KR20210010267A - A method and apparatus for channel state measurement and reporting in sidelink communication - Google Patents

Abstract

The present invention relates to a communication technique and a system for combining IoT technology with a 5G communication system for supporting a higher data transmission rate after a 4G system. The present invention can be applied to intelligent services (e.g., smart home, smart building, smart city, smart car or connected car, healthcare, digital education, retail, security and safety-related services, etc.) based on 5G communication technology and IoT-related technology. According to an embodiment of the present invention, a method of a transmission terminal comprises: a step of receiving channel state information (CSI) determined based on channel busy ratio (CBR) information and the CBR information from a reception terminal; a step of determining a transmission parameter based on the CSI; and a step of transmitting the transmission parameter to the reception terminal.

Description

Method and device for measuring and reporting channel status in sidelink communication {A METHOD AND APPARATUS FOR CHANNEL STATE MEASUREMENT AND REPORTING IN SIDELINK COMMUNICATION}

The present invention relates to a mobile communication system, and in particular, a receiving terminal in a process in which a vehicle terminal supporting vehicle communication (vehicle-to-everything, hereinafter V2X) transmits and receives information using a sidelink with another vehicle terminal and a pedestrian mobile terminal. It relates to a method and apparatus for measuring the channel state and reporting it to a transmitting terminal.

Efforts are being made to develop an improved 5G communication system or a pre-5G communication system in order to meet the increasing demand for wireless data traffic after the commercialization of 4G communication systems. For this reason, the 5G communication system or the pre-5G communication system is called a communication system after a 4G network (Beyond 4G Network) or a system after an LTE system (Post LTE). In order to achieve a high data rate, the 5G communication system is being considered for implementation in the ultra-high frequency (mmWave) band (eg, such as the 60 Giga (60 GHz) band). In order to mitigate the path loss of radio waves in the ultra-high frequency band and increase the transmission distance of radio waves, in 5G communication systems, beamforming, massive MIMO, and Full Dimensional MIMO (FD-MIMO) ), array antenna, analog beam-forming, and large scale antenna technologies are being discussed. In addition, in order to improve the network of the system, in 5G communication system, advanced small cell, advanced small cell, cloud radio access network (cloud RAN), ultra-dense network , Device to Device communication (D2D), wireless backhaul, moving network, cooperative communication, CoMP (Coordinated Multi-Points), and interference cancellation And other technologies are being developed. In addition, in the 5G system, advanced coding modulation (ACM) methods such as Hybrid FSK and QAM Modulation (FQAM) and SWSC (Sliding Window Superposition Coding), advanced access technologies such as Filter Bank Multi Carrier (FBMC), NOMA (non orthogonal multiple access), and sparse code multiple access (SCMA) have been developed.

On the other hand, the Internet is evolving from a human-centered network in which humans generate and consume information, to an Internet of Things (IoT) network that exchanges and processes information between distributed components such as objects. IoE (Internet of Everything) technology, which combines IoT technology with big data processing technology through connection with cloud servers, is also emerging. In order to implement IoT, technology elements such as sensing technology, wired/wireless communication and network infrastructure, service interface technology, and security technology are required, and recently, a sensor network for connection between objects, machine to machine , M2M), and MTC (Machine Type Communication) technologies are being studied. In the IoT environment, intelligent IT (Internet Technology) services that create new value in human life by collecting and analyzing data generated from connected objects can be provided. IoT is the field of smart home, smart building, smart city, smart car or connected car, smart grid, healthcare, smart home appliance, advanced medical service, etc. through the convergence and combination of existing IT (information technology) technology and various industries. Can be applied to.

Accordingly, various attempts have been made to apply a 5G communication system to an IoT network. For example, technologies such as sensor network, machine to machine (M2M), and MTC (Machine Type Communication) are implemented by techniques such as beamforming, MIMO, and array antenna. There is. As the big data processing technology described above, a cloud radio access network (cloud RAN) is applied as an example of the convergence of 5G technology and IoT technology.

The present invention relates to a wireless communication system, in which a receiving terminal measures a channel state and reports it to a transmitting terminal while a vehicle terminal supporting V2X transmits and receives information using a sidelink with another vehicle terminal and a pedestrian mobile terminal. It relates to a method and apparatus.

Specifically, the present invention proposes a method for transmitting a reference signal for measuring a channel state in a sidelink by a transmitting terminal, and a method for measuring and reporting a channel through the receiving terminal.

The method of the transmitting terminal of the present invention for solving the above and the problem is to receive channel state information (CSI) and the CBR information determined based on channel busy ratio (CBR) information from a receiving terminal. Step, determining a transmission parameter based on the CSI, and transmitting the transmission parameter to a receiving terminal.

In addition, the method of the receiving terminal of the present invention for solving the above and the problem is the step of determining channel state information (CSI) based on channel busy ratio (CBR) information, and transmitting the CSI. And receiving a transmission parameter determined based on the CSI.

In addition, in the transmitting terminal of the present invention for solving the above and the problem, channel state information (CSI) determined based on channel busy ratio (CBR) information from the transmitting and receiving unit and the receiving terminal, and And a control unit for receiving the CBR information, determining a transmission parameter based on the CSI, and transmitting the transmission parameter to a receiving terminal.

In addition, in the receiving terminal of the present invention for solving the above and the problem, channel state information (CSI) is determined based on the transmission/reception unit and channel busy ratio (CBR) information, and the It characterized in that it comprises a control unit for transmitting the CSI, and receiving a transmission parameter determined based on the CSI.

According to the present invention, by proposing a method for a receiving terminal to measure a channel state and report it to a transmitting terminal in sidelink communication, transmission efficiency of the sidelink can always be improved. In addition, the channel status reporting method according to the proposed method can be effectively used for congestion control.

In addition, in order for the receiving terminal to more stably support link state measurement through this, a reference signal transmission method according to the proposed method of the present invention may be used.

1A and 1B are diagrams illustrating a system according to an embodiment of the present disclosure.
2 is a diagram illustrating a V2X communication method performed through a sidelink according to an embodiment of the present disclosure.
FIG. 3 is a diagram illustrating a resource pool defined as a set (set) of resources on time and frequency used for transmission and reception of a sidelink according to an embodiment of the present disclosure.
4 is a diagram illustrating a method for a base station to allocate transmission resources in a sidelink according to an embodiment of the present disclosure.
5 is a diagram illustrating a method of directly allocating transmission resources of a sidelink through sensing by a terminal in a sidelink according to an embodiment of the present disclosure.
6 is a diagram illustrating an example in which a receiving terminal measures a channel state in a sidelink and reports it to a transmitting terminal according to an embodiment of the present disclosure.
7 is a diagram illustrating a channel state information framework of an NR sidelink system according to an embodiment of the present disclosure.
8 is a diagram illustrating a CSI-RS pattern according to an embodiment of the present disclosure.
9 is a diagram illustrating CSI-RS transmission resources and CSI-RS reporting resources according to an embodiment of the present disclosure.
10 is a diagram illustrating a process of measuring and exchanging CBR between a transmitting terminal and a receiving terminal according to an embodiment of the present disclosure.
11 is a block diagram illustrating an internal structure of a terminal according to an embodiment of the present disclosure.
12 is a block diagram showing an internal structure of a base station according to an embodiment of the present disclosure.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

In describing the embodiments, descriptions of technical contents that are well known in the technical field to which the present disclosure pertains and are not directly related to the present disclosure will be omitted. This is to more clearly convey the gist of the present disclosure by omitting unnecessary description.

For the same reason, some components in the accompanying drawings are exaggerated, omitted, or schematically illustrated. In addition, the size of each component does not fully reflect the actual size. The same reference numerals are assigned to the same or corresponding components in each drawing.

Advantages and features of the present disclosure, and a method of achieving them will be apparent with reference to the embodiments described below in detail together with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below, but may be implemented in a variety of different forms, and only these embodiments make the present disclosure complete, and those skilled in the art to which the present disclosure pertains. It is provided to completely inform the scope of the present disclosure to the person, and the present disclosure is only defined by the scope of the claims. The same reference numerals refer to the same components throughout the specification.

At this time, it will be appreciated that each block of the flowchart diagrams and combinations of the flowchart diagrams may be executed by computer program instructions. Since these computer program instructions can be mounted on the processor of a general purpose computer, special purpose computer or other programmable data processing equipment, the instructions executed by the processor of the computer or other programmable data processing equipment are described in the flowchart block(s). It creates a means to perform functions. These computer program instructions can 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 way, so that the computer-usable or computer-readable memory It is also possible to produce an article of manufacture containing instruction means for performing the functions described in the flowchart block(s). Computer program instructions can also be mounted on a computer or other programmable data processing equipment, so that a series of operating steps are performed on a computer or other programmable data processing equipment to create a computer-executable process to create a computer or other programmable data processing equipment. It is also possible for instructions to perform processing equipment to provide steps for executing the functions described in the flowchart block(s).

In addition, each block may represent a module, segment, or part of code that contains one or more executable instructions for executing the specified logical function(s). In addition, it should be noted that in some alternative execution examples, functions mentioned in blocks may occur out of order. For example, two blocks shown in succession may in fact be executed substantially simultaneously, or the blocks may sometimes be executed in reverse order depending on the corresponding function.

In this case, the term'~ unit' used in the present embodiment refers to software or hardware components such as FPGA or ASIC, and'~ unit' performs certain roles. However,'~ part' is not limited to software or hardware. The'~ unit' may be configured to be in an addressable storage medium, or may be configured to reproduce one or more processors. Thus, as an example,'~ unit' 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, database, data structures, tables, arrays, and variables. The components and functions provided in the'~ units' may be combined into a smaller number of elements and'~ units', or may be further divided into additional elements and'~ units'. In addition, components and'~ units' may be implemented to play one or more CPUs in a device or a security multimedia card. Also, in an embodiment, the'~ unit' may include one or more processors.

In a detailed description of the embodiments of the present disclosure, a wireless access network New RAN (NR) based on a 5G mobile communication standard disclosed by 3rd generation partnership project long term evolution (3GPP), a mobile communication standard standardization organization, and a packet core ( 5G System, or 5G Core Network, or NG Core: next generation core) is the main target, but the main point of this disclosure is to the extent that other communication systems with similar technical backgrounds do not depart from the scope of the present disclosure. It can be applied with slight modifications, which will be possible at the judgment of a person skilled in the technical field of the present disclosure.

In the 5G system, in order to support network automation, a network data collection and analysis function (NWDAF), which is a network function that provides a function of analyzing and providing data collected from a 5G network network, may be defined. The NWDAF can collect/storage/analyze information from 5G networks and provide the results to an unspecified network function (NF), and the analysis results can be used independently in each NF.

For convenience of description below, some terms and names defined in the 3GPP standard (5G, NR, LTE or similar system standard) may be used. However, the present disclosure is not limited by terms and names, and may be equally applied to systems conforming to other standards.

In addition, terms for identifying access nodes, terms for network entities (network entities), terms for messages, terms for interfaces between network entities, and various identification information used in the following description Terms and the like referring to them are exemplified for convenience of description. Therefore, it is not limited to the terms used in the present disclosure, and other terms that refer to objects having an equivalent technical meaning may be used.

In order to meet the increasing demand for wireless data traffic after the commercialization of 4G communication systems, efforts are being made to develop an improved 5G communication system (NR, New Radio). In order to achieve a high data rate, the 5G communication system has been designed to enable resources in the ultra high frequency (mmWave) band (eg, the 28 GHz frequency band). In order to mitigate the path loss of radio waves in the ultra-high frequency band and increase the transmission distance of radio waves, in 5G communication systems, beamforming, massive MIMO, and Full Dimensional MIMO (FD-MIMO) ), array antenna, analog beam-forming, and large scale antenna technologies are being discussed. In addition, unlike LTE, the 5G communication system resources various subcarrier spacings such as 30 kHz, 60 kHz, and 120 kHz, including 15 kHz, and the physical control channel uses Polar Coding. The data channel (Physical Data Channel) uses LDPC (Low Density Parity Check). In addition, as a waveform for uplink transmission, not only DFT-S-OFDM but also CP-OFDM are used. In LTE, HARQ (Hybrid ARQ) retransmission in units of TB (Transport Block) is a resource, whereas 5G may additionally resource HARQ retransmission based on a CBG (Code Block Group) in which several code blocks (CBs) are grouped.

In addition, in order to improve the network of the system, in 5G communication system, advanced small cell, advanced small cell, cloud radio access network (cloud RAN), ultra-dense network , Device to Device communication (D2D), wireless backhaul, vehicle communication network (V2X (Vehicle to Everything) network), cooperative communication, CoMP (Coordinated Multi-Points), and reception Technology development such as interference cancellation is being made.

On the other hand, the Internet is evolving from a human-centered network in which humans generate and consume information, to an Internet of Things (IoT) network that exchanges and processes information between distributed components such as objects. IoE (Internet of Everything) technology, which combines IoT technology with big data processing technology through connection with cloud servers, is also emerging. In order to implement IoT, technology elements such as sensing technology, wired/wireless communication and network infrastructure, service interface technology, and security technology are required, and recently, a sensor network for connection between objects, machine to machine , M2M), and MTC (Machine Type Communication) technologies are being studied. In the IoT environment, intelligent IT (Internet Technology) services that create new value in human life by collecting and analyzing data generated from connected objects can be provided. IoT is the field of smart home, smart building, smart city, smart car or connected car, smart grid, healthcare, smart home appliance, advanced medical service, etc. through the convergence and combination of existing IT (information technology) technology and various industries. Can be applied to.

Accordingly, various attempts have been made to apply a 5G communication system to an IoT network. For example, technologies such as sensor network, machine to machine (M2M), and machine type communication (MTC) are implemented by techniques such as beamforming, MIMO, and array antenna, which are 5G communication technologies. . As the big data processing technology described above, a cloud radio access network (cloud RAN) is applied as an example of the convergence of 5G technology and IoT technology. In this way, a plurality of services can be provided to users in a communication system, and in order to provide such a plurality of services to users, a method and apparatus using the same are required to provide each service within the same time period according to characteristics. . Various services provided in 5G communication systems are being studied, and one of them is a service that satisfies the requirements of low latency and high reliability.

In the case of vehicle communication, LTE-based V2X has been standardized in 3GPP Rel-14 and Rel-15 based on a D2D (Device-to-Device) communication structure, and currently intends to develop V2X based on 5G NR (New Radio). Efforts are going on. NR V2X plans to support unicast communication, groupcast (or multicast) communication, and broadcast communication between the terminal and the terminal. In addition, NR V2X, unlike LTE V2X, which aims to transmit and receive basic safety information necessary for vehicle driving on the road, is a group driving (Platooning), advanced driving (Advanced Driving), extended sensor (Extended Sensor), remote driving (Remote Driving). Together, it aims to provide more advanced services.

Since only broadcast communication was supported in the sidelink of the existing LTE system-based D2D and V2X, the function of the receiving terminal measuring the channel state and reporting it to the transmitting terminal was not supported. In the case of NR V2X, not only broadcast communication but also unicast and groupcast communication between the terminal and the terminal are considered, and since it aims to support advanced services that require more improved transmission efficiency, the receiving terminal reports the channel status to the transmitting terminal. Function is required. Specifically, in the measurement and reporting of the channel state in the sidelink, the receiving terminal measures the channel using a reference signal transmitted by the transmitting terminal, and sidelink channel state information of the sidelink using this SL CSI) is a function that provides feedback to the transmitting terminal. At this time, the reference signal transmitted by the transmitting terminal to report and receive SL CSI in the sidelink is referred to as a sidelink channel state information reference signal (SL CSI-RS). However, terms used in the present invention may be changed, and terms such as SL CSI-RS, CSI-RS, and reference signals may be used interchangeably.

The receiving terminal estimates the channel state by using the SL CSI-RS and reports the SL CSI to the transmitting terminal through this. Accordingly, the transmitting terminal may use the SL CSI information to allocate transmission resources and determine transmission parameters. In addition, by using the SL CSI-RS transmitted by the transmitting terminal, the receiving terminal can measure the SL reference signal received power (RSRP), and can feed this back to the transmitting terminal. The transmitting terminal may use the information to perform power control. In addition, the receiving terminal may perform radio link monitoring (RLM) using the SL CSI-RS transmitted by the transmitting terminal.

In the case of a Uu interface between base station terminals, when the terminal reports SL CSI information to the base station, the base station determines a transmission parameter, which is only referred to, but in the case of the sidelink of V2X, other operations may be considered. Considering that the sidelink of V2X is communication between terminals, a method of allowing the transmitting terminal to follow the SL CSI information transmitted by the receiving terminal may also be considered.

In addition, in the sidelink of V2X, the setting range of the transmission parameter may be determined according to whether the corresponding channel is congested. This is a congestion control function in which a terminal determines whether to access a channel when the channel is congested, and sets a transmission parameter to increase a transmission success probability of the terminal when it is accessed. Accordingly, the terminal may measure the channel busy ratio (CBR) and determine the setting range of the transmission parameter accordingly. Accordingly, the CBR may be considered together in the process of the receiving terminal performing SL CSI transmission or when the transmitting terminal determines a transmission parameter based on the SL CSI reported by the receiving terminal.

In addition, when periodic SL CSI-RS transmission is not supported in the V2X sidelink, measurement inaccuracies may occur when the receiving terminal estimates a channel using this, measures SL RSRP, or performs RLM. Therefore, the terminal operation to solve this problem should be defined. However, there is no discussion about this. Therefore, the present invention proposes a CSI-RS transmission, measurement, and CSI reporting method suitable for this in consideration of a transmission scenario in the sidelink. Specifically, we propose a terminal operation method and apparatus for SL CSI-RS transmission and SL CSI reporting method considering CBR reflection, SL RSRP reporting, and RLM support when operating in a unicast between a terminal and a terminal in the sidelink.

The embodiment of the present specification is proposed to support the above-described scenario, and the receiving terminal measures the channel state while the vehicle terminal supporting V2X exchanges information using a sidelink with another vehicle terminal and a pedestrian mobile terminal. Thus, it relates to a method and apparatus for reporting this to a transmitting terminal. Specifically, a method for transmitting a reference signal for measuring a channel state in a sidelink by a transmitting terminal and a method for measuring and reporting a channel through the receiving terminal are proposed. And it relates to the operation of the receiving and transmitting terminal according to the proposed method.

1 is a diagram illustrating a system according to an embodiment of the present disclosure.

Referring to FIG. 1, (a) of FIG. 1 shows an example of a case in which all V2X terminals (UE-1 and UE-2) are located within the coverage of a base station (In-Coverage, IC).

All V2X terminals may receive data and control information from the base station through downlink (DL) or transmit data and control information to the base station through uplink (UL). At this time, the data and control information may be data and control information for V2X communication. The data and control information may be data and control information for general cellular communication. In addition, V2X terminals can transmit/receive data and control information for V2X communication through a sidelink (SL).

Referring to FIG. 1, (b) of FIG. 1 shows an example of a case in which UE-1 is located within the coverage of a base station and UE-2 is located outside the coverage of a base station among V2X terminals. That is, (b) of FIG. 1 shows an example of partial coverage (PC) in which some V2X terminals (UE-2) are located outside the coverage of the base station.

The V2X terminal (UE-1) located within the coverage of the base station may receive data and control information from the base station through downlink or transmit data and control information to the base station through uplink.

The V2X terminal (UE-2) located outside the coverage of the base station cannot receive data and control information from the base station through downlink, and cannot transmit data and control information to the base station through uplink.

The V2X terminal (UE-2) can transmit/receive data and control information for V2X communication through the sidelink with the V2X terminal (UE-1).

Referring to FIG. 1, (c) of FIG. 1 shows an example of a case in which all V2X terminals are located out of coverage (OOC) of a base station.

Therefore, the V2X terminals (UE-1, UE-2) cannot receive data and control information from the base station through downlink, and cannot transmit data and control information to the base station through uplink.

The V2X terminals (UE-1, UE-2) may transmit/receive data and control information for V2X communication through a sidelink.

