiment.

Figure 14 is a flowchart configuring a procedure for reporting channel sensing results of a terminal according to an embodiment.

Figure 15 is a flowchart configuring a procedure for reporting the results of a terminal's transmission performance to a base station according to an embodiment.

Figure 16 is a diagram showing the structure of a terminal according to an embodiment of the present invention.

Figure 17 is a diagram showing the structure of a base station according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the attached drawings. At this time, it should be noted that in the attached drawings, identical components are indicated by identical symbols whenever possible. Additionally, detailed descriptions of well-known functions and configurations that may obscure the gist of the present disclosure will be omitted.

In describing the embodiments in this specification, description of technical content that is well known in the technical field to which the present disclosure belongs and that is not directly related to the present disclosure will be omitted. This is to convey the gist of the present disclosure more clearly without obscuring it by omitting unnecessary explanation.

For the same reason, some components are exaggerated, omitted, or schematically shown in the accompanying drawings. Additionally, the size of each component does not entirely reflect its actual size. In each drawing, identical or corresponding components are assigned the same reference numbers.

The advantages and features of the present disclosure and methods for achieving them will become clear by referring to the embodiments described in detail below along with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below and may be implemented in various different forms, and the present embodiments are merely intended to ensure that the disclosure is complete and to provide common knowledge in the technical field to which the present disclosure pertains. It is provided to fully inform those who have the scope of the disclosure, and the disclosure is only defined by the scope of the claims. The same reference numerals may refer to the same elements throughout the specification.

At this time, it will be understood that each block of the processing flow diagram diagrams and combinations of the flow diagram diagrams can be performed by computer program instructions. These computer program instructions can be mounted on a processor of a general-purpose computer, special-purpose computer, or other programmable data processing equipment, so that the instructions performed through the processor of the computer or other programmable data processing equipment are described in the flow chart block(s). It creates the means to perform functions. These computer program instructions may also be stored in computer-usable or computer-readable memory that can be directed to a computer or other programmable data processing equipment to implement a function in a particular manner, so that the computer-usable or computer-readable memory The instructions stored in may also be capable of producing manufactured items containing instruction means to perform the functions described in the flow diagram block(s). Computer program instructions can also be mounted on a computer or other programmable data processing equipment, so that a series of operational steps are performed on the computer or other programmable data processing equipment to create a process that is executed by the computer, thereby generating a process that is executed by the computer or other programmable data processing equipment. Instructions that perform processing equipment may also provide steps for executing the functions described in the flow diagram block(s).

Additionally, each block may represent a module, segment, or portion of code that includes one or more executable instructions for executing specified logical function(s). Additionally, it should be noted that in some alternative embodiments it is possible for the functions mentioned in the blocks to occur out of order. For example, it is possible for two blocks shown in succession to be performed substantially at the same time, or it is possible for the blocks to be performed in reverse order depending on the corresponding function.

In various embodiments of the present disclosure described below, a hardware approach method is explained as an example. However, since various embodiments of the present disclosure include technology using both hardware and software, the various embodiments of the present disclosure do not exclude software-based approaches.

At this time, the term '˜unit' used in this embodiment refers to software or hardware components such as FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit), and '˜unit' refers to What roles do they perform? However, '~part' is not limited to software or hardware. The '~ part' may be configured to reside in an addressable storage medium and may be configured to reproduce on one or more processors. Therefore, as an example, '~ part' refers to components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, and procedures. , subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and 'parts' may be combined into a smaller number of components and 'parts' or may be further separated into additional components and 'parts'. Additionally, components and 'parts' may be implemented to regenerate one or more CPUs within a device or a secure multimedia card. Additionally, in an embodiment, '~ part' may include one or more processors.

Terms used in the following description to identify a connection node, a term referring to network entities, a term referring to messages, a term referring to an interface between network objects, and a term referring to various types of identification information. The following are examples for convenience of explanation. Accordingly, the present disclosure is not limited to the terms described below, and other terms referring to objects having equivalent technical meaning may be used.

For convenience of description below, the present disclosure uses terms and names defined in the 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) standard or the New Radio (NR) standard. However, the present disclosure is not limited by the above terms and names, and can be equally applied to systems complying with other standards.

Hereinafter, the base station (BS) is the entity that performs resource allocation for the terminal, and includes a radio access network (RAN) node, gNode B (next generation node B, gNB), eNode B (evolved node B, eNB), and Node B, may be at least one of a wireless access unit, a base station controller, or a node on a network. In this disclosure, eNB may be used interchangeably with gNB for convenience of explanation. That is, a base station described as an eNB may represent a gNB.

Hereinafter, a terminal may include a user equipment (UE), a mobile station (MS), a cellular phone, a smartphone, a computer, and/or a multimedia system capable of performing communication functions. Of course, it is not limited to the above example.

In particular, the present disclosure is applicable to 3GPP NR (5th generation mobile communication standard). In addition, the present disclosure provides intelligent services (e.g., smart home, smart building, smart city, smart car or connected car, healthcare, digital education, retail, It can be applied to security and safety-related services, etc.) Additionally, the term terminal can refer to other wireless communication devices as well as mobile phones, NB-IoT devices, and sensors.

Wireless communication systems have moved away from providing early voice-oriented services to, for example, 3GPP's HSPA (High Speed Packet Access), LTE (Long Term Evolution or E-UTRA (Evolved Universal Terrestrial Radio Access)), and LTE-Advanced. Provides high-speed and/or high-quality packet data services such as communication standards such as (LTE-A), LTE-Pro, 3GPP2's High Rate Packet Data (HRPD), UMB (Ultra Mobile Broadband), and IEEE's 802.16e. It is developing into a broadband wireless communication system.

As a representative example of a broadband wireless communication system, the LTE system uses OFDM (Orthogonal Frequency Division Multiplexing) in the downlink (DL), and SC-FDMA (Single Carrier Frequency Division Multiple Access) in the uplink (UL). ) method is adopted. Uplink refers to a wireless link through which a terminal (or UE) transmits data or control signals to a base station (or eNB, gNB), and downlink refers to a wireless link through which a base station transmits data or control signals to the terminal. The multiple access method described above differentiates each user's data or control information by allocating and operating the time-frequency resources to carry data or control information for each user so that they do not overlap, that is, orthogonality is established. .

As a future communication system after LTE, the 5G communication system must be able to freely reflect the various requirements of users and service providers, so services that simultaneously satisfy various requirements must be supported. Services considered for 5G communication systems include enhanced mobile broadband communication (eMBB), massive machine-type communication (mMTC), and ultra-reliable low-latency communication (URLLC).

According to one embodiment, eMBB may aim to provide more improved data transmission rates than those supported by existing LTE, LTE-A, or LTE-Pro. For example, in a 5G communication system, eMBB must be able to provide a peak data rate of 20Gbps in the downlink and 10Gbps in the uplink from the perspective of one base station. In addition, the 5G communication system may need to provide the maximum transmission rate and at the same time provide an increased user perceived data rate. In order to meet these requirements, the 5G communication system may require improvements in various transmission and reception technologies, including more advanced multiple antenna (Multiple Input Multiple Output, MIMO) transmission technology. In addition, while the current LTE transmits signals using a maximum of 20 MHz transmission bandwidth in the 2 GHz band, the 5G communication system uses a frequency bandwidth wider than 20 MHz in the 3 to 6 GHz or above 6 GHz frequency band, meeting the requirements of the 5G communication system. Data transfer speed can be satisfied.

At the same time, mMTC is being considered to support application services such as the Internet of Things (IoT) in 5G communication systems. In order to efficiently provide the Internet of Things, mMTC may be required to support access to a large number of terminals within a cell, improve coverage of terminals, improve battery time, and/or reduce terminal costs. Since the Internet of Things provides communication functions by attaching various sensors and various devices, it must be able to support a large number of terminals (for example, 1,000,000 terminals/km^2) within a cell. Additionally, due to the nature of the service, terminals supporting mMTC are likely to be located in shadow areas that cannot be covered by cells, such as the basement of a building, so wider coverage may be required compared to other services provided by the 5G communication system. Terminals that support mMTC must be composed of low-cost terminals, and since it is difficult to frequently replace the terminal's battery, a very long battery life time, such as 10 to 15 years, may be required.

Lastly, in the case of URLLC, it is a cellular-based wireless communication service used for specific purposes (mission-critical), such as remote control of robots or machinery, industrial automation, It can be used for services such as unmanned aerial vehicles, remote health care, and emergency alerts. Therefore, the communication provided by URLLC may need to provide very low latency (ultra-low latency) and very high reliability (ultra-reliability). For example, a service that supports URLLC must meet an air interface latency of less than 0.5 milliseconds and may have a packet error rate of less than 10^-5. . Therefore, for services that support URLLC, the 5G system must provide a smaller transmission time interval (TTI) than other services, and at the same time, a design that requires allocating wide resources in the frequency band to ensure the reliability of the communication link. Specifications may be required.

The three services considered in the above-described 5G communication system, namely eMBB, URLLC, and mMTC, can be multiplexed and transmitted in one system. At this time, different transmission/reception techniques and transmission/reception parameters can be used between services to satisfy the different requirements of each service. However, the above-described mMTC, URLLC, and eMBB are only examples of different service types, and the service types to which this disclosure is applied are not limited to the above-described examples.

In addition, hereinafter, embodiments of the present disclosure will be described using LTE, LTE-A, LTE Pro, 5G (or NR), or 6G systems as examples, but the present disclosure can also be applied to other communication systems with similar technical background or channel type. Examples may be applied. Additionally, the embodiments of the present disclosure may be applied to other communication systems through some modifications without significantly departing from the scope of the present disclosure at the discretion of a person with skilled technical knowledge.

Hereinafter, the present disclosure relates to an apparatus and method for controlling congestion in a wireless communication system. Specifically, the present disclosure is intended to control channel congestion in sidelink communication between terminals, and performs congestion control according to the result of determining whether the channel is congested based on CBR (channel busy ratio) and CR (channel occupancy ratio). It relates to a device and method for doing so.

In the following description, terms referring to signals, terms referring to channels, terms referring to control information, terms referring to network entities, terms referring to device components, etc. are used for convenience of explanation. This is exemplified. Accordingly, the present disclosure is not limited to the terms described below, and other terms having equivalent technical meaning may be used.

In the following description, physical channel and signal may be used interchangeably with data or control signals. For example, PDSCH (physical downlink shared channel) is a term that refers to a physical channel through which data is transmitted, but PDSCH can also be used to refer to the data itself. That is, in the present disclosure, the expression ‘transmitting a physical channel’ can be interpreted equivalently to the expression ‘transmitting data or a signal through a physical channel’.

Hereinafter, in this disclosure, upper signaling refers to a signal transmission method in which a signal is transmitted from a base station to a terminal using a downlink data channel of the physical layer, or from the terminal to the base station using an uplink data channel of the physical layer. High-level signaling can be understood as radio resource control (RRC) signaling or media access control (MAC) control element (CE).

In addition, in the present disclosure, the expressions greater than or less than are used to determine whether a specific condition is satisfied or fulfilled, but this is only a description for expressing an example and excludes descriptions of more or less. It's not about doing it. Conditions written as ‘more than’ can be replaced with ‘more than’, conditions written as ‘less than’ can be replaced with ‘less than’, and conditions written as ‘more than and less than’ can be replaced with ‘greater than and less than’.

In addition, the present disclosure describes various embodiments using terms used in some communication standards (eg, 3rd Generation Partnership Project (3GPP)), but this is only an example for explanation. Various embodiments of the present disclosure can be easily modified and applied to other communication systems.

In the present disclosure, a transmitting terminal refers to a terminal that transmits sidelink data and control information or a terminal that receives sidelink feedback information. Additionally, in this disclosure, a receiving terminal refers to a terminal that receives sidelink data and control information or a terminal that transmits sidelink feedback information.

Various attempts are being made to apply 5G communication systems to IoT networks. For example, technologies such as sensor network, machine to machine (M2M), and machine type communication (MTC) are combined with 5G communication technologies such as beamforming, multiple-input multiple-output (MIMO), and It is implemented using techniques such as array antennas. The application of cloud radio access network (RAN) as a big data processing technology can also be understood as an example of the convergence of 5G technology and IoT technology. In this way, a plurality of services can be provided to the user in a communication system, and in order to provide such a plurality of services to the user, a method and a device using the same that can provide each service within the same time period according to the characteristics are required. . A variety of services provided by 5G communication systems are being studied, one of which is a service that satisfies the requirements of low latency and high reliability.

In the case of vehicle communication, standardization of the LTE-based V2X (vehicle to everything) system based on the D2D (device-to-device) communication structure has been completed in 3GPP Rel-14 and Rel-15, and currently 5G NR (new radio) Efforts are underway to develop a V2X system based on this. In the NR V2X system, unicast communication, groupcast (or multicast) communication, and/or broadcast communication between terminals will be supported. In addition, unlike LTE V2X, which aims to transmit and receive basic safety information required for vehicle driving on the road, NR V2X provides group driving (platooning), advanced driving, extended sensors, and remote driving. Our goal is to provide more advanced services.

In the sidelink of V2X, whether the terminal can access the channel and the setting range of transmission parameters can be determined depending on whether the channel is congested. This means that when the channel is congested, the terminal drops transmission or controls channel access through scheduling adjustment, and when the terminal accesses the channel, it increases the probability of successful transmission by selecting transmission parameters according to the channel congestion situation. It is a congestion control function that allows The terminal can measure the channel busy ratio (CBR) and select parameters for transmission accordingly. CBR is an index indicating how much the current channel is occupied by terminals, and the range of selectable transmission parameters can be determined according to the CBR value. In addition to measuring CBR, the terminal can perform congestion control by measuring channel occupancy ratio (CR). CR is an index indicating how much of the channel the terminal occupies, and the CR limit at which the terminal can occupy the channel can be determined according to the CBR value. For example, if the channel is congested (when the CBR value is measured to be high), the CR limit is set low and the terminal must perform congestion control so that the measured CR does not exceed the CR limit. For example, the terminal must satisfy CR restrictions by dropping transmission or implementing scheduling.

Because HARQ (hybrid automatic repeat and request) ACK (acknowledgement)/NACK (negative acknowledgment) feedback and CSI (channel state information) feedback are considered in the NR sidelink, the operation of the transmitting terminal for congestion control compared to the LTE sidelink In addition, the operation of the receiving terminal with respect to feedback on transmission may also be considered. Therefore, an operation in which the transmitting terminal and the receiving terminal exchange CBR information can be considered. In addition, in the NR sidelink, the retransmission method is a blind-based retransmission method that performs retransmission not based on HARQ feedback information, as well as a HARQ feedback-based retransmission method that performs retransmission based on HARQ ACK/NACK feedback. method may be supported. When the terminal measures CR, not only the record of occupying and using the channel in the past based on the current point in time, but also the portion of the channel that is permitted to occupy and use the channel in the future may also be reflected. In the case of the retransmission method based on HARQ ACK/NACK feedback, the sending terminal reserves resources to occupy and use in the future, but if ACK is reported from the receiving terminal, retransmission may not be performed, so the resources are reserved for retransmission. Resources placed may be released. Therefore, this aspect should be reflected when measuring CR. Hereinafter, in this disclosure, embodiments for performing congestion control in NR sidelink will be described in detail.

Various embodiments of the present disclosure are intended to perform congestion control in the process of transmitting and receiving information between a vehicle terminal supporting V2X and other vehicle terminals and pedestrian portable terminals using a side link. Specifically, the transmitting terminal can determine whether the channel is congested by measuring the CBR and CR, and determine whether the terminal can access the channel and the setting range of the transmission parameters according to the determination result. Additionally, in this disclosure, the operation of the base station and the operation of the terminal according to various embodiments are described in detail.

According to various embodiments of the present disclosure, a method of operating a first terminal in a wireless communication system includes a process of receiving a signal for requesting a channel state between the first terminal and a second terminal from a second terminal, and information on the channel state. It includes a process of performing measurement and a process of transmitting information about a channel state generated based on the results of the performed measurement to a second terminal, and the information about the channel state is a channel between the first terminal and the second terminal. This may contain information to indicate the level of congestion.

According to various embodiments of the present disclosure, in a wireless communication system, a device of a first terminal includes a transceiver and at least one processor connected to the transceiver, and the at least one processor is connected to the first terminal and the second terminal. configured to receive a signal for requesting the channel state between the second terminals, perform measurement on the channel state, and transmit information about the channel state generated based on the results of the performed measurement to the second terminal, Information about the status may include information indicating the degree to which the channel between the first terminal and the second terminal is congested.

1A to 1D illustrate examples of scenarios for sidelink communication in a wireless communication system according to various embodiments of the present disclosure.

FIG. 1A illustrates an in-coverage (IC) scenario where the

sidelink terminals

120 and 125 are located within the coverage 110 of the base station 100.

Referring to FIG. 1A, the

sidelink terminals

120 and 125 receive data and control information from the base station through the downlink (DL), or receive data and control information from the base station through the uplink (UL). can be transmitted. At this time, the data and control information may be data and control information for sidelink communication, or may be data and control information for general cellular communication rather than sidelink communication. Additionally, in FIG. 1A, the

sidelink terminals

120 and 125 may transmit and/or receive data and control information for sidelink communication through the sidelink.

FIG. 1B shows partial coverage, where among the sidelink terminals, the first terminal 120 is located within the coverage 110 of the base station 100 and the second terminal 125 is located outside the coverage 110 of the base station 100. , PC) is an example.

Referring to FIG. 1B, the first terminal 120 located within the coverage 110 of the base station 100 receives data and control information from the base station through the downlink or transmits data and control information to the base station through the uplink. You can. The second terminal 125 located outside the coverage of the base station 100 cannot receive data and control information from the base station through the downlink and cannot transmit data and control information to the base station through the uplink. The second terminal 125 can transmit and receive data and control information for sidelink communication with the first terminal 120 through a sidelink.

FIG. 1C is an example of a case where sidelink terminals (e.g., first terminal 120, second terminal 125) are located outside the coverage 110 of the base station 100 (out-of coverage, OOC). . Accordingly, the first terminal 120 and the second terminal 125 cannot receive data and control information from the base station through the downlink and cannot transmit data and control information to the base station through the uplink. The first terminal 120 and the second terminal 125 may transmit and/or receive data and control information for sidelink communication through the sidelink.

1D shows that the first terminal 120 and the second terminal 125 performing sidelink communication are connected to different base stations (e.g., the first base station 100 and the second base station 105) (e.g., : RRC connected state) or camping (e.g., RRC disconnected state, i.e., RRC idle state), and performing inter-cell sidelink communication.

Referring to FIG. 1D, the first terminal 120 may be a sidelink transmitting terminal, and the second terminal 125 may be a sidelink receiving terminal. Alternatively, the first terminal 120 may be a sidelink receiving terminal and the second terminal 125 may be a sidelink transmitting terminal. The first terminal 120 can receive a sidelink-specific system information block (SIB) from the base station 100 to which it is connected (or to which it is camping), and the second terminal 125 can receive a system information block (SIB) dedicated to the sidelink. You can receive a sidelink-only SIB from another base station 105 (or where you are camping). At this time, the information on the sidelink-only SIB received by the first terminal 120 and the information on the sidelink-only SIB received by the second terminal 125 may be different from each other. Therefore, in order to perform sidelink communication between terminals located in different cells, information may be unified or additional assumptions and interpretation methods may be required.

In the examples of FIGS. 1A to 1D, for convenience of explanation, a sidelink system consisting of two terminals (e.g., a first terminal 120 and a second terminal 125) is described as an example, but the present disclosure does not apply to this. It is not limited and can also be applied to a sidelink system in which three or more terminals participate. Additionally, the uplink and downlink between the base station 100 and sidelink terminals may be referred to as a Uu interface, and the sidelink between sidelink terminals may be referred to as a PC5 interface. In the following description, uplink or downlink and the Uu interface may be used interchangeably, and sidelink and PC5 may be used interchangeably.

Meanwhile, in the present disclosure, the terminal is a vehicle supporting vehicle-to-vehicular communication (vehicular-to-vehicular, V2V), a vehicle supporting communication between a vehicle and a pedestrian (vehicular-to-pedestrian, V2P), or a pedestrian's handset (e.g. Smartphone), a vehicle that supports communication between a vehicle and a network (vehicular-to-network, V2N), or a vehicle that supports communication between a vehicle and infrastructure (vehicular-to-infrastructure, V2I). . Additionally, in the present disclosure, the terminal may mean an RSU (road side unit) equipped with a terminal function, an RSU equipped with a base station function, or an RSU equipped with a part of the base station function and a part of the terminal function.

Additionally, in the present disclosure, the base station may be a base station that supports both V2X communication and general cellular communication, or may be a base station that supports only V2X communication. At this time, the base station may be a 5G base station (gNB), a 4G base station (eNB), or an RSU. Accordingly, in this disclosure, the base station may also be referred to as an RSU.

2A and 2B show examples of transmission methods of sidelink communication in a wireless communication system according to various embodiments of the present disclosure. FIG. 2A illustrates a unicast method, and FIG. 2B illustrates a groupcast method.

Referring to FIG. 2A, the transmitting terminal 200 and the receiving terminal 205 can perform one-to-one communication. The transmission method shown in FIG. 2A may be referred to as unicast communication. As shown in Figure 2b, the transmitting terminal 230 or 245 and the receiving

terminals

235, 240, 250, 255, and 260 can perform one-to-many communication. The transmission method shown in FIG. 2b may be referred to as groupcast or multicast.

Referring to Figure 2b, the first terminal 230, the second terminal 235, and/or the third terminal 240 form one group, perform group cast communication, and the fourth terminal (245), the fifth terminal 250, the sixth terminal 255, and/or the seventh terminal 260 form another group and perform group cast communication. Terminals may perform group cast communication within the group they belong to, and may perform unicast, group cast, or broadcast communication with at least one other terminal belonging to different groups. In FIG. 2B, two groups are illustrated, but the present disclosure is not limited thereto and can also be applied when a larger number of groups are formed.

Meanwhile, although not shown in FIG. 2A or 2B, sidelink terminals may perform broadcast communication. Broadcast communication refers to a method in which all sidelink terminals receive data and control information transmitted through the sidelink by the sidelink transmitting terminal. For example, in FIG. 2B, if the first terminal 230 is a transmitting terminal, the remaining

terminals

235, 240, 245, 250, 255, and 260 receive data and control information transmitted by the first terminal 230. can do.

The aforementioned sidelink unicast communication, groupcast communication, and broadcast communication are supported in in-coverage scenario, partial-coverage scenario, or out-of-coverage scenario. It can be.

In the case of the NR sidelink, unlike the LTE sidelink, it supports a transmission type in which the vehicle terminal transmits data to only one specific terminal through unicast and a transmission type in which data is transmitted to a plurality of specific terminals through groupcast. This can be considered. For example, when considering a service scenario such as platooning, which is a technology that connects two or more vehicles to one network and moves in a group form, these unicast and group cast technologies can be useful. Specifically, unicast communication may be used for the purpose of controlling one specific terminal by the leader terminal of a group connected by platooning, and group cast may be used for the purpose of simultaneously controlling a group consisting of a plurality of specific terminals. Communication may be used.

FIG. 3 illustrates an example of a sidelink resource pool in a wireless communication system according to various embodiments of the present disclosure. A resource pool can be defined as a set of resources in the time and frequency domain used for transmission and reception of sidelinks.

Referring to FIG. 3, the resource allocation unit (resource granularity) on the time axis within the resource pool may be one or more orthogonal frequency division multiplexing (OFDM) symbols. Additionally, the resource allocation unit on the frequency axis may be one or more physical resource blocks (PRBs).

According to one embodiment, when a resource pool is allocated in the time domain and the frequency domain, an area composed of resources indicated by hatching indicates an area set as a resource pool in the time and frequency domain. In the present disclosure, a case in which resource pools are allocated discontinuously in time is described, but the present disclosure is not limited to this and can also be applied to a case in which resource pools are allocated continuously in time. In addition, in the present disclosure, the case where the resource pool is allocated continuously on frequency is described, but the present disclosure is not limited to this and can also be applied when the resource pool is allocated discontinuously on the frequency.

Referring to FIG. 3, the time domain 300 of the configured resource pool illustrates a case where resources are allocated discontinuously in the time domain. In the time domain 300 of the resource pool, the unit (resource granularity) of resource allocation on the time axis may be a slot. Specifically, one slot consisting of 14 OFDM symbols can be the basic unit of resource allocation on the time axis. Referring to the time domain 300 of the configured resource pool, shaded slots represent slots allocated to the resource pool in time, and the slots allocated to the resource pool in time may be indicated using system information. For example, slots allocated to a time resource pool may be indicated using time resource pool configuration information within the SIB. Specifically, at least one slot set as a time resource pool may be indicated through a bitmap. Referring to FIG. 3, physical slots 300 belonging to discontinuous resource pools on the time axis may be mapped to logical slots 325. In general, a set of slots belonging to a resource pool for a physical sidelink shared channel (PSSCH) can be expressed as (t ₀ , t ₁ , ..., t _i , ..., t _Tmax ).

Referring to FIG. 3, the frequency domain 305 of the set resource pool illustrates a case where resources are continuously allocated in the frequency domain. In the frequency domain 305 of the resource pool, the unit of resource allocation on the frequency axis may be a sub-channel 310. Specifically, one subchannel 310 consisting of one or more resource blocks (RBs) may be defined as the basic unit of resource allocation on frequency. That is, the subchannel 310 can be defined as an integer multiple of RB. Referring to FIG. 3, the subchannel size (sizeSubchannel) may be composed of five consecutive PRBs, but the present disclosure is not limited to this, and the size of the subchannel may be set differently. In addition, one subchannel is generally composed of consecutive PRBs, but does not necessarily have to be composed of consecutive PRBs. The subchannel 310 can be the basic unit of resource allocation for PSSCH. Additionally, a subchannel for a physical sidelink feedback channel (PSFCH) may be defined independently of the PSSCH.

Referring to FIG. 3, the start position of the subchannel on frequency in the resource pool may be indicated by startRB-Subchannel (315). When resource allocation on the frequency axis is made in units of subchannels 310, the RB index where the subchannel starts (startRB-Subchannel) 315, information indicating how many RBs the subchannel consists of (sizeSubchannel) ( 310), and configuration information on the total number of subchannels (numSubchannel) may be used to configure the resource pool on the frequency. Additionally, resource pool configuration on frequency can also be performed through configuration information on the RB index (EndRB-Subchannel) 320 where the subchannel ends. According to various embodiments, subchannels allocated to a resource pool on a frequency may be indicated using system information. For example, at least one of startRB-Subchannel, sizeSubchannel, EndRB-SubChannel, and numSubchannel may be indicated as frequency resource pool configuration information within the SIB. If the subchannel for PSFCH is defined independently from PSSCH, subchannel configuration information for PSFCH and PSSCH may be indicated to the terminal, respectively.

FIG. 4 illustrates an example of a signal flow for allocating transmission resources of a sidelink in a wireless communication system according to various embodiments of the present disclosure. Figure 4 illustrates signal exchange between a transmitting terminal 401, a receiving terminal 402, and a base station 403.

As described below, the method by which a base station allocates transmission resources for sidelink communication may be referred to as mode 1. Mode 1 is a method based on scheduled resource allocation by the base station. For example, in mode 1 resource allocation, the base station can allocate resources used for sidelink transmission to RRC-connected terminals according to a dedicated scheduling method. Because the base station can manage the resources of the sidelink, scheduled resource allocation is advantageous for interference management and management of resource pools (e.g., dynamic allocation and/or semi-persistent transmission).

Referring to FIG. 4, in step 407, the transmitting terminal 401 camped on the cell (405) may receive a sidelink SIB from the base station (403). In step 409, the receiving terminal 402 may receive a sidelink SIB from the base station 403. For example, the receiving terminal 402 refers to a terminal that receives data transmitted by the transmitting terminal 401. Sidelink SIBs may be transmitted periodically or on demand. In addition, the sidelink SIB is one of sidelink resource pool information for sidelink communication, parameter setting information for sensing operation, information for setting sidelink synchronization, or carrier information for sidelink communication operating at different frequencies. It can contain at least one. In the above, steps 407 and 409 are described sequentially, but this is for convenience of explanation, and steps 407 and 409 may be performed in parallel.

According to one embodiment, in step 413, when data traffic for sidelink communication is generated in the transmitting terminal 401, the transmitting terminal 401 may be connected to the base station 403 by RRC. For example, the RRC connection between the transmitting terminal 401 and the base station 403 may be referred to as Uu-RRC. Uu-RRC connection may be performed before generating data traffic of the transmitting terminal 401. Additionally, in the case of mode 1, the transmitting terminal 401 can transmit to the receiving terminal 402 through the sidelink while a Uu-RRC connection is established between the base station 403 and the receiving terminal 402. In addition, in the case of mode 1, the transmitting terminal 401 can transmit to the receiving terminal 402 through the sidelink even when a Uu-RRC connection is not established between the base station 403 and the receiving terminal 402. there is.

According to one embodiment, in step 415, the transmitting terminal 401 may request transmission resources for performing sidelink communication with the receiving terminal 402 from the base station 403. At this time, the transmitting terminal 401 may request transmission resources for the sidelink from the base station 403 using at least one of an uplink physical uplink control channel (PUCCH), an RRC message, or MAC CE. For example, when MAC CE is used, MAC CE is an indicator to indicate that it is a buffer status report (BSR) for sidelink communication and D2D (device-to-device) communication (or V2X communication) It may be a MAC CE regarding buffer status reporting having a new format that includes at least one of information about the size of data stored in the buffer. For example, MAC CE may be called sidelink BSR MAC CE. Additionally, when PUCCH is used, the transmitting terminal 401 may request sidelink resources through bits of a scheduling request (SR) transmitted through an uplink physical control channel.

According to one embodiment, in step 417, the base station 403 may transmit downlink control information (DCI) to the transmitting terminal 401 through the PDCCH. That is, the base station 403 may instruct the transmitting terminal 401 on final scheduling for sidelink communication with the receiving terminal 402. For example, the base station 403 may allocate sidelink transmission resources to the transmitting terminal 401 according to at least one of a dynamic grant (DG) method or a configured grant (CG) method.

According to one embodiment, in the case of the dynamic grant (DG) method, the base station 403 can allocate resources for one transport block (TB) transmission by transmitting a DCI to the transmitting terminal 401. Sidelink scheduling information included in DCI may include parameters related to the initial transmission time and/or retransmission transmission time, and parameters related to the frequency allocation location information field. The DCI for the dynamic grant method may be CRC (cyclic redundancy check) scrambling based on the sidelink-v2x-radio network temporary identifier (SL-V-RNTI) to indicate that the transmission resource allocation method is the dynamic grant method.

According to one embodiment, in the case of the configuration grant (CG) method, a semi-persistent scheduling (SPS) interval is set in Uu-RRC, so that resources for transmitting a plurality of TBs can be periodically allocated. In this case, the base station 403 can allocate resources for a plurality of TBs by transmitting DCI to the transmitting terminal 401. Sidelink scheduling information included in DCI may include parameters related to the initial transmission time and/or retransmission transmission time, and parameters related to the frequency allocation location information field. In the case of the setup grant method, the initial transmission timing (occasion) and/or the transmission timing and frequency allocation location of retransmission may be determined according to the transmitted DCI, and the resource may be repeated at SPS intervals. The DCI for the setup grant method may be CRC scrambled based on SL-SPS-V-RNTI to indicate that the transmission resource allocation method is the setup grant method. Additionally, the configuration grant method can be divided into type 1 CG and type 2 CG. In the case of type 2 CG, the base station 403 can activate and/or deactivate resources set by a configuration grant through DCI. Accordingly, in mode 1, the base station 403 can instruct the transmitting terminal 401 on final scheduling for sidelink communication with the receiving terminal 402 by transmitting DCI through the PDCCH.

According to one embodiment, when broadcast transmission is performed between

terminals

401 and 402, in step 419, the transmitting terminal 401 transmits the information to the receiving terminal 402 through PSCCH without setting the RRC of an additional sidelink (step 411). ) can broadcast the SCI to Additionally, in step 421, the transmitting terminal 401 may broadcast data to the receiving terminal 402 through PSSCH.

According to one embodiment, when unicast or groupcast transmission is performed between

terminals

401 and 402, in step 411, the transmitting terminal 401 transmits one-to-one with other terminals (e.g., receiving terminal 402). RRC connection can be performed. In this case, to distinguish it from Uu-RRC, the RRC connection between

terminals

401 and 402 may be referred to as PC5-RRC. In the case of the group cast transmission method, PC5-RRC connections can be established individually between terminals within the group.

Referring to FIG. 4, the PC5-RRC connection (step 411) is shown as an operation after the transmission of the sidelink SIB (steps 407 and 409), but the PC5-RRC connection (step 411) is performed before the transmission of the sidelink SIB. It may be performed in or before the broadcast of the SCI (step 419). If RRC connection between terminals is required, PC5-RRC connection of the sidelink is performed, and in step 419, the transmitting terminal 401 can transmit SCI to the receiving terminal 402 through PSCCH by unicast or group cast. there is. At this time, group cast transmission of SCI can be understood as group SCI. Additionally, in step 421, the transmitting terminal 401 may transmit data to the receiving terminal 402 through PSSCH as unicast or group cast. In mode 1, the transmitting terminal 401 may identify sidelink scheduling information included in the DCI received from the base station 403 and perform scheduling for the sidelink based on the sidelink scheduling information. SCI may include scheduling information as follows.

* Fields related to transmission time and frequency allocation location information for initial transmission and retransmission

* NDI (new data indicator) field

*RV(redundancy version) field

* Information field to indicate reservation interval

According to one embodiment, the information field for indicating the reservation interval indicates that when resources for multiple TBs (i.e., multiple MAC PDUs (protocol data units)) are selected, the interval between TBs is It is indicated as a fixed value, and when resources for one TB are selected, '0' may be indicated as the value of the gap between TBs.

According to one embodiment, in step 423, the receiving terminal 402 transmits whether demodulation/decoding of the data received in step 421 was successful to the transmitting terminal 401 through first HARQ feedback information. For example, the first HARQ feedback information includes ACK (success) or NACK (failure) information, and the receiving terminal 402 may transmit the first HARQ feedback information to the transmitting terminal 401 through the PSFCH channel.

According to one embodiment, in step 425, the transmitting terminal 401 transmits the transmission result as second HARQ feedback information to the base station 403 based on the first HARQ feedback information received from the receiving terminal 402. The second HARQ feedback is transmitted to the base station through PUCCH. For example, the second HARQ feedback information may or may not be the same as the first HARQ feedback information. For example, the second HARQ feedback information may include a plurality of first HARQ feedback information. The plurality of first HARQ feedback information may include a plurality of HARQ feedback information received from one receiving terminal, or may include one or a plurality of HARQ feedback information received from multiple terminals. Through the second HARQ feedback information, the base station allocates resources for retransmission to the transmitting terminal 401, allocates resources for new transmission, or makes resource allocation if there are no more transmission resources to allocate to the transmitting terminal 401. It may be possible to stop. PUCCH (425) transmission resources can be determined by DCI information transmitted from the base station to the transmitting terminal on PDCCH (417). It may be possible for the PSFCH (423) transmission resource to be determined by the SCI of the PSCCH (419) or by the transmission resource area in which the PSSCH (421) is transmitted and received.

FIG. 5 illustrates another example of a signal flow for allocating transmission resources of a sidelink in a wireless communication system according to various embodiments of the present disclosure. Figure 5 illustrates signal exchange between a transmitting terminal 501, a receiving terminal 502, and a base station 503.

As described below, the method in which the terminal directly allocates transmission resources of the sidelink through sensing in the sidelink may be referred to as mode 2. Mode 2 may also be referred to as UE autonomous resource selection. Specifically, according to mode 2, the base station 503 provides the sidelink transmission and reception resource pool for the sidelink to the terminal as system information or an RRC message (e.g., RRC Reconfiguration message, PC5 RRC message), and the transmitting terminal (501) Resource pools and resources can be selected according to established rules. Unlike mode 1, in which the base station described in FIG. 4 is directly involved in resource allocation, mode 2, described in FIG. 5, is where the transmitting terminal 501 autonomously selects resources based on a resource pool previously received through system information and data can be transmitted.

Referring to FIG. 5, in step 507 according to an embodiment, the transmitting terminal 501 that is camping on (505) may receive a sidelink SIB from the base station (503). In step 509, the receiving terminal 502 may receive a sidelink SIB from the base station 503. Here, the receiving terminal 502 refers to a terminal that receives data transmitted by the transmitting terminal 501. Sidelink SIBs may be transmitted periodically or on demand. In addition, sidelink SIB information includes sidelink resource pool information for sidelink communication, parameter setting information for sensing operation, information for setting sidelink synchronization, or carrier information for sidelink communication operating at different frequencies. It may include at least one of: In the above, steps 507 and 509 are described sequentially, but this is for convenience of explanation, and steps 507 and 509 may be performed in parallel.

In the case of FIG. 4 described above, the base station 503 and the transmitting terminal 501 operate with RRC connected, while in FIG. 5, the base station 503 and the transmitting terminal 501 operate with the base station 503 in step 513. And it can operate regardless of whether RRC is connected between the transmitting terminals 501. That is, the base station 503 and the transmitting terminal 501 can perform mode 2-based sidelink communication even in idle mode 513 in which RRC is not connected. In addition, even when RRC is connected, the base station 503 is not directly involved in resource allocation and can operate so that the transmitting terminal 501 autonomously selects transmission resources. In this case, the RRC connection between the transmitting terminal 501 and the base station 503 may be referred to as Uu-RRC.

According to one embodiment, in step 515, when data traffic for sidelink communication is generated in the transmitting terminal 501, the transmitting terminal 501 sets a resource pool through system information received from the base station 503, Time and frequency domain resources can be directly selected through sensing within the configured resource pool.

According to one embodiment, when broadcast transmission is performed between

terminals

501 and 502, in step 520, the transmitting terminal 501 transmits the information to the receiving terminal 502 through PSCCH without setting an RRC of an additional sidelink (step 513). ) can broadcast the SCI to Additionally, in step 525, the transmitting terminal 501 may broadcast data to the receiving terminal 502 through PSSCH.

When unicast and/or groupcast transmission is performed between

terminals

501 and 502, in step 511, the transmitting terminal 501 performs a one-to-one RRC connection with other terminals (e.g., receiving terminal 502). can do. For example, to distinguish it from Uu-RRC, the RRC connection between

terminals

501 and 502 may be referred to as PC5-RRC. In the case of the groupcast transmission method, PC5-RRC connections are established individually between terminals in the group. In Figure 5, the PC5-RRC connection (step 511) is shown in operation after the transmission of the sidelink SIB (steps 507 and 509), but the PC5-RRC connection (step 511) is performed before the transmission of the sidelink SIB or SCI. It may be performed before transmission (step 520). If (in case that) RRC connection between terminals is required, PC5-RRC connection of the sidelink is performed, and in step 520, the transmitting terminal 501 unicasts or sends SCI to the receiving terminal 502 through PSCCH. It can be transmitted via group cast. At this time, group cast transmission of SCI can be understood as group SCI. Additionally, in step 525, the transmitting terminal 501 may transmit data to the receiving terminal 502 through PSSCH as unicast or group cast. In mode 2, the transmitting terminal 501 can directly perform scheduling for the sidelink by performing sensing and transmission resource selection operations. SCI may include scheduling information as follows.

* Transmission time and frequency allocation location information field for initial transmission and retransmission

* NDI (new data indicator) field

*RV(redundancy version) field

* Information field to indicate reservation interval

According to one embodiment, the information field for indicating the reservation interval is one value with a fixed interval between TBs when resources for multiple TBs (i.e., multiple MAC PDUs) are selected. Indicated as , and when resources for one TB are selected, '0' may be indicated as the value of the interval between TBs.