Referring to FIG. 1, (d) of FIG. 1 shows an example of a scenario for performing V2X communication between V2X terminals (UE-1 and UE-2) located in different cells. Specifically, (d) of FIG. 1 shows a case in which V2X terminals (UE-1, UE-2) are connected to different base stations (RRC connection state) or camping (RRC connection release state, that is, RRC idle state). Shows. At this time, the V2X terminal (UE-1) may be a V2X transmitting terminal and the V2X terminal (UE-2) may be a V2X receiving terminal. Alternatively, the V2X terminal (UE-1) may be a V2X receiving terminal, and the V2X terminal (UE-2) may be a V2X transmitting terminal. The V2X terminal (UE-1) can receive a system information block (SIB) from the base station to which it has accessed (or is camping), and the V2X terminal (UE-2) has access to it (or You can receive the SIB from another base station (which you are camping). In this case, as the SIB, an existing SIB may be used, or a separately defined SIB for V2X may be used. In addition, information of the SIB received by the V2X terminal (UE-1) and the information of the SIB received by the V2X terminal (UE-2) may be different from each other. Accordingly, in order to perform V2X communication between terminals UE-1 and UE-2 located in different cells, information may be unified, or an assumption and interpretation method thereof may be additionally required.

In FIG. 1, for convenience of description, a V2X system consisting of V2X terminals (UE-1 and UE-2) is illustrated, but the present invention is not limited thereto, and communication between more V2X terminals may be achieved. In addition, an interface (uplink and downlink) between the base station and V2X terminals may be referred to as a Uu interface, and a sidelink between V2X terminals may be referred to as a PC5 interface. Therefore, in the present disclosure, these can be mixed and used.

Meanwhile, in the present disclosure, the terminal is a vehicle supporting vehicle-to-vehicular communication (V2V), a vehicle supporting vehicle-to-pedestrian communication (vehicular-to-pedestrian, V2P), or a handset of a pedestrian (for example, , 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 a traffic infrastructure (vehicular-to-infrastructure, V2I). have. In addition, in the present disclosure, the terminal may include a road side unit (RSU) 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.

Further, according to an embodiment of the present disclosure, the base station may be a base station supporting both V2X communication and general cellular communication, or may be a base station supporting only V2X communication. In this case, the base station may be a 5G base station (gNB), a 4G base station (eNB), or an RSU. Therefore, in this disclosure, the base station may be referred to as an RSU.

2 is a diagram illustrating a V2X communication method performed through a sidelink according to an embodiment of the present disclosure.

Referring to Figure 2 (a), UE-1 (201, for example, TX terminal) and UE-2 (202, for example, RX terminal) can perform one-to-one communication, which is It can be called unicast communication.

Referring to (b) of FIG. 2, the TX terminal and the RX terminal may perform one-to-many communication, which may be referred to as groupcast or multicast.

In Figure 2 (b), UE-1 (211), UE-2 (212), and UE-3 (213) form a group (Group A) to perform groupcast communication And, UE-4 (214), UE-5 (215), UE-6 (216), and UE-7 (217) form another group (Group B) groupcast communication Can be done. Each terminal performs groupcast communication only within a group to which it belongs, and communication between different groups may be performed through unicast, groupcast, or broadcast communication. 2(b) shows that two groups (Group A and Group B) are formed, but are not limited thereto.

Meanwhile, although not shown in FIG. 2, V2X terminals may perform broadcast communication. Broadcast communication refers to a case in which all V2X terminals receive data and control information transmitted by a V2X transmitting terminal through a sidelink. As an example, when it is assumed in FIG. 2 (b) that UE-1 211 is a transmitting terminal for broadcast, all terminals (UE-2 212, UE-3 213, UE -4 (214), UE-5 (215), UE-6 (216), and UE-7 (217) may receive data and control information transmitted by UE-1 (211).

In NR V2X, unlike in LTE V2X, support in a form in which a vehicle terminal transmits data to only one specific node through unicast and a form in which data is transmitted to a plurality of specific nodes through groupcast can be considered. For example, in a service scenario such as Platooning, which is a technology in which two or more vehicles are connected in a single network and grouped and moved in a cluster form, such unicast and group cast technologies may be usefully used. Specifically, unicast communication may be required for the purpose of a group leader node connected by platooning to control one specific node, and groupcast communication may be required for the purpose of simultaneously controlling a group consisting of a specific number of nodes. have.

3 is a diagram illustrating a resource pool defined as a set (set) of resources on a time and frequency used for transmission and reception of a sidelink according to an embodiment of the present disclosure.

The resource allocation unit on the time axis within the resource pool may be one or more OFDM symbols. Also, the resource granularity of the frequency axis may be one or more physical resource blocks (PRBs).

When the resource pool is allocated on time and frequency (310), a colored area indicates a region set as a resource pool on time and frequency. In the present disclosure, a case in which the resource pool is non-contiguously allocated over time is described as an example, but the resource pool may be continuously allocated over time. In addition, although the present disclosure describes a case where a resource pool is continuously allocated on a frequency, the resource pool may be non-contiguously allocated on a frequency.

Referring to FIG. 3, a case 320 is shown in which resource pools are allocated non-contiguously over time. Referring to FIG. 3, a case in which a granularity of resource allocation over time is made of a slot is illustrated. Specifically, one slot composed of a plurality of OFDM symbols may be a basic unit of resource allocation on the time axis. In this case, the number of OFDM symbols constituting the slot may be, for example, 14, and the number of OFDM symbols may be changed. Referring to FIG. 3, a colored slot indicates a slot included in a resource pool in time, and a slot to which the resource is allocated may be indicated through time resource pool configuration information included in the SIB. In this case, the time resource pool setting information may be set by being included in the resource pool setting information together with the frequency resource pool setting information, or the time resource pool setting information and the frequency resource pool setting information may be respectively set. For example, a slot in which a resource is set may be indicated through a bitmap.

Referring to FIG. 3, a physical slot 320 belonging to a non-contiguous resource pool in time may be mapped to a logical slot 321. In general, a set (set) of slots belonging to a physical sidelink shared channel (PSSCH) resource pool may be represented by (t ₀ ,t ₁ ,...,t _i ,...,t _Tmax ).

Referring to FIG. 3, a case 330 in which a resource pool is continuously allocated on a frequency is shown.

Resource allocation in the frequency axis may be performed in units of sub-channels 331. The subchannel 331 may be defined as a resource allocation unit on a frequency composed of one or more RBs. That is, the subchannel 331 may be defined as an integer multiple of RB. Referring to FIG. 3, a subchannel 3-31 may be composed of five consecutive PRBs, and a size of a subchannel (sizeSubchannel) may be a size of five consecutive PRBs. However, the contents shown in the drawings are only an example of the present invention, and the size of the subchannel may be set differently, and one subchannel is generally configured as a continuous PRB, but it is not necessarily configured as a continuous PRB. The subchannel 331 may be a basic unit of resource allocation for PSSCH.

The startRB-Subchannel 332 may indicate the start position of the subchannel 331 on the frequency in the resource pool. When resource allocation in the frequency axis is performed in units of subchannels 331, the RB index (startRB-Subchannel, 332) where the subchannel 331 starts, and information on how many RBs the subchannel 331 consists of (sizeSubchannel) And, resources on a frequency may be allocated through configuration information about the total number of subchannels 331 (numSubchannel). In this case, information on startRB-Subchannel, sizeSubchannel, and numSubchannel may be set through frequency resource pool configuration information included in the SIB.

4 is a diagram illustrating a method for a base station to allocate transmission resources in a sidelink according to an embodiment of the present disclosure.

A method for the base station to allocate transmission resources in the sidelink will be referred to as Mode 1 below. Mode 1 may be a scheduled resource allocation. Mode 1 may represent a method in which a base station allocates resources used for sidelink transmission to RRC-connected terminals in a dedicated scheduling scheme. The mode 1 method can be effective for interference management and resource pool management because the base station can manage the resources of the sidelink.

Referring to FIG. 4, the transmitting terminal 401 and the receiving terminal 402 camping on 405 may receive a sidelink system information block (SL-SIB) from the base station 403 (410). Here, the receiving terminal 402 represents a terminal that receives data transmitted by the transmitting terminal 401. The SL-SIB information includes sidelink resource pool information for sidelink transmission/reception, parameter setting information for sensing operation, information for setting sidelink synchronization, or carrier information for sidelink transmission/reception operating at different frequencies. I can.

When data traffic for V2X is generated in the transmitting terminal 401, the transmitting terminal 401 may be RRC connected to the base station 403 (420). Here, the RRC connection between the terminal and the base station may be referred to as Uu-RRC. The Uu-RRC connection process 420 may be performed before the transmission terminal 401 generates data traffic. In addition, in Mode 1, in a state in which the Uu-RRC connection process 420 between the base station 403 and the receiving terminal 402 is made, the transmitting terminal may perform transmission to the receiving terminal through a sidelink. In contrast, in Mode 1, the transmitting terminal may perform transmission to the receiving terminal through the sidelink even when the Uu-RRC connection process 420 between the base station 403 and the receiving terminal 402 is not performed.

The transmitting terminal 401 may request a transmission resource capable of V2X communication with the receiving terminal 402 from the base station (430). At this time, the transmitting terminal 401 may request a sidelink transmission resource from the base station 403 using an uplink physical uplink control channel (PUCCH), an RRC message, or a MAC CE. Meanwhile, the MAC CE may be a buffer status report (BSR) MAC CE of a new format (including at least an indicator indicating that the buffer status report for V2X communication and information on the size of data buffered for D2D communication). have. In addition, the transmitting terminal 401 may request a sidelink resource through a scheduling request (SR) bit transmitted through an uplink physical control channel.

Next, the base station 403 may allocate a V2X transmission resource to the transmission terminal 401. The base station may allocate transmission resources in a dynamic grant or configured grant scheme.

In the case of the dynamic grant scheme, the base station may allocate resources for TB transmission through downlink control information (DCI). Sidelink scheduling information included in the DCI may include parameters related to a transmission time point of initial transmission and retransmission and a frequency allocation location information field. DCI for the dynamic grant method may be CRC scrambled with SL-V-RNTI to indicate that it is a dynamic grant method.

In the case of the configured grant scheme, the base station may periodically allocate resources for TB transmission by setting a semi-persistent scheduling (SPS) interval through Uu-RRC. In addition, the base station may allocate resources for multiple TBs through DCI in order to allocate resources in the configured grant scheme. The sidelink scheduling information included in the DCI may include parameters related to a transmission time point of initial transmission and retransmission and a frequency allocation location information field. When resources are allocated in the configured grant scheme, an initial transmission and retransmission transmission time (occasion) and a frequency allocation position may be determined according to the DCI, and the resource may be repeated at SPS interval intervals. DCI for the configured grant scheme may be CRC scrambled with SL-SPS-V-RNTI to indicate that the configured grant scheme.

In addition, the configured grant (CG) scheme can be divided into type1 CG and type2 CG. In the case of Type2 CG, it is possible to activate/deactivation resources set as configured grant through DCI.

Accordingly, in the case of Mode1, the base station 403 may instruct the transmitting terminal 401 to schedule for sidelink communication with the receiving terminal 402 through DCI transmission through the PDCCH (440).

In the case of broadcast transmission, the transmitting terminal 401 may broadcast sidelink control information (SCI) to the receiving terminal 402 through the PSCCH by broadcast without RRC setting 415 for the sidelink (460). In addition, the transmitting terminal 401 may broadcast data to the receiving terminal 402 through the PSSCH (470).

In contrast, in the case of unicast or groupcast transmission, the transmitting terminal 401 may perform a one-to-one RRC connection with other terminals. In this case, the RRC connection between terminals may be referred to as PC5-RRC 415 in distinction from Uu-RRC. Even in the case of groupcast, the PC5-RRC 415 may be individually connected between the terminal and the terminal in the group.

4, although the connection of the PC5-RRC 415 is shown as an operation after transmission 410 of SL-SIB, it is performed at any time before transmission 410 of SL-SIB or broadcast 460 of SCI. It could be. If the RRC connection between the terminals is required, the PC5-RRC connection of the sidelink is performed, and the transmitting terminal 401 may transmit the SCI to the receiving terminal 402 through the PSCCH in unicast or groupcast (460). At this time, the groupcast transmission of SCI may be interpreted as a group SCI. In addition, the transmitting terminal 401 may transmit data to the receiving terminal 402 through the PSSCH in unicast or groupcast (470). In the case of Mode 1, the transmitting terminal 401 analyzes the sidelink scheduling information included in the DCI received from the base station 403, performs scheduling for the sidelink through it, and transmits the following scheduling information in the SCI. have.

- Initial transmission and retransmission transmission time and frequency allocation location information field

- NDI (new data indicator) field

- RV (redundancy version) field

- Information field indicating the reservation interval

When selecting a resource for a plurality of TBs (multiple MAC PDUs) through an information field indicated by the reservation interval, an interval between TBs is indicated as a fixed value, and if a resource is selected for only one TB, the corresponding value This can be set to '0'.

5 is a diagram illustrating a method of directly allocating transmission resources of a sidelink through sensing by a terminal in a sidelink according to an embodiment of the present disclosure.

Hereinafter, a method in which the terminal directly allocates the transmission resource of the sidelink through sensing in the sidelink is referred to as Mode 2. In the case of Mode 2, it may be referred to as UE autonomous resource selection.

In Mode 2, the base station 503 provides a pool of sidelink transmission/reception resources for V2X as system information, and the transmitting terminal 501 may select a transmission resource according to a predetermined rule. Unlike Mode 1, in which the base station is directly involved in resource allocation, in FIG. 5, there is a difference in that the transmitting terminal 501 autonomously selects a resource and transmits data based on a resource pool previously received through system information.

Referring to FIG. 5, a transmitting terminal 501 and a receiving terminal 502 camping on 505 may receive SL-SIBs from the base station 503 (510). Here, the receiving terminal 502 represents a terminal that receives data transmitted by the transmitting terminal 501. The SL-SIB information includes sidelink resource pool information for sidelink transmission/reception, parameter setting information for sensing operation, information for setting sidelink synchronization, or carrier information for sidelink transmission/reception operating at different frequencies. I can.

The difference between FIG. 4 and FIG. 5 is that in FIG. 4, the base station 503 and the terminal 501 operate in an RRC connected state, whereas in FIG. 5, the terminal is in an idle mode 520 (not RRC-connected). State) can also work. In addition, even in the RRC connection state 520, the base station 503 may not directly participate in resource allocation and allow the transmitting terminal 501 to autonomously select a transmission resource. Here, the RRC connection between the terminal 501 and the base station 503 may be referred to as a Uu-RRC 520.

When data traffic for V2X is generated in the transmitting terminal 501, the transmitting terminal 501 sets a resource pool through system information received from the base station 503, and the transmitting terminal 501 senses within the set resource pool. Resource in the time/frequency domain may be directly selected through (530).

In the case of broadcast transmission, the transmitting terminal 501 may broadcast the SCI to the receiving terminal 502 through the PSCCH by broadcast without the RRC setting 520 for the additional sidelink (550). In addition, the transmitting terminal 510 may broadcast data to the receiving terminal 502 through the PSSCH (560).

In contrast, in the case of unicast and groupcast transmission, the transmitting terminal 501 may perform a one-to-one RRC connection with other terminals. Here, different from Uu-RRC, the RRC connection between terminals may be PC5-RRC. Even in the case of groupcast, PC5-RRC can be individually connected between terminals in the group.

In FIG. 5, the connection of the PC5RRC 515 is shown as an operation after the transmission 510 of the SL-SIB, but may be performed at any time before the transmission 510 of the SL-SIB or the transmission 550 of the SCI. If an RRC connection between terminals is required, a sidelink PC5-RRC connection is performed (515), and the transmitting terminal 501 may transmit the SCI to the receiving terminal 502 through PSCCH in unicast or groupcast (550). . At this time, the groupcast transmission of SCI may be interpreted as a group SCI. In addition, the transmitting terminal 501 may transmit data to the receiving terminal 502 through the PSSCH in unicast or groupcast (560). In the case of Mode 2, the transmitting terminal 501 directly performs scheduling for the sidelink by performing sensing and transmission resource selection operations, and may include the following scheduling information in SCI and transmit.

-Initial transmission and retransmission transmission time and frequency allocation location information field

-NDI field

-RV field

-Information field indicating reservation interval

When selecting a resource for a plurality of TBs (multiple MAC PDUs) through an information field indicated by the reservation interval, an interval between TBs is indicated as a fixed value, and if a resource is selected for only one TB, the corresponding value This can be set to '0'.

6 is a diagram illustrating an example in which a receiving terminal measures a channel state in a sidelink and reports it to a transmitting terminal according to an embodiment of the present disclosure.

Referring to FIG. 6, FIG. 610 shows a transmitter (or a transmitter, a transmitter, a transmitter, and a transmitter can be used in combination), and FIG. 620 shows a receiver (or receiver, a receiver, a receiver). In general, the transmitting unit and the receiving unit may be indicated as subjects that transmit and receive data, respectively. In the V2X system, the terminal may be a transmission unit or a reception unit.

In addition, the receiving unit 620 may be a single terminal or a plurality of terminals. For example, when the receiving unit 620 is a plurality of terminals, it may be a scenario such as group driving (Platooning). The transmitting terminal corresponding to the transmitting unit 610 may transmit the SL CSI-RS to obtain channel information from the receiving terminal, and the receiving terminal corresponding to the receiving unit may receive it (630). At this time, configuration information for transmitting the SL CSI-RS and reporting the SL CSI may be transmitted to the receiving terminal. Details of the specific setting information will be described later.

In addition, the transmitting terminal may make a request for SL CSI to the receiving terminal. At this time, the transmitting terminal may transmit a request for CSI while transmitting the CSI-RS, or may transmit a request for CSI before and after each step disclosed in this figure.

The SL CSI-RS transmission step in step 630 includes a method in which an SL CSI-RS resource is configured and transmitted, a condition in which an SL CSI-RS is transmitted, and a method for setting an SL CSI-RS pattern, and details are detailed in the following embodiments. Explain.

In addition, SL CSI transmission channel configuration, SL CSI triggering/activation method, and effective SL CSI determination methods are required, and specific details will be described in detail in the following embodiments.

The receiver may measure the channel state of the sidelink using the received SL CSI-RS (640).

The receiver generates (650) information on the SL CSI using the channel state measurement result. In the following embodiment, a method for ensuring the accuracy of measurement using SL CSI-RS when the SL CSI-RS is not transmitted in the entire band in the sidelink but is transmitted only in the scheduled PSSCH region, the receiving terminal SL CSI-RS EPRE It proposes a method of obtaining and considering CBR when generating SL CSI.

And, the terminal corresponding to the receiving unit transmits the SL CSI to the terminal corresponding to the transmitting unit. Detailed operations for this will be described through the following examples.

In the present disclosure, the SL CSI-RS transmission and SL CSI report consider a case of operating in a unicast between a terminal and a terminal in a sidelink. However, the embodiment of the present invention is not limited thereto, and for example, when a terminal and a terminal can operate in unicast in a group, the SL CSI-RS transmission and SL CSI reporting method proposed in the present invention can be applied.

In the present invention, aperiodic SL CSI-RS transmission and aperiodic SL CSI reporting are considered. In addition, the SL CSI may contain various information. For example, information that may be included in SL CSI includes a channel quality indicator (CQI), a precoding matrix indicator (PMI), a rank indicator (RI), a CSI-RS resource indicator (CRI), and an SS/PBCH block resource indicator (SSBRI). ), LI (layer indicator), and LI-RSRP. In addition, a channel busy ratio (CBR) may be considered as information that may be included in SL CSI.

In order for the receiving terminal to provide the SL CSI information to the transmitting terminal, the receiving terminal must receive the SL CSI-RS. Accordingly, the receiving terminal must be configured with resource setting/resource configuration for receiving SL CSI-RS and report setting/report configuration for reporting the generated CSI.

Specific details will be described below. 7 is a diagram illustrating a channel state information framework of an NR sidelink system according to an embodiment of the present disclosure.

The CSI framework of FIG. 7 may consist of two elements: resource setting and report setting. The report setting may configure at least one or more links by referring to the ID of the resource setting.

According to an embodiment of the present disclosure, the resource setting may include information related to a reference signal (RS). At least one resource setting (700, 705, 715) may be set in the receiving terminal. Each resource setting may include at least one resource set (720, 725). Each resource set may include at least one resource 730 and 735. Each resource (730, 735) is detailed information about the RS, for example, transmission band information in which the RS is transmitted (for example, Sidelink bandwidth part, SL BWP), the location information of the resource element (RE) in which the RS is transmitted, RS transmission It may include an offset in the period and time axis, the number of RS ports, and the like. As described above, the corresponding RS may be referred to as SL CSI-RS, and when periodic SL CSI-RS is not supported, the RS transmission period and offset information on the time axis may not be included.

According to an embodiment of the present disclosure, the report setting may include information related to the SL CSI reporting method. The base station may configure at least one report setting (740, 745, 750) to the terminal. At this time, each report setting is the setting information of enable/disable for SL CSI reporting, the setting information of enable/disable for CBR reporting, and the type of the channel through which the report is transmitted (e.g., PSSCH or physical sidelink feedback channel (PSFCH), etc. And information on the band in which the SL CSI is reported (eg, SL BWP), configuration information for the codebook when PMI is supported, time-domain behavior for SL CSI reporting, frequency granularity for SL CSI reporting, and measurement restriction. Configuration information for, the effective SL CSI window configuration information, and reportQuantity, which is information included in the SL CSI, may be included in the parameter information of the SL-CSI-ReportConfig. It may be information on whether it is periodic or non-periodic, and the present invention considers a case in which the SL CSI report is set aperiodically, and the frequency granularity for the SL CSI report means a unit on the frequency for the SL CSI report.

In the present disclosure, a non-subband-based aperiodic SL CSI report may be transmitted through PSSCH or PSFCH only for a frequency domain corresponding to a corresponding PSSCH, unlike a Uu interface between base station terminals in consideration of a sidelink transmission environment.

The setting information for the measurement restriction means setting whether or not the measurement section is restricted in time or frequency for the channel measurement when measuring a channel.

The effective SL CSI window configuration information is information for determining that the SL CSI is not valid when the SL CSI window is exceeded in consideration of the CSI feedback delay. Details will be described later.

Finally, reportQuantity indicates information included in SL CSI, and the present invention considers setting of CQI, CQI-RI, or CQI-RI-PMI. In addition, reportQuantity may include CBR information of the receiving terminal. In this case, the report setting may include at least one ID (ID of resource setting) for referring to information on a channel referenced by the UE or reference signal (or RE location) for interference measurement when CSI is reported. Through this method, resource configuration and report setting may be linked, and may be schematically illustrated as, for example, links 760, 765, 770, and 775 of FIG. 7. However, the embodiment of the present disclosure is not limited thereto. For example, a method of linking by including the ID of at least one resource setting and the ID of a report setting in one measurement setting (mea-Config) is also possible.

According to an embodiment of the present disclosure, when one reporting setting 740 and one resource setting 700 are connected according to the link (7-60), the resource setting 700 is determined by channel measurement. Can be used. In addition, the receiving terminal may report the CSI using the information included in the reporting setting.

According to an embodiment of the present disclosure, when linking one reporting setting 745 and two resource settings 700 and 705 according to a link (765, 770), one of the resource settings is channel measurement (channel measurement), and the rest of the resource settings can be used for interference measurement.

In addition, according to an embodiment of the present disclosure, resource setting and report setting may be connected to a resource pool and may be (pre-)configuration for each resource pool. Information configured for each resource pool may be indicated through SL-SIB or UE-specific higher level signaling. When indicated through SL-SIB, a corresponding value may be set in the resource pool information among corresponding system information. Even if it is configured through an upper layer, it may be configured to be UE-specific through Uu-RRC or PC5-RRC as information in the resource pool. In addition, in the side link, a method of setting a resource setting and a report setting may be different depending on whether the terminal is in an IC/PC/OCC environment or a transmission resource allocation mode (Mode1/2). As described above, each resource setting in the channel state information framework of the NR sidelink system may include at least one resource set, and each resource set may include at least one resource. have. Hereinafter, when detailed information on the SL CSI-RS is set in each resource setting, a condition and method in which the actual SL CSI-RS is transmitted will be described. Prior to this, in the case of a Uu interface between base station terminals, the CSI-RS is transmitted over the entire band of the configured frequency. In addition, the UE feeds back the CSI report for all frequency bands in the form of wideband or sub-band, so that the base station can receive the CSI report for the entire frequency band. However, considering that the sidelink of V2X is communication between terminals, it is considered that the SL CSI-RS transmission is limited to the transmission region of the PSSCH. In other words, the SL CSI-RS together with the PSSCH may be transmitted only in a frequency domain in which resources are allocated to the PSSCH.

As described above, in the present invention, aperiodic SL CSI-RS transmission is considered. The following methods can be considered as a condition in which aperiodic SL CSI-RS is transmitted.

SL CSI-RS transmission conditions

-Method 1: When data is transmitted only when SL CSI report is enabled and SL CSI report is triggered/activated, SL CSI-RS is transmitted along with data through PSSCH.

-Method 2: When SL CSI reporting is enabled, SL CSI-RS is transmitted along with data through PSSCH whenever data is transmitted.

-Method 3: Method 1 or Method 2 may be used depending on specific conditions.

-Method 4: When the signal transmission method is set to unicast, the SL CSI-RS is transmitted along with the data through the PSSCH whenever data is transmitted.

For example, if SL CSI-RS is set to be used for SL RLM (sidelink radio link monitoring) or SL RSRP (sidelink reference signal received power) measurement and reporting, the PSSCH together with data is transmitted whenever data is transmitted. When SL CSI-RS is transmitted and SL CSI-RS is not configured for SL RLM or SL RSRP measurement and reporting, when data is transmitted only when SL CSI reporting is enabled and SL CSI reporting is triggered/activated, PSSCH SL CSI-RS is transmitted with data through.

As described above, SL CSI reporting can be triggered/activated only when SL CSI reporting is enabled. Enable/disable for SL CSI reporting may be set in the report setting of the channel state information framework as described above. In the proposed method 1/2/3, it is assumed that the SL CSI-RS is transmitted only in the scheduled PSSCH region.

In more detail, method 1 is a method of transmitting a CSI-RS when SL CSI report is triggered/activated through signaling. The signaling method for triggering/activation of SL CSI report will be described in more detail below.

In more detail, method 2 is a method in which data and SL CSI-RS are transmitted through PSSCH whenever data is transmitted when SL CSI reporting is enabled without signaling for triggering/activating SL CSI reporting. In the case of Method 2, since the SL CSI-RS is transmitted together with data, the more frequently the data is scheduled, the more SL CSI-RS samples for measuring the channel state may be increased.

Meanwhile, even in the case of Method 1, if the SL CSI report is triggered/activated every time data is transmitted, the transmission frequency of the SL CSI-RS can be increased. In this case, the SL CSI-RS may be periodically transmitted under the assumption that data is transmitted periodically. However, method 1 has a disadvantage of triggering/activating SL CSI reporting in order to increase the transmission frequency of the SL CSI-RS compared to method 2.

Therefore, in the case of Method 3, if the SL CSI-RS is set for the purpose of measurement such as SL RLM or SL RSRP, which needs to know the average state of the channel rather than grasping the current state of the channel by considering the disadvantages of Method 1, Method 2 is used. Otherwise, method 1 is used.

Meanwhile, in the case of Method 4, when the signal transmission method is set to unicast regardless of whether SL CSI reporting is enabled/disabled, it is a method of transmitting SL CSI-RS together with data through PSSCH whenever data is transmitted. This is a method considering that SL CSI-RS transmission is supported only in unicast.

A method of discriminating whether a signal transmission method is broadcast, unicast, or groupcast may include various methods.

For example, the signal transmission method may be classified in an upper layer. It can also be classified by resource pool. This is a case in which different transmission methods are used for each resource pool. In addition, when more than one transmission method can be used in one resource pool at the same time, it can be distinguished by indicating configuration information on a signal transmission method in the resource pool. Unlike this, it can be classified by the SCI format or by indicating configuration information on the signal transmission method in the SCI field. In addition, it is possible to simultaneously use a method that is classified by the DCI format transmitted by the base station to the terminal, or indicates the configuration information for the signal transmission method in the DCI field and the SCI format, or indicates the configuration information for the signal transmission method in the SCI field. have.

However, in all of the above methods 1/2/3/4, since the SL CSI-RS is not transmitted in the entire band, but is transmitted only in the scheduled PSSCH region, when the frequency region of the scheduled PSSCH is small, the SL CSI-RS sample is insufficient. There is a problem in which inaccuracy may occur in the measurement result. Therefore, a method for solving this problem will be described in more detail through examples to be described later.

Meanwhile, the SL CSI-RS pattern can reuse the CSI-RS pattern in the NR system as much as possible. However, in the present invention, the SL CSI-RS pattern is not limited to only the CSI-RS pattern in the NR system. [Table 1] may be considered as the SL CSI-RS pattern. [Table 1] shows the SL CSI-RS pattern considering only up to 2 ports.

In Table 1, Rows 2, 3, and 6 are patterns already defined as CSI-RS patterns in the NR system, and are shown through FIG. 8.

8 is a diagram illustrating a CSI-RS pattern according to an embodiment of the present disclosure.

Referring to FIG. 8, a pattern 810 is an example showing a 1 port CSI-RS pattern corresponding to Row 2 in [Table 1], and as shown in the figure, the frequency density per port in each RB. of each port per PRB) is a pattern of 3. This may be used for the purpose of securing a sample of SL CSI-RS according to a pattern used as a tracking reference signal (TRS) in NR or a frequency domain of a PSSCH scheduled in a sidelink. In addition, in the pattern 810, a method of allowing and not allowing data and FDM to a RE in which the SL CSI-RS is not transmitted in a symbol in which the SL CSI-RS is transmitted may be considered. If the SL CSI-RS and the FDM of data are not allowed in a symbol in which the SL CSI-RS is transmitted, the power of the SL CSI-RS may be boosted by 6dB. This may be a method for improving the accuracy of measurement using SL CSI-RS in an environment where the samples of SL CSI-RS according to the frequency domain of the PSSCH scheduled in the sidelink are insufficient.

The pattern 820 is an example of a pattern corresponding to 1 port SL CSI-RS in Row 3 in [Table 1], and as shown in the figure, a pattern having a frequency density per port of 1 in each RB. In the sidelink, a pattern having a density of 0.5 among the patterns corresponding to Row 3 of [Table 1] may not be used.

The pattern 830 is an example of a 2-port SL CSI-RS pattern corresponding to Row 6 in [Table 1], and as shown in the figure, a pattern having a frequency density per port of 1 in each RB. In the case of this pattern, FD-CDM2 is applied and an orthogonal cover code of length 2 is applied to two REs of adjacent frequencies, so that two ports can be distinguished. In the sidelink, a pattern having a density of 0.5 among the patterns corresponding to Row 6 of [Table 1] may not be used.

In [Table 1], Rows 1, 4, and 6 are patterns newly defined as the SL CSI-RS pattern of the sidelink, and are illustrated through FIG. 8. The SL CSI-RS patterns of Rows 1, 4, and 6 may be used for the purpose of securing a sample of SL CSI-RS according to the frequency domain of the PSSCH scheduled in the sidelink.

The pattern 840 is an example of a 1 port SL CSI-RS pattern corresponding to Row 1 in [Table 1], and as shown in the figure, a pattern having a frequency density per port of 6 in each RB. In the pattern 840, a method of allowing and not allowing data and FDM to a RE in which the SL CSI-RS is not transmitted in a symbol in which the SL CSI-RS is transmitted may be considered. If the SL CSI-RS and the FDM of data are not allowed in a symbol in which the SL CSI-RS is transmitted, the power of the SL CSI-RS may be boosted by 3dB. This may be a method for improving the accuracy of measurement using SL CSI-RS in an environment where the samples of SL CSI-RS according to the frequency domain of the PSSCH scheduled in the sidelink are insufficient.

The pattern 850 is an example showing a 2-port SL CSI-RS pattern corresponding to Row 4 (Alt 1) in [Table 1], and as shown in the figure, a pattern having a frequency density per port of 6 in each RB to be. The pattern 850 is a pattern in which the pattern corresponding to the pattern 840 is expanded to 2 ports, and may be a value determined as a value corresponding to k0 = 0 and k1 = 1 in [Table 1]. And in [Table 1], different ports may be mapped to REs corresponding to k0 and k1, respectively.

Pattern 860 is an example of a 2-port SL CSI-RS pattern corresponding to Row 4 (Alt 2) in [Table 1], and as shown in the figure, a pattern having a frequency density per port of 6 in each RB to be. In the pattern 860, unlike the pattern 850, FD-CDM2 is applied and an orthogonal cover code of length 2 is applied to two REs of adjacent frequencies, so that two ports can be distinguished.

The pattern 870 is an example showing a 2-port SL CSI-RS pattern corresponding to Row 5 in [Table 1], and as shown in the figure, a pattern having a frequency density per port of 3 in each RB. In the case of this pattern, FD-CDM2 is applied and an orthogonal cover code of length 2 is applied to two REs of adjacent frequencies, so that two ports can be distinguished. In the pattern 870, a method of allowing and not allowing data and FDM to a RE in which the SL CSI-RS is not transmitted in a symbol in which the SL CSI-RS is transmitted may be considered. If the SL CSI-RS and the FDM of data are not allowed in a symbol in which the SL CSI-RS is transmitted, the power of the SL CSI-RS may be boosted by 3dB. This may be a method for improving the accuracy of measurement using SL CSI-RS in an environment where the samples of SL CSI-RS according to the frequency domain of the PSSCH scheduled in the sidelink are insufficient.

In addition, although the CSI-RS pattern in the NR system is relatively free to set the position on time and frequency, the SL CSI-RS pattern of the sidelink shown in FIG. 8 may have restrictions on the position on the time and frequency that can be set.

[Table 1]

Next, a method of selecting a channel according to a configuration for a channel through which SL CSI is transmitted and a transmission resource allocation mode (Mode1/2) will be described. The channel through which SL CSI is transmitted can be considered in the following ways.

SL CSI transmission channel

-Method 1: SL CSI is piggybacked and transmitted through PSSCH with data

-Method 2: SL CSI is transmitted through PSSCH without data (SL CSI only transmission)

-Method 3: SL CSI is transmitted through PSFCH

When the receiving terminal reports the SL CSI to the transmitting terminal through the PSSCH as in Method 1 or Method 2, the channel selection method may be different according to the transmission resource allocation mode (Mode1/2). In the sidelink, a mode in which a corresponding base station sets the allocation of transmission resources as described with reference to FIG. 4 (Mode1) and a mode in which the terminal allocates transmission resources through direct sensing as described with reference to FIG. 5 (Mode2) are supported. .

In the case of Mode1, the UE requests transmission resources to the base station for SL CSI reporting (see step 430 in FIG. 4) and is allocated PSSCH resources through DCI from the base station (see step 440 in FIG. 4). Therefore, the terminal can transmit data through the PSSCH allocated from the base station, and at this time, the receiving terminal can report SL CSI information to the transmitting terminal through the PSSCH (method 1 or method 2).

In this case, as one method, the receiving terminal may determine whether to use method 1 or method 2, and when reporting the SL CSI to the transmitting terminal, it may indicate whether method 1 or method 2 is used. As a method of indicating method 1 or method 2, an explicit signaling method and an implicit indication method may be considered while the receiving terminal transmits SCI to the transmitting terminal through the PSCCH.

As an explicit method, method 1 or method 2 may be indicated to the SCI using a predetermined number of bit information (eg, 1 bit information).

In an implicit method, for example, a condition in which the MCS index is a predetermined value (e.g., 29) in the SCI field, the CSI report field is ON, and the size of the scheduled PRB is less than a predetermined value or a set value (X). If satisfied, it can be interpreted as instructing Method 2, otherwise instructing Method 1. Or the opposite interpretation is possible.

Alternatively, when the transmitting terminal requests SL CSI report through SCI through PSCCH, whether the receiving terminal uses method 1 or method 2 can be explicitly or implicitly indicated through SCI.

As an explicit method, method 1 or method 2 may be indicated to the SCI using a predetermined number of bit information (eg, 1 bit information).

In an implicit method, for example, a condition in which the MCS index is a predetermined value (e.g., 29) in the SCI field, the CSI report field is ON, and the size of the scheduled PRB is less than a predetermined value or a set value (X). If satisfied, it can be interpreted as instructing Method 2, otherwise instructing Method 1. Or the opposite interpretation is possible.

The transmitting terminal receiving the SL CSI reported by the receiving terminal through the PSSCH through the indication method for Method 1 or Method 2 proposed above can decode the PSSCH and interpret the corresponding information.

In contrast, in the case of Mode2, the UE directly selects the PSSCH resource through sensing. In addition, the transmitting terminal informs the receiving terminal of transmission resource allocation information through SCI. Therefore, Mode2 can operate not only in IC but also in OCC/PC environment. In Mode2, when the receiving terminal feeds back the SL CSI to the transmitting terminal, the receiving terminal directly determines the PSSCH resource for transmitting the SL CSI through Mode2 sensing and resource selection, and the transmitting terminal through Mode2 sensing and resource selection. A method of requesting feedback from the SL CSI to the determined PSSCH resource can be considered.

In Mode 2, as described above, when the receiving terminal reports SL CSI to the transmitting terminal, the method in which the receiving terminal explicitly or implicitly instructs the transmitting terminal to use SCI through SCI, and the transmitting terminal has the SL CSI to the receiving terminal. When requesting a report, a method of explicitly or implicitly indicating through SCI may be considered.

Method 3 is a method in which the receiving terminal reports the SL CSI to the transmitting terminal through the PSFCH. For Method 3, it is assumed that a PSFCH format capable of transmitting SL CSI is defined. In this case, the UE may be allocated PSFCH transmission resources in the resource pool. Unlike the PSSCH transmission resource allocation method, the UE may be configured with a PSFCH transmission resource having a period of N slots (pre-). In more detail, the method of preconfiguration is a method of pre-storing the PSFCH transmission resource period N in the terminal. Unlike this, a PSFCH transmission resource period N value may be set in an upper layer. In the case of using the upper layer, the PSFCH transmission resource period N value may be set through Uu-RRC or PC5-RRC. The (pre-)configuration for the PSFCH transmission resource may also include a configuration that does not allocate the PSFCH transmission resource.

If PSSCH and PSFCH are simultaneously supported as a channel through which SL CSI is transmitted, the UE receiving SL CSI may not know information on the channel through which SL CSI is transmitted, and whether SL CSI is transmitted through PSSCH or transmitted through PSFCH. There is uncertainty about whether it will be. In order to solve this problem, the following two methods can be considered.

Setting for the channel through which SL CSI is transmitted (if both PSSCH and PSFCH are supported as a channel through which SL CSI is transmitted)

Method 1: When the transmitting terminal triggers/activates the SL CSI report, the receiving terminal signals whether to feed back the SL CSI to the PSSCH or the PSFCH through 1-bit SCI.

-Method 2: When the receiving terminal feeds back the SL CSI to the transmitting terminal, whether the SL CSI is transmitted through PSSCH or PSFCH is signaled to the transmitting terminal through 1-bit SCI.

Method 1 is a method in which the transmitting terminal instructs the receiving terminal of information on a channel on which SL CSI is to be transmitted. In contrast, method 2 is a method in which the receiving terminal determines a channel to which the SL CSI is to be fed back and informs the transmitting terminal of the channel. Compared to Method 1, Method 2 has an advantage that the UE performing the feedback can directly determine a channel that is attached to the feedback among the currently valid feedback channels.