FIG. 6 shows an example of a channel structure of a slot used for sidelink communication in a wireless communication system according to various embodiments of the present disclosure. Figure 6 illustrates physical channels mapped to slots for sidelink communication.

Referring to FIG. 6, the preamble 615 is mapped before the start of the slot 600, that is, at the end of the previous slot 605. Thereafter, from the start of the slot 600, the PSCCH 620, PSSCH 625, gap 630, PSFCH 635, and gap 640 are sequentially mapped.

Before transmitting a signal in slot 600, the transmitting terminal transmits a preamble 615 in one or more symbols. The preamble 615 can be used to ensure that the receiving terminal can correctly perform automatic gain control (AGC) to adjust the strength of the amplification when amplifying the power of the received signal. Additionally, the preamble 615 may or may not be transmitted depending on whether the transmitting terminal transmits the previous slot 605. That is, if the transmitting terminal transmits a signal to the same terminal in a slot (e.g., slot 605) preceding the corresponding slot (e.g., slot 600), transmission of the preamble 615 may be omitted. The preamble 615 is a 'synchronization signal', 'sidelink synchronization signal', 'sidelink reference signal', 'midamble', 'initial signal', 'wake-up signal' or the like. It may be referred to by other terms that have equivalent technical meaning.

A PSCCH 620 including control information may be transmitted using symbols transmitted at the beginning of a slot, and then a PSSCH 625 scheduling the control information of the PSCCH 620 may be transmitted. At least a portion of SCI, which is control information, may be mapped to the PSSCH 625. Afterwards, a gap 630 exists, and the PSFCH 635, a physical channel that transmits feedback information, is mapped.

Referring to FIG. 6, the PSFCH 635 is illustrated as being located at the last part of the slot. By securing a gap 630, which is a certain amount of empty time, between the PSSCH 625 and the PSFCH 635, the terminal that has transmitted or received the PSSCH 625 prepares to transmit or receive the PSFCH 635 (e.g. : Transmission and reception switching) can be performed. After PSFCH 635, there is a gap 640, which is an empty section for a certain period of time.

The terminal can receive the location of a slot in which PSFCH can be transmitted in advance. Receiving pre-configuration may refer to a procedure that is determined in advance during the process of creating a terminal, or is delivered when connecting to a sidelink-related system, or is delivered from the base station when connected to a base station, or is delivered from another terminal. .

In the embodiment of FIG. 6, it has been explained that the preamble signal for performing AGC is transmitted separately in the physical channel structure within the sidelink slot. However, according to another embodiment, a separate preamble signal is not transmitted, and while receiving a physical channel for control information or data transmission, the receiver of the receiving terminal operates AGC using the control degree or a physical channel for data transmission. It is also possible to perform .

FIG. 7A shows a first example of the distribution of a feedback channel in a wireless communication system according to various embodiments of the present disclosure. Figure 7a illustrates a case where resources for transmitting and receiving PSFCH are allocated in every slot.

Referring to FIG. 7A, the arrow indicates the slot of the PSFCH where HARQ-ACK feedback information corresponding to the PSSCH is transmitted. Referring to FIG. 7A, HARQ-ACK feedback information for the PSSCH 711 transmitted in the slot 701 is transmitted on the PSFCH 722 in the slot 702. Since the PSFCH is allocated to every slot, the PSFCH may correspond 1:1 to a slot containing the PSSCH. For example, when configuring the period of a resource capable of transmitting and receiving PSFCH based on a parameter such as periodicity_PSFCH_resource, periodicity_PSFCH_resource in FIG. 7A may indicate 1 slot. Alternatively, the period may be set in milliseconds (msec) and may be indicated by a value allocated to each slot according to subcarrier spacing (SCS).

FIG. 7B shows a second example of the distribution of a feedback channel in a wireless communication system according to various embodiments of the present disclosure. Figure 7b illustrates a case where resources are allocated to transmit and receive PSFCH in every four slots.

Referring to FIG. 7b, the arrow indicates the slot of the PSFCH where HARQ-ACK feedback information corresponding to the PSSCH is transmitted. Referring to FIG. 7B, among the four slots (751, 752, 753, and 754), only the last slot (754) includes the PSFCH (774). Similarly, of the next four slots (755, 756, 757, 758), only the last slot (758) includes PSFCH (778). Accordingly, HARQ-ACK feedback information for the PSSCH 761 of the slot 751, the PSSCH 762 of the slot 752, and the PSSCH 763 of the slot 753 are received from the PSFCH 774 of the slot 754. is transmitted. Similarly, the HARQ-ACK feedback information for the PSSCH 765 of slot 755, the PSSCH 766 of slot 756, and the PSSCH 767 of slot 757 is the PSSCH 778 of slot 758. is transmitted from

In Figure 7b, the slot index may be an index for slots included in the resource pool. That is, the four slots are not actually physically consecutive slots, but may be slots listed consecutively among slots included in a resource pool (or slot pool) used for sidelink communication between terminals. The reason that the HARQ-ACK feedback information of the PSSCH transmitted in the 4th slot cannot be transmitted in the PSFCH of the same slot may be because the terminal does not have enough time to finish decoding the PSSCH transmitted in the slot and transmit the PSFCH in the same slot. . That is, this may be because the minimum processing time required to process the PSSCH and prepare the PSFCH is not small enough.

Therefore, when the UE that has received PSSCH in slot n is set or given resources to transmit PSFCH in slot n+x, it uses the smallest x among integers greater than or equal to K to provide HARQ-ACK feedback of PSSCH. The information is transmitted using the PSFCH of slot n+x. K may be a value preset by the transmitting terminal, or a value set in the resource pool through which the corresponding PSSCH or PSFCH is transmitted. To set K, each terminal can exchange its capability information with the transmitting terminal in advance. For example, K may be determined based on at least one of subcarrier spacing, terminal capability, settings with the transmitting terminal, or resource pool settings.

FIG. 8 shows an example of signal flow for measuring and reporting sidelink channel status in a wireless communication system according to various embodiments of the present disclosure. FIG. 8 is a flowchart showing signal exchange between a transmitting terminal 801 and a receiving terminal 802.

Referring to FIG. 8, in step 805 according to an embodiment, the transmitting terminal 801 may transmit a sidelink channel state information reference signal (CSI-RS) to the receiving terminal 802. That is, the transmitting terminal 801 transmits a sidelink CSI-RS to receive channel information from the receiving terminal 802, and the receiving terminal 802 receives the sidelink CSI-RS. Additionally, the transmitting terminal 801 may request a report of sidelink channel state information (CSI) from the receiving terminal 802. Sidelink CSI reporting can be enabled or disabled.

According to one embodiment, in step 807, the receiving terminal 802 measures the channel state of the sidelink between the transmitting terminal 801 and the receiving terminal 802 using the received sidelink CSI-RS.

According to one embodiment, in step 809, the receiving terminal 802 generates information about the sidelink CSI using the channel state measurement result. That is, when sidelink CSI reporting is enabled, the receiving terminal 802 can generate information about CSI measurement results to report to the transmitting terminal 801.

According to one embodiment, in step 811, the receiving terminal 802 may transmit sidelink CSI to the transmitting terminal 801. In this disclosure, sidelink CSI-RS transmission and sidelink CSI reporting are considered when unicast transmission is performed between terminals in the sidelink. That is, in the case of broadcast transmission, sidelink CSI-RS transmission and sidelink CSI reporting may not be supported. Additionally, even in the case of groupcast transmission, sidelink CSI-RS transmission and sidelink CSI reporting methods for groupcast are not considered. Therefore, if the terminals do not operate as unicast through the PC5-RRC connection, the transmitting terminal of the sidelink cannot receive the SL CSI report from the receiving terminal. Additionally, in the case of unicast transmission between sidelink terminals, only aperiodic sidelink CSI reporting is considered.

The present disclosure is intended to perform congestion control in the sidelink of V2X communication. Whether the terminal accesses the channel is determined depending on whether the corresponding channel of the sidelink is congested, and through restrictions on the setting range of transmission parameters. Congestion control is performed. That is, when the channel is congested, the terminal drops transmission or controls channel access through scheduling adjustment, and when the terminal accesses the channel, the probability of successful transmission is selected by selecting transmission parameters based on the channel congestion situation. This can be improved.

For congestion control, the terminal can measure CBR (channel busy ratio). CBR is an index indicating how much the current channel is occupied by terminals, and can be used to determine whether the corresponding channel of the sidelink is congested. The CBR measured at a specific slot n can be defined as follows.

* CBR is defined as the ratio of subchannels in the resource pool where the sidelink received signal strength indicator (RSSI) measured by the terminal exceeds a (pre)set threshold. Here, CBR measurement can be performed in slot [n-X, n-1], and the slot index is based on the physical slot index.

** CBR measurement from a transmission perspective can be performed for the PSSCH region. Referring to FIG. 6, it is assumed that the PSSCH area and the PSCCH area are located in adjacent resource areas. Here, when the frequency resource area where the PSSCH is allocated and the frequency area where the PSCCH is transmitted overlap, the PSSCH area and the PSCCH area are interpreted as being adjacent. If the PSSCH area and the PSCCH area are not located in adjacent resource areas, CBR measurement may be performed in the PSCCH area.

According to another embodiment, CBR measurement from a transmission perspective may be performed simultaneously on both the PSSCH region and the PSCCH region. Referring to FIG. 6, the PSSCH associated with a portion of the PSCCH is transmitted on time resources that overlap with non-overlapping frequency resources. However, according to another example, there is a case in which at least a portion of the PSSCH and the PSCCH associated with each other are transmitted on non-overlapping time resources. There may be. Here, ‘related’ means that the PSCCH contains at least the information necessary to decode the PSSCH. When the PSCCH and PSSCH are multiplexed, the transmission power of the PSCCH area and the PSSCH area may be constant. Under the assumption that the resulting RSSI can be measured equally in the PSCCH area and the PSSCH area, CBR measurement can be performed simultaneously in both areas without distinguishing between the PSSCH area and the PSCCH area. Specifically, in FIG. 6, RSSI can be measured in symbols of the PSCCH area and the PSSCH area. When the PSCCH and PSSCH are multiplexed as shown in FIG. 6, it may be difficult for the UE to distinguish between the PSCCH area and the PSSCH area when measuring CBR. Therefore, CBR measurement can be performed on symbols in both the PSCCH region and the PSSCH region without distinguishing between the PSCCH region and the PSSCH region.

In addition, when a PSFCH area exists as shown in FIG. 6, this is a channel through which feedback is transmitted, so it can be excluded from CBR measurement from a transmission perspective. That is, a UE that transmits at least one of control information and data and measures CBR on at least one of PSCCH and PSCCH may not perform CBR measurement on PSFCH. Conversely, the other terminal that received the data transmits feedback information through the PSFCH, so CBR measurement can be performed on the PSFCH. For CBR measurement for the PSFCH area, please refer to the description below.

** CBR measurement from the perspective of feedback on transmission can be performed for the PSFCH area. The above-described measurement can be understood with reference to the PSFCH region shown in FIGS. 6 and 7.

*** In this case, it is assumed that ACK/NACK feedback for transmission is transmitted through PSFCH, and it is assumed that SL CSI feedback for transmission is transmitted through PSFCH. When SL CSI feedback is transmitted through PSSCH, CBR is measured in the PSSCH area as described above.

** X is the value of the size of the window in which CBR is measured, and

*** If X is a single fixed value, X can be set to 100 slots. If X is a configurable value, the configuration value of X may be included in resource pool configuration information. Before the terminal is connected to the RRC with the base station, the corresponding values can be pre-configured in the terminal or set through SIB from the base station. After the terminal is RRC-connected to the base station, X can be set to be UE specific. Additionally, X can be set through the PC5-RRC connection between the terminal and the terminal. For example, X can be set as one value among {100*2 ^μ , 100} slots through resource pool configuration information. Here, μ is an index corresponding to numerology, and is set to the following value according to SCS (subcarrier spacing).

**** SCS=15kHz, μ=0

**** SCS=30kHz, μ=1

**** SCS=60kHz, μ=2

**** SCS=120kHz, μ=3

Among the two setting methods above, if X=100*2 ^μ is set, the CBR window is fixed to 100ms regardless of the SCS. If X=100 is set, the CBR window is fixed to 100ms depending on the SCS. This is a method in which the measurement time (ms) can vary.

** Sidelink RSSI refers to received signal strength. That is, the sidelink RSSI represents the power (unit: [W]) received by the receiving terminal, and is observed by the valid OFDM symbol positions of the channel in the slot of the sidelink and the configured subchannel.

*** In this case, the configured subchannel may mean a subchannel allocated as a resource pool. Additionally, subchannels may be set differently depending on the corresponding channel. For example, the minimum configurable subchannel size for PSSCH is 4 RB, and up to 20 subchannels can be allocated. PSFCH has a minimum configurable subchannel size of 2 RB, and up to 40 subchannels can be allocated. The present disclosure is not limited to this, and the size of subchannels or the maximum number of subchannels may vary depending on the SCS.

According to one embodiment, by defining CBR, whether the channel is congested can be determined based on the measured CBR value, and the terminal can report the measured CBR to the base station. Specifically, when the base station and the terminal are connected through Uu-RRC, the CBR value measured by the terminal can be reported to the base station through Uu-RRC. In mode 1 of the sidelink resource allocation methods, when the transmitting terminal requests the base station for transmission resources to perform sidelink communication with the receiving terminal, the base station can allocate transmission resources using the reported CBR information. In addition, the base station determines transmission parameter information such as PSSCH demodulation reference signal (DMRS) pattern information, modulation and coding scheme (MCS) settings, and/or the number of transmission layers, and sends the determined transmission parameter information to the terminal. You can instruct. As described above, the base station can signal allocation information about transmission resources to the transmitting terminal through DCI. The base station can indicate transmission parameter information such as PSSCH DMRS pattern information, MCS settings, and number of transmission layers through the upper layer. For example, the base station can transmit transmission parameter information to the terminal through Uu-RRC. However, the present disclosure does not exclude that transmission parameter information such as PSSCH DMRS pattern information, MCS settings, and number of transport layers are signaled through DCI. When a sidelink CSI report is transmitted from the receiving terminal, transmission parameters need to be dynamically changed based on the sidelink CSI. In this case, the transmitting terminal does not follow the transmission parameters such as the pattern information, MCS settings, and number of transport layers of the PSSCH DMRS signaled by the base station, but directly based on the sidelink CSI. Transmission parameters such as the number of can be determined.

Meanwhile, in mode 2 among the sidelink resource allocation methods, the terminal must not only directly perform resource allocation through sensing but also determine channel access and transmission parameters by reflecting the CBR measured by the terminal. Therefore, in mode 2, the terminal can perform congestion control by measuring CR along with CBR measurement. In this case, the priority of the packet may be reflected. When the transmitting terminal transmits a packet, a value indicating the priority of the transmitted packet may be transmitted to the receiving terminal through SCI. CR may be an index indicating how much of the channel the terminal occupies, and the CR limit at which the terminal can occupy the channel may be determined according to the CBR value. For example, when the channel is congested (i.e., when the CBR value is measured to be high), the CR limit is set low, and the terminal must perform congestion control so that the measured CR does not exceed the CR limit. To perform congestion control, the terminal must drop transmission or ensure that the measured CR satisfies the CR limit through scheduling implementation. If the channel is not congested (i.e., the CBR value is measured to be low), the CR limit is set high, and the probability that the measured CR does not exceed the CR limit increases, making it easier for the terminal to occupy and use the channel. It can become possible.

Below, various embodiments of the operation of the terminal to perform congestion control in the NR sidelink are described.

According to the first embodiment of the present disclosure, the terminal may measure CR for congestion control in mode 2. Among the sidelink resource allocation methods, when the terminal selects resources through sensing in mode 2, the terminal can reserve resources for the transmission of one TB or reserve resources for the transmission of multiple TBs. there is. Setting whether to reserve resources for transmission of one TB or multiple TBs may be determined at the top. Additionally, in mode 2, the terminal can reserve resources not only for initial transmission of the TB but also for retransmission of the corresponding TB. In mode 2, when the terminal reserves transmission resources through sensing, under the assumption that transmission occurs from the reserved resources, when the terminal measures CR, it records not only the past channel occupancy and use records based on the current point, but also the future. The portion of the channel that is scheduled to be occupied and used can be calculated. Therefore, the CR measured for PSSCH transmission in slot n can be defined as follows.

Definition of CR measured for PSSCH transmission

* CR is the number of subchannels used by the terminal by occupying the channel in the slots [n-a, n-1] section and the number of subchannels permitted to be used by the terminal by occupying the channel in the slots [n, n+b] section. It is defined as the sum divided by the total number of subchannels set as a transmission resource pool in the slots [n-a, n+b] section.

** Here, the channel corresponds to PSSCH.

** Here, the slot index is based on the physical slot index.

** Here, a is a positive integer, and b is 0 or a positive integer. Additionally, n+b cannot be set to a value that exceeds the last transmission opportunity permitted through transmission resource reservation.

*** M and N may be values determined by the terminal implementation to satisfy the condition of a+b+1=M and a≥N. Here, M=1000 and N=500 can be used, but are not limited thereto. If the values of M and N are configurable, the values of M and N may be included in resource pool configuration information. Before the terminal is RRC-connected to the base station, values (e.g., values of M and N) may be pre-configured in the terminal or set through SIB from the base station. After the terminal is RRC connected to the base station, it can be set to a UE-specific value. For example, M may be a value of one of {1000*2 ^μ , 1000} slots, and N may be a value of one of {500*2 ^μ , 500} slots and can be set through resource pool setting information. Here, μ is an index corresponding to numerology and is set to the following value according to SCS (subcarrier spacing).

**** SCS=15kHz, μ=0

**** SCS=30kHz, μ=1

**** SCS=60kHz, μ=2

**** SCS=120kHz, μ=3

Of the two setting methods described above, when set to M=1000*2 ^μ and N=500*2 ^μ , the CBR window is fixed to 100ms regardless of SCS, and when set to M=1000, N=500. , This is a method in which the measurement time (ms) of the CBR window can vary depending on the SCS.

** CR is measured for each (re)transmission.

** When calculating CR, the terminal assumes that the transmission parameters used in slot n are reused in transmissions that are permitted to occupy and use the channel at slot [n, n+b].

** As explained through the third embodiment below, CR can be measured for priority level.

** The CR measurement method may vary depending on whether the transmission types such as broadcast, unicast, and group cast described above can be set simultaneously in one resource pool or are set separately for each resource pool. According to the definition of CR, if different transmission types can be configured simultaneously in one resource pool, CR can be measured simultaneously for all transmission types. If different transmission types are defined to be set separately into resource pools, CR can be measured separately for each transmission type. For example, broadcast may be referred to as a first transmission type, unicast may be referred to as a second transmission type, and groupcast may be referred to as a third transmission type.

According to the CR value measured based on the above definition, the degree of channel occupancy of the terminal can be determined by reflecting how much the terminal has occupied the channel in the past and how much the channel will occupy in the future. Additionally, as described above, the terminal must perform congestion control so that the measured CR value does not exceed the CR limit determined by CBR. Therefore, CR needs to be measured accurately.

According to the above description, CR is defined under the assumption that when the terminal reserves transmission resources through sensing in mode 2, transmission occurs on the reserved resources. However, depending on the retransmission scheme supported by the NR sidelink, this assumption may not always be satisfied. Therefore, in order to solve the above-mentioned problem, a method of always setting the above-described b value to 0 may be considered. Setting b to 0 means that the calculation of CR is not applied to resources permitted to occupy and use the channel at the time of slot [n, n+b], that is, reserved transmission resources. However, setting b to 0 does not take into account the fairness of channel occupancy between terminals that are allowed to use many resources at slot [n, n+b] and terminals that are not allowed to use many resources. Therefore, below, a method in which the case of not transmitting on reserved transmission resources is taken into account will be described.