Unlike the channel state information framework in the Uu interface between base station terminals, in the channel state information framework of the NR sidelink system, difficulties may arise in the process of the transmitting terminal requesting the SL CSI report and the receiving terminal performing the SL CSI report. have.

Specifically, in the case of Mode1, the UE may transmit SL CSI information through the PSSCH resource allocated from the base station (see SL CSI transmission channel method 1 or method 2). However, when the transmitting terminal requests the SL CSI report, but the receiving terminal does not receive the allocation of PSSCH resources from the base station in time, the SL CSI report of the receiving terminal may be delayed.

In Mode2, when the receiving terminal feeds back the SL CSI to the transmitting terminal, the receiving terminal directly determines the PSSCH resource for transmitting the SL CSI through Mode2 sensing and resource selection, and the transmitting terminal through Mode2 sensing and resource selection. A method of requesting feedback from SL CSI to the determined PSSCH resource may be considered. Even in Mode2, even when the receiving terminal feeds back the SL CSI to the transmitting terminal, the available PSSCH resources may not be allocated in time.

To solve this problem, the following effective SL CSI window setting method can be considered.

How to set the effective SL CSI window

-Method 1: If an effective SL CSI window is set in the transmitting terminal and it is determined that it is difficult to receive the SL CSI feedback from the receiving terminal in the SL CSI window, if the SL CSI request is not made or the feedback cannot be received until the SL CSI window is exceeded, the receiving terminal It can be determined that no feedback will come from.

-Method 2: When the effective SL CSI window is set in the receiving terminal and the SL CSI window is passed, the SL CSI report is not reported to the transmitting terminal.

The effective SL CSI window may be set in the report setting of the channel state information framework of the NR sidelink system. Also, the SL CSI window may be set in units of slots. In addition, the SL CSI window can be set by reflecting the feedback delay requirement.

As in Method 1 and Method 2, the SL CSI window may be set separately for the transmitting terminal and the receiving terminal, and the SL CSI window may be set in common for the transmitting terminal and the receiving terminal.

Method 1 is to determine whether the PSSCH resource is effective in receiving the SL CSI feedback by referring to the effective SL CSI window when the transmitting terminal requests feedback for the SL CSI through the PSSCH resource determined through sensing and resource selection in Mode2. I can. For example, when a valid PSSCH resource does not satisfy the feedback delay, the transmitting terminal may not make an SL CSI request. In addition, the transmitting terminal may refer to the effective SL CSI window and determine that feedback will not be received from the receiving terminal when the SL CSI window passes.

In the method 2, the transmission time of the PSSCH resource allocated from the base station in Mode1 by the receiving terminal by referring to the effective SL CSI window, or the PSSCH resource selected to transmit the SL CSI through sensing and resource selection in Mode2 passes through the SL CSI window and feedback. If the delay is not satisfied, the receiving terminal may not report the SL CSI to the transmitting terminal. In the case of using the effective SL CSI window as described above, it is possible to more effectively operate the SL CSI request and report in the sidelink.

In addition, if both PSSCH and PSFCH are supported as a channel through which SL CSI is transmitted, and the receiving terminal can select the channel to report SL CSI to the transmitting terminal, the terminal reporting the SL CSI can transmit faster among the available PSSCH and PSFCH resources. You can use the method of sending by selecting a channel. In addition, when the receiving terminal reports the SL CSI using the corresponding channel, a method of informing the transmitting terminal of information on which channel has been selected and transmitted may be used. At this time, the receiving terminal may consider a method of notifying the transmitting terminal through the SCI of the PSCCH.

As described above, when SL CSI is transmitted through PSSCH or PSFCH, the SL CSI report is a non-subband-based aperiodic SL CSI report that is reported only for the frequency domain corresponding to the PSSCH transmitted by the transmitting terminal. In the case of a Uu interface between base station terminals, whether to use a wideband PMI/CQI that reports one PMI or CQI for the entire frequency band and transmits CSI-RS in all bands, or divides the frequency band into several subbands, CSI was reported by determining whether to use subband PMI/CQI reporting one PMI or CQI per subband, but since the sidelink is communication between the terminal and the terminal, the SL CSI-RS is not transmitted in all bands, but the PSSCH Since the SL CSI-RS is transmitted through the PSSCH only in the frequency domain to which the raw resource is allocated, a non-subband based aperiodic SL CSI report is used.

As described above, in the present invention, aperiodic SL CSI reporting is considered. SL CSI reporting may be enabled/disabled separately from triggering/activation of aperiodic SL CSI reporting. Enable/disable for SL CSI reporting may be set in the report setting of the channel state information framework of the NR sidelink system. In addition, SL CSI reporting can be triggered/activated only when SL CSI reporting is enabled. Various methods for triggering/activation of SL CSI reporting can be considered as follows.

SL CSI reporting triggering/activation method

-Method 1: When SL CSI reporting is enabled, SL CSI reporting is automatically triggered/activated.

-Method 2: SL CSI reporting is enabled and SL CSI reporting is triggered/activated by SCI.

-Method 3: SL CSI reporting is enabled and SL CSI reporting is triggered/activated by MAC CE.

-Method 4: SL CSI report is triggered/activated when SL HARQ-ACK reporting is enabled and the receiving terminal transmits NACK to the transmitting terminal a predetermined number of times (X(≥1)).

-Method 5: If the SL RSRP value reported by the receiving terminal to the transmitting terminal is lower than the threshold X, the SL CSI report is triggered/activated.

-Method 6: When SL CSI reporting is enabled and CSI-RS transmission is configured, SL CSI reporting is triggered/activated.

-Method 7: SL CSI reporting is triggered/activated when SL CSI reporting is enabled and the timer configured in the receiving terminal ends.

-Method 8: When SL CSI reporting is enabled and the timer configured in the transmitting terminal is ended, SL CSI reporting is triggered/activated.

First, Method 1, Method 4, Method 5, Method 6, and Method 7 do not use additional signaling for triggering/activation of SL CSI reporting by the transmitting terminal to the receiving terminal.

Method 2, Method 3, Method 6, and Method 8 are methods in which the transmitting terminal uses additional signaling to trigger/activate the SL CSI report to the receiving terminal. Specifically, Method 2 is a method using SCI, Method 3 is a method using MAC CE, and Method 6 is a method of triggering/activation of SL CSI reporting by implicit method.

Method 6 is a method of indirectly determining whether SL CSI report is triggered/activated according to whether or not CSI-RS transmission is set. At this time, the configuration of SL CSI-RS transmission may be included in the configuration of the SL CSI-RS in the resource set in the resource setting of the channel state information framework of the NR sidelink system. Alternatively, SL CSI-RS transmission may be configured through SCI or MAC CE. Therefore, Method 6 is a method in which SL CSI report is triggered/activated when SL CSI-RS transmission is configured and SL CSI-RS is transmitted.

Method 8 is a method of triggering/activating SL CSI reporting after SL CSI reporting is enabled and the timer configured in the transmitting terminal is ended. Timer may be operated from the time when SL CSI reporting is enabled. In addition, an operation of randomly selecting whether to trigger/activate SL CSI reporting at a time when the timer set in the transmitting terminal is ended may be additionally considered. Next, the timer can be restarted immediately after the timer expires. Alternatively, the timer may be restarted after the timer has ended and you have selected whether to trigger/activate SL CSI reporting. At this time, the setting value of the timer may be the same as before or may be selected again with a different value.

Specifically, in Method 8, when the timer set in the transmitting terminal ends, the SL CSI-RS is transmitted from the pool of available resources afterwards, and one of the methods 2, 3, and 6 can be used to trigger/activate SL CSI reporting. have. In the case of Method 8, it can be used as a simple method of operating aperiodic SL CSI reporting in the sidelink, and can be described as an operation of a transmitting terminal for this. In addition, the SCI format for triggering/activating the SL CSI report in Method 2 may be designed in the same manner as the general SCI format or may be designed in different forms. In addition, as an extended form of Method 4, SL HARQ-ACK reporting is enabled in sidelink groupcast, and SL CSI reporting triggering/activation may be used only for terminals that have transmitted NACK X (≥1) times among terminals in the group. have.

In the case of Method 7, when SL CSI reporting is enabled and a timer configured in the receiving terminal is ended, SL CSI reporting is triggered/activated. Timer may be operated from the time when SL CSI reporting is enabled. In addition, an operation of randomly selecting whether to trigger/activate SL CSI reporting at a time when the timer configured in the receiving terminal is ended may be additionally considered. Next, the timer can be restarted immediately after the timer expires. Alternatively, the timer may be restarted after the timer has ended and you have selected whether to trigger/activate SL CSI reporting. At this time, the setting value of the timer may be the same as before or may be selected again with a different value.

In Method 7 and Method 8, each of the receiving terminal and the transmitting terminal sets a timer. The timer may be configured by the terminal, or a method of setting the timer to the report setting of the channel state information framework of the NR sidelink system described above may be used. For example, one timer value may be set in the report setting of the channel state information framework, and a method in which the terminal randomly selects a timer from among the set values and multiple timer values may be considered.

When there is more than one information included in the SL CSI, there may be a dependency between SL CSI information. Specifically, when the UE feeds back CQI+RI, the CQI may be calculated based on the RI. In the present invention, it is assumed that CQI+RI is always reported together with CQI and RI. When the UE feeds back CQI+RI+PMI, the CQI is calculated based on the determined PMI and RI. Below, the generation method for SL CSI will be described in more detail through the definition of CQI in the sidelink and the definition of CSI reference resource. First, the CQI in the sidelink may be defined as follows.

SL CQI

In FIG. 6, the terminal 620 corresponding to the receiver in the sidelink determines each CQI value reported in slot n as the highest CQI index that satisfies the following condition.

* One PSSCH TB transport block composed of a combination of a modulation scheme corresponding to the CQI index, a target code rate, and a transport block size must be capable of receiving so as not to exceed the next transport block error probability. Here, the PSSCH TB transport block occupies a sidelink physical resource block or subchannels named as SL CSI reference resource.

** 0.1, if the upper layer is set, cqi-Table in SL-CSI-ReportConfig indicates the following'table1' (below [Table 2] or [Table 5]) or'table2' (below [Table 3] or [Table 5] 6])

** 0.00001, if cqi-Table in SL-CSI-ReportConfig indicates the following'table3' (below [Table 4] or [Table 7]) by setting the upper layer

If the target transport block error probability is set to 0.1 above, it is set to use'table1' (below [Table 2] or [Table 5]) or'table2' (below [Table 3] or [Table 6]). This is the case. Both'table1' and'table2' are CQI tables designed in consideration of a target transport block error probability of 0.1.

In'table1' (below [Table 2] or [Table 5]), modulation is considered to be QPSK, 16QAM, 64QAM, and in'table2' (below [Table 3] or [Table 6]), modulation is QPSK, 16QAM, 64QAM, Up to 256QAM was considered. If only up to 64QAM is supported in the sidelink,'table1' (below [Table 2] or [Table 5]) can be used, and if the sidelink supports up to 256QAM,'table2' (below [Table 3]). Or [Table 6]) may be used. In addition, it is possible to indicate whether to use'table1' (below [Table 2] or [Table 5]) or'table2' (below [Table 3] or [Table 6]) depending on the situation through the setting. The configuration may be indicated by SL-SIB through configuration in the resource pool, or through Uu-RRC or PC5-RRC connection. Also, a method of indicating through SCI may be considered.

When the target transport block error probability is set to 0.00001, it is a case where'table3' (below [Table 4] or [Table 7]) is used. 'table3' (below [Table 4] or [Table 7]) is a CQI table designed in consideration of a target transport block error probability of 0.00001, and modulation is considered up to QPSK, 16QAM, and 64QAM.

The reason why two target transport block error probabilities of 0.1 and 0.00001 are considered as described above is that service requirements may be different. The NR sidelink also defines PQI (PC5 5QIs) for various QoS requirements, and the PQI includes Default priority level, Packet delay budget, Packet error rate, Default maximum date burst volume, and Default averaging window. Here, the packet error rate can be set to various values between 10^-1 and 10^-5. As described above, it is possible to operate using two target transport block error probability settings of 1 and 0.00001, but to support more accurate QoS, it is also possible to support setting a more detailed target transport block error probability other than 1 and 0.00001. For example, when a target transport block error probability setting of 0.001 is additionally introduced, a corresponding CQI table may be additionally defined.

[Table 2], [Table 3], and [Table 4] below are CQI tables composed of 4 bits, and [Table 5], [Table 6], and [Table 7] are CQI tables composed of 5 bits. When using the CQI tables of [Table 2], [Table 3] and [Table 4], the number of feedback bits is 1 compared to the case of using the CQI tables of [Table 5], [Table 6], and [Table 7]. It is possible to save a bit. In contrast, in the case of using the CQI table of [Table 5], [Table 6], and [Table 7], it is possible to map the index of the MCS table used by the transmitting terminal and one-to-one mapping. It may be more convenient to receive reports and determine transmission parameters.

In the following [Tables 2 to 7], the reception terminal reporting the CQI index 0 to the transmission terminal may be interpreted as an operation indicating that the current channel state is a state in which reception is impossible. In addition, in Tables 2 to 7 below, reporting the CQI index 1 by the receiving terminal to the transmitting terminal may be interpreted as an operation indicating that the current channel state is a state in which PSCCH reception is possible but PSSCH reception is not possible.

In addition, when the channel busy ratio (CBR) is considered during SL CSI transmission, the indexes usable in the CQI table may be limited. The specific method will be described in more detail below. Therefore, in this case, the highest CQI index in the CQI definition may be selected in a CQI index region limited by CBR.

[Table 2]

[Table 3]

[Table 4]

[Table 5]

[Table 6]

[Table 7]

Next, the CSI reference resource in the sidelink can be defined as follows.

SL CSI reference resource definition

The SL CSI reference resource for receiving the CSI-RS in order for the UE 620 corresponding to the receiving end to generate SL CSI information on the sidelink may be defined as follows.

* In the frequency domain, the SL CSI reference resource is defined by a sidelink physical resource block or a group of subchannels corresponding to the band inducing SL CSI.

* In the time domain, the CSI reference resource 910 is defined as slot n-nCSIref when the channel state information is reported in sidelink slot n (920).

** For aperiodic SL CSI reporting, nCSIref can be classified as follows.

*** When it is set to report the channel status information in the same slot as the sidelink slot from which the SL CSI request was sent, nCSIref is 0, indicating the sidelink slot from which the CSI request was sent.

In cases other than ***, nCSIref may be a value corresponding to a sidelink slot in which the SL CSI-RS closest to n is transmitted that is greater than or equal to the time required for the UE to calculate CSI.

According to an embodiment of the present disclosure, when reporting the channel state information, the terminal is the channel state information measured based on the CSI-RS resource 930 at the same time point as or before the CSI reference resource corresponding to the corresponding channel state information report. Can report. The related operation can be determined by setting information for measurement restriction in the CSI report setting of the channel state information framework of the NR sidelink system. When the measurement restriction is set, the channel state is measured using only the CSI-RS resource at the same time as the CSI reference resource. If the measurement restriction is not set, both the CSI-RS resource at the same time as the CSI reference resource and the previous time are used. Thus, channel measurement can be performed.

When it is set to determine the CQI index in the SL CSI reference resource, the UE corresponding to the receiver in the sidelink may assume some or all of the following for the purpose of inducing the CQI index.

* A OFDM symbol is used as a control channel.

* B OFDM symbols are used as AGC symbols.

* C OFDM symbols are used as GP.

* The number of PSSCH and DMRS symbols is D.

* The same SCS as the SL BWP is set for PSSCH reception.

* The reference resource uses the CP length and SCS set for PSSCH reception.

* No RE is used as SSB.

* The value of RV is 0.

* The EPRE of PSSCH and CSI-RS is the same.

* No RE is assigned to NZP CSI-RS or ZP CSI-RS.

* It is assumed that the number of front-loaded DMRS symbols is one and the number of additional DMRSs is a value set by the SCI or resource pool.

* It is assumed that the PSSCH symbol does not include the DMRS.

* PRB bundling size is assumed to be 2PRB.

* PSSCH transmission can be performed up to two transmission layers. In order to calculate the CQI index, the UE assumes that the PSSCH transmission of [0, v-1] corresponding to v layers is transmitted to the antenna port of [0,...,P-1] as shown in the following equation. .

는 PSSCH 심볼에 대한 vector를 나타낸다. 그리고 P는 SL CSI-RS 포트 수를 나타낸다. 만약 하나의 CSI-RS 포트가 설정되는 경우에 W(i)는 1이 된다. SL-CSI-ReportConfig의 reportQuantity가 'CQI-RI-PMI'로 설정된 경우 W(i)는 x(i)에 적용할 수 있는 보고된 PMI에 해당되는 precoding matrix가 된다. SL-CSI-ReportConfig의 reportQuantity가 'CQI' 또는 'CQI-RI'로 설정된 경우 W(i)는 layer 수 v에 의해 1/sqrt(v)로 스케일된 identity matrix가 된다. here

Denotes a vector for the PSSCH symbol. And P represents the number of SL CSI-RS ports. If one CSI-RS port is configured, W(i) is 1. When the reportQuantity of SL-CSI-ReportConfig is set to'CQI-RI-PMI', W(i) becomes a precoding matrix corresponding to the reported PMI applicable to x(i). When the reportQuantity of SL-CSI-ReportConfig is set to'CQI'or'CQI-RI', W(i) becomes an identity matrix scaled to 1/sqrt(v) by the number of layers v.

In the above, the assumption about the use of time domain resources of the slot for determining the sidelink CQI index is as follows. When it is configured to report the CQI index in the SL CSI reference resource, the UE corresponding to the receiving end in the sidelink assumes the following for the purpose of inducing the CQI index.

[Assumption set 1]

* The first two OFDM symbols in the slot are used as control channels.

* The number of PSSCH and DMRS symbols in a slot is 8

* One OFDM symbol is used as a GP.

* Two OFDM symbols are used as PSFCH.

* One OFDM symbol is used as a GP.

Alternatively, the following assumption set 2 could be applied.

[Assumption set 2]

* The first two OFDM symbols in the slot are used as control channels.

* The number of PSSCH and DMRS symbols in a slot is 11

* One OFDM symbol is used as a GP.

The assumption set 1 may be for a case where a resource occupied by the PSFCH exists in a slot, and the assumption set 2 may be for a case where a resource occupied by the PSFCH does not exist in the slot.

Whether to apply the assumption used by the UE measuring and reporting CSI when generating CSI as the assumption set 1 or the assumption set 2 may be determined according to the resource pool setting, or in the bit field of PC5-RRC or SCI. Can be determined accordingly.

Alternatively, the assumption used when generating the CSI may be determined according to the presence or absence of PSFCH resources included in the slot in which the sidelink CSI-RS is transmitted. That is, if the PSFCH resource exists in the slot in which the CSI-RS is transmitted, the assumption set 1 is applied, and if the PSFCH resource does not exist in the slot in which the CSI-RS is transmitted, the assumption set 2 is applied.

As another example, a method of generating CSI feedback information including a CQI index by assuming the use of time domain resources of a slot for determining a sidelink CQI index using the structure of a slot in which an actual sidelink CSI-RS is transmitted is It is possible. That is, when a CSI-RS is transmitted in the sidelink, it is always transmitted with the PSSCH, so the CQI index, etc., assuming that the actual mapping resources such as the number of symbols and frequency resources occupied by the PSSCH in the slot in which the CSI-RS is transmitted is used. It may be possible to produce.

<First Example>

In the sidelink, because the SL CSI-RS is not transmitted in the entire band and is transmitted only in the scheduled PSSCH region, the frequency region of the scheduled PSSCH is small, and there is a problem that inaccuracy may occur in the measurement result due to insufficient samples of the SL CSI-RS. And, a method for solving this is proposed in Example 1. To solve this problem, the following methods can be considered.

How to ensure the accuracy of measurements using SL CSI-RS

* Method 1: How to increase the frequency density per port per RB of SL CSI-RS

* Method 2: How to power boosting the SL CSI-RS

* Method 3: A method of forcing the PSSCH to be scheduled so that the number of subchannels (or the number of RBs) on the frequency is more than a predetermined value (X)

* Method 4: How to prevent SL CSI-RS from being transmitted when the number of subchannels (or number of RBs) in the frequency of the PSSCH is less than a predetermined value (X)

* Method 5: SL CSI-RS transmission is allowed even when the number of subchannels (or RBs) X on the frequency is less than the number X, but limits the UE operation

Method 1 is a method of using a pattern in which the frequency density per port per RB of SL CSI-RS is greater than 1 as suggested in [Table 1]. In [Table 1], a pattern in which the frequency density per port per RB of SL CSI-RS is 6 when SL CSI-RS port is 1, and port per RB of SL CSI-RS when SL CSI-RS port is 2 A pattern with 3 and 6 per frequency densities was proposed.

In [Table 1], when the SL CSI-RS port is 1, the pattern in which the frequency density per port per RB of SL CSI-RS is 3 is the pattern used as TRS in NR Uu, and SL CSI- according to the frequency domain of the scheduled PSSCH. It can be used for the purpose of obtaining a sample of RS.

When Method 1 is used, the following operation of the receiving terminal can be considered. The first is a method in which a pattern in which the frequency density per port per RB of the SL CSI-RS is greater than 1 is always used, and the UE uses this to not only measure SL RLM and SL RSRP, but also report SL CSI. The second is a method in which the UE does not use the SL CSI-RS for SL RLM and SL RSRP measurements but only for SL CSI reporting when a pattern having a frequency density per port per RB of SL CSI-RS is transmitted.

Method 2 is a method of applying power boosting to SL CSI-RS. A method in which a transmitting terminal can apply 3dB power boosting to SL CSI-RS RE for the SL CSI-RS patterns of pattern 840 and pattern 870 to be. This may be a method for improving the accuracy of measurement using SL CSI-RS in an environment where the samples of SL CSI-RS according to the frequency domain of the PSSCH scheduled in the sidelink are insufficient. For a method of obtaining the SL CSI-RS EPRE of the receiving terminal according to the power boosting of the SL CSI-RS, refer to Embodiment 2.

Method 3 is a method of forcing the PSSCH to be scheduled so that the number of subchannels (or the number of RBs) on the frequency is more than a predetermined value (X). For example, a method may be considered in which the PSSCH is scheduled to be 10 RB or more in frequency, or a minimum size Subchannel that can be set as described in FIG. 3 is 10 RB or more. However, when the method 3 is used, there is a disadvantage that scheduling constraints occur.

Method 4 is a method in which the SL CSI-RS is not transmitted when the number of subchannels (or the number of RBs) in the frequency of the PSSCH is less than a predetermined value (X). When Method 4 is used, the following operation of the receiving terminal can be considered. Since SL CSI-RS is not transmitted, the UE does not perform SL RLM and SL RSRP measurements using the corresponding SL CSI-RS. It also does not measure and report SL CSI. Meanwhile, the predetermined value of the present disclosure is denoted by X for convenience of description, but may be set differently according to each embodiment and method.

Method 5 is a method of limiting the operation of the receiving terminal although SL CSI-RS transmission is allowed when the number of subchannels (or the number of RBs) on the frequency of the PSSCH is less than a predetermined value (X). When Method 5 is used, the following operation of the receiving terminal can be considered. The first method determines that the SL CSI-RS received by the receiving terminal is not valid and does not perform SL RLM and SL RSRP measurements using the corresponding SL CSI-RS. Also, the receiving terminal does not measure and report SL CSI.

Another method determines that the SL CSI-RS received by the receiving terminal is not valid and does not perform SL RLM and SL RSRP measurements using the corresponding SL CSI-RS. However, when the SL CSI report is triggered/activated along with the SL CSI-RS transmission that cannot guarantee the accuracy of the measurement, the SL CSI-RS that cannot guarantee the accuracy of the measurement is not used for SL CSI generation, as described above. When there is a received SL CSI-RS in the SL CSI window of the receiving terminal, the SL CSI can be generated and reported using the corresponding SL CSI-RS. This operation is referred to above.

If there is no SL CSI-RS received in the SL CSI window of the UE, the receiving UE may not report the SL CSI to the transmitting UE or may report the SL CSI set to the default value. Here, the default value may be the previously fed back SL CSI.

In the method 3/4/5, the number of subchannels (or the number of RBs) on the frequency of the PSSCH means the number of subchannels, the total number of RBs determined by the number of transmitted subchannels, or one subchannel is It can also mean the number of RBs constituting.

<Second Example>

In Embodiment 2 of the present invention, a terminal operation related to SL CSI-RS power configuration is proposed. The terminal-to-terminal communication environment in the sidelink is very different from the base station-terminal communication environment in Uu. In the case of downlink communication between the base station and the terminal in Uu, the base station transmits a signal with a fixed power, and the size of the signal received by the terminal varies according to the reception environment of the terminal. Therefore, when the base station does not boost the CSI-RS power when transmitting the CSI-RS in the downlink of Uu, the CSI-RS is transmitted with the same power as the data transmitted on the PDSCH.

However, in the sidelink, the power control operation of the transmitting terminal is supported. Therefore, the power of the signal transmitted by the terminal is not fixed and may vary. In addition, the power of the SL CSI-RS transmitted by the transmitting terminal is not fixed and may vary. In order for the receiving terminal to generate SL CSI, it receives the SL CSI-RS, determines the channel state through channel estimation, and feeds back CSI information such as CQI and RI suitable for the PSSCH to the transmitting terminal. Therefore, the receiving terminal needs to know the SL CSI-RS energy per resource element (EPRE) corresponding to the transmission power of the reference signal SL CSI-RS, and based on this, it receives the SL CSI-RS, performs channel estimation, and determines the appropriate SL CSI. Can be generated and reported. The transmission power of the SL CSI-RS in the sidelink (SL CSI-RS EPRE) may be defined as the average power (in [W]) for the RE through which the SL CSI-RS set in the system BW is transmitted. The following may be considered as a method for the receiving terminal to obtain the SL CSI-RS EPRE in the sidelink.

Method for receiving terminal to obtain SL CSI-RS EPRE

* Method 1: Directly receive information on SL CSI-RS transmit power

* Method 2: When information on other reference transmission power is transmitted to the receiving terminal, use it or receive offset information for it

* Method 3: Assume the maximum transmit power for PSSCH

* Method 4: Receive reference power information for SL CSI-RS transmission power

Method 1 may transmit SL CSI-RS transmission power through a specific number of bits (eg, [x] bits). For example, the transmit power can be displayed from -41 dBm to 31 dBm in 1 dBm steps. For example, the transmitting terminal may transmit information on the SL CSI-RS EPRE through 7 bits. The specific number may be a predetermined number, or a transmission terminal of a predetermined sidelink may include information on the SL CSI-RS EPRE as a bit field in the sidelink control information (SCI) transmitted through the sidelink control channel. Meanwhile, when information on the SL CSI-RS EPRE is directly transmitted through SCI, signaling overhead may occur.

Method 2 is a method of using when information on other reference transmission power is transmitted to the receiving terminal in the sidelink or by receiving and using offset information for this. For example, the other reference transmission power may include a synchronization signal, a DMRS transmitted through a PSBCH, or a transmission power of another reference signal. However, the above is only an example and there is no limitation on a reference signal that can be used as another reference transmission power in the present disclosure.

If information on other reference transmission power is transmitted to the receiving terminal, the transmitting terminal does not need to separately transmit information on the SL CSI-RS transmission power to the receiving terminal. If the information on the different reference transmission power and the SL CSI-RS transmission power are the same, the receiving terminal may determine that the different reference transmission power is assumed to be the SL CSI-RS transmission power. On the contrary, if the information on the different reference transmission power and the SL CSI-RS transmission power are not the same, the transmitting terminal may transmit only offset information of the other reference transmission power and the SL CSI-RS transmission power to the receiving terminal. In this case, the offset information may be defined as a ratio of the EPRE of another reference signal and the SL CSI-RS EPRE. The offset information may be transmitted through SCI, and may be signaled with a smaller number of bits than the number of bits used to transmit SL CSI-RS transmission power in Method 1.

When Method 1 or Method 2 is used, there is an advantage in that SL CSI information can be generated based on the SL CSI-RS EPRE transmitted by the actual transmitting terminal. In addition, when Method 1 or Method 2 is used, the receiving terminal may perform path loss estimation from the SL CSI-RS EPRE. In this case, the path attenuation estimation may be calculated as a difference between the SL CSI-RS EPRE and the SL RSRP measured at the receiving end.

Method 3 is a method of assuming the SL CSI-RS EPRE as the maximum transmission power for the PSSCH. Therefore, the maximum transmission power for the _PSSCH may be a value set to P _{CMAX, PSSCH} . Here, P _CMAX,PSSCH may be a carrier transmitted with a maximum transmission power set at a PSSCH transmission time and a value defined for a corresponding cell. However, when congestion control is performed, the actual maximum transmission power may be limited. In this case, the maximum transmission power value limited by the CBR may be applied. For details on this, refer to [Table 8] below.

Method 4 is a method of transmitting reference power information for SL CSI-RS transmission power to a receiving terminal. If the reference power for the SL CSI-RS transmission power is determined as the maximum transmission power for the PSSCH, the same method as in Method 3 may be used. However, in method 4, the base station or the transmitting terminal may set the reference power for the SL CSI-RS transmission power, and it may be possible to change the setting value.

For example, a method in which reference power is set differently according to CBR may be considered. Specifically, the reference power value can be applied differently depending on the CBR. When it is determined that the channel occupancy is high due to high CBR, the reference power may be set low. In contrast, when it is determined that the channel occupancy is low due to low CBR, the reference power may be set high. At this time, the reference power can be set within a range from -41 dBm to 31 dBm. The reference power information for the SL CSI-RS transmission power of the base station may be included in the resource pool configuration. The corresponding value may be previously stored in the terminal (pre-configuration). Alternatively, the information may be a value transmitted through SL-SIB or set through Uu-RRC or PC5-RRC. Alternatively, a method of indicating the information through SCI may be considered.

When the above-described receiving terminal uses methods 3 and 4 of obtaining the SL CSI-RS EPRE, the SL CSI-RS EPRE may differ from the actual SL CSI-RS EPRE transmitted by the transmitting terminal. Therefore, when the SL CSI-RS is received using methods 3 and 4, channel estimation is performed, and SL CSI is generated, the SL CSI suitable for the actual sidelink channel environment may not be reported. Therefore, when Method 3 or Method 4 is used, the transmitting terminal needs to correct and use the SL CSI information received from the receiving terminal. In this case, although the transmitting terminal may directly correct the information on the SL CSI from the transmitting unit, the transmitting terminal may request correction when generating the SL CSI to the receiving terminal.

On the other hand, even in the case of using the methods 1 and 2, when correction is required for the SL CSI information fed back by the receiving terminal, the transmitting terminal may request correction to the receiving terminal.

Method of requesting correction when transmitting terminal generates SL CSI to receiving terminal

* The transmitting terminal transmits powerControlOfffset to the receiving terminal

In the above, powerControlOfffset may be defined as a ratio of SL CSI-RS EPRE and PSSCH EPRE, which is assumed when the receiving terminal generates and reports SL CSI. For example, powerControlOfffset can be displayed from -8 dB to 15 dB in 1 dB steps. The value can be transferred to the receiving terminal through PC5-RRC. Alternatively, a method of signaling through SCI may also be considered. However, in the case of signaling by SCI, a method of indicating that the powerControlOfffset is divided into values of a smaller range than the above example may be considered in consideration of signaling overhead.

<Third Example>

Embodiment 3 of the present invention proposes a method for a transmitting terminal to determine a transmission parameter according to whether SL CSI is reported in a sidelink. Therefore, the operation of the transmitting terminal to determine the transmission parameter may vary depending on whether or not there is an SL CSI report. Here, whether there is an SL CSI report or not may be determined by one of the following conditions.

Determination condition for whether there is an SL CSI report in determining the transmission parameter

* Condition 1: depending on whether SL CSI reporting is enabled or not

* Condition 2: According to whether SL CSI report is triggered/activated

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

Condition 1 is a method of determining that there is an SL CSI report when SL CSI reporting is enabled. Condition 2 is a method of determining that there is an SL CSI report when SL CSI report is enabled and SL CSI report is activated. Condition 1 and Condition 2 may or may not be the same condition depending on how the aforementioned SL CSI report is triggered/activated.

Finally, condition 3 is a method of determining that there is an SL CSI report when the transmitting terminal actually receives the CSI report from the receiving terminal. The reason why the transmitting terminal considers a method of determining a transmission parameter according to whether the receiving terminal reports the SL CSI is because SL CSI reporting may not always be supported in the sidelink.

Meanwhile, in the present invention, it is considered that the SL CSI-RS transmission and SL CSI report operate in a unicast between the terminal and the terminal in the sidelink. In other words, SL CSI-RS transmission and SL CSI reporting may not be supported in broadcast. Also, in the case of groupcast, SL CSI-RS transmission for groupcast and SL CSI reporting method are not separately considered. Therefore, when the terminal-to-terminal unicast path is not operated, the transmitting terminal of the sidelink cannot receive the SL CSI report from the receiving terminal. In addition, only aperiodic SL CSI reporting is considered even in the case of a sidelink terminal-to-terminal unicast.

Therefore, the case in which the transmitting terminal receives the SL CSI report from the receiving terminal in the sidelink may be very limited. When a vehicle terminal performs sidelink communication with another vehicle terminal, a very high moving speed may be considered. Therefore, the terminal-to-terminal channel changes very quickly. In such an environment, it is necessary to improve the performance of channel estimation by increasing the number of symbols in time of the PSSCH demodulation reference signal (DMRS) to increase the tracking performance for a channel that changes in time. Alternatively, a low modulation and coding scheme (MCS) needs to be used to increase reception performance. If the transmitting terminal receives the SL CSI report from the receiving terminal, information on the terminal-to-terminal channel state may be obtained from the SL CSI. However, when the transmitting terminal does not receive the SL CSI report from the receiving terminal, it may be difficult to select a transmission parameter so that the receiving terminal can successfully receive the data transmitted by the transmitting terminal because the terminal-to-terminal channel state cannot be known.

As described above, there are Mode 1, which is a method in which the base station allocates transmission resources in the sidelink, and Mode 2, which is a method in which the terminal directly allocates transmission resources of the sidelink through sensing. First, in the case of Mode1, the base station may signal the transmission time point and frequency allocation location information of initial transmission and retransmission to the transmitting terminal through DCI. In addition, in Mode1, the base station may instruct the transmitting terminal with information such as pattern information of the PSSCH DMRS, MCS configuration, and the number of transmission layers through Uu-RRC. If the base station instructs the transmitting terminal to transmit such information through Uu-RRC, the transmitting terminal can set the transmission parameter accordingly.

However, if there is no such information set in Uu-RRC, the transmitting terminal must directly select the transmission parameter. In this case, depending on whether the receiving terminal reports the SL CSI, a method for the transmitting terminal to set information such as PSSCH DMRS pattern information, MCS configuration, and the number of transmission layers may vary. If there is no SL CSI report, a parameter to be selected by the transmitting terminal may be determined by the terminal implementation.

If there is an SL CSI report, the transmitting terminal may determine the channel state through SL CSI and directly determine the appropriate PSSCH DMRS pattern information, MCS configuration, and transmission parameters such as the number of transmission layers. For details on this, refer to the method for the transmitting terminal to select a transmission parameter for SL CSI reporting in Embodiments 3 and 4 . In addition, the transmitting terminal may transmit the selected PSSCH DMRS pattern information, MCS configuration, and information on the number of transmission layers to the receiving terminal through SCI. In contrast, a method of transmitting the pattern information of the PSSCH DMRS through the Pc5-RRC and transmitting the information on the MCS configuration information and the number of transmission layers through the SCI may be considered.

When there is an SL CSI report, the transmitting terminal may transmit the SL CSI report received from the receiving terminal to the base station in Mode 1 so that the base station can indicate more accurate transmission parameters to the transmitting terminal. Specifically, a method of transmitting through PUCCH or PUSCH may be considered. In contrast, when the base station and the terminal are connected by Uu-RRC, the transmitting terminal can transmit the SL CSI report to the base station through Uu-RRC.

When the base station receives the SL CSI report in Mode 1, the base station may instruct the transmitting terminal with information such as the pattern information of the PSSCH DMRS, the MCS configuration, and the number of transmission layers through Uu-RRC. In this case, it may be possible to indicate a transmission parameter more suitable for the channel condition.

In contrast, in Mode2, the transmitting terminal may determine a transmission time point and a frequency allocation position for initial transmission and retransmission through direct sensing. In the case of Mode2, unlike Mode1, the transmitting terminal must directly select all transmission parameters without involvement of the base station. Even in Mode2, the method of setting parameters of the transmitting terminal may vary depending on whether the SL CSI is reported.

If there is an SL CSI report, the transmitting terminal may determine the channel state through SL CSI and configure transmission parameters such as PSSCH DMRS pattern information, MCS configuration, and the number of transmission layers. In addition, the transmitting terminal may transmit all information on the selected PSSCH DMRS pattern information, MCS configuration, and the number of transmission layers to the receiving terminal through SCI. In contrast, a method of transmitting the pattern information of the PSSCH DMRS through the Pc5-RRC and transmitting the information on the MCS configuration information and the number of transmission layers through the SCI may also be considered.

If there is no SL CSI report, the transmitting terminal may configure the PSSCH DMRS pattern information, MCS configuration, and the number of transmission layers according to the absolute speed of the transmitting terminal. An example of this will be described through [Table 8].

[Table 8]

Referring to [Table 8], in Mode2, a set of transmission parameters (SL-PSSCH-TxParameters) may be determined for each synchronization source of the terminal according to the absolute speed of the transmitting terminal. Here, the synchronization source may be a base station or a GNSS. If the base station is not connected to the Uu-RRC terminal, the GNSS or the terminal may be a synchronization source. One SL-PSSCH-TxConfig may be configured for each synchronization source.

In addition, transmission that can be selected according to whether the speed is greater than the threshold (parametersAboveThres) or less (parametersBelowThres) by setting a threshold for the absolute speed of the terminal (thresUE-Speed) and comparing the absolute speed of the transmitting terminal with the threshold. A parameter set (SL-PSSCH-TxParameters-Mode2) may be determined.

In the transmission parameter set (SL-PSSCH-TxParameters), the PSSCH DMRS pattern information (additional-dmrsPSSCH), the MCS setting range (minMCS-PSSCH, maxMCS-PSSCH), the number of transmission layers (Txlayer-NumberPSSCH), and the subchannel allocation range (minSubChannel At least one of -NumberPSSCH, maxSubchannel-NumberPSSCH) and the number of retransmissions (allowedRetxNumberPSSCH) may be included.

In this case, the reason that the subchannel allocation range is included is because the actual coding rate can be determined by the set MCS, the number of transport layers, and the number of RBs to which the PSSCH is allocated. Here, the subchannel may be a unit of PSSCH allocation consisting of one or more RBs.

In [Table 8], the additional-dmrsPSSCH indicates the number of additional DMRS symbols in the pattern information of the PSSCH DMRS. When set to 0, only front-loaded DMRS is transmitted, and when the additional DMRS symbol is set to 3, front-loaded DMRS This represents a case in which up to 4 DMRS symbols are transmitted including. DMRS pattern information other than the number of additional DMRS symbols may be included.

In addition, although the MCS setting range is indicated as minMCS-PSSCH and maxMCS-PSSCH in [Table 8], it may be considered that only maxMCS-PSSCH is set.

In [Table 8], Txlayer-NumberPSSCH indicates the number of transport layers, n1 indicates layer 1 transmission, and n2 indicates layer 2 transmission. And both means that the UE can autonomously set the setting for layer 1 or 2.

In [Table 8], allowedRetxNumberPSSCH indicates the setting of the number of retransmissions of the terminal, n0 indicates no retransmission, and n1, n2, n3 indicates 2, 3, and 4 retransmissions, respectively, including initial transmission. In addition, all means that the terminal can be set autonomously.