Specifically, in the NR sidelink, blind retransmission, which performs retransmission not based on HARQ-ACK feedback information, as well as HARQ feedback-based retransmission, which performs retransmission based on HARQ-ACK/NACK feedback, will be supported as a retransmission method. You can. In the case of the blind retransmission method, retransmission is always performed regardless of whether the initial transmission and reception of the retransmission are successful. However, in the case of the HARQ feedback-based retransmission method, whether to retransmit can be determined based on the ACK/NACK feedback result.

Additionally, in mode 2 of the NR sidelink, the terminal can reserve transmission resources through sensing for blind retransmission and HARQ feedback-based retransmission methods. Additionally, in the case of the HARQ feedback-based retransmission method, reserved transmission resources may be released based on HARQ ACK/NACK feedback. For example, when the transmitting terminal receives an ACK for a previous transmission, resources reserved for the next retransmission may be released. That is, in the definition of CR described above, the assumption that transmission necessarily occurs in the reserved resource when the terminal reserves transmission resources through sensing may not be satisfied. Therefore, in order to accurately measure CR, the case in which reserved resources can be released must be considered. As the maximum number of HARQ feedback-based retransmissions increases, and the number of resource reservations for transmission of multiple TBs increases, when the case in which reserved resources can be released is not considered, the inaccuracy of CR measurement becomes very high. You can. To solve this problem, in the definition of CR described above, when calculating the sum of the number of subchannels permitted to occupy and use the channel at the time of slot [n, n+b], the following is used depending on the retransmission method: Calculation methods may be applied.

How to apply a weighted sum when HARQ feedback-based retransmission is used

* When HARQ feedback-based retransmission is used in the sidelink, the weighted sum of the number of subchannels allowed to occupy the channel for the i-th transmission of the TB at the time of slot [n, n+b] This applies. For example, the weight is defined as W(i), where i=1 means the initial transmission, i is a positive integer and means the ith retransmission. The weight for the initial transmission is W(1)=1. The following methods can be considered to apply the weight W(i)(i>1) for retransmission.

** Method 1-1: The value of W(i)(i>1) can be determined by terminal implementation.

** Method 1-2: The value of W(i)(i>1) can be set. Information about the value of W(i) may be included in resource pool setting information. Before the terminal is RRC-connected to the base station, a value (e.g., the value of W(i)) may be pre-configured in the terminal, or may be set through SIB from the base station. After the terminal is RRC connected to the base station, it can be set to a UE-specific value. Additionally, information about W(i) can be set through the PC5-RRC connection between the terminal and the terminal.

** Method 1-3: Defined as W(i)=(0.1) ^i-1 . If the maximum number of retransmissions is 4, W(2)=0.1, W(3)=0.01, and W(4)=0.001.

** Method 1-4: Defined as W(2)=0.1, W(i)=0(i>2). The weighted sum is not applied after the third retransmission.

** Method 1-5: Defined as W(i)=0(i>1). That is, the weighted sum is not applied.

When the blind retransmission method is used in the sidelink, retransmission is performed regardless of whether reception of the initial transmission and retransmission is successful, so the above-described weighted sum is not applied.

When the above-described definition of CR measured for PSSCH transmission and HARQ feedback-based retransmission are used, the measured value of CR to which the weighted sum is applied can be expressed by <Equation 1> below.

In <Equation 1>, A, B(i), W(i), C, and NumMAXReTx can be defined as follows.

* A: Number of subchannels occupied and used in the channel at slot [n-a, n-1]

* B(i): Number of subchannels allowed to occupy and use the channel for the i-th transmission of TB at slot [n, n+b]

* W(i): Weight applied to the number of subchannels allowed to occupy and use the channel for the i-th transmission of TB at slot [n, n+b]

* C: Total number of subchannels set as a transmission resource pool at slot [n-a, n+b]

* NumMAXReTX: Maximum number of retransmissions supported for one TB

[Equation 1] represents the CR calculation method proposed in this disclosure when HARQ feedback-based retransmission is used, and can also be transformed into other expressions showing the same meaning. Additionally, in [Equation 1], when W(i)=1 is applied to all i, the weighted sum can also be applied to the blind retransmission method.

As described above, when b>0 is applied when HARQ feedback-based retransmission is used and when blind retransmission is used, the number of subchannels permitted to be used by occupying the channel at the time of CR window [n, n+b] We looked at how to reflect this. This can be described in the same way as <Table 1> below.

Referring to <Table 1> below, when SL HARQ is disabled, it is assumed that blind retransmission is used, and the subchannel permitted to be used by occupying the channel at the time of CR window [n, n+b] They can be reflected in the CR calculation without dropping them. In contrast, when SL HARQ is disabled (enabled), it is assumed that HARQ feedback-based retransmission is used, and subchannels permitted to be used by occupying the channel at the CR window [n, n+b] are subject to HARQ feedback. It can be assumed that it can be released based on At this time, when HARQ feedback-based retransmission is used for accurate CR calculation, the proposed weighted sum application method can be applied.

Referring to [Table 1], when evaluating the SL CR, the UE determines that if SL HARQ feedback is disabled, the transmission parameters used in slot n are added to the existing grant(s) in slot [n+1, n+b] without packet drop. It can be assumed that it is reused accordingly. Additionally, when evaluating the SL CR, the UE ensures that the transmission parameters used in slot n are reused according to the existing grant(s) in slot [n+1, n+b], and that the existing grant(s) are reused when SL HARQ feedback is disabled. It can be assumed that can be released by the UE.

As described above, a blind retransmission method that performs retransmission without HARQ feedback information and a HARQ feedback-based retransmission method that performs retransmission based on HARQ ACK/NACK feedback are considered in the NR sidelink. The two retransmission methods described above can be used separately depending on the transmission type. In the case of broadcast communication, HARQ feedback is not supported, so blind retransmission can be used. In the case of unicast or groupcast communication, HARQ feedback is supported, so at least one of blind retransmission or HARQ feedback-based retransmission methods can be set and used.

In the above-described embodiment, the case set to blind retransmission and the case set to HARQ feedback-based retransmission were separately described. However, it is not limited to this, and blind retransmission and HARQ feedback-based retransmission can be set and used simultaneously in mode 2 of the NR sidelink. For example, when up to 4 retransmissions are allowed, blind retransmission is used up to 2 retransmissions, and whether to perform additional retransmissions may be determined based on HARQ feedback. That is, based on the HARQ feedback result, whether additional retransmission can be determined. For example, blind retransmission may be performed for the first two retransmissions, and when NACKs are consecutively received, additional HARQ feedback-based retransmission may be performed or two blind retransmissions may be performed. In general, by considering the above method, if the number of blind retransmissions is set to A, the number of HARQ feedback-based retransmissions is set to B, and a maximum of 4 retransmissions are allowed, examples in which A and B are set as follows: can be considered.

* Example 1: A=0, B=4

* Example 2: A=1, B=1

* Example 3: A=1, B=2

* Example 4: A=2, B=0

A=0 means blind retransmission is off, A=1 means two consecutive blind retransmissions, and A=2 means four consecutive blind retransmissions. In addition, B = 0 means the case where HARQ feedback-based retransmission is off, and B = 1 means the case where whether to perform two blind retransmissions after the first two blind retransmissions can be determined based on HARQ feedback. it means. Additionally, B=2 means that the first two blind retransmissions occur and whether the third and fourth retransmissions are determined based on HARQ feedback. Additionally, B=4 means that all 4 retransmissions are judged based on HARQ feedback. As described above, the proposed CR calculation method can be applied even when blind retransmission and HARQ feedback-based retransmission are set at the same time (i.e., Examples 2 and 3). Specifically, when blind retransmission and HARQ feedback-based retransmission are supported simultaneously, for resources reserved for HARQ feedback-based retransmission at slot [n, n+b], A and A described in Examples 1 to 4 above B may apply.

According to the second embodiment of the present disclosure, an operation in which a terminal measures CBR for congestion control in a V2X sidelink and a method in which the transmitting end and the receiving end exchange CBR information are proposed. In the NR sidelink, not only the CBR measurement for transmission but also the CBR measurement for transmission feedback can be considered. For LTE sidelink, HARQ ACK/NACK feedback or sidelink CSI feedback is not considered. However, in the case of NR sidelink, since HARQ ACK/NACK feedback and sidelink CSI feedback are considered, not only the operation of the transmitting terminal but also the operation of the receiving terminal with respect to feedback on transmission can be considered for congestion control. Therefore, the transmitting terminal can measure the CBR from a transmission perspective, and the receiving terminal can measure the CBR from a feedback perspective on transmission. In the sidelink, the CBR measurement of the terminal may be defined as a default feature or as an optional feature. Additionally, the case of not using CBR through settings by a higher layer may be considered, regardless of CBR measurement capability. When CBR measurement is set to a selectable operation, the CBR measurement capability can be divided into four cases as shown in [Table 2] below, depending on the CBR measurement capabilities of the transmitting terminal and the receiving terminal.

Referring to [Table 2], when the CBR measurement of the terminal is set as the default operation in the sidelink, the CBR measurement ability of the terminals may correspond to the fourth case.

Figure 9 shows an example of signal flow for measuring and delivering CBR in a wireless communication system according to various embodiments of the present disclosure. Figure 9 is a flowchart illustrating signal exchange between the transmitting end 901 and the receiving end 902.

Referring to FIG. 9, the transmitting end 901 according to one embodiment can be understood as a subject that transmits a signal, and the receiving end 902 can be understood as a subject that receives a signal. Accordingly, in the V2X system, transmitting terminals can operate as a transmitting end (901) and receiving terminals can operate as a receiving end (902). That is, in Figure 9, the CBR measurement operation according to the CBR measurement capabilities of the transmitting terminal and the receiving terminal and, if necessary, the operation of transmitting the CBR measured by the transmitting terminal to the receiving terminal or transmitting the CBR measured by the receiving terminal to the transmitting terminal are explained. .

Referring to FIG. 9, in step 905 according to one embodiment, the transmitting end 901 and the receiving end 902 may exchange information about CBR capabilities. As described above, when the transmitting terminal measures CBR from a transmission perspective and the receiving terminal measures CBR from a feedback perspective on transmission, the transmitting terminal and the receiving terminal may need information about each other's CBR capabilities. For example, if the transmitting terminal and the receiving terminal obtain information about each other's CBR capabilities, when the transmitting terminal requests sidelink CSI, the receiving terminal can be instructed to reflect the CBR and feed back the sidelink CSI. As another example, assuming that the basic operation of the receiving terminal is to report sidelink CSI based on CBR when the receiving terminal has CBR capability, the transmitting terminal can determine whether CBR is reflected in the SL CSI reported by the receiving terminal. You can. Additionally, depending on the environments of the transmitting terminal and the receiving terminal, the difference between the CBR measured by the transmitting terminal and the CBR measured by the receiving terminal may increase. Therefore, when the transmitting terminal and the receiving terminal become aware of each other's CBR capabilities, they can request CBR information from each other if necessary. Information about the CBR capabilities of the transmitting terminal and the receiving terminal can be exchanged during the PC5-RRC connection process. As described in Figures 4 and 5, in the case of unicast transmission of the sidelink, PC5-RRC connection can be performed between terminals.

As shown in FIG. 9, a transmitting terminal or a receiving terminal capable of CBR measurement can perform CBR measurement (steps 907 and 909). Additionally, depending on the sidelink situation, a situation may occur in which the transmitting terminal or the receiving terminal cannot measure CBR even though it has the ability to measure CBR. Additionally, depending on the environments of the transmitting terminal and the receiving terminal, the difference between the CBR measured by the transmitting terminal and the CBR measured by the receiving terminal may increase. In this case, in step 911, the transmitting end may transmit the CBR measurement result to the receiving end, or in step 913, the receiving end may transmit the CBR measurement result to the transmitting end. In FIG. 9 ,

steps

911 and 913 are shown as being performed sequentially, but this is for convenience of explanation, and steps 911 and 913 may be performed in parallel regardless of order.

For example, in the case of a transmitting terminal capable of measuring CBR, the transmitting terminal may measure the CBR (step 907) and transmit the measured CBR measurement result to the receiving terminal (step 911).

Likewise, in the case of a receiving terminal capable of measuring CBR, the receiving terminal may measure the CBR (step 909) and transmit the measured CBR measurement result to the transmitting terminal (step 913).

Additionally, if both the transmitting terminal and the receiving terminal have CBR measurement capabilities, steps 911 to 913 can all be performed.

However, the embodiment of the present disclosure is not limited to this, and even if the transmitting terminal and the receiving terminal have CBR measurement capabilities, the step of transmitting the CBR measurement result may be omitted. That is, a transmitting terminal with CBR measurement capability may not perform step 911, and a receiving terminal with CBR measurement capability may not perform step 913.

For example, whether to transmit the measured CBR information may be determined by the terminal depending on the channel environment. Alternatively, whether to transmit the CBR measurement result may be determined or set in advance (for example, CBR transmission may be set to be performed when the receiving terminal or the transmitting terminal has CBR measurement capability).

Alternatively, the CBR measurement result may be transmitted according to an indicator indicating transmission of the CBR measurement result. For example, the transmitting terminal that has received the CBR measurement capability of the receiving terminal may transmit an indicator to instruct the receiving terminal to transmit the CBR measurement result. Accordingly, the transmitting terminal can receive the CBR measurement result from the receiving terminal.

According to one embodiment, if the transmitting end and the receiving end have each other's CBR information (in case that), the transmitting end and the receiving end can more accurately determine the channel congestion situation. Specifically, the CBR level can be determined using both the CBR level of the receiving end (i.e., RX (receive) level) and the CBR level of the transmitting end (i.e., TX (transmit) level). For example, the CBR level may be determined based on Max(CBR level(TX), CBR level(RX)), which is the maximum of the CBR level of the transmitting end and the CBR level of the receiving end. In this case, the worst case for the CBR of each transmitting end and receiving end can be considered. Hereinafter, the CBR information of the transmitting end and the receiving end described in the second embodiment may be reflected to set the CR limit and transmission and feedback parameter ranges reflecting the CBR.

According to the third embodiment of the present disclosure, congestion control may be performed so that the CR value measured based on the CR defined in the first embodiment does not exceed the CR limit determined by the CBR. When the UE is configured with a CR restriction using the upper parameter and the UE transmits the PSSCH in slot n, the priority value k must satisfy the conditions of [Equation 2] below.

Here, CR(i) refers to the CR value measured in slot n-Y for PSSCH transmission in which the priority level of the priority field in SCI is set to i. Here, the value of Y is the processing time required before measuring the CR and transmitting the PSSCH in slot n, and can be defined in units of slots, and the value of Y can be a fixed value or a configurable value.

Alternatively, the value of Y may be determined according to the SCS as shown in <Table 3>. In <Table 3> below, μ is the value corresponding to SCS, refer to the definition above.

In <Table 3>, the value of Y that varies depending on SCS was proposed based on the PSSCH preparation time in the NR system. Specifically, it is assumed that in the NR system, the PUSCH preparation time is 10 symbols when μ = 0, 12 symbols when μ = 1, 23 symbols when μ = 2, and 36 symbols when μ = 3.

For example, if the value of Y is a single fixed value, Y=4. Additionally, if the value of Y is configurable, information indicating the value of Y may be included in the resource pool setting information. Before the terminal is RRC-connected to the base station, the corresponding values can be pre-configured in the terminal and can be set through SIB (system information block) from the base station. After RRC connection with the base station, it can be set to a terminal-specific value. Additionally, the value of Y can be set through the PC5-RRC connection between the terminal and the terminal. Additionally, CR _Limit (k) is a CR limit value determined to correspond to the CR value measured at nY and the priority value k, and can be set using the upper parameter. For example, the CR limit value may be determined by the CBR value measured in slot nY. This is explained in detail in FIG. 10 below. The UE must drop PSSCH transmission in slot n or satisfy the CR limitation of <Equation 2> through UE implementation. <Equation 2> can also be applied to a terminal transmitting sidelink CSI when the sidelink CSI is transmitted through PSSCH. When the terminal transmitting sidelink CSI reports the sidelink CSI through PSSCH, if the CR measured by the terminal does not satisfy the conditions of <Equation 2>, the terminal drops the report of the sidelink CSI or implements the terminal. An operation to satisfy the CR limit of <Equation 2> can be considered.

In the above-mentioned [Equation 2], the performance of congestion control by the transmitting terminal through CR measurement for PSSCH was explained. However, in the NR sidelink, performance of congestion control by the receiving terminal can be considered through CR measurement for PSFCH. As described above, when the HARQ feedback-based retransmission method is used, HARQ feedback information is transmitted on the PSFCH, and as described in FIGS. 6 and 7, CBR can be measured in the area where the PSFCH is transmitted. Therefore, congestion control can be performed so that the CR limit determined by the CBR measured in the area where the PSFCH is transmitted is not exceeded. When the terminal is set to CR limit through the upper parameter, and the receiving terminal transmits HARQ ACK/NACK feedback to the transmitting terminal through PSFCH in slot n, the priority value k is expressed as [Equation 3]: The conditions must be satisfied.

Here, CR ^FB (i) means the CR value measured in slot nZ for the PSFCH on which HARQ ACK/NACK feedback for PSSCH transmission with the priority level of the field set to i in the SCI is transmitted. Here, the value of Z is the processing time required before measuring CR and transmitting PSFCH in slot n, and can be defined in units of slots. The value of Z may be a fixed value or a configurable value. Alternatively, the value of Z may be determined according to the SCS as shown in <Table 3> above. For example, if the value of Z is a single fixed value, Z=4. Additionally, if the value of Z is configurable, information indicating the value of Z may be included in the resource pool setting information. Before the terminal is RRC-connected to the base station, the values of Z can be pre-configured in the terminal, and the terminal can receive the value of Z from the base station through SIB. After RRC connection with the base station, the terminal may have the value of Z set in a terminal-specific manner. Additionally, the value of Y may be set through the PC5-RRC connection between the terminal and the terminal.

In addition, for the definition of CR, refer to the contents measured by the receiving terminal for PSFCH transmission below. also,

is a CR limit value determined to correspond to the CR value measured at nZ and the priority value k, which can be set through the upper parameter. For example, the CR limit value may be determined based on the CBR value measured in slot nZ. These details are explained in detail in FIG. 11 below. The UE must drop HARQ ACK/NACK transmission on the PSFCH in slot n or satisfy the CR limitation of [Equation 3] through UE implementation.

Unlike the definition of CR measured by the transmitting terminal for PSSCH transmission, the CR measured by the receiving terminal for PSFCH transmission in slot n may be defined according to the following.

Definition of CR measured for PSFCH transmission

* CR is defined as the number of subchannels used by the UE by occupying a channel at slot [n-a, n-1] divided by the total number of subchannels configured as PSCFH at slot [n-a, n-1].

** Here, the channel corresponds to PSFCH.

** Here, the slot index is based on the physical slot index.

** Here, a is a positive integer and may be fixed to a predetermined value or determined as a configurable value.

*** For example, if a is determined to be a fixed value, a value of a=500 may be considered. However, the value of a may be determined by a different value. In contrast, if the value of a is configurable, information indicating the value of a may be included in resource pool setting information. Before the terminal is RRC-connected to the base station, the corresponding values can be pre-configured in the terminal and can be set through SIB from the base station. After RRC connection with the base station, the value of a may be set UE-specific.

** CR is measured for each HARQ ACK/NACK transmission.

** As explained through <Equation 3> and FIG. 11, CR can be measured for the priority level.

In the above, through <Equation 3>, the performance of congestion control using CBR and CR when the UE performs HARQ ACK/NACK feedback through PSFCH was explained. In this embodiment, when HARQ ACK/NACK feedback is disabled (enabled) and a HARQ feedback-based retransmission method is used, if the condition of <Equation 3> is not satisfied for congestion control, the receiving terminal sends HARQ ACK to the transmitting terminal. /NACK This refers to an operation that does not provide feedback. In addition, other congestion control methods may be considered for HARQ ACK/NACK feedback. That is, the CBR measurement value for the PSFCH channel can be used without using the CR measurement of <Equation 3>. In this case, the CBR measurement value for the PSFCH channel can be used by both the transmitting terminal and the receiving terminal.