In [Table 8], maxTxPower indicates the maximum transmission power value limited for congestion control when CBR is used.

The configuration of the transmission parameter SL-PSSCH-TxParameters in [Table 8] may be (pre-)configuration. This may be a value previously stored in the terminal, and may be a value set through SL-SIB or Uu-RRC from the base station. In the present invention, there is no restriction on other parameters and setting values that may be included in the transmission parameter set (SL-PSSCH-TxParameters).

Next, when there is an SL CSI report in Mode1 and Mode2, an operation in which the transmitting terminal selects a transmission parameter will be described in more detail.

The CQI and RI are considered as SL CSI reports transmitted by the receiving terminal, and the MCS and the number of transmission layers are considered as transmission parameters selected by the transmitting terminal. The selection range of the MCS may be determined from an MCS index selectable in the defined MCS table. The selection range of the number of transmission layers may be determined within the maximum number of transmission layers supported by the transmission terminal. The following describes a case in which CBR is not considered when selecting a transmission parameter, and for a description of a case in which CBR is considered, see Example 4 below. In addition, the following method can be applied to both cases where the receiving terminal reports SL CSI by reflecting CBR or reports SL CSI without reflecting CBR. In this case, the following method can be considered.

Method for transmitting terminal to select transmission parameter for SL CSI report

* Method 1: Select by terminal implementation

* Method 2: CQI level received by SL CSI report, selection of UE implementation in a range of values lower than RI level

* Method 3: Transmission parameter selection based on CQI level and RI level received by SL CSI report

In the method 1, when the transmitting terminal receives the feedback of the CQI and the RI through the SL CSI report, it is a method of only referring to this and determining the transmission parameter selection by the terminal implementation.

Method 2 is, when the transmitting terminal receives CQI and RI feedback through the SL CSI report, the MCS of the transmission parameters is determined by the terminal implementation in a range lower than the feedback CQI level, and the number of transmission layers is the terminal in a range lower than the feedbacked RI level. This is how you decide to implement it.

Method 3 is, when the transmitting terminal receives CQI and RI feedback through SL CSI report, the transmitting terminal selects the MCS as a value corresponding to the feedback received CQI level, and the number of transmission layers is a value corresponding to the feedback received RI level. It's a way to make a choice.

[Example 3-1]

In Embodiment 3-1 of the present invention, an additional method for the transmitting terminal to select a transmission parameter according to whether or not there is an SL CSI report described in Embodiment 3 will be described. Conditions for determining whether there is an SL CSI report was described in Example 3. As described above, SL CSI reporting on the sidelink can be supported in unicast, and therefore, when there is an SL CSI report, it can be limited only to unicast, and when there is no SL CSI report, broadcast, unicast, groupcast It can be all. This is because SL CSI reporting can be enabled/disabling even in unicast. In addition, transmission parameters that can be adaptively selected by the transmitting terminal according to channel conditions may include the following.

* MCS (Modulation and Coding Scheme)

** Transmission performance and transmission throughput may vary depending on the MCS selection.

* DMRS pattern information

** When more than one additional DMRS symbol number in time and one or more DMRS patterns in frequency are supported, which pattern to use may be included.

** As the number of additional DMRS symbols increases in time, time tracking performance can be increased during channel estimation, thus supporting High Doppler, and increasing the number of DMRS REs can improve channel estimation capability. In addition, when more than one DMRS pattern on a frequency is supported, channel estimation performance may vary according to a DMRS pattern used. In addition, transmission throughput may vary depending on the number of DMRS REs.

* MIMO transmission method

** The number of transmission layers or a method of selecting a precoder may be included.

** Depending on the number of transmission layers and the selection of a precoder, performance according to channels may vary. In addition, transmission throughput may vary depending on the number of transmission layers.

In the present invention, the transmission parameters are not limited to the above-described parameters as transmission parameters that can be adaptively selected by the transmitting terminal.

In addition, according to the above, there are Mode 1, which is a method in which the base station allocates transmission resources in the sidelink, and Mode 2, which is a method in which the terminal directly allocates transmission resources of the sidelink through sensing. In Mode1, the following methods can be used by the supporting station to determine the state of the sidelink.

* Method 1: When the transmitting terminal feeds back HARQ feedback information received from the receiving terminal to the base station in Mode1

* Method 2: When the transmitting terminal feeds back CSI information received from the receiving terminal to the base station in Mode1

* Method 3: When the transmitting terminal feeds back both HARQ feedback information and CSI information received from the receiving terminal in Mode1 to the base station

In Mode 1, in order for the base station to determine the state of the sidelink, it may be possible when one of the above methods is provided. Specifically, when the transmitting terminal receives the HARQ NACK feedback multiple times, it may be determined that the channel state is poor due to a high-speed environment or low SNR. In addition, by receiving the feedback of the CSI information, the transmitting terminal may determine that the channel state is poor due to a high-speed environment or low SNR. When the above methods are used, since the base station can determine the channel state of the sidelink, it will be useful for the base station to instruct the transmitting terminal about the transmission parameters such as the MCS, DMRS pattern information, or MIMO transmission method presented above in Mode1. I can.

At this time, the base station may use Uu-RRC to indicate a transmission parameter such as MCS, DMRS pattern information, or MIMO transmission method to the transmitting terminal. In addition, the base station may include the following information in DCI and transmit it to the terminal in order to determine the channel state of the sidelink through one of the above methods.

* DCI field triggering HARQ feedback: HARQ feedback can be turned on/off through 1-bit information.

* DCI field triggering CSI reporting: CSI reporting can be turned on/off through 1-bit information.

DCI may include all of the above information or may include only one of the two. If the information is included in the DCI, the terminal receiving the information may transmit the SCI including the following information to another terminal.

* SCI field triggering HARQ feedback: HARQ feedback can be turned on/off through 1-bit information.

* SCI field triggering CSI reporting: CSI reporting can be turned on/off through 1-bit information.

All of the above information may be included in the SCI, or only one of them may be included. If the information is included in the SCI, the terminal receiving the information may perform an operation of performing HARQ feedback or CSI report to the transmitting terminal.

If all of the above methods 1/2/3 are not used, it is difficult for the base station to determine the state of the sidelink in Mode1, and therefore, in Mode1, for transmission parameters such as the MCS, DMRS pattern information, or MIMO transmission method. It may be difficult for the base station to give an indication to the transmitting terminal.

Below, based on the above description, various methods for the transmitting terminal to select a transmission parameter are proposed. First, an example of the set and subset of transmission parameters is presented as follows.

* MCS: All indexes defined in the sidelink MCS table can be defined as an MCS set. For example, when a 5bit MCS table is used, MCS set={0,...,31} can be set. The MCS subset may be defined as all or part of the MCS set.

* Additional DMRS: The number of DMRS symbols supported in the sidelink may be defined as an additional DMRS set. For example, when the number of DMRS symbols of 1,2,3,4 is supported, Additional DMRS set={0,1,2,3}. Here, the information included in the additional DMRS set (a number in the example) indicates the number of symbols of the additional DMRS.

For example, if the additional DMRS is set to 0, this may mean that the additional DMRS is not set and only the front-loaded DMRS of one symbol is transmitted.If the additional DMRS is set to 3, this means that the additional DMRS is set to 3 symbols. This may mean that DMRS symbols of a total of 4 symbols including front-loaded DMRS are transmitted. Additional DMRS subset may be defined as all or part of the Additional DMRS set.

** In the above, the number of DMRS symbols is not indicated by the additional DMRS, but may be indicated by the general number of DMRS symbols. In this case, the DMRS symbol set={1,2,3,4} is used, and the DMRS symbol subset can be defined as a part of the DMRS symbol set.

* Number of transport layers: The number of transport layers supported in the sidelink may be defined as a transport layer set. For example, when only up to 2 layers are supported, transmission layer set={1,2} may be set. The transport layer subset may be defined as all or part of the transport layer set.

Note that in the above, MCS set/subset, Additional DMRS set/subset, and transmission layer set/subset may be replaced with other terms representing the same meaning.

Also, the information included in the set is not limited to the above proposal. For example, the number of symbols included in the Additional DMRS set may be reduced to Additional DMRS set={1,3}. In the case of a transport layer set, both may be included, such as layer set={1,2,both}, indicating that both 1 and 2 are possible. In addition, the above examples can be applied crosswise. Also, the set for the transmission parameter may be a set mapped by CBR or priority, or may be a set mapped by simultaneously reflecting CBR and priority. For example, when the MCS set is mapped by reflecting the CBR and the priority at the same time, the MCS set mapped by the priority of the packet to be transmitted by the UE and the CBR measured by the UE may be used. The mapping may be included in the resource pool configuration, which may be indicated by system information (SIB), (pre-)configuration, or overwritten by RRC information. More specifically, assuming that MCS set = {0,...,31} when CBR and priority are not considered, the MCS set corresponding to CBR and priority is considered MCS set = {0,... ,10} can be mapped and set. In addition, as described above, the subset for transmission parameters may be set as all or part of the set for transmission parameters. In the following, various methods for the transmitting terminal to select a transmission parameter are proposed. If there is feedback below, it may be that one of the following conditions is satisfied.

* If there is an SL CSI report

* If you have SL HARQ feedback

* If there is both SL CSI report and SL HARQ feedback

In addition, a criterion and an operation for determining a transmission parameter using the feedback information may be interpreted as a terminal implementation.

[Suggested Method 1] Proposed Method 1 is commonly applied to Mode1 and Mode2.

* If you have feedback

** The transmitting terminal selects an appropriate parameter from a set of transmission parameters. (This may be interpreted as a terminal implementation.)

* No feedback

** The transmitting terminal selects an appropriate parameter from a subset of transmission parameters. (This may be interpreted as a terminal implementation.)

*** The subset of transmission parameters can be determined by the absolute speed of the transmitting terminal. For example, a threshold value for the speed of the transmitting terminal is set, and a subset of the transmission parameter used when the terminal speed exceeds the threshold value and a subset of the transmission parameter used when the terminal speed does not exceed the threshold value are set. I can. The configuration may be included in the resource pool configuration, which may be indicated as system information (SIB), (pre-)configuration, or overwritten as RRC information.

[Suggested Method 2] In Proposed Method 2, operations classified according to Mode1 and Mode2 are applied.

* If you have feedback

** The transmitting terminal selects an appropriate parameter from a set of transmission parameters. (This may be interpreted as a terminal implementation.)

*** For Mode2, follow the above method. However, in the case of Mode1, when the transmitting terminal receives transmission parameter information set by the base station to an upper layer, the corresponding parameter is selected as a transmission parameter. However, if there is no parameter set as a higher layer, the transmitting terminal selects an appropriate parameter from the set of transmission parameters (this may be interpreted as a terminal implementation).

* No feedback

** The transmitting terminal selects an appropriate parameter from a subset of transmission parameters. (This may be interpreted as a terminal implementation.)

*** The subset of transmission parameters can be determined by the absolute speed of the transmitting terminal. For example, a threshold value for the speed of the transmitting terminal is set, and a subset of the transmission parameter used when the terminal speed exceeds the threshold value and a subset of the transmission parameter used when the terminal speed does not exceed the threshold value are set. I can. The configuration may be included in the resource pool configuration, which may be indicated as system information (SIB), (pre-)configuration, or overwritten as RRC information.

*** For Mode2, follow the above method. However, in the case of Mode1, when the transmitting terminal receives transmission parameter information set by the base station to an upper layer, the corresponding parameter is selected as a transmission parameter. However, if there is no parameter set as a higher layer, the transmitting terminal selects an appropriate parameter from the set of transmission parameters (this may be interpreted as terminal implementation).

[Suggested Method 3] In Proposed Method 2, operations classified according to Mode1 and Mode2 are applied.

* If you have feedback

** The transmitting terminal selects an appropriate parameter from a set of transmission parameters. (This may be interpreted as a terminal implementation.)

*** It is applied in common to Mode1 and Mode2.

* No feedback

** The transmitting terminal selects an appropriate parameter from a subset of transmission parameters. (This may be interpreted as a terminal implementation.)

*** The subset of transmission parameters can be determined by the absolute speed of the transmitting terminal. For example, a threshold value for the speed of the transmitting terminal is set, and a subset of the transmission parameter used when the terminal speed exceeds the threshold value and a subset of the transmission parameter used when the terminal speed does not exceed the threshold value are set. I can. The configuration may be included in the resource pool configuration, which may be indicated as system information (SIB), (pre-)configuration, or overwritten as RRC information.

*** For Mode2, follow the above method. However, in the case of Mode1, when the transmitting terminal receives transmission parameter information set by the base station to an upper layer, the corresponding parameter is selected as a transmission parameter. However, if there is no parameter set as a higher layer, the transmitting terminal selects an appropriate parameter from the set of transmission parameters (this may be interpreted as terminal implementation).

[Suggested Method 4] Proposed Method 4 is commonly applied to Mode1 and Mode2.

* Regardless of the presence or absence of feedback, the transmitting terminal selects an appropriate parameter from a set of transmission parameters. (This may be interpreted as a terminal implementation.)

[Suggested Method 5] In Proposed Method 5, operations classified according to Mode1 and Mode2 are applied.

* Regardless of the presence or absence of feedback, the transmitting terminal selects an appropriate parameter from a set of transmission parameters. (This may be interpreted as a terminal implementation.)

** For Mode2, follow the above method. However, in the case of Mode1, when the transmitting terminal receives transmission parameter information set by the base station to an upper layer, the corresponding parameter is selected as a transmission parameter. However, if there is no parameter set as a higher layer, the transmitting terminal selects an appropriate parameter from the set of transmission parameters (this may be interpreted as terminal implementation).

[Suggested Method 6] In Proposed Method 6, operations classified according to Mode1 and Mode2 are applied.

* In the case of Mode1, when the transmitting terminal receives transmission parameter information set by the base station to an upper layer, the corresponding parameter is selected as a transmission parameter. However, if there is no parameter set as a higher layer, the transmitting terminal selects an appropriate parameter from the set of transmission parameters (this may be interpreted as terminal implementation).

* In the case of Mode2, the transmitting terminal selects an appropriate parameter from a subset of transmission parameters. (This may be interpreted as a terminal implementation.)

** The subset of transmission parameters can be determined by the absolute speed of the transmitting terminal. For example, a threshold value for the speed of the transmitting terminal is set, and a subset of the transmission parameter used when the terminal speed exceeds the threshold value and a subset of the transmission parameter used when the terminal speed does not exceed the threshold value are set. I can. The configuration may be included in the resource pool configuration, which may be indicated as system information (SIB), (pre-)configuration, or overwritten as RRC information.

[Suggested Method 7] In Proposed Method 7, operations classified according to Mode1 and Mode2 are applied.

* In the case of Mode1, when the transmitting terminal receives transmission parameter information set by the base station to an upper layer, the corresponding parameter is selected as a transmission parameter. However, if there is no parameter set as a higher layer, the transmitting terminal selects an appropriate parameter from a subset of transmission parameters. (This may be interpreted as a terminal implementation.)

** The subset of transmission parameters can be determined by the absolute speed of the transmitting terminal. For example, a threshold value for the speed of the transmitting terminal is set, and a subset of the transmission parameter used when the terminal speed exceeds the threshold value and a subset of the transmission parameter used when the terminal speed does not exceed the threshold value are set. I can. The configuration may be included in the resource pool configuration, which may be indicated as system information (SIB), (pre-)configuration, or overwritten as RRC information.

* In the case of Mode2, the transmitting terminal selects an appropriate parameter from a subset of transmission parameters. (This may be interpreted as a terminal implementation.)

** The subset of transmission parameters can be determined by the absolute speed of the transmitting terminal. For example, a threshold value for the speed of the transmitting terminal is set, and a subset of the transmission parameter used when the terminal speed exceeds the threshold value and a subset of the transmission parameter used when the terminal speed does not exceed the threshold value are set. I can. The configuration may be included in the resource pool configuration, which may be indicated as system information (SIB), (pre-)configuration, or overwritten as RRC information.

When the transmitting terminal determines a transmission parameter according to the proposed method, information about this can be transmitted to the receiving terminal. Specifically, when the number of MCS, the number of DMRS symbols, and the number of transmission layers are determined, all of the corresponding information may be included in the SCI and transmitted. Unlike this, all of the corresponding information can be transmitted through PC5-RRC. Alternatively, a method of delivering SCI and PC5-RRC in combination can be considered. For example, it is possible to consider a method of transferring the number of MCS and transport layers through SCI and the number of DMRS symbols through PC5-RRC.

<Fourth Example>

Embodiment 4 of the present invention proposes a method for determining a transmission parameter by reflecting CBR as a method for a transmitting terminal to determine a transmission parameter in a sidelink. In this case, a method of reflecting CBR is proposed even when the receiving terminal transmits SL CSI. First, in the sidelink of V2X, the setting range of the transmission parameter may be determined according to whether the corresponding channel is congested. This is a congestion control function in which a terminal determines whether to access a channel when a channel is congested, and sets a transmission parameter to increase a transmission success probability of the terminal when the terminal is connected. Therefore, the terminal can determine the setting range of the transmission parameter based on the CBR. For example, the UE may appropriately determine a range of transmission parameters that can be selected according to the measured CBR value. Transmission parameters that can be considered may include the MCS for the PSSCH, the number of transport layers, the size of the subchannel to which the PSSCH is allocated, the number of retransmissions, and the maximum value of the transmission power.

Specifically, when the channel is congested (when the CBR value is measured high), the size of the subchannel to which the PSSCH is allocated is reduced, the maximum value of the transmission power is reduced, and the number of retransmissions is reduced to minimize interference between terminals in a congestion situation. can do. In addition, it is possible to set the MCS low and lower the number of transmission layers to adjust the transmitted signal to be successfully received. Therefore, setting the range of the transmission parameter by reflecting the CBR is a very effective method for selecting a parameter suitable for the channel situation along with congestion control.

First of all, CBR can be defined as follows.

CBR

CBR measured in slot n is as follows.

* The SL RSSI (Sidelink Received Signal Strength Indicator) measured by the UE in the resource pool is defined as the ratio of subchannels exceeding the (pre-)configured threshold. Here, the CBR measurement may be made in slot [n-X, n-1]. Here, the slot index is based on the physical slot index.

** CBR measurement in terms of transmission may be measured for the PSSCH region. In this case, it is assumed that the PSSCH region and the PSCCH region are located in adjacent resource regions. Here, when the frequency resource region to which the PSSCH is allocated and the frequency region in which the PSCCH is transmitted overlap, it is interpreted that the PSSCH region and the PSCCH region are adjacent. If the PSSCH region and the PSCCH region are not located in adjacent resource regions, CBR measurement may be performed in the PSCCH region.

** CBR measurement from the viewpoint of transmission feedback can be measured for the PSFCH region.

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

** X is the window value at which CBR is measured, and the value of X may be a fixed value or a configurable value.

*** When X is a fixed value, it can be set to 100 slots. When X is a configurable value, the setting of the corresponding value can be included in the resource pool configuration information, and the corresponding values can be pre-configurated in the terminal before the terminal is connected to the base station, and can be set through SIB from the base station. After the RRC connection and may be configured to be UE specific. It can also be configured through the PC5-RRC connection between the terminal and the terminal.

** SL RSSI means the received signal strength and indicates how much power (in [W]) is received from the receiving terminal, and is observed by the effective OFDM symbol positions of the corresponding channel in the slot of the sidelink and the set subchannel.

*** The subchannel set here may mean a subchannel allocated to a resource pool. In addition, the subchannel may be set differently according to the corresponding channel. For example, PSSCH has a minimum configurable subchannel size of 4RB and a maximum of 20 subchannels can be allocated, and PSFCH has a minimum configurable subchannel size of 2RB and a maximum of 40 subchannels can be allocated. May be. This is an example, and the size of the subchannel or the maximum number of subchannels may vary according to the SCS.