According to one embodiment, when HARQ ACK/NACK feedback is disabled and a HARQ feedback-based retransmission method is used, the transmitting terminal measures the CBR for the PSFCH channel, and if the measured value is greater than the set threshold, the transmitting terminal The HARQ ACK/NACK feedback request can be canceled. Specifically, the transmitting terminal can indicate HARQ ACK/NACK feedback cancellation information by including 1 bit of information in the SCI. In contrast, when HARQ ACK/NACK feedback is disabled and a HARQ feedback-based retransmission method is used, the receiving terminal measures the CBR for the PSFCH channel and if the measured value is greater than the set threshold, HARQ ACK/NACK feedback is provided to the receiving terminal. A method that does not do so may be used. Here, the threshold value may be included in resource pool setting information. Before the terminal is connected to the RRC with the base station, the corresponding values can be pre-configured in the terminal and set through SIB from the base station. After the UE is RRC-connected to the base station, the threshold can be set UE-specific. Additionally, the threshold can be set through the PC5-RRC connection between the terminal and the terminal.

According to the fourth embodiment of the present disclosure, congestion control can be performed by setting a CR limit according to CBR and determining the range of transmission parameters that can be set according to CBR. CBR can be measured as a value between 0 and 100, but can be quantized depending on the CBR range. For example, Therefore, in the sidelink, the CR limit and the range of transmission parameters that can be set can be determined depending on the CBR level and the priority of the packet to be transmitted. The terminal can perform congestion control through CBR and CR limits and range of transmission parameters that are mapped to the highest priority of the packet to be transmitted. In FIG. 10 below, an example of CR limits and transmission parameter ranges being set according to CBR and packet priority in the sidelink is shown.

Referring to FIG. 10, the CR limit (1060) and transmission parameter range (1070) corresponding to the CBR level (1030) and the priority (1020) of the packet to be transmitted are set through the resource pool setting (1010). Here, the CBR level determined through resource pool settings and the range of CR limits and transmission parameters corresponding to the priority of the packet to be transmitted can be pre-configured in the terminal before RRC connection with the base station and set through SIB from the base station. You can receive it. After the terminal is RRC-connected to the base station, the terminal may receive terminal-specific settings for the above-mentioned values. Additionally, the CR limit and transmission parameter range corresponding to the CBR level and the priority of the packet to be transmitted may be set through the PC5-RRC connection between the terminal and the terminal. According to FIG. 10, the measured CBR can be used by mapping to the minimum and maximum values of the CBR range set according to the corresponding CBR level. According to Figure 10, the CBR level is. It can be divided into up to X CBR levels. Specific details on the range of transmission parameters (tx-Parameters) are described in detail in <Table 4> below.

As described above, congestion control can be performed by setting the transmission parameter range. For example, when the channel is congested (when the CBR value is measured to be high), the size of the subchannel to which PSSCH is allocated is reduced, the maximum value of transmission power is reduced, and the number of retransmissions is reduced, thereby reducing the number of terminals in a congested situation. Liver interference can be minimized or reduced. At the same time, by setting the MCS low and reducing the number of transmission layers, it may be possible to adjust the transmitted signal to be successfully received. Therefore, setting the range of transmission parameters by reflecting the CBR is advantageous for selecting parameters appropriate for the channel situation along with congestion control.

We will look in detail at how the transmission parameter range is set through an example in [Table 4] below. The transmission parameter set (SL-PSSCH-TxParameters) described in [Table 4] includes MCS setting range (minMCS-PSSCH, maxMCS-PSSCH), PSSCH DMRS pattern information (additional-dmrsPSSCH), and number of transmission layers (Txlayer-NumberPSSCH). ) as well as the subchannel allocation range (minSubChannel-NumberPSSCH, maxSubchannel-NumberPSSCH), and/or the number of retransmissions (allowedRetxNumberPSSCH). Additionally, assuming that CBR measurement is used, the transmission parameter set (SL-PSSCH-TxParameters) may include maximum transmission power information (maxTxPower). Some of the parameters included in the transmission parameter set (SL-PSSCH-TxParameters) described in Table 4 below may not be used, and other parameters may be additionally considered.

In [Table 4], minMCS-PSSCH and maxMCS-PSSCH can be used to indicate the MCS setting range. Alternatively, a method of setting only maxMCS-PSSCH and selecting an MCS in a range smaller than maxMCS-PSSCH may also be considered. Additionally, in [Table 4], Txlayer-NumberPSSCH indicates the number of transmission layers, where n1 may mean 1 layer transmission and n2 may mean 2 layer transmission. Additionally, both may mean that the terminal can autonomously set settings for layer 1/2. In [Table 4], allowedRetxNumberPSSCH means setting the number of retransmissions of the terminal, n0 means no retransmission, and n1, n2, and n3 mean 2, 3, and 4 retransmissions, respectively, including initial transmission. Additionally, all means that the terminal can autonomously set the value. In [Table 4], the subchannel allocation range can be indicated through minSubChannel-NumberPSSCH and maxSubchannel-NumberPSSCH. Here, the maximum number of subchannels (maxSubChannel) may vary depending on the channel bandwidth and SCS. In [Table 4], maxTxPower represents the maximum transmission power value limited for congestion control when CBR is used. In [Table 4], additional-dmrsPSSCH is PSSCH DMRS pattern information and means the number of additional DMRS symbols. When additional-dmrsPSSCH is set to 0, it indicates that only the front-loaded DMRS is transmitted, and when the additional DMRS symbol is set to 3, it indicates that up to 4 DMRS symbols are transmitted, including the front-loaded DMRS. DMRS pattern information other than the number of additional DMRS symbols may be included. Here, the density of DMRS can be increased through additional-dmrsPSSCH, and through this, reception performance can be improved by improving channel estimation performance in a low SNR region.

According to one embodiment, the transmission parameter set (SL-PSSCH-TxParameters) in [Table 4] can be set regardless of CBR. As described in the second embodiment, operations that do not use CBR through higher setting may also be considered. Regardless of CBR, the case where the transmission parameter set (SL-PSSCH-TxParameters) is set may only apply when there is no SL CSI report. In other words, if there is an SL CSI report, the transmission parameter set (SL-PSSCH-TxParameters) cannot be set regardless of CBR. When there is an SL CSI report, the transmitting terminal determines the channel status through SL CSI and selects transmission parameters. In this case, whether there is an SL CSI report can be determined by one of the following conditions.

Conditions for determining whether there is a SL CSI report or not

* Condition 1: Depending on whether SL CSI reporting is enabled

* Condition 2: Depending on whether SL CSI reporting has been triggered/activated

* Condition 3: Depending on whether the sending terminal has received a CSI report from the receiving terminal

Condition 1 is a method of determining that there is SL CSI reporting when SL CSI reporting is deactivated. Condition 2 is a method of determining that there is SL CSI reporting when SL CSI reporting is disabled and SL CSI reporting is activated. Condition 1 and Condition 2 may be the same or different depending on how SL CSI reporting is triggered and/or activated. For example, when SL CSI reporting is disabled, the case where SL CSI reporting is triggered/activated corresponds to the case where Condition 1 and Condition 2 are the same. Additionally, Condition 3 is a method for determining that there is an SL CSI report when the transmitting terminal actually receives a CSI report from the receiving terminal. If there is no SL CSI report according to condition 3, a transmission parameter set (e.g. SL-PSSCH-TxParameters) can be set regardless of CBR. If there is no SL CSI report, the transmitting terminal cannot know the terminal-to-device channel status, so there may be difficulty in selecting transmission parameters so that the receiving terminal successfully receives data transmitted by the transmitting terminal. Therefore, in this case, a set of transmission parameters (eg, SL-PSSCH-TxParameters) can be determined for each synchronization source of the terminal according to the absolute speed of the transmitting terminal. Here, the synchronization source may be at least one of a base station or GNSS (eg, global navigation satellite system).

According to one embodiment, in the case of a terminal that is not connected to the base station and Uu-RRC, at least one of GNSS or the terminal may be the synchronization source. By setting a threshold for the absolute speed of the terminal and comparing the threshold with the absolute speed of the transmitting terminal, a set of transmission parameters (SL-PSSCH-TxParameters) that can be selected is determined or identified depending on whether the speed is greater than or less than the threshold. It can be. At this time, the corresponding threshold value may be included in resource pool setting information. Before the terminal is RRC-connected to the base station, values (e.g., threshold values) can be pre-configured in the terminal and can be set through SIB from the base station. After the terminal is RRC connected to the base station, the corresponding values can be set in a terminal-specific manner. Additionally, the terminal can receive threshold settings through the PC5-RRC connection between the terminal.

Accordingly, the method by which the transmitting terminal selects transmission parameters may be determined according to the following cases.

* Case 1: If there is no SL CSI report and only a transmission parameter set (SL-PSSCH-TxParameters) unrelated to CBR is set, the transmitting terminal can select transmission parameters within the transmission parameter set.

** Case 1 corresponds to a case where CBR is set not to be used by the higher level settings.

** Case 1 corresponds to the case where a set of transmission parameters according to the absolute speed of the transmitting terminal is used.

** Case 1 may be limited to mode 2. In mode 1, the base station may indicate resource scheduling information through DCI and transmission parameter information other than resource scheduling through Uu-RRC or DCI. For example, the transmitting terminal follows transmission parameters other than resource scheduling indicated by the base station. If transmission parameters are not indicated through Uu-RRC in mode 1, case 1 above may be applied or transmission parameters may be selected by UE implementation. Referring to [Table 4], among the parameters included in SL-PSSCH-TxParameters, the resource scheduling information may include the subchannel allocation range (minSubChannel-NumberPSSCH, maxSubchannel-NumberPSSCH) and the number of retransmissions (allowedRetxNumberPSSCH). Parameters other than the above information in SL-PSSCH-TxParameters may be included in transmission parameter information other than resource scheduling.

* Case 2: When there is no SL CSI report, the first transmission parameter set (SL-PSSCH-TxParameters) unrelated to CBR is set, and the second transmission parameter set (SL-PSSCH-TxParameters) reflecting CBR through higher setting is set. When set, the transmitting terminal selects a transmission parameter within the range of parameters overlapping between the two transmission parameter sets. If no overlapping parameters exist, the transmission parameters may be selected or identified by the terminal implementation.

** Case 2 corresponds to a case where CBR is set to use by higher level settings.

** Case 2 corresponds to a case where a set of transmission parameters according to the absolute speed of the transmitting terminal and a set of transmission parameters reflecting CBR are used.

** For example, in the case of the MCS setting range described in <Table 4>, the MCS setting range of the first transmission parameter set is 0 to 5 and the MCS setting range of the second transmission parameter set is 3 to 9, so the overlapping Transmission parameters are selected from MCS setting range 3 to 5.

** Case 2 may be limited to mode 2. In Mode 1, the base station can indicate resource scheduling information through DCI and transmission parameter information other than resource scheduling through Uu-RRC or DCI. At this time, the transmitting terminal follows transmission parameters other than resource scheduling indicated by the base station. If transmission parameters are not indicated through Uu-RRC in mode 1, case 2 above may be applied or transmission parameters may be selected by UE implementation. Referring to <Table 4>, among the parameters included in SL-PSSCH-TxParameters, resource scheduling information may include the subchannel allocation range (minSubChannel-NumberPSSCH, maxSubchannel-NumberPSSCH) and the number of retransmissions (allowedRetxNumberPSSCH). Parameters other than the above information in SL-PSSCH-TxParameters may be included in transmission parameter information other than resource scheduling.

* Case 3: If there is an SL CSI report and CBR is set not to be used by the upper configuration, the parameters in the transmission parameter set (SL-PSSCH-TxParameters) may be selected or identified by the terminal implementation.

** Case 3 may be limited to mode 2. In mode 1, the base station can indicate resource scheduling information through DCI and transmission parameter information other than resource scheduling through Uu-RRC or DCI. At this time, the transmitting terminal follows transmission parameters other than resource scheduling indicated by the base station. If transmission parameters are not indicated through Uu-RRC in mode 1, the transmission parameters can be selected by the terminal implementation as in case 3 above. Referring to <Table 4>, among the parameters included in SL-PSSCH-TxParameters, resource scheduling information may include the subchannel allocation range (minSubChannel-NumberPSSCH, maxSubchannel-NumberPSSCH) and the number of retransmissions (allowedRetxNumberPSSCH). Parameters other than the above information in SL-PSSCH-TxParameters may be included in transmission parameter information other than resource scheduling.

* Case 4: If there is an SL CSI report and a transmission parameter set (SL-PSSCH-TxParameters) reflecting CBR is set through higher configuration, the transmitting terminal may select or identify transmission parameters within the transmission parameter set.

** Case 4 corresponds to the case where CBR is set to use by higher level settings.

** Case 4 may be limited to mode 2. In mode 1, the base station can indicate resource scheduling information through DCI and transmission parameter information other than resource scheduling through Uu-RRC or DCI. At this time, the transmitting terminal follows transmission parameters other than resource scheduling indicated by the base station. If transmission parameters are not indicated through Uu-RRC in mode 1, case 4 above applies or the transmission parameters can be selected by terminal implementation. Referring to <Table 4>, among the parameters included in SL-PSSCH-TxParameters, resource scheduling information may include the subchannel allocation range (minSubChannel-NumberPSSCH, maxSubchannel-NumberPSSCH) and the number of retransmissions (allowedRetxNumberPSSCH). Parameters other than the above information in SL-PSSCH-TxParameters may be included in transmission parameter information other than resource scheduling.

Below, operations after the transmitting terminal selects transmission parameters from the transmission parameter set (SL-PSSCH-TxParameters) in <Table 4> are described.

* The sending terminal can transmit based on the selected MCS and deliver the relevant information to the receiving terminal through SCI.

* The transmitting terminal can transmit based on the number of transmission layers selected and deliver the relevant information to the receiving terminal through SCI.

* In mode 2, the transmitting terminal may perform resource selection using the sensing result in consideration of the selected subchannel allocation length and number of retransmissions, and transmit the determined resource allocation information to the receiving terminal through SCI.

* The transmitting terminal can perform transmission using the selected transmission power and transmit information about the reference transmission power to the receiving terminal.

** The reference transmission power may be at least one of the transmission power of a synchronization signal, DMRS transmitted on a physical sidelink broadcast channel (PSBCH), SL CSI-RS, or another reference signal. The reference transmission power may be referred to as EPRE (energy per resource element), and may be the synchronization signal of the sidelink set within the system bandwidth (BW), DMRS transmitted on PSBCH, SL CSI-RS, or other sidelink. It can be defined as the average power (unit: watt [W]) for the resource element (RE) through which the reference signal is transmitted.

* The transmitting terminal can transmit using the pattern information of the selected PSSCH DMRS and deliver the information to the receiving terminal through SCI or deliver it to the receiving terminal through PC5-RRC.

According to the fifth embodiment of the present disclosure, a method of performing congestion control on feedback for transmission according to CBR is proposed. As described above, since CSI feedback and HARQ ACK/NACK feedback are considered in the NR sidelink, not only the operation of the transmitting terminal but also the operation of the receiving terminal for feedback on transmission can be considered for congestion control compared to the LTE sidelink. there is. CBR can be measured as a value between 0 and 100, but can be quantized depending on the CBR range. For example, Therefore, in the sidelink, the CR limit and the range of feedback parameters that can be set can be determined depending on the CBR level and the priority of the packet to be transmitted. The terminal can perform congestion control through the range of CR limits and feedback parameters mapped to the CBR and the priority of the received packet. In FIG. 11 below, an example of CR limits and feedback parameter ranges being set according to CBR and packet priority in the sidelink is shown.

Referring to FIG. 11, through the resource pool setting 1110, the CR limit 1160 and the range 1170 of the feedback parameter corresponding to the CBR level 1130 and the priority 1120 of the packet to be transmitted are set. For example, the CBR level determined through resource pool settings and the range of CR limits and feedback parameters corresponding to the priority of the received packet may be pre-configured in the terminal before the terminal is RRC-connected to the base station. It can be set through SIB from . After the terminal is RRC-connected to the base station, the terminal may receive terminal-specific settings for the above-mentioned values. Additionally, the range of CR limits and feedback parameters corresponding to the CBR level and the priority of the received packet may be set through the PC5-RRC connection between the terminal and the terminal.

According to FIG. 11, the measured CBR can be used by mapping to the minimum and maximum values of the CBR range set according to the corresponding CBR level. According to FIG. 11, the CBR level can be divided into up to X CBR levels. In this embodiment, a method of determining a CSI feedback parameter according to CBR is described. A method of performing congestion control for HARQ-ACK/NACK feedback according to CBR can be explained with reference to the third embodiment. As described above, CBR refers to a value measured by the terminal to determine whether the channel is congested in a certain time period, and the terminal can perform congestion control using the CBR value. In addition, when the receiving terminal generates SL CSI information, it selects parameters appropriate for the channel situation in consideration of the congestion situation, and when the selected parameter is fed back to the transmitting terminal, the transmitting terminal uses it as more effective information to select transmission parameters. It can be.

FIG. 12 is a diagram illustrating an example of a channel access procedure in an unlicensed band in a wireless communication system according to various embodiments of the present disclosure. A situation in which a base station performs a channel access procedure to occupy an unlicensed band is described. According to FIG. 12, a base station that wishes to transmit a downlink signal in an unlicensed band can perform a channel access procedure for the unlicensed band for a minimum T_f + m_p*T_sl time (e.g., delay period 1212 in FIG. 12). there is. T_f is an initial delay interval value and can be used to check whether the channel is in an idle state. T_sl is the channel connection attempt section, and m_p is the number of possible channel connections. If the base station wants to perform a channel access procedure with channel access priority class 3 (p=3), the size of the delay section required to perform the channel access procedure is m_p for T_f + m_p*T_sl The size of T_f + m_p*T_sl can be set using =3. Here, T_f is a fixed value of 16us (e.g., section 1210 in FIG. 12), of which the first T_sl time may be idle. In the remaining time (T_f - T_sl) after the T_sl time among the T_f times, the base station accesses the channel. The procedure may not be performed. At this time, even if the base station performs the channel access procedure in the remaining time (T_f - T_sl), channel access may not be established. In other words, the T_f - T_sl time is the delay time in performing the channel access procedure at the base station.

If the unlicensed band is idle for all of m_p*T_sl time, N can be N-1. At this time, N may be selected as an arbitrary integer value between 0 and the contention interval value (CW_p) at the time of performing the channel access procedure. For channel access priority type 3, the minimum and maximum contention interval values are 15 and 63, respectively. If the unlicensed band is determined to be idle in the delay section and the additional section performing the channel access procedure, the base station can transmit a signal through the unlicensed band during the T_mcot,p time (8 ms). In this disclosure, for convenience of explanation, embodiments are described based on downlink channel access priority classes. In the case of uplink, the same channel access priority classes in [Table 5] may be used, or a separate channel access priority class for uplink signal transmission may be used.

The initial contention interval value (CW_p) is the minimum contention interval value (CW_min,p). The base station that selects the N value performs a channel access procedure in the T_sl section (e.g., slot section 1220 in FIG. 12), and when the unlicensed band is determined to be idle through the channel access procedure performed in the T_sl section, N is N- Change the value to 1, and when N = 0, signals can be transmitted through the unlicensed band for a maximum T_mcot,p time (e.g., maximum occupancy time 1230 in FIG. 12). If the unlicensed band determined through the channel access procedure at T_sl time is not in an idle state, the base station can perform the channel access procedure again without changing the N value.

According to one embodiment, the size of the value of the contention period (CW_p) is the downlink transmitted through the downlink data channel in a reference subframe, reference slot, or reference transmission period (reference TTI). One or more terminals that have received data transmit or report downlink data to the base station, that is, downlink data received in a reference subframe, reference slot, or reference transmission interval (reference TTI). Among the reception results (ACK/NACK), it can be changed or maintained depending on the NACK ratio (Z). At this time, the reference subframe, reference slot, or reference transmission interval (reference TTI) is the time when the base station initiates the channel access procedure, and the time when the base station selects the N value to perform the channel access procedure. The downlink signal transmission interval (or the first subframe, slot, or transmission time interval (TTI) of MCOT (maximum channel occupancy time)) most recently transmitted by the base station through the unlicensed band immediately before two points in time, the above It may be determined based on any one of the start subframe, start slot, or start transmission period of the transmission period.

Referring to FIG. 12, the base station may attempt to access a channel in order to occupy an unlicensed band. At the time of initiating the channel access procedure (1202, 1270), at or immediately before the base station selects the value of N (1222) to perform the channel access procedure, the base station transmits the most recently transmitted downlink signal through the unlicensed band. The first slot (or start slot that starts the channel occupancy period) of the section (channel occupancy time, hereinafter MCOT, 1230), subframe, or transmission section (1240) is the reference slot, reference subframe, or It can be defined as a standard transmission section. The first slot of the transmission section 1230 is hereinafter expressed as a reference slot for convenience of explanation.

For example, among all slots in the downlink signal transmission section 1230, one or more consecutive slots, including the first slot in which a signal is transmitted, may be defined as a reference slot. Additionally, according to one embodiment, if the downlink signal transmission period starts after the first symbol of the slot, the slot where downlink signal transmission starts and the slot following the slot may be defined as a reference slot. If the rate of NACK among the reception results for downlink data transmitted or reported to the base station by one or more terminals that received downlink data transmitted through the downlink data channel in this reference slot is greater than Z, the base station The value or size of the contention interval used in the access procedure (1270) can be determined as the contention interval that is next larger than the contention interval used in the previous channel access procedure (1202). In other words, the base station can increase the size of the contention section used in the channel access procedure 1202. The base station can perform the next channel access procedure (1270) by selecting the value of N (1222) from the range defined according to the contention section of the increased size.

If the base station cannot obtain a reception result for the downlink data channel transmitted in the reference slot of the transmission period 1230, for example, between the reference slot and the time when the base station initiates the channel access procedure (1270) When the time interval is less than n slots or symbols (in other words, when the base station initiates the channel access procedure before the minimum time for the terminal to report to the base station the reception results for the downlink data channel transmitted in the reference slot), The first slot of the most recent downlink signal transmission section transmitted before the downlink signal transmission section 1230 may be the reference slot.

In other words, reception of downlink data transmitted at the time when the base station initiates the channel access procedure (1270), or when the base station selects the value of N to perform the channel access procedure, or in the reference slot immediately before that (1240) If the result is not received from the terminal, the base station receives the terminal's downlink data for the reference slot in the most recently transmitted downlink signal transmission section among the reception results for the downlink data channel previously received from the terminals. The results can be used to determine or identify the competitive zone. Additionally, the base station can determine the size of the contention interval used in the channel access procedure (1270) using the downlink data reception results received from the terminals for downlink data transmitted through the downlink data channel in the reference slot.

For example, a base station that transmitted a downlink signal through a channel access procedure (e.g., CW_p=15) set according to channel access priority type 3 (p=3), among the downlink signals transmitted through the unlicensed band, , if more than 80% of the terminal's reception results for downlink data transmitted to the terminal through the downlink data channel in the reference slot are determined to be NACK, the contention period is changed from the initial value (e.g., CW_p=15) to the next. It can be increased to the contention interval value (for example, CW_p=31). The ratio value of 80% is exemplary and various variations are possible.

If more than 80% of the terminal's reception results are not determined to be NACK, the base station can maintain the value of the contention interval as the existing value or change it to the initial value of the contention interval. At this time, the change in contention interval can be commonly applied to all channel access priority types or can be applied only to the channel access priority type used in a specific channel access procedure. At this time, in the reference slot where the change in contention section size is determined, the change in contention section size among the reception results for downlink data transmitted or reported by the terminal to the base station for downlink data transmitted through the downlink data channel. The method for determining the Z value is as follows.

If the base station transmits one or more codewords (CW) or TB to one or more terminals in the reference slot, the base station selects the TB received by the terminal in the reference slot from among the reception results transmitted or reported by the terminal. The Z value can be determined by the ratio of NACK. For example, when two codewords or two TBs are transmitted to one terminal in a reference slot, the base station can receive or report the reception results of downlink data signals for two TBs from the terminal. If, among the two reception results, the NACK ratio (Z) is equal to or greater than a predefined or set threshold between the base station and the terminal (e.g., Z=80%), the base station changes or increases the contention section size. You can do it.

At this time, if the terminal bundles the reception results of downlink data for one or more slots (e.g., M slots) including the reference slot and transmits or reports to the base station, the base station It can be determined that has been transmitted. And the base station can determine the Z value based on the ratio of NACK among the M reception results and change, maintain, or initialize the contention section size.

If the reference slot is the second of two slots included in one subframe, or if a downlink signal is transmitted from a symbol after the first symbol in the reference slot, the reference slot and the next slot are used as the reference slot. This is determined, and the Z value can be determined as the ratio of NACK among the reception results transmitted or reported by the terminal to the base station for the downlink data received in the reference slot.

In addition, when the scheduling information or downlink control information for the downlink data channel transmitted by the base station is transmitted in the same cell or frequency band as the cell or frequency band in which the downlink data channel is transmitted, or the downlink data transmitted by the base station In the case where scheduling information or downlink control information for a channel is transmitted through an unlicensed band, but is transmitted in a different cell or at a different frequency from the cell in which the downlink data channel is transmitted, reception of the downlink data received by the terminal in the reference slot If it is determined that the result is not transmitted, or if the reception result for downlink data transmitted by the terminal is determined to be at least one of DTX (discontinuous transmission), NACK/DTX, or any state, the base station transmits the terminal's reception result as NACK The Z value can be determined by determining .

According to one embodiment, when scheduling information or downlink control information for a downlink data channel transmitted by a base station is transmitted through a licensed band, the reception result for downlink data transmitted by the terminal is DTX, or NACK/ If at least one of DTX or any state is determined, the base station may not reflect the terminal's reception result in the reference value Z of the contention interval change. In other words, the base station may ignore the terminal's reception result and determine the Z value.

According to one embodiment, when the base station transmits scheduling information or downlink control information for a downlink data channel through a licensed band, among the reception results of downlink data for the reference slot transmitted or reported by the terminal to the base station, If the base station does not actually transmit downlink data (no transmission), the base station can determine the Z value by ignoring the reception result transmitted or reported by the terminal for the downlink data.

Additionally, in 5G NR, it may be possible to consider and apply it as a reference duration instead of a reference slot. The period from the start of the COT to the end of the first slot in which at least one unicast PDSC is transmitted and received without puncturing in a scheduled resource may be referred to as a reference interval. Alternatively, the reference interval may be from the start of the COT to the end of the first transmission burst in which at least one unicast PDSCH is included without puncturing in the scheduled resource. And, in the case of TB unit transmission method, if the HARQ-ACK value for at least one unicast PDSCH within the reference interval is ACK, the terminal determines the contention interval size as the minimum value, otherwise, the contention interval size value It may be possible to further increase it by 1. In the case of the CBG unit transmission method, if the ratio of HARQ-ACK information values for PDSCHs within the reference interval is at least 10% or more, the terminal determines the contention interval size to be the minimum value, otherwise, the contention interval size value is set to the minimum value. It may be possible to further increase it by 1.

In the case of downlink, the contention section size of the base station is adjusted using CBG-based HARQ-ACK information, data information that is not unicast, data transmission not in slot units, or a no transmission event in which data is scheduled but not actually transmitted. It may be possible to decide. For example, when CBG-based HARQ-ACK information transmission is set, it may be possible to determine the Z value by individually considering the ACK or NACK information and HARQ-ACK information for each CBG. In addition, in the case of non-unicast data information, there is no HARQ-ACK information transmission, so when determining ACK or NACK information, it may always be possible to judge it as ACK, NACK, or neither. Not determining the ACK/NACK information means that the Z value is not determined by considering the feedback information for the corresponding unicast data information because it is not available.

According to one embodiment, adjusting the contention section size of the terminal in the uplink case is similar to adjusting the contention section size of the base station in the downlink case, but when determining the reference section, unicast PUSCH, not unicast PDSCH, is considered, and HARQ-ACK In the case of information, it may be possible to make an implicit determination using HARQ-ACK information explicitly indicated through the base station or through a New Data Indicator (NDI) included in the DCI that schedules the PUSCH. For example, if the 1-bit NDI value for a specific HARQ process number is toggled differently from before, the terminal determines that the transmission of the previously transmitted PUSCH was successful (ACK), and if it is not toggled, the terminal determines that the transmission of the previously transmitted PUSCH was successful (ACK). It may be possible to determine that transmission of a previously transmitted PUSCH failed (NACK). Being toggled means that the NDI value changes from 1 to 0 or from 0 to 1, and not toggled means that the NDI value remains from 1 to 1 or from 0 to 0. it means.

If HARQ-ACK information for the previously transmitted PUSCH is available within the determined reference interval, if it is ACK, the terminal determines the contention interval size to be the minimum value, and if it is NACK, the contention interval size value can be further increased by 1. Additionally, HARQ-ACK information for a previously transmitted PUSCH within the determined reference interval may not always be available. Therefore, if the transmission of the PUSCH is an initial transmission or a PUSCH transmitted during the reference period, the UE applies the size of the contention section to be the same as the size of the contention section used immediately before. On the other hand, if the transmission of the PUSCH is a retransmission, the UE applies the contention section size as the same as the size of the contention section used immediately before. Increase the section size value by 1.

The channel access procedure in the unlicensed band can be classified depending on whether the channel access procedure initiation point of the communication device is fixed (frame-based equipment, FBE) or variable (load-based equipment, LBE). In addition to the time of starting the channel access procedure, the communication device may be determined to be an FBE device or an LBE device depending on whether the transmit/receive structure of the communication device has one cycle or no cycle. Here, the fact that the channel access procedure start time is fixed may mean that the channel access procedure of the communication device may be started periodically according to a predefined period or a period declared or set by the communication device. As another example, the fact that the channel access procedure start time is fixed may mean that the transmission or reception structure of the communication device has one cycle. For example, saying that the channel access procedure start time is variable may mean that the channel access procedure start time of the communication device is possible at any time when the communication device wants to transmit a signal through an unlicensed band. As another example, saying that the channel access procedure start time is variable may mean that the transmission or reception structure of the communication device does not have a single period and can be determined as needed.

The channel access procedure in the unlicensed band allows the communication device to use the unlicensed band for a fixed time or a time calculated according to a predefined rule (for example, at least a time calculated through one random value selected by the base station or terminal). Measures the strength of a signal received through a predefined threshold, channel bandwidth, the bandwidth of the signal through which the signal to be transmitted is transmitted, and/or the strength of the transmitted power. It may include a procedure for determining the idle state of the unlicensed band by comparing with a threshold calculated by a function that determines the size of.

For example, the communication device measures the strength of the received signal for If it is less than the calculated threshold T (e.g. -72dBm), it is determined that the unlicensed band is idle, and the set signal can be transmitted. At this time, the maximum time for continuous signal transmission after the channel access procedure may be limited according to the maximum channel occupancy time (MCOT) defined by country, region, and frequency band for each unlicensed band. . Additionally, the above-described maximum time may also be limited depending on the type of communication device (eg, base station or terminal). For example, in the case of Japan, in the 5 GHz unlicensed band, a base station or terminal can occupy a channel and transmit a signal without performing an additional channel access procedure for up to 4 ms for an unlicensed band determined to be idle after performing a channel access procedure.

More specifically, when a base station or terminal wants to transmit a downlink or uplink signal in an unlicensed band, the channel access procedures that the base station or terminal can perform can be divided into at least the following types.

- Type 1: Transmit uplink/downlink signals after performing channel access procedures for a variable period of time

- Type 2: Transmit uplink/downlink signals after performing channel access procedures for a fixed time

- Type 3: Transmission of downlink or uplink signals without performing channel access procedures

A transmitting device (eg, a base station or terminal) that wishes to transmit a signal in an unlicensed band can determine the method (or type) of the channel access procedure depending on the type of signal to be transmitted. In 3GPP, the LBT procedure, which is a channel access method, can be broadly divided into four categories. The four categories are a first category that does not perform LBT, a second category that performs LBT without random backoff, and a method that performs LBT through random backoff in a fixed-size competition window. The third category may include a fourth category that performs LBT through random backoff in a contention window of variable size. According to one embodiment, in the case of type 1, the third category and the fourth category may be exemplified, in the case of type 2 the second category may be exemplified, and in the case of type 3 the first category may be exemplified. At this time, in the case of type 2 or the second category in which the channel access procedure is performed for a fixed time, it may be divided into one or more types depending on the fixed time for performing the channel access procedure. For example, Type 2 is a type that performs the channel attach procedure for a fixed time Aμs (e.g. 25us) (Type 2-1) and a type that performs the channel attach procedure for a Bμs fixed time (e.g. 16us) (Type 2-1) It can be divided into 2-2).

Although the above description mainly describes the downlink, in which a base station transmits a signal to a terminal, or the uplink, in which a terminal transmits a signal to a base station, it can also be fully applied to the sidelink, in which a terminal transmits a signal to another terminal.

Hereinafter, in this disclosure, for convenience of explanation, the transmitting device is assumed to be a base station or a terminal, and the terms transmitting device and base station may be used interchangeably. Additionally, a sidelink can be assumed instead of a downlink, and in this case, the base station may be replaced by a terminal.

For example, if the base station wishes to transmit a downlink signal including a downlink data channel in an unlicensed band, the base station may perform a type 1 channel access procedure. And when the base station wants to transmit a downlink signal that does not include a downlink data channel in an unlicensed band, for example, when it wants to transmit a synchronization signal or a downlink control channel, the base station performs a type 2 channel access procedure. And a downlink signal can be transmitted.

At this time, the method of the channel access procedure may be determined depending on the transmission length of the signal to be transmitted in the unlicensed band or the length of time or section used by occupying the unlicensed band. Generally, in the Type 1 method, the channel access procedure can be performed for a longer time than when the channel access procedure is performed in the Type 2 method. Therefore, if the communication device wishes to transmit a signal for a short time period or a time period of less than a standard time (eg, Xms or Y symbol), a type 2 channel access procedure can be performed. On the other hand, if the communication device wishes to transmit a signal for a long time period or a time exceeding or exceeding a reference time (for example, Xms or Y symbols), a type 1 channel access procedure may be performed. In other words, different types of channel access procedures may be performed depending on the usage time of the unlicensed band.

If the transmitting device performs a Type 1 channel access procedure according to at least one of the above-mentioned criteria, the transmitting device that wishes to transmit a signal in the unlicensed band must check the Quality of service Class (QCI) of the signal that it wishes to transmit in the unlicensed band. Identifier) determines the channel access priority class (or channel access priority). The transmitting device may perform a channel access procedure using at least one of the predefined setting values as shown in [Table 5] previously described for the determined channel access priority type. [Table 5] shows the mapping relationship between channel access priority types and QCI. At this time, the channel access priority type and QCI mapping relationship shown in [Table 5] is only an example and is not limited to this.

For example,

QCI

1, 2, and 4 are services such as Conversational Voice, Conversational Video (Live Streaming), and Non-Conversational Video (Buffered Streaming), respectively. It means the QCI value for .

Alternatively, the type of channel access procedure performed may be different depending on whether the transmitting device supports LBE or FBE. For example, in the case of a transmitting device supporting LBE, it is possible to perform at least one channel access method of types 1 to 3, while in the case of a transmitting device supporting FBE, it is possible to perform only the channel access method of type 2. It may be possible.

Alternatively, it may be possible for the transmitting device to apply different types of channel access methods depending on specific situations. As an example, it may be possible for a transmitting device to use a type 1 channel access method to initiate channel occupancy (MCOT). As another example, after the transmitting device occupies the channel, different transmission bursts exist within the channel-occupied section and the gap between these bursts is more than Xus (for example, 16us). , the transmitting device may use a type 2 channel access method. In another example, after the transmitting device occupies the channel, the gap between different transmission bursts within the channel-occupied section is Xus (e.g., 16us) or less, and the total length of the second burst is Yus (e.g. For example, if it is 584us or less, the transmitting device can use a type 3 channel access method. The transmission burst may be at least one of downlink, uplink, or sidelink synchronization/control/data channels, or a combination thereof. The transmission burst may mean a bundle of channels in which the transmission channels are consecutively concatenated from a time resource perspective.

Hereinafter, in the description, the terms communication device and terminal are used as the same concept, and may be used interchangeably. The transmitting end refers to a communication device that transmits data, and the receiving end refers to a communication device that receives data. Additionally, the transmitting end may refer to a communication device that occupies a channel for data transmission, and the receiving end may refer to a communication device that sends the feedback to the transmitting end when sending HARQ-ACK feedback according to data reception.

Below, an embodiment related to mode 1 operation in an unlicensed band will be described in detail. If the band between the terminal and the base station or between the terminal and the terminal is a licensed band, as described above in FIG. 4, the terminal performs sidelink control and data information transmission in the PSCCH/PSSCH transmission resource area allocated from the base station without any additional operation. It is possible to perform. However, if the terminal and the base station communicate in a licensed band, and the sidelink communication between the terminals is in an unlicensed band, the terminal performs channel sensing (LBT) before using the PSCCH/PSSCH transmission resource area allocated from the base station, so that the channel becomes idle. Sidelink control and data information transmission will be possible only when it is determined to be (Idle). Additionally, if the channel is determined to be busy as a result of channel sensing (LBT), sidelink control and data information transmission are not performed on the corresponding transmission resource. For reference, in the above description, the standard for the terminal to judge a channel as idle or busy is to judge the channel as idle if the received energy intensity as a result of channel sensing by the terminal is below a certain threshold. Conversely, as a result of channel sensing by the terminal, the channel is judged to be idle. If the intensity is above a certain threshold, the channel is judged to be busy.

Therefore, it is difficult for the base station to determine whether the transmitting terminal has succeeded in sidelink control and transmitting data information using the sidelink resources scheduled by the base station, and due to the nature of the unlicensed band, resources other than those scheduled for the terminal performing sidelink communication are used. It is difficult to determine whether a terminal using a different RAT (Radio Access Technology) is connected in a different resource area.

For example, if the resource area scheduled by the base station in mode 1 in a specific time and frequency resource area is A, resources B other than A are terminals that use other RATs such as IEEE-based Wi-Fi (wireless fidelity). It may be possible to use this. For reference, a terminal performing the sidelink communication technology may be able to operate based on the 3GPP standard. In addition, since unlicensed bands can be used for free as long as they comply with country-specific regulations for coexistence, communication between heterogeneous devices using their own communication technologies can be possible. Therefore, the base station knows that it has scheduled resources such as A to each sidelink terminal in the unlicensed band, but may not know or be unable to identify the existence of terminals using different RATs, such as B.

Therefore, it may be desirable for the terminal to directly or indirectly provide unlicensed band channel occupancy status information to the base station. If the base station can receive unlicensed band channel occupancy information from the terminal, then during mode 1 scheduling, potential channel occupancy failures for transmitting and receiving sidelink information can be reduced. The channel occupation failure means that the sidelink terminal is busy as a result of channel sensing for sidelink control and data transmission. When the sidelink channel is an unlicensed band, the basic operation of mode 1 is similar to that described above in FIG. 4, but when the base station provides SIB information to terminals, unlicensed band-related information may be additionally provided. For example, the method for channel access (dynamic channel access method or semi-static channel access method), priority information for channel access, section for channel access, etc. may apply, as shown in [Table 6]. May contain information.

The following description explains how the terminal provides unlicensed band channel information to the base station. The sixth and seventh embodiments, as described in FIG. 4, relate to a method of adding the unlicensed band channel information when the terminal sends HARQ-ACK information to the base station through the PUCCH (425). The eighth embodiment relates to a method for the terminal to report the results of sensing for a specific frequency/time resource region to the base station.

According to one embodiment, when the terminal transmits HARQ feedback information to the base station on PUCCH, the terminal may be able to add at least one of the following information in addition to HARQ feedback information consisting of ACK or NACK and transmit it together. For example, the terminal may transmit to the base station by adding at least one of first type information or second type information in addition to HARQ feedback information.