According to the definition of CBR, it is possible to determine whether the corresponding channel is congested based on the measured CBR value. The terminal may report the measured CBR to the base station. Specifically, when the base station and the terminal are connected by Uu-RRC, the terminal may report the CBR to the base station through Uu-RRC. Therefore, in Mode 1, when a transmitting terminal requests a transmission resource for sidelink communication with the receiving terminal from the base station, the base station can allocate transmission resources using the reported CBR information, determine related transmission parameters, and instruct the terminal. have.

However, in the case of Mode2, not only the UE performs resource allocation through sensing, but also the CBR measured by the UE (or CBR received from the receiving UE) can be used to determine a transmission parameter. An example of this will be described through [Table 9].

[Table 9]

Referring to [Table 9], CBR (SL-CBR) can be measured as a value between 0 and 100, but it can be classified and quantized according to the CBR range. For example, CBR values can be classified into CBR levels up to 16, and CBR measurement results can be mapped to CBR levels. In this case, the number of CBR levels is only an example, and may be a predetermined number or a settable number.

In addition, tx-Parameters included in SL-CBR-PSSCH-TxConfig of [Table 9] may include parameters included in SL-PSSCH-TxParameters described in [Table 8], and the parameters may be set according to CBR level. I can.

In addition, the cr-Limit included in the SL-CBR-PSSCH-TxConfig is a parameter for congestion control, and the UE measures the channel occupancy ratio (CR) to drop the transmission, or the CR limit may not be exceeded through implementation. This can be applied when the transmitting terminal transmits data to the receiving terminal, and even when the receiving terminal reports SL CSI to the transmitting terminal, when the CR measured by the receiving terminal does not satisfy the CR limit, SL CSI report and HARQ Dropping the report can also be considered.

In addition, the SL-PSSCH-TxParameters described in [Table 8] may be determined for each priority of a transport packet as well as a CBR level. An example of this will be described through [Table 10].

[Table 10]

Referring to [Table 10], the SL-PPPP-TxConfigIndex may map transmission parameters (refer to SL-PSSCH-TxParameters in [Table 8]) based on packet priority and CBR. For example, in the above [Table 9], when the CBR levels of SL-CBR-Levels-Config are divided into 16 and cbr-RangeCommonConfigList is configured up to 4, sl-CBR-PSSCH-TxConfigList is up to 16x4=64. Can be made. In other words, a list (sl-CBR-PSSCH-TxConfigList) in which up to 64 parameters in the SL-CBR-PSSCH-TxConfig are classified and mapped in sequence may be configured. The cbr-ConfigIndex in [Table 10] is a parameter indicating which of the parameter sets 1 to 4 classified by CBR level 16 out of 64 parameter lists, and the parameter list of 64 parameters for the measured CBR level. It can be determined which parameter indicates. According to [Table 10], the parameter to be finally mapped may be determined by priority and CBR level. Also, if the CBR level is not available, refer to the CBR level set in defaultTxConfigIndex in [Table 10].

Here, the tx-ConfigIndexList becomes information on the transmission parameters (tx-Parameters) described in [Table 9].

In [Table 10], the defaultTxConfigIndex is a default value used when there is no CBR measurement result available to the terminal. Therefore, when the UE measures the CBR and knows the corresponding CBR level and the priority of the packet to be transmitted, the range of the corresponding transmission parameter SL-PSSCH-TxParameters is determined (see Table 8 for SL-PSSCH-TxParameters).

In the case of Mode2, the priority of the packet means the priority of the packet corresponding to the highest priority among packets intended to be transmitted by the terminal. At this time, the transmission parameter SL-PSSCH-TxParameters may be set (pre-)configuration. That is, the setting may be a value previously stored in the terminal, and may be a value set by the base station through SL-SIB or Uu-RRC.

Measurement of the CBR by the terminal in the sidelink may be set as a default feature or may be set as an optional feature. If it is determined as a selectable operation, it can be classified into 4 cases as shown in [Table 11] according to the CBR measurement capability of the transmitting terminal and the receiving terminal.

[Table 11]

In the above [Table 11], a case in which the CBR measurement of the terminal in the sidelink is determined as a default feature may correspond to Case 4. If the operation in which the terminal measures CBR is a selectable operation, not only when the transmitting terminal selects a transmission parameter, but also when the receiving terminal transmits SL CSI, the CBR measurement capability between the transmitting terminal and the receiving terminal is affected. Exchange of information may be necessary. At this time, information exchange can be performed by PC5-RRC.

As described with reference to FIGS. 4 and 5, in a sidelink unicast, a terminal-to-terminal PC5-RRC connection may be performed. An example of a method of reflecting CBR even when the receiving terminal transmits SL CSI will be described in more detail through [Table 12].

[Table 12]

Referring to Table 12, when the SL CSI information includes CQI and RI, the SL CSI parameter configuration (SL-CBR-CSI-Config) reflecting CBR may be determined through the following method.

First, the range of parameter selection for RI may be determined within the maximum number of transmission layers supported by the transmitting terminal. In [Table 12], allowedRI indicates a reportable RI, and n1 indicates rank 1 and n2 indicates rank 2. And both means that the UE can autonomously set the settings for ranks 1 and 2.

Next, a parameter selection range for CQI (minCQI, maxCQI) may be determined by the SL CQI table used. For example, when the SL CQI table reuses the CQI table used in NR Uu, a parameter selection range (minCQI, maxCQI) for CQI may be determined within a maximum of 16 levels. In contrast, when the SL CQI table reuses the MCS table used in NR Uu, a parameter selection range (minCQI, maxCQI) for CQI may be determined within a maximum of 32 levels. As shown in [Table 12], when the receiving terminal reports CQI and RI as SL CSI information, it may be selected within a selection range for CQI and RI set by the CBR level. Therefore, the CQI reflecting the CBR in the sidelink can be defined as follows.

SL CQI with CBR

In the sidelink, the UE corresponding to the receiver determines each CQI value reported in slot n as the highest CQI index that satisfies the following condition.

* One PSSCH TB transport block composed of a combination of the modulation scheme, target code rate, and transport block size corresponding to the CQI index must be capable of receiving so as not to exceed the following transport block error probability. Here, the PSSCH TB transport block is SL. It occupies a sidelink physical resource block or subchannels named as a CSI reference resource.

** 0.1, if the upper layer is set, cqi-Table in SL-CSI-ReportConfig indicates the following'table1' (below [Table 2] or [Table 5]) or'table2' (below [Table 3] or [Table 5] 6])

** 0.00001, if cqi-Table in SL-CSI-ReportConfig indicates the following'table3' (below [Table 4] or [Table 7]) by setting the upper layer

The CQI index that can be selected in the cqi-Table is limited in the table selected from [Table 2] to [Table 7] by the selection range (SL-CBR-CSI-Config) of the SL CSI parameter, so that only some CQI indexes are used. I can. In [Table 12], the selection range (SL-CBR-CSI-Config) of SL CSI parameters that can be selected according to the CBR level can be (pre-)configuration. This may be a value previously stored by the UE, and may be a value set through SL-SIB or Uu-RRC from the base station.

Next, when there is an SL CSI report in Mode1 and Mode2, an operation in which the transmitting terminal selects a transmission parameter will be described in more detail. Hereinafter, a case in which CBR is considered when selecting a transmission parameter is described, and can be applied to both cases where the receiving terminal reports SL CSI by reflecting CBR or reports SL CSI without reflecting CBR.

The CQI and RI are considered as the SL CSI report transmitted by the receiving terminal. In addition, the MCS and the number of transmission layers are considered as transmission parameters selected by the transmitting terminal. As described in [Table 9] and [Table 10], the selection range of the MCS and the number of transmission layers is determined by the UE reflecting CBR (directly measuring CBR or receiving CBR) and knowing the corresponding CBR level and the priority of the packet to be transmitted. The corresponding transmission parameter SL-PSSCH-TxParameters (refer to [Table 8]) is determined, and the MCS selection range (minMCS-PSSCH, maxMCS-PSSCH) and the number of transmission layers selection range (Txlayer-NumberPSSCH) in SL-PSSCH-TxParameters are determined. I can. At this time, the transmission parameter SL-PSSCH-TxParameters may be set (pre-)configuration. This may be a value previously stored in the terminal, and may be a value set by the base station through SL-SIB or Uu-RRC. In this case, the following method can be considered.

Method for transmitting terminal to select transmission parameter for SL CSI report (reflecting CBR)

* Method 1: Select by terminal implementation

* Method 2: CQI level received by SL CSI report, selection of UE implementation in a range of values lower than RI level

* Method 3: Transmission parameter selection based on CQI level and RI level received by SL CSI report

Method 1 is a method of determining by UE implementation in the MCS selection range of SL-PSSCH-TxParameters and the number of transmission layers selection range of SL-PSSCH-TxParameters when the transmitting terminal receives the feedback of the CQI and RI through the SL CSI report. to be.

In method 2, when the transmitting terminal receives the feedback of the CQI and the RI through the SL CSI report, the MCS among the transmission parameters may be determined by the UE implementation in a range lower than the feedback CQI level among the MCS selection ranges of SL-PSSCH-TxParameters. In addition, the number of transport layers may be determined by the UE implementation in a range lower than the feedbacked RI level among the selection range of the number of transport layers of SL-PSSCH-TxParameters. In Method 2, if there is no range lower than the feedback CQI level among the MCS selection ranges of SL-PSSCH-TxParameters for the MCS, Method 1 may be used. In Method 2, if there is no range lower than the feedback received RI level among the selection range of the number of transmission layers in SL-PSSCH-TxParameters for the number of transmission layers, Method 1 can be used.

Method 3 is, when the transmitting terminal receives CQI and RI feedback through SL CSI report, the transmitting terminal selects the MCS value corresponding to the CQI level that is fed back from the MCS selection range of SL-PSSCH-TxParameters among transmission parameters, and transmits layer The number is a method of selecting the number of transmission layers corresponding to the received RI level in the range of selection of the number of transmission layers of SL-PSSCH-TxParameters. In Method 3, if there is no MCS corresponding to the CQI level received from the MCS selection range of SL-PSSCH-TxParameters for the MCS, Method 1 may be used or the CQI level is not in the MCS selection range of SL-PSSCH-TxParameters A method of selecting an MCS corresponding to may be used. In Method 3, if the number of transport layers corresponding to the fed-back RI level does not exist in the selection range of the number of transport layers of SL-PSSCH-TxParameters for the number of transport layers, Method 1 may be used or the number of transport layers of SL-PSSCH-TxParameters Although not in the selection range, a method of selecting the number of transmission layers corresponding to the RI level may be used.

The transmission parameter selection of the transmitting terminal reflecting the CBR described above and the SL CSI report of the receiving terminal reflecting the CBR may be enabled/disabled by configuration.

In [Table 11], even if it corresponds to Case 3 or Case 4, which is a case in which the transmitting terminal can measure CBR, it can be interpreted as Case 1 and Case 2, respectively, when CBR reflection is disabled (ie Transmission parameters cannot be selected by reflecting CBR). Refer to the following examples accordingly.

Likewise, in the case of Case 2 or Case 4, which is a case in which the receiving terminal can measure CBR in [Table 11], when CBR reflection is disabled, it can be interpreted as Case 1 and Case 3 respectively (ie , SL CSI reporting cannot be performed by reflecting CBR). Refer to the following examples accordingly.

In addition, even if it falls under Case 4 in which both the transmitting and receiving terminals can measure CBR in [Table 11], it can be interpreted as Case 1 when the CBR reflection in the transmitting and receiving terminals is disabled. . When only the CBR reflection in the transmitting terminal is disabled, it can be interpreted as Case 2. In contrast, when only CBR reflection in the receiving terminal is disabled, it can be interpreted as Case3. Refer to the following examples accordingly.

10 is a diagram illustrating a process of measuring and exchanging CBR between a transmitting terminal and a receiving terminal according to an embodiment of the present disclosure.

Referring to FIG. 10, the CBR of the transmitting terminal and the receiving terminal described in Table 11 is measured according to the measurement capability, and if necessary, the CBR measured by the transmitting terminal is transmitted to the receiving terminal or the CBR measured by the receiving terminal is transmitted to the transmitting terminal. The transfer operation is shown.

Specifically, in FIG. 10, FIG. 1010 shows a transmission unit, and FIG. 1020 shows a reception unit. In general, the transmitting unit and the receiving unit may be indicated as subjects that transmit and receive data. In the V2X system, the terminal may be a transmission unit or a reception unit.

As described through Table 11, CBR capability information of the transmitting terminal and the receiving terminal may be exchanged during the PC5-RRC connection process (1030). However, the exchange of the CBR capability information may be omitted.

And, only the transmitting or receiving terminal with the CBR measurement capability can perform CBR measurement (1040, 1050). On the other hand, depending on the situation of the sidelink, a situation in which CBR cannot be measured may occur even though there is a capability of CBR measurement. In addition, a difference may occur between the CBR measured by the transmitting terminal and the CBR measured by the receiving terminal according to the environment of the transmitting terminal and the receiving terminal.

Accordingly, a method in which the transmitting terminal transmits the CBR measurement result to the receiving terminal (1060) or the receiving terminal transmits the CBR result to the transmitting terminal (1070) may be considered.

For example, in the case of a transmitting terminal with CBR capability, CBR may be measured in step 1040 and the CBR measurement result measured in step 1060 may be transmitted to the receiving terminal.

Likewise, in the case of a receiving terminal with CBR capability, CBR may be measured in step 1050 and the CBR measurement result measured in step 1070 may be transmitted to the receiving terminal.

In addition, when both the transmitting terminal and the receiving terminal have CBR capability, steps 1040 to 1070 may be performed.

However, the embodiment of the present disclosure is not limited thereto, and even when the transmitting terminal and the receiving terminal have CBR capability, the step of transmitting the same may be omitted. That is, a transmitting terminal with CBR capability may not perform step 1060, and a receiving terminal with CBR capability may not perform step 1070.

For example, whether to transmit the measured CBR information may be determined by the terminal according to the channel environment. Alternatively, whether to transmit the CBR measurement result may be determined or set in advance (for example, the receiving terminal or the transmitting terminal may be set to perform CBR transmission if there is CBR capability).

Alternatively, it is also possible to transmit the CBR measurement result according to an indicator indicating transmission of the CBR measurement result. For example, the transmitting terminal receiving the CBR capability of the receiving terminal may transmit an indicator instructing to transmit the CBR measurement result to the receiving terminal, and accordingly, can receive the CBR measurement result from the receiving terminal.

When the transmitting terminal and the receiving terminal receive CBR information measured by another terminal, the channel congestion condition can be more accurately determined. Accordingly, the transmitting terminal can determine the transmission parameter using the CBR information, and the receiving terminal can determine the receiving parameter using the CBR information. In this case, the CBR information may be a measurement result or a received result by the terminal itself. For a specific method of using CBR information, refer to the following examples.

The operation of the receiving terminal and the operation of the transmitting terminal will be described when the receiving terminal reports SL CSI and when the transmitting terminal determines a transmission parameter through the following embodiments. First, a case in which there is no information exchange for CBR between the terminal and the terminal is described through Example 5 below. A case in which the transmitting terminal informs the receiving terminal of the CBR information will be described with reference to Embodiment 6 below. A case in which the receiving terminal notifies the CBR information to the transmitting terminal is described through Example 7 below. Finally, a case in which CBR information is exchanged between the transmitting terminal and the receiving terminal will be described with reference to Embodiment 8 below.

<Fifth Example>

In Embodiment 5 of the present invention, a case where there is no exchange of CBR information between a transmitting terminal and a receiving terminal is described. In [Table 11], for each of the four cases, the operation of the receiving terminal and the operation of the transmitting terminal in which the receiving terminal reports SL CSI to the transmitting terminal and the transmitting terminal determines the transmission parameter will be described. As described above, information can be exchanged on the CBR measurement capability between the transmitting terminal and the receiving terminal by the PC5-RRC. In an embodiment of the present invention, CQI and RI are considered as SL CSI reporting.

First, Case 1 of [Table 11] corresponds to the case where neither the transmitting terminal nor the receiving terminal has CBR measurement capability. First, the range of selection for the RI of the receiving terminal may be determined within the maximum number of transmission layers supported by the transmitting terminal. In addition, for the selection of the CQI of the receiving terminal, refer to the definition of'SL CQI' described above.

The receiving terminal feeds back the selected RI and CQI to the transmitting terminal through SL CSI. The transmitting terminal may determine the transmission parameter using one of the'method for the transmitting terminal to select a transmission parameter for SL CSI report' of the third embodiment.

Next, Case 2 of [Table 11] is applicable when only the receiving terminal has CBR measurement capability. In this case, two methods for the receiving terminal to report SL CSI can be considered.

The first method is a method of reporting SL CSI by reflecting CBR because the receiving terminal has CBR measurement capability. As described above through [Table 11] of Embodiment 4, when the receiving terminal reports CQI and RI as SL CSI information, it may be selected within a selection range for CQI and RI set by the CBR level.

Alternatively, as in Case 1, the receiving terminal may select the RI and CQI without reflecting the CBR. The transmitting terminal may determine the transmission parameter using one of the'method for the transmitting terminal to select a transmission parameter for SL CSI report' of the above-described embodiment 3.

Next, Case 3 of [Table 11] corresponds to the case that only the transmitting terminal has CBR measurement capability. In this case, as in Case 1, the receiving terminal includes the determined RI and CQI in the SL CSI without reflecting the CBR and feeds it back to the transmitting terminal. The transmitting terminal may determine the transmission parameter using one of the'method for the transmitting terminal to select a transmission parameter for SL CSI report' of the above-described embodiment 4.

Finally, Case 4 of [Table 11] is applicable when both the transmitting terminal and the receiving terminal have CBR measurement capability. In this case, two methods for the receiving terminal to report SL CSI can be considered.

The first method is a method of reporting SL CSI by reflecting the measured CBR because the receiving terminal has CBR measurement capability. As described above through [Table 11] of Embodiment 4, when the receiving terminal reports CQI and RI as SL CSI information, it may be selected within a selection range for CQI and RI set by the CBR level. Alternatively, as in the case of Case 1, the receiving terminal may select RI and CQI without reflecting CBR.

The transmitting terminal may determine the transmission parameter using one of the'method for the transmitting terminal to select a transmission parameter for SL CSI report' of the above-described embodiment 4.

<Sixth Example>

In Embodiment 6 of the present invention, among methods for exchanging CBR information between a transmitting terminal and a receiving terminal, a method of transmitting CBR information of a transmitting terminal to a receiving terminal is considered. At this time, the operation of the receiving terminal and the operation of the transmitting terminal in which the receiving terminal reports the SL CSI to the transmitting terminal and the transmitting terminal determines the transmission parameter will be described. It is assumed that the transmitting terminal is a terminal capable of measuring CBR. This may correspond to Case 3 and Case 4 in [Table 11].

According to the present embodiment, a method of generating SL CSI information by reflecting the UE receiving the CBR information and feeding it back to the transmitting UE may be considered. As described above, the CBR is a value obtained by measuring whether the channel is congested in a certain time interval, and congestion control may be performed using the CBR value. In addition, when the receiving terminal generates SL CSI information, it may be more effective information for the transmitting terminal to select a transmission parameter when determining a parameter suitable for a channel situation in consideration of such a congestion situation and feeding it back to the transmitting terminal. However, depending on the environment of the transmitting terminal and the receiving terminal, a difference between the CBR measured by the transmitting terminal and the CBR measured by the receiving terminal may occur. Therefore, as in the present embodiment, a method of transmitting CBR information of a transmitting terminal to a receiving terminal can be considered.

For example, the transmitting terminal may transmit 16 CBR levels with 4 bits of information. When V2V is considered in the communication environment of the sidelink, channel congestion information may rapidly change according to the movement of the transmitting vehicle. Accordingly, in consideration of this, the transmitting terminal may consider a method of transmitting the CBR information measured by the transmitting terminal to the receiving terminal through SCI. In contrast, assuming that channel congestion information does not change rapidly, a method of transmitting CBR information from a transmitting terminal to a receiving terminal through PC5-RRC may also be considered. Meanwhile, in the above embodiment, a method of transmitting a CBR level as CBR information has been described as an example, but the present disclosure is not limited thereto, and a method of transmitting a CBR measurement result is also possible.