Hereinafter, as described in FIG. 4, the transmitting terminal (or first terminal) may refer to a subject transmitting PSCCH/PSSCH, and the receiving terminal (or second terminal) may refer to a subject receiving PSCCH/PSSCH.

- Type 1 information: Type 1 information is when the transmitting terminal cannot transmit the sidelink control and data information because the channel sensing result is busy before transmitting the sidelink control and data information on the sidelink resource provided by the base station. It may be information that means. In other words, this may be information indicating a case where the first type information transmission terminal fails to occupy a channel.

- Second type information: The second type information is a terminal that receives the sidelink control and data information because the channel sensing result is idle before the transmitting terminal transmits the sidelink control and data information on the sidelink resource provided by the base station. This may be information indicating a case where the sidelink feedback information was not transmitted because the channel sensing result was busy before the receiving terminal transmitted the corresponding sidelink feedback information. That is, the second type of information may be information indicating a case where transmission is not possible due to channel occupation failure. That is, the second type of information may be information indicating a case where the transmitting terminal succeeds in occupying the channel, but the receiving terminal fails to occupy the channel. If only NACK-only feedback is transmitted in a situation where the transmitting terminal transmits sidelink control and data information to the receiving terminal, the second type information may be invalid. The NACK-only feedback may mean that the receiving terminal transmits feedback only when demodulation/decoding of data received from the transmitting terminal fails. That is, if demodulation/decoding of data is successful, the terminal may not transmit feedback. Additionally, in order to determine the second type of information, the transmitting terminal may be able to determine only when the energy reception intensity is below a certain level. This is because, even if the receiving terminal determines that the channel is idle as a result of channel sensing and transmits feedback information to the transmitting terminal, the transmitting terminal may not be able to demodulate/decode it properly.

For reference, in this situation, NACK information may mean a case where the sidelink HARQ feedback information received by the transmitting terminal from the receiving terminal indicates NACK after the transmitting terminal transmits sidelink control and data information. in other words. NACK information in this situation may mean that both the transmitting terminal and the receiving terminal succeeded in occupying the channel and transmitted and received control and data information, but the receiving terminal failed to demodulate/decode the data.

If (in case that) the existing ACK or NACK structure is used as is, it is difficult for the transmitting terminal to separately transmit the three pieces of information (e.g., first type information, second type information, NACK) to the base station. Therefore, NACK can be sent. Additionally, when the base station also receives a NACK from the transmitting terminal, it may be difficult to distinguish whether the NACK sent by the transmitting terminal refers to first type information, second type information, or the NACK itself. Therefore, it may be possible to consider at least one of the following methods to solve this problem.

When a plurality of methods exist, the base station may be able to select one of the plurality of methods based on terminal-common, terminal-specific, or group terminal-specific higher signal information. Alternatively, it may be possible to determine one of the following methods according to the DCI information of the PDCCH to which the base station allocates resources.

According to one embodiment, when one of the following methods is determined by DCI information, there may be an explicit method or an implicit method. The explicit method means determining one of the following methods as a separate bit field, and the implicit method is to determine one of the following methods by using the existing field of information allocating existing sidelink resources (e.g. resource allocation field, HARQ process field, etc.). It may be possible for a method to be determined. Alternatively, when the terminal reports to the base station, it may be possible to indicate which of the following methods was selected when reporting HARQ-ACK information.

- Method 2-1: The transmitting terminal can distinguish three states (ACK, NACK, first type information) and transmit HARQ-ACK information on PUCCH. Because there are a total of three states, the terminal needs 2 bits of information. For example, it may be possible to indicate 00 as NACK, 11 as ACK, and 10 as first type information. However, this is only an example and it may be possible for a different bitmap to be applied to each state. According to method 2-1, the second type information may not be separately indicated, and it may be possible for the second type information to be included in NACK information or to be included in first type information.

- Method 2-2: The transmitting terminal can distinguish three states (e.g. ACK, NACK, second type information) and transmit HARQ-ACK information on PUCCH. Because there are a total of three states, the terminal may need 2 bits of information. For example, it may be possible to indicate NACK if 00, ACK if 11, and second type information if 10. However, this is only an example and it may be possible for a different bitmap to be applied to each state. According to this method, the first type information may not be separately indicated, and it may be possible for the first type information to be included in NACK information or to be included in second type information.

- Method 2-2: The transmitting terminal can transmit HARQ-ACK information on PUCCH by distinguishing four states (e.g., ACK, NACK, first type information, second type information). Because there are a total of 4 states, the terminal may need 2 bits of information. For example, it may be possible to indicate NACK if 00, ACK if 11, first type information if 10, and second type information if 01. However, this is only an example and it may be possible for a different bitmap to be applied to each state.

According to one embodiment, it may be possible for the terminal to provide information indicating whether or not to access a channel consisting of n bits (or at least one bit) separately from the existing HARQ-ACK information on the PUCCH transmitted to the base station. For example, if ACK means 1 and NACK means 0, the terminal is allocated 5 scheduling resources from the base station and performs sidelink control and data transmission on each transmission resource, for a total of 5 scheduling resources. Information about channel access can be reported to the base station using bit information. For example, in the case of 11100, it means that the sidelink control and data transmission corresponding to the first three were successful, and the sidelink control and data transmission corresponding to the last two failed.

According to one embodiment, when the base station receives NACK, as described above, it cannot determine whether it is due to the first type information, the second type information, or the NACK itself, so 1 bit is added to the NACK information. It may be possible to tell whether it is due to type 1 information or not. That is, the transmitting terminal may be able to send feedback information to the base station with a total of 6 bits configured in the form of 11100 + X. If X=1, it means that the NACK information is the first type information, and if X=0, it means that the NACK information is not the first type information. However, this is only an example and various methods may be considered as follows, and at least one of these methods may be applied. When a plurality of methods exist, the base station may be able to select one of the plurality of methods based on terminal-common, terminal-specific, or group terminal-specific higher signal information. Alternatively, it may be possible to determine one of the following methods according to the DCI information of the PDCCH to which the base station allocates resources.

According to one embodiment, when one of the following methods is determined by DCI information, there may be an explicit method or an implicit method. For example, the explicit method means determining one of the following methods as a separate bit field, and the implicit method refers to the existing field of information that allocates existing sidelink resources (e.g. resource allocation field, HARQ process field, etc.) It may be possible for one method to be determined. Alternatively, when the terminal reports to the base station, it may be possible to indicate which of the following methods was selected when reporting HARQ-ACK information.

- Method 3-1: The transmitting terminal can inform the base station with 1-bit information that at least one of the NACK information is related to the first type of information. For example, when the transmitting terminal transmits a total of 5 pieces of feedback information, if at least one value 0 corresponding to NACK is included, it may be possible to indicate whether the 0 is due to first type information or not with 1 bit. That is, in a situation configured as "11100X", the first 5 bits mean ACK or NACK for each sidelink control and data channel transmission/reception. In this case, NACK refers to the remaining states except ACK. Then, for the two NACKs indicated with a value of 0, X has a value of 1 if at least one is due to the first type information. If both NACKs with a value of 0 are not due to type 1 information, X has a value of 0. Therefore, 1 bit of X has the role of providing additional information about whether the bit value indicated as NACK is first type information or not. As another example, if X=1 in the case of “11111X”, it may be possible to consider this as an error case. This is because the indication value of X is meaningless because it is all ACK. Alternatively, in the case of “11111X”, it may be possible to determine that both the values 0 and 1 for X are possible. However, from the base station's perspective, the bit value corresponding to X must be ignored. This is because there is no NACK information.

- Method 3-2: The transmitting terminal can inform the base station with 1-bit information that at least one of the NACK information is related to the second type of information. For example, when the transmitting terminal transmits a total of 5 pieces of feedback information, if at least one value 0 corresponding to NACK is included, it may be possible to indicate whether it is due to second type information or not with 1 bit for 0. That is, in a situation configured as "11100X", the first 5 bits mean ACK or NACK for each sidelink control and data channel transmission/reception. In this case, NACK refers to the remaining states except ACK. Then, for the two indicated by NACK with a value of 0, X has a value of 1 if at least one is due to the second type information. If both NACKs with a value of 0 are not due to type 1 information, X has a value of 0. Therefore, 1 bit of X has the role of providing additional information about whether the bit value indicated as NACK is second type information or not. As another example, if X=1 in the case of “11111X”, it may be possible to consider this as an error case. This is because the indication value of X is meaningless because it is all ACK. Alternatively, in the case of “11111X”, it may be possible to determine that both the values 0 and 1 for X are possible. However, from the base station's perspective, the bit value corresponding to X must be ignored. This is because there is no NACK information.

- Method 3-3: The transmitting terminal can inform the base station with 2-bit information that at least one of the NACK information is related to the first type information or the second type information. For example, when the transmitting terminal transmits a total of 5 pieces of feedback information, if at least one value 0 corresponding to NACK is included, it may be possible to indicate whether or not it is due to the first type information with 1 bit for 0. That is, in a situation configured as "11100XY", the first 5 bits mean ACK or NACK for each sidelink control and data channel transmission/reception. In this case, NACK refers to the remaining states except ACK. Then, for the two NACKs indicated with a value of 0, X has a value of 1 if at least one is due to the first type information. If both NACKs with a value of 0 are not due to type 1 information, X has a value of 0. Similarly, if at least one of the two indicated by NACK with a value of 0 is due to the second type information, Y has a value of 1. If both NACKs with a value of 0 are not due to the second type information, Y has a value of 0. Therefore, 1 bit of Y has the role of providing additional information about whether the bit value indicated as NACK is first type information or not. If both X and Y are 1, the base station can determine that at least two pieces of information marked as NACK are first type information and second type information, respectively. As another example, in the case of “11111XY”, if X=1 or Y=1, it may be possible to consider this as an error case. This is because the indication values of X and Y are meaningless because they are all ACKs. Alternatively, in the case of "11111XY", it may be possible to determine that either X or Y is possible as a value of 0 or 1. However, from the base station's perspective, the bit values corresponding to X and Y must be ignored. This is because there is no NACK information.

- Method 3-4: The transmitting terminal divides the ACK/NACK information into n groups (or at least one group 0) and informs each group whether it is related to the first type of NACK information. Example For example, when the transmitting terminal transmits a total of 5 pieces of feedback information, and in a situation where each group can contain a maximum of 3 pieces of feedback information, 2 groups will be formed. Expressing this in a mathematical formula, ceiling(5/ 3) It can be expressed as = 2. Therefore, the bit size indicating the first type information is 2. And, if there is at least a value of 0 corresponding to NACK for each group, the first bit is set to 1 bit for the corresponding 0. It may be possible to tell whether it is due to type information or _not . That is, in a situation consisting of "10100X ₁ Here, NACK refers to the remaining states excluding ACK. The first group is 101, and for one NACK with a value of 0, if at least one is due to the first type information, X ₁ has a value of 1. . If the ₁ indicated by NACK with a value of 0 is not due to the first type information, then If at least one of the NACKs is due _to type ₁ information, then Therefore _, _X ₁ _and It may be possible for the bits indicating the presence or absence of first type information recognition for each group to be arranged as follows: "101X ₁ 00X ₂ ". This is only an example. In addition, it may be possible for bits indicating groups of bits and first type information related thereto to be mapped in various ways. Additionally, although two groups were assumed in the above example, more groups are possible. The number of groups is determined or identified by the number of HARQ-ACK bits transmitted on the PUCCH, and the size of the bits providing the first type information may also vary depending on the number of groups.

- Method 3-5: The transmitting terminal divides the ACK/NACK information into n groups (at least one group) and informs each group whether the NACK information is related to the second type of information. For example, when transmitting a total of 5 pieces of feedback information, if each group can contain up to 3 pieces of feedback information, 2 groups will be formed. If this is expressed mathematically, it can be expressed as ceiling(5/3)=2. Accordingly, the bit size indicating the second type information is 2. And, if there is at least a value of 0 corresponding to NACK for each group, it may be possible to indicate whether it is due to second type information or not with 1 bit for 0. That is, in a situation consisting _of "10100X ₁ In this case, NACK refers to the remaining states except ACK. The first group is 101, and for one NACK with a value of 0, if at least one is due to the first type information, X ₁ has a value of 1. If the one indicated by NACK with a value of 0 is not due to the second type information, X ₁ has a value of 0. The second group is 00, and if at least one of the 1 items indicated by NACK with a value of 0 is due to the second type information, X ₂ has a value of 1. If the one indicated by NACK with a value of 0 is not due to the second type information, X ₂ has a value of 0. Accordingly, X ₁ _and _In "10100X ₁ "101X ₁ 00X ₂ ". However, this is only an example, and it may be possible for bits indicating groups of bits and second type information related thereto to be mapped in various ways. Additionally, although two groups were assumed in the above example, more groups are possible. The number of groups is determined or identified by the number of HARQ-ACK bits transmitted on PUCCH, and the size of bits providing second type information may also vary depending on the number of groups.

- Method 3-6: The transmitting terminal divides the ACK/NACK information into n groups (or at least one group 0) and informs each group whether it is related to the second type of NACK information. Example For example, when transmitting a total of 5 pieces of feedback information, if each group can contain a maximum of 3 pieces of feedback information, 2 groups will be formed. Expressing this in a mathematical formula, ceiling(5/3)= It may be expressed as 2. Accordingly, the bit sizes indicating the first type information and the second type information are each 2. And, if there is at least a value of 0 corresponding to NACK for each group, 2 bits for 0. It may be possible to tell whether it is due to the first type information and _the second type information. That is, in a _{situation consisting of "10100X 1} _Y ₁ It means ACK or NACK regarding whether to transmit or receive. In this case, NACK means the remaining states excluding ACK. The first group is 101, and for each one indicated by NACK with a value of 0, at least one is provided. If it _is due to type ₁ information, If at least one of the items indicated by NACK with a value of 0 is due to the second type information, Y ₁ has a value of 1. If one item indicated by a NACK with a value of 0 is due to the second type information, Y 1 has a value of 1. Otherwise, Y ₁ has a value of 0. The second group is 00, and if at least one of the 1 indicated by NACK with a value of 0 is due to the first type information, X ₂ has a value of 1. has. If ₁ indicated by NACK with a value of 0 is not due to the first type information, If at least one of the 1 occurrences is due to the second type information, Y ₂ has the value of 1. If the one indicated by NACK with a value of 0 is not due to the second type information, Y ₂ has a value of 0. Accordingly, X ₁ _and Y ₁ and Y ₂ , which are composed of 1 bit for each group, have the role of providing additional information about whether the bit value indicated as NACK is second type information or not. In " _10100X ₁ _Y ₁ "101X ₁ Y ₁ 00X ₂ Y ₂ ". However, this is only an example, and it may be possible for bits indicating groups of bits and related first type information and second type information to be mapped in various ways. Additionally, although two groups are assumed in the above-described example, more groups are possible. The number of groups is determined by the number of HARQ-ACK bits transmitted on PUCCH, and the size of bits providing first type and second type information may also vary depending on the number of groups.

- Method 3-7: This is a combination of the above methods, and the transmitting terminal can separately include bit fields indicating first type and second type information and transmit them to the base station, and each bit size can be different. For example, it may be possible that there is 1 group of HARQ-ACK information bits corresponding to the first type of information, while there are 2 groups of HARQ-ACK information bits corresponding to the second type of information. . In this _case _,

According to one embodiment, the terminal can sense the sidelink channel status operating in the unlicensed band according to the base station settings or instructions and report the sensing result to the base station. For example, the channel through which the terminal reports the sensing result may be PUCCH or PUSCH, and information indicating the sensing result may be information such as UCI or MAC CE. The method by which the base station sets up or instructs the terminal to report the sensing results may be indicated by a higher-order signal or an L1 signal. Depending on the settings, the terminal may report the sensing results temporarily (or aperiodically), periodically, or in an event manner. In the case of the event method, it is reported when the sensing value changes by more than a certain threshold compared to what was previously reported.

Figure 13 is a diagram explaining a channel sensing method in which a terminal reports to a base station according to an embodiment. The terminal may receive related configuration information for channel sensing before reporting channel sensing from the base station. For example, in Figure 13, the terminal receives at least one of a time interval 1300, a frequency interval 1302, a time unit 1306, a frequency unit 1304, and a set 1316 composed of time or frequency units from the base station. It can be set as a higher level signal in advance. A value that is not set may be determined as a default value or may be considered not to be considered when the terminal reports channel sensing information. For example, the frequency unit may correspond to a subchannel, one RB, or a plurality of RBs. For example, the time unit may correspond to one of a slot, a subslot, a subframe, a frame, or a symbol. For example, the time interval may be a time unit such as 1ms or 2ms, a value composed of a plurality of slots, or a value composed of a plurality of subframes. For example, the frequency section may be a plurality of subchannels, a plurality of RBs, or (one or more) sidelink resource pool units.

Based on the information of the time section 1300, frequency section 1302, time unit 1306, and/or frequency unit 1304 of FIG. 13, the minimum frequency and time unit capable of sensing in the terminal will be configured. can be performed, and the terminal performs sensing for each minimum unit. At this time, the channel sensing method may be a method of measuring the resource area where the reference signal is transmitted and received (hereinafter, channel sensing method 1), or a method of measuring the received energy intensity (hereinafter, channel sensing method 2), or another method. This may be a method of demodulating/decoding the SCI included in the PSCCH transmitted by the terminal (hereinafter referred to as channel sensing method 3).

According to one embodiment, in channel sensing method 1 and channel sensing method 2, the terminal determines or identifies whether the measured value is greater than, equal to, or less than the value set by the base station or a predetermined threshold, and accordingly, the corresponding minimum unit The star sensing result is determined or determined as a value of 0 or 1. For example, if the signal strength measured through

channel sensing method

1 or 2 is 10 and the threshold value is 5, it may be possible to determine the sensing result as 1. For example, if the signal strength measured through

channel sensing method

1 or 2 is 3 and the threshold is 5, it may be possible to determine the sensing result as 0. For example, if the signal strength measured through

channel sensing method

1 or 2 is 5 and the threshold value is 5, it may be possible to determine the sensing result as 0 or 1.

According to one embodiment, in channel sensing method 3, if the terminal can determine the SCI value as a result of SCI demodulation/decoding, it may be possible to determine 1, otherwise, it may be possible to determine 0. The criteria for determining the sensing result as 0 or 1 are merely examples, and it may be possible to determine the opposite or a combination of the above-described factors. Additionally, the channel sensing method may be able to consider additional information other than values of 0 or 1. For example, it may be possible to consider channel sensing methods 2 and 3 simultaneously. For example, it is determined whether the signal strength measured through channel sensing method 2 is greater than or equal to the threshold, and additionally, it is determined whether SCI demodulation/decoding was performed through channel sensing method 3. Accordingly, even if the signal strength measured through channel sensing method 2 is greater than the threshold, it may be possible to further distinguish depending on whether SCI demodulation/decoding has been successfully performed according to channel sensing method 3.

13 as an example, if the signal strength measured through channel sensing method 2 in a specific frequency/time unit (or resource) 1310 is less than the threshold, the terminal will not allow any other terminal to transmit the signal at the minimum frequency/time unit. It can be determined that is not being transmitted. And, if the signal strength measured through channel sensing method 2 in a specific frequency/time unit (or resource) 1314 is greater than the threshold, but SCI demodulation/decoding fails through channel sensing method 3, the terminal This means a case where a signal was transmitted at the minimum frequency/time unit, but the terminal did not obtain SCI information. An example of this case may be when terminals with different RAT interfaces (e.g., Wi-Fi) transmit and receive signals on resources including the minimum frequency/time unit.

And, if the signal strength measured through channel sensing method 2 in a specific frequency/time unit (or resource) 1312 is greater than the threshold, but SCI demodulation/decoding is successful through channel sensing method 3, in this case, other sidelinks This corresponds to the case where the terminal transmits PSCCH. Therefore, the terminal can determine that a terminal operating in the same RAT has transmitted and received a signal at the minimum frequency/time unit. Although the above example was described as a combination of channel sensing 2 and 3, it may be fully possible to operate with other channel sensing combinations. Additionally, when various channel sensing methods are available, the base station may be able to set in advance which channel sensing method or combination thereof is to be applied as a higher level signal. Additionally, it may be possible to report to the base station which terminal can apply which channel sensing method or combination thereof according to the terminal capability report.

According to the channel sensing methods described above, it may be possible to determine the bitmap size that the terminal reports to the base station. For example, when the terminal reports based only on

channel sensing method

2, 1 bit of information is configured for each minimum frequency/time resource, including a time section 1300, a frequency section 1302, a time unit 1306, The total number of resources is determined according to the frequency unit 1304. For example, as shown in Figure 13, a total of 64 resources are divided according to time section 1300, frequency section 1302, time unit 1306, and frequency unit 1304, so 64 bits are required to report the channel sensing result. is needed.

As another example, when channel sensing method 2 or 3 is considered together, a total of 3 states must be reported as described above, and 2 bits of information are required for each minimum frequency/time resource, so a total of 128 bits are required. do. For example, the frequency/time unit (or resource) 1310 may be expressed as 00, 1312 as 10, and 1314 as 11. This is only an example and may be determined by other bit values. A method of determining the bit order may include first mapping from the reference time to the frequency axis and then mapping in the next time order, or mapping from the reference frequency to the time axis and then mapping in the next frequency order. The order of time or frequency may be mapped from the smallest value to the largest value, or from the largest value to the smallest value.

When the terminal reports a bit value representing the channel sensing result to the base station, the base station can optimize and perform mode 1 scheduling based on the channel sensing result reported by the terminal. As described above, the size of the bit reported by the terminal is determined according to the time interval 1300, frequency interval 1302, time unit 1306, and/or frequency unit 1304, so there is a possibility that the bit size becomes larger. You can. Accordingly, it may be possible to consider a method combining a plurality of time and frequency minimum units.

In FIG. 13, 16 resources defined by four time units 1306 and four frequency units 1304 can be formed into one time and frequency group unit 1316. A total of 64 resources shown in FIG. 13 are grouped into four time units and four frequency units, and these groups can be understood as one new time and frequency group unit. The terminal can report the channel sensing result in time and frequency group units as 1 bit, and at this time, the terminal performs channel sensing for each group depending on whether more than 1/2 of the time and frequency group units have a value of 1. The result can be reported as a value of 1 or 0. The terminal determines 1 if more than 1/2 of the channel sensing results for resources belonging to each time and frequency group have a value of 1, and 0 otherwise. Here, the value of 1/2 is only an example, other values are possible, and it can be set as a higher signal from the base station. The above example can be fully applied to a situation where channel sensing results in time and frequency group units are reported in 2 bits.

According to one embodiment, the method of determining the time and frequency group unit 1316 and the method of determining the number are specifically described again by taking the time section 1300 and/or the frequency section 1302 as an example. In the time and frequency group unit 1316, when the time group is T, the frequency group unit is F, the time section 1300 is A, and the frequency section 1302 is B, the number of groups in terms of time is ceiling(A/T) Or it can be determined by flooring (A/T). In terms of frequency, the number of groups can be determined by ceiling (B/F) or flooring (B/F). If there are a total of 2 time groups and the total number of slots in the time section is 7, the number of slots for each group cannot be the same, so it may be possible for the first group to be composed of 4 slots and the second group to be composed of 3 slots. there is. Likewise, if there are a total of 2 frequency groups and the total number of subchannels in the frequency section is 7, the number of slots for each group cannot be the same, so the first group consists of 4 subchannels and the second group consists of 3 subchannels. It may be possible.

Figure 14 is a flowchart configuring a procedure for reporting channel sensing results of a terminal according to an embodiment. As described in the eighth embodiment, the terminal can receive sidelink channel status request information in advance from the base station as an upper signal. The request information is either information instructing the terminal to report the channel status only once (aperiodically), information instructing it to report periodically, or information instructing the terminal to report only when a specific condition is satisfied (e.g., an event occurs). It can contain at least one. The configuration information transmitted from the base station to the terminal may also indicate or determine a method of performing channel sensing by the terminal. If the terminal reports that it supports multiple channel sensing methods as a terminal capability, the base station may configure or instruct to perform one or multiple channel sensing methods.

In addition, the base station sets at least one of the time section 1300, frequency section 1302, time unit 1306, frequency unit 1304, or time and frequency group 1316 for channel sensing described in FIG. 13 to the terminal. It may be possible to do or instruct. The terminal performs sidelink channel sensing according to the base station configuration information, generates information, and reports the channel sensing information to the base station. Reporting of the channel sensing information can be done through PUCCH or PUSCH. At this time, it may be possible to receive settings from the base station in advance regarding which physical channel the information generated by the terminal is sent.

According to one embodiment, a method performed by a first terminal of a wireless communication system includes receiving a signal for requesting a channel state between the first terminal and the second terminal from a second terminal, It may include performing measurement and transmitting information about the channel state generated based on the results of the performed measurement to the second terminal. The information about the channel state may include information indicating the degree to which the channel between the first terminal and the second terminal is congested.

According to one embodiment, a first terminal of a wireless communication system includes a transceiver and at least one processor connected to the transceiver, and the at least one processor is configured to transmit a signal from a second terminal between the first terminal and the second terminal. It is set to receive a signal for requesting a channel state, perform measurement on the channel state, and transmit information about the channel state generated based on the results of the performed measurement to the second terminal, and the channel The information about the status may include information indicating the degree to which the channel between the first terminal and the second terminal is congested.

Referring to FIG. 15, as described in the sixth and seventh embodiments, the transmitting terminal is allocated resources for sidelink signal transmission from the base station. Additionally, the transmitting terminal performs channel sensing in the unlicensed band before transmitting a signal on the allocated sidelink channel, and can decide whether to transmit the signal depending on whether the channel sensing result is idle or busy. For example, if the channel sensing result is busy, the transmitting terminal does not perform signal transmission, and if the channel sensing result is idle, the transmitting terminal performs signal transmission. And when the receiving terminal needs to send feedback for the corresponding signal transmission, the transmitting terminal receives feedback information from the receiving terminal in an indicated or preset resource area. If the transmitting terminal fails to send a signal, the transmitting terminal does not need to receive feedback information from the receiving terminal. Through the above process, the transmitting terminal reports the results of sidelink signal transmission and reception to the base station.

The above-described sixth to eighth embodiments mainly explain that the sidelink terminal operating in the unlicensed band sends related information to the base station because the base station does not know the unlicensed band channel usage information, but they can be sufficiently applied to other similar environments. It may be possible. For example, if the base station operates only in the first RAT (e.g., NR) band and does not know whether to use the channel of the second RAT (e.g., LTE), the sidelink terminal operating in the second RAT informs the base station. It may be possible to send information related to the second RAT.

According to one embodiment, the information includes 2 bits, and the 2 bits are ACK (acknowledgement), NACK (negative acknowledgment), the failure of the transmission of the PSCCH due to the failure of the channel access procedure, or the PSSCH. It may indicate failure of the reception of the PSFCH due to the failure of the transmission or the failure of the channel access procedure.

According to one embodiment, the information includes bits for indicating acknowledgment (ACK) or negative acknowledgment (NACK) and indicating that the NACK indicated by at least one of the bits is due to the failure of the channel access procedure. It may contain bits that do.

According to one embodiment, the method includes transmitting channel information measured for each of the scheduled resources based on the resource information to the base station, and receiving, from the base station, resource information of the unlicensed band based on the channel information. It may include receiving and performing at least one of transmission of PSCCH, transmission of PSSCH, or reception of PSFCH with respect to the resource information in the unlicensed band based on the channel information.

According to one embodiment, the information includes bits for indicating acknowledgment (ACK) or negative acknowledgment (NACK) and indicating that the NACK indicated by at least one of the bits is due to the failure of the channel access procedure. Can contain bits.

According to one embodiment, the controller transmits channel information measured for each of the scheduled resources based on the resource information to the base station, and receives resource information of the unlicensed band based on the channel information from the base station. It may be configured to receive and perform at least one of transmission of PSCCH, transmission of PSSCH, or reception of PSFCH with respect to the resource information in the unlicensed band based on the channel information.

According to one embodiment, the information includes 2 bits, and the 2 bits are ACK (acknowledgement), NACK (negative acknowledgment), failure of the transmission of the PSCCH due to failure of the channel access procedure, or the transmission of the PSSCH It may indicate failure of transmission or reception of the PSFCH due to the failure of the channel access procedure.

According to one embodiment, the information includes bits for indicating acknowledgment (ACK) or negative acknowledgment (NACK) and indicating that the NACK indicated by at least one of the bits is due to a failure of the channel access procedure. Can contain bits.

According to one embodiment, the method includes receiving measured channel information for each of the scheduled resources based on the resource information from the first terminal, and providing the first terminal with the license-exempt information based on the channel information. It may include transmitting band resource information.

Figure 16 is a diagram showing the structure of a terminal according to embodiments of the present disclosure.

Referring to FIG. 16, the terminal of the present disclosure may include a transmission/reception unit 1610, a storage unit 1620, and/or a terminal control unit (or terminal processor 1630). The terminal control unit 1630, transceiver unit 1610, and storage unit 1620 of the terminal may operate according to the above-described communication method of the terminal. However, the components of the terminal are not limited to the examples described above. For example, the terminal may include more or fewer components than the aforementioned components. In addition, the terminal control unit 1630, the transceiver unit 1610, and the storage unit 1620 may be implemented in the form of a single chip.

The transceiver unit 1610 is a general term for the terminal receiver unit and the terminal transmitter unit. The transceiver unit 1610 can transmit and receive signals with other terminals, base stations, or network entities. Signals transmitted and received with other terminals or base stations may include control information and data. To this end, the transceiver 1610 may be comprised of an RF (radio frequency) transmitter that up-converts and amplifies the frequency of the transmitted signal, and an RF receiver that amplifies the received signal with low noise and down-converts the frequency. However, this is only an example of the transceiver 1610, and the components of the transceiver 1610 are not limited to the RF transmitter and RF receiver.

Additionally, the transceiver 1610 may include a wired or wireless transceiver and may include various components for transmitting and receiving signals. Additionally, the transceiver 1610 may receive a signal through a wireless channel and output it to the terminal control unit 1630, and transmit the signal output from the terminal control unit 1630 through a wireless channel. Additionally, the transceiver unit 1610 may receive a communication signal and output it to the terminal control unit 1630, and transmit the signal output from the terminal control unit 1630 to another terminal or base station through a wired or wireless network.

The storage unit 1620 can store programs and data necessary for operation of the terminal. Additionally, the storage unit 1620 may store control information or data included in signals obtained from the terminal. The storage unit 1620 may be composed of a storage medium such as ROM, RAM, hard disk, CD-ROM, and DVD, or a combination of storage media.

The terminal control unit 1630 can control a series of processes so that the terminal can operate according to the embodiment of the present disclosure described above. The terminal control unit 1630 may include at least one processor. For example, the terminal control unit 1630 may include a communication processor (CP) that performs control for communication and an application processor (AP) that controls upper layers such as application programs.

Figure 17 is a diagram showing the structure of a base station according to embodiments of the present disclosure.

Referring to FIG. 17, the base station of the present disclosure may include a transceiver unit 1710, a storage unit 1720, and a base station control unit (or processor, 1730). The base station control unit 1730, transceiver unit 1710, and storage unit 1720 of the base station may operate according to the above-described communication method of the base station. However, the components of the base station are not limited to the above examples. For example, a base station may include more or fewer components than those described above. In addition, the base station control unit 1730, transceiver unit 1710, and storage unit 1720 of FIG. 17 may be implemented in the form of a single chip.

The transceiving unit 1710 is a general term for the receiving unit of the base station and the transmitting unit of the base station, and can transmit and receive signals to and from a terminal and/or network entity. At this time, the transmitted and received signals may include control information and data. To this end, the transceiver 1710 may be composed of an RF transmitter that up-converts and amplifies the frequency of the transmitted signal, and an RF receiver that amplifies the received signal with low noise and down-converts the frequency. However, this is only an example of the transceiver 1710, and the components of the transceiver 1710 are not limited to the RF transmitter and RF receiver. The transceiver 1710 may include a wired or wireless transceiver and may include various components for transmitting and receiving signals.

In addition, the transceiver 1710 may receive a signal through a communication channel (e.g., a wireless channel) and output it to the base station control unit 1730, and transmit the signal output from the base station control unit 1730 through the communication channel. . Additionally, the transceiver unit 1710 may receive a communication signal and output it to the base station control unit 1730, and transmit the signal output from the base station control unit 1730 to a terminal or network entity through a wired or wireless network.

The storage unit 1720 can store programs and data necessary for the operation of the base station. Additionally, the storage unit 1720 may store control information or data included in signals obtained from the base station. The storage unit 1720 may be composed of a storage medium such as ROM, RAM, hard disk, CD-ROM, and DVD, or a combination of storage media.

The base station control unit 1730 can control a series of processes so that the base station can operate according to the above-described embodiment of the present disclosure. The base station control unit 1730 may include at least one processor. Methods according to embodiments described in the claims or specification of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

The storage unit may store at least one of information transmitted and received through the transmitting and receiving unit and information generated through the base station control unit.

Methods according to embodiments described in the claims or specification of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

When implemented as software, a computer-readable storage medium that stores one or more programs (software modules) may be provided. One or more programs stored in a computer-readable storage medium are configured to be executable by one or more processors in an electronic device (configured for execution). One or more programs include instructions that cause the electronic device to execute methods according to embodiments described in the claims or specification of the present disclosure.

These programs (software modules, software) include random access memory, non-volatile memory including flash memory, read only memory (ROM), and electrically erasable programmable ROM. (EEPROM: Electrically Erasable Programmable Read Only Memory), magnetic disc storage device, Compact Disc-ROM (CD-ROM: Compact Disc-ROM), Digital Versatile Discs (DVDs), or other types of It can be stored in an optical storage device or magnetic cassette. Alternatively, it may be stored in a memory consisting of a combination of some or all of these. Additionally, multiple configuration memories may be included.

In addition, the program may be operated through a communication network such as the Internet, an intranet, a local area network (LAN), a wide LAN (WLAN), or a storage area network (SAN), or a combination thereof. It may be stored on an attachable storage device that is accessible. This storage device can be connected to a device performing an embodiment of the present disclosure through an external port. Additionally, a separate storage device on a communication network may be connected to the device performing an embodiment of the present disclosure.

In the specific embodiments of the present disclosure described above, elements included in the disclosure are expressed in singular or plural numbers depending on the specific embodiment presented. However, singular or plural expressions are selected to suit the presented situation for convenience of explanation, and the present disclosure is not limited to singular or plural components, and even components expressed in plural may be composed of singular or singular. Even expressed components may be composed of plural elements.

Meanwhile, in the detailed description of the present disclosure, specific embodiments have been described, but of course, various modifications are possible without departing from the scope of the present disclosure. For example, part or all of some embodiments may be combined with part or all of one or more other embodiments, and it is natural that the form of such combination also corresponds to the embodiments proposed in the present disclosure. Therefore, the scope of the present disclosure should not be limited to the described embodiments, but should be determined not only by the scope of the patent claims described later, but also by the scope of the claims and their equivalents.

Claims

In a method performed by a first terminal in a wireless communication system,

Receiving, from a base station, resource information of an unlicensed band for sidelink communication with a second terminal;

For the resource information in the unlicensed band, a channel access procedure for at least one of transmission of a physical sidelink control channel (PSCCH), transmission of a physical sidelink shared channel (PSSCH), or reception of a physical sidelink feedback channel (PSFCH) identifying that an access procedure has failed; and

Method comprising transmitting, to the base station, information indicating failure of the channel access procedure.
In claim 1,

The information includes 2 bits,

The 2 bits are ACK (acknowledgement), NACK (negative acknowledgment), failure of the transmission of the PSCCH due to the failure of the channel access procedure, or failure of the transmission of the PSSCH, or due to the failure of the channel access procedure. A method for indicating failure of the reception of the PSFCH.
In claim 1,

The information includes bits for indicating acknowledgment (ACK) or negative acknowledgment (NACK) and a bit indicating that the NACK indicated by at least one of the bits is due to the failure of the channel access procedure, method.
In claim 1,

Transmitting, to the base station, channel information measured for each of scheduled resources based on the resource information;

Receiving resource information of the unlicensed band based on the channel information from the base station: and

A method comprising performing at least one of transmission of PSCCH, transmission of PSSCH, or reception of PSFCH with respect to the resource information in the unlicensed band based on the channel information.
In a first terminal in a wireless communication system,

transceiver; and

Including a controller coupled to the transceiver,

The controller:

From the base station, receive resource information of an unlicensed band for sidelink communication with a second terminal,

For the resource information in the unlicensed band, a channel access procedure for at least one of transmission of a physical sidelink control channel (PSCCH), transmission of a physical sidelink shared channel (PSSCH), or reception of a physical sidelink feedback channel (PSFCH) fails. identify things,

A first terminal configured to transmit, to the base station, information indicating failure of the channel access procedure.
In claim 5,

The information includes 2 bits,

The 2 bits are ACK (acknowledgement), NACK (negative acknowledgment), failure of the transmission of the PSCCH due to the failure of the channel access procedure, or failure of the transmission of the PSSCH, or due to the failure of the channel access procedure. A first terminal indicating failure of the reception of the PSFCH.
In claim 5,

The information includes bits for indicating acknowledgment (ACK) or negative acknowledgment (NACK) and a bit indicating that the NACK indicated by at least one of the bits is due to the failure of the channel access procedure. 1 terminal.
In claim 5,

The controller:

Transmitting measured channel information for each of the resources scheduled based on the resource information to the base station,

From the base station, receive resource information of the unlicensed band based on the channel information,

A first terminal configured to perform at least one of transmission of PSCCH, transmission of PSSCH, or reception of PSFCH with respect to the resource information in the unlicensed band based on the channel information.
In a method performed by a base station in a wireless communication system,

Transmitting, to a first terminal, resource information of an unlicensed band for sidelink communication with a second terminal; and

From the first terminal, with respect to the resource information in the unlicensed band, at least one of transmission of a physical sidelink control channel (PSCCH), transmission of a physical sidelink shared channel (PSSCH), or reception of a physical sidelink feedback channel (PSFCH) A method comprising receiving information indicating that a channel access procedure for a channel connection procedure has failed.
In claim 9,

The information includes 2 bits,

The 2 bits are ACK (acknowledgement), NACK (negative acknowledgment), failure of the transmission of the PSCCH due to failure of the channel access procedure, or failure of the transmission of the PSSCH, or failure of the channel access procedure. A method for indicating failure of said reception of PSFCH.
In claim 9,

The information includes bits for indicating acknowledgment (ACK) or negative acknowledgment (NACK) and a bit indicating that the NACK indicated by at least one of the bits is due to failure of the channel access procedure. .
In claim 9,

Receiving, from the first terminal, channel information measured for each of the resources scheduled based on the resource information; and

A method comprising transmitting resource information of the unlicensed band based on the channel information to the first terminal.
In a base station in a wireless communication system,

transceiver; and

Including a controller coupled to the transceiver,

The controller:

Transmitting, to the first terminal, resource information of an unlicensed band for sidelink communication with the second terminal,

From the first terminal, with respect to the resource information in the unlicensed band, at least one of transmission of a physical sidelink control channel (PSCCH), transmission of a physical sidelink shared channel (PSSCH), or reception of a physical sidelink feedback channel (PSFCH) A base station configured to receive information indicating that a channel access procedure for a base station has failed.
In claim 13,

The information includes 2 bits,

The 2 bits are ACK (acknowledgement), NACK (negative acknowledgment), failure of the transmission of the PSCCH due to failure of the channel access procedure, or failure of the transmission of the PSSCH, or failure of the channel access procedure. A base station indicating failure of said reception of PSFCH.
In claim 13,

The information includes bits for indicating acknowledgment (ACK) or negative acknowledgment (NACK) and a bit indicating that the NACK indicated by at least one of the bits is due to failure of the channel access procedure. .