First, when the CBR information of the transmitting terminal is signaled to the receiving terminal, a method and operation for generating SL CSI information by the receiving terminal reflecting this will be described. In this embodiment, CQI and RI are considered as SL CSI information. However, in the present invention, the SL CSI information is not limited to CQI and RI. According to the present invention, a selection range of SL CSI parameters that can be selected according to the CBR level can be (pre-)configuration. This may be a value previously stored in the terminal, and may be a value set by the base station through SL-SIB or Uu-RRC. Alternatively, it may be a value to be set through the PC5-RRC of the terminal.

Therefore, referring to [Table 12], when the CBR level is determined, a selection range of the corresponding SL CSI parameter may be determined. First, a case in which the receiving terminal is a terminal capable of measuring CBR and a case in which CBR measurement is not possible are described separately. If the receiving terminal is a terminal in which CBR measurement is not possible, the receiving terminal may determine CSI (CQI/RI) within a selection range for CQI and RI determined based on the CBR level received from the transmitting terminal.

In contrast, when the receiving terminal is a terminal capable of measuring CBR, the CBR level may be determined using both the CBR level (RX) measured by the receiving terminal and the CBR level (TX) received from the transmitting terminal. For example, a CBR level is determined based on Max (CBR level (TX), CBR level (RX)), and CSI (CQI/RI) may be determined within a selection range for CQI and RI determined based on this. However, the method for determining the CBR is only an example of a method for determining the CBR level and is not limited thereto. For example, although a method of using the maximum value has been described above, a method of using the minimum value may be considered. Alternatively, a method of using an average value may be considered.

In addition, the transmitting terminal may transmit a CBR value other than the CBR level, and the receiving terminal may determine the CBR level by using the average, weighted average, etc. with the measured CBR value.

Next, when the receiving terminal reports the SL CSI reflecting the CBR information to the transmitting terminal, the method and operation for the transmitting terminal to determine the transmission parameter are described in'The transmitting terminal selects the transmission parameter for the SL CSI report. Either of'method' can be used.

<Seventh Example>

In the seventh embodiment of the present invention, among methods for exchanging CBR information between a transmitting terminal and a receiving terminal, a method of transmitting CBR information of a receiving terminal to a transmitting terminal is considered. In this case, a method for the receiving terminal to report the SL CSI to the transmitting terminal and the transmitting terminal to determine a transmission parameter will be described. It is assumed that the receiving terminal is a terminal capable of measuring CBR. It may correspond to Case 2 and Case 4 in [Table 11].

According to this embodiment, a method of generating SL CSI information by reflecting the CBR measured by the receiving terminal and feeding it back to the transmitting terminal may be considered. In addition, the transmitting terminal may determine the transmission parameter by reflecting the CBR information and SL CSI received from the receiving terminal.

First, when the receiving terminal measures the CBR, a method of generating the SL CSI information by the receiving terminal reflecting the CBR will be described. In this embodiment, CQI and RI are considered as SL CSI information. However, in the present invention, the SL CSI information is not limited to CQI and RI. According to the present invention, a selection range of SL CSI parameters that can be selected according to the CBR level can be (pre-)configuration. This may be a value previously stored in the terminal, and may be a value set by the base station through SL-SIB or Uu-RRC. Alternatively, it may be a value to be set through the PC5-RRC of the terminal.

Therefore, referring to [Table 12], the receiving terminal may determine CSI (CQI/RI) within a selection range for CQI and RI determined based on the determined CBR level. As described above, the CBR is a value obtained by measuring whether the channel is congested in a certain time interval, and congestion control may be performed using the CBR value. In this way, when the receiving terminal generates SL CSI information, it may be more effective information for the transmitting terminal to select a transmission parameter when selecting a parameter suitable for a channel situation in consideration of such a congestion situation and feeding it back to the transmitting terminal. However, depending on the environment of the transmitting terminal and the receiving terminal, a difference between the CBR measured by the transmitting terminal and the CBR measured by the receiving terminal may occur. Therefore, as in this embodiment, a method of transmitting CBR information of a receiving terminal to a transmitting terminal can be considered.

For example, 16 CBR levels can be transmitted with 4 bits of information. When the receiving terminal feeds back the SL CSI information to the transmitting terminal, the receiving terminal may also feed back CBR information of the receiving terminal. This may be interpreted as including CBR information in SL CSI information. According to the above-described method, SL CSI is transmitted by piggybacking through PSSCH with data, SL CSI is transmitted through PSSCH without data (SL CSI only transmission), or SL CSI is transmitted through PSFCH. Was considered. CBR information may also be transmitted through the transport channel together with SL CSI information. On the other hand, assuming that the channel congestion information does not change rapidly, a method of transmitting CBR information from the receiving terminal to the transmitting terminal through PC5-RRC may also be considered. Meanwhile, in the above embodiment, a method of transmitting a CBR level as CBR information has been described as an example, but the present disclosure is not limited thereto, and a method of transmitting a CBR value is also possible.

In addition, the receiving terminal may transmit the CBR information according to a request or configuration of the transmitting terminal separately from transmission of the CSI information.

Next, when the receiving terminal reports the SL CSI reflecting the CBR information to the transmitting terminal and also feeds back the CBR information, the method and operation of the transmitting terminal determining the transmission parameter are described in the'transmitting terminal in the SL CSI report. One of the'method of selecting a transmission parameter for' may be used.

<Eighth Example>

In the eighth embodiment of the present invention, among methods for exchanging CBR information between a transmitting terminal and a receiving terminal, a method in which a transmitting terminal and a receiving terminal exchange CBR information with each other is considered. In this case, a method for the receiving terminal to report the SL CSI to the transmitting terminal and the transmitting terminal to determine a transmission parameter will be described. It is assumed that both the transmitting terminal and the receiving terminal are terminals capable of measuring CBR. It may correspond to Case 4 in [Table 11].

According to the present embodiment, a method of generating SL CSI information by reflecting the CBR measured by the receiving terminal and the CBR information transmitted by the transmitting terminal and feeding it back to the transmitting terminal may be considered. In addition, the transmitting terminal may determine the transmission parameter by reflecting the CBR measured by the transmitting terminal, CBR information received from the receiving terminal, and SL CSI.

As described above, the CBR is a value obtained by measuring whether the channel is congested in a certain time interval, and congestion control may be performed using the CBR value. In addition, when the receiving terminal generates SL CSI information, it may be more effective information for the transmitting terminal to select a transmission parameter when selecting a parameter suitable for a channel situation in consideration of such a congestion situation and feeding the back to the transmitting terminal. However, a difference between the CBR measured by the transmitting terminal and the CBR measured by the receiving terminal may occur depending on the environment of the transmitting terminal and the receiving terminal. Therefore, as in the present embodiment, a method of exchanging CBR information between a transmitting terminal and a receiving terminal can be considered.

For example, 16 CBR levels can be transmitted with 4 bits of information. Assuming that the channel congestion information does not change rapidly, a method of exchanging CBR information between the transmitting terminal and the receiving terminal through PC5-RRC can be considered. In contrast, when V2V is considered in a sidelink communication environment, channel congestion information may rapidly change according to the movement of a transmitting vehicle. Therefore, taking this into account, a method of transmitting CBR information to the receiving terminal through SCI may be considered. Meanwhile, in the above embodiment, a method of transmitting a CBR level as CBR information has been described as an example, but the present disclosure is not limited thereto, and a method of transmitting a CBR value is also possible.

When the CBR information of the transmitting terminal is transmitted to the receiving terminal through SCI, the receiving terminal can feed back the CBR information of the receiving terminal to the transmitting terminal. It is possible to consider a method in which the receiving terminal is piggybacked and transmitted through the PSSCH to be fed back CBR information to the transmitting terminal, transmitted through the PSSCH without data, or transmitted through the PSFCH. Alternatively, when the SL CSI is fed back, CBR information of the receiving terminal may be fed back together with it. It can be interpreted that CBR is included in SL CSI information.

First, when the CBR information of the transmitting terminal is signaled to the receiving terminal, a method and operation for generating SL CSI information by the receiving terminal reflecting this will be described. In this embodiment, CQI and RI are considered as SL CSI information. However, in the present invention, the SL CSI information is not limited to CQI and RI. According to the present invention, a selection range of SL CSI parameters that can be selected according to the CBR level can be (pre-)configuration. This may be a value previously stored in the terminal, and may be a value set by the base station through SL-SIB or Uu-RRC. Alternatively, it may be a value to be set through the PC5-RRC of the terminal.

Therefore, referring to [Table 12], when the CBR level is determined, a selection range of the corresponding SL CSI parameter may be determined. According to the assumption of this embodiment, the CBR level may be determined using both the CBR level (RX) measured by the receiving terminal and the CBR level (TX) received from the transmitting terminal. For example, a CBR level is determined based on Max (CBR level (TX), CBR level (RX)), and CSI (CQI/RI) may be determined within a selection range for CQI and RI determined based on this.

Next, the transmitting terminal may determine the transmission parameter by reflecting the CBR measured by the transmitting terminal, the CBR information received from the receiving terminal, and the SL CSI, and the ‘transmitting terminal selects the transmission parameter for SL CSI report. Either of'method' can be used. However, in this case, the transmitting terminal may determine the CBR level by using both the CBR level (TX) according to the CBR measured by the transmitting terminal and the CBR level (RX) measured by the receiving terminal. For example, if the CBR level is determined based on Max (CBR level (TX), CBR level (RX)) and the priority of the packet to be transmitted is known, the corresponding transmission parameter SL-PSSCH-TxParameters (refer to [Table 8]) is Can be determined. However, the method for determining the CBR is only an example of a method for determining the CBR level and is not limited thereto. For example, although a method of using the maximum value has been described above, a method of using the minimum value may be considered. Alternatively, a method of using an average value may be considered.

In addition, the receiving terminal or the transmitting terminal may transmit a CBR value other than the CBR level, and the receiving terminal may determine the CBR level using the average, weighted average, etc. with the CBR value measured by the receiving terminal.

On the other hand, Examples 1 to 8 can be interpreted in combination. That is, the method of the present disclosure may be implemented by combining some or all of the contents included in each embodiment within a range not impairing the essence of the invention.

For example, even if both the transmitting terminal and the receiving terminal have CBR capability, the transmitting terminal may reflect the CBR measurement result and not transmit it to the receiving terminal, and transmit it using the CBR measurement result and CSI received from the receiving terminal. The parameters can be determined.

In addition, as described above, or in consideration of both the CBR measurement result received from the receiving terminal and the CBR measurement result measured by the transmitting terminal, the transmission parameter may be determined. At this time, as described above, the transmitting terminal may request and receive the CBR measurement result, or may receive the CBR measurement result without a separate request if the receiving terminal has CBR measurement capability.

Accordingly, the method of the transmitting terminal of the present invention receives channel state information (CSI) and the CBR information determined based on channel busy ratio (CBR) information from the receiving terminal, and is based on the CSI. Thus, it may include determining a transmission parameter, and transmitting the transmission parameter to a receiving terminal.

In this case, the CBR is determined as a ratio of the subchannel in which the received signal strength exceeds a predetermined threshold in the resource pool, and the CBR information may include a CBR level determined based on the CBR measurement result.

In addition, the determining of the transmission parameter includes determining an MCS value corresponding to a channel quality indicator (CQI) included in the CSI and the number of transport layers corresponding to a rank indicator (RI), and the CQI and RI may be determined based on the range of CQI and the range of RI determined by the CBR information.

In addition, in the receiving of the CSI, before receiving the CSI, if the transmitting terminal has CBR measurement capability, the CBR is measured, and the CBR measurement result can be transmitted, and the CBR information is the CBR measurement of the transmitting terminal. It may be determined based on the result and the CBR measurement result of the receiving terminal.

In addition, the CBR information may be determined based on at least one of a CBR level corresponding to a CBR measurement result of the transmitting terminal and a maximum value, minimum value, or average value of a CBR level corresponding to a CBR measurement result of the receiving terminal.

[Example 9]

In Embodiment 9 of the present invention, an operation in which the UE performs RLM/RLF in the sidelink will be described. First, for RLM/RLF in the Uu link between the base station and the terminal, the receiving terminal performs RLM (Radio Link Monitoring) for the link state using the reference signal transmitted by the base station, and accordingly, IS (In Synchronization)/OOS (Out If the link status for Synchronization) is transmitted to the upper layer of the terminal, RLF (Radio Link Failure) can be declared based on this. If the UE declares an RLF in the base station-to-terminal Uu link, a procedure for the UE to find the base station again may be performed to recover the link again.

In the case of the LTE Uu link, a Cell-specific Reference Signal (CRS) was used as a reference signal for RLM, and in the case of the NR Uu link, Synchronization Signal Block (SSB) or CSI-RS was used as a reference signal for RLM. The RLM/RLF in the sidelink may be different from that of the RLM/RLF in the Uu link.

First of all, RLM/RLF can be performed only in unicast on the sidelink. Also, in order for the receiving terminal to perform RLM/RLF, the reference signal periodically transmitted by the transmitting terminal may not be guaranteed. Finally, when the receiving terminal does not transmit the reference signal to the transmitting terminal, it may be difficult for the transmitting terminal to perform RLM/RLF. In this embodiment, the RLM/RLF execution operation is specifically proposed in consideration of the problem occurring in supporting RLM/RLF in the sidelink.

First, depending on how broadcast, unicast, and groupcast transmissions are classified in the sidelink, the method in which RLM/RLF is configured and operated in the sidelink may vary. First, conditions for determining that the transmission is unicast in order to perform RLM/RLF are presented below.

[Prerequisites for performing RLM/RLF]

* Condition 1: Broadcast, unicast, and groupcast transmission methods can be classified through the resource pool. In other words, this is a case in which one or more transmission methods among broadcast, unicast, and groupcast are not simultaneously used in one resource pool. In this case, only the terminal in the resource pool set to unicast can perform RLM/RLF.

* Condition 2: When one or more of broadcast, unicast, and groupcast transmission methods are simultaneously used in one resource pool, the transmission method can be classified through resource pool setting. Specifically, information on which transmission method is used for resource pool configuration is included, and resource pool configuration may be indicated by system information (SIB), (pre-)configuration, or overwritten by RRC information. In this case, only the terminal for which the transmission method is set in unicast in the resource pool setting can perform RLM/RLF.

* Condition 3: The transmission method of broadcast, unicast, and groupcast can be classified by the SCI format or by a field that identifies the transmission method in the SCI. The method classified by the SCI format is a method available when each transmission method is classified by the SCI format. Alternatively, the current transmission method may be classified and indicated by including 2 bits of information in the SCI. In this case, when the terminal receiving the SCI understands the transmission method from the SCI and the transmission method is set to unicast, the terminal can perform RLM/RLF.

** In the case of condition 3, broadcast, unicast, and groupcast transmission methods may be classified according to DCI format, or may be used together with a method classified by a field identifying a transmission method in DCI. The method classified by DCI format is a method that is possible when each transmission method is classified by DCI format. Alternatively, information of a predetermined number of bits (eg, 2 bits) may be included in the DCI to identify and indicate a current transmission method. In this case, even if each transmission method is not classified by the DCI format, the transmission method may be classified using a predetermined number of bits.

In this case, when the terminal checks the transmission method based on the DCI and the transmission method is set to unicast, the terminal can perform RLM/RLF. In addition, the corresponding terminal may signal a corresponding transmission method to another terminal through SCI.

* Condition 4: Broadcast, unicast, and groupcast transmission methods can be classified only by upper layers. A detailed method of classifying a transmission method by an upper layer will be described below, and the method corresponding to condition 4 in the present invention is not limited to the following method. In general, when the transmission method is classified by the upper layer, it may be included in condition 4.

** As one method of condition 4, broadcast, unicast, and groupcast transmission methods can be identified through a destination L2 ID included in the MAC PDU transmitted from the application layer. In this case, only the terminal that has received the MAC PDU in which the destination L2 ID is set to unicast can perform RLM/RLF.

** Another method of condition 4 is to classify broadcast, unicast, and groupcast transmission methods through PC5-RRC settings. In this case, only the terminal configured to perform RLM/RLF with PC5-RRC can perform RLM/RLF.

A method of performing the RLM/RLF when it is determined as unicast transmission by the above and the prerequisite for performing RLM/RLF is satisfied and RLM/RLF is performed will be described in detail.

First, when performing RLM/RLF, the UE performs a related operation within the sidelink BWP. If a plurality of sidelink BWPs are supported to be set, the terminal may perform an RLM/RLF-related operation such as an operation of measuring a link state only in an active sidelink BWP. That is, the terminal may not perform a sidelink RLM/RLF operation in a BWP other than the active sidelink BWP.

In the sidelink, the terminal may be a transmitting terminal or a receiving terminal at any time. If two-way communication between terminals is performed, that is, when the terminals transmit and receive signals with each other, since signals received by both terminals exist, RLM/RLF can be performed using this.

However, when one-way communication is performed, that is, when only one terminal transmits a signal and the other terminal only receives a signal, the transmitting terminal performing the transmission does not have a signal received for the link. Therefore, in order for the transmitting terminal to perform RLM/RLF, a method different from the case of bidirectional communication may be required.

First, a method of performing RLM/RLF by a receiving terminal using a data signal received from a transmitting terminal on the assumption of bidirectional communication may be considered as follows.

[Method for the receiving terminal to perform RLM/RLF when there is a received data signal]

* When a data signal is received, signals usable as RLM/RLF may include SSB, PSCCH DMRS, PSSCH DMRS, SL PTRS, and SL CSI-RS.

** When more than one signal can be used for RLM/RLF (that is, when RLM/RLF is supported), information on which signal to use can be set. The information may be set as resource pool information, and the resource pool configuration may be indicated by system information (SIB), (pre-)configuration, or overwritten by RRC information.

** When the above signal is used, a statistical PSSCH error probability can be obtained from this by determining a reference signal received power (RSRP) of the received signal. When the link state for IS (In Synchronization)/OOS (Out of Synchronization) is transmitted to the upper layer of the terminal through the PSSCH error probability, Radio Link Failure (RLF) can be declared based on this.

* It is also possible to perform RLM/RLF by checking success/failure through PSCCH decoding.

** In the case of this method, in order to derive the error probability of the PSCCH from success/failure through PSCCH decoding, it is necessary to receive the PSCCH several times to obtain statistics. When the link status for IS (In Synchronization)/OOS (Out of Synchronization) is transmitted to the upper level of the terminal through the PSSCH error probability, Radio Link Failure (RLF) can be declared based on this.

* Even though the actual scheduling is not received, a method of transmitting a dummy signal through PSCCH or PSSCH or PSCCH/PSSCH may be considered.

** This method may be a method for performing RLM/RLF when there is no signal to be periodically transmitted. In addition, a detailed method of performing RLM/RLF when PSCCH/PSSCH is received as described above may be similar to an operation of determining IS/OOS using the received signal.

Next, a method of performing RLM/RLF by a transmitting terminal when there is no data signal received in consideration of one-way communication may be considered as follows.

[Method for transmitting terminal to perform RLM/RLF when there is no received data signal]

* By using the AM (Acknowledged mode) at the RLC end, the RLF can be declared when the ACK is not received for a predetermined time or when the number of retransmissions exceeds a predetermined threshold.

* RLF can be declared when continuous NACK is received using HARQ ACK/NACK in the physical layer or when feedback is not received for a predetermined time after receiving the feedback previously.

** When RLF is declared by counting the number of consecutive NACKs, a threshold value is set and a condition of RLF declaration may be determined when consecutive NACKs of X≥1 or more are received for a predetermined time. In addition, the number of consecutive NACKs is counted within a predetermined time, and the accumulated counting can be reset when the predetermined time elapses.

* When using the SL CSI report in the physical layer, the CQI index may indicate 0, or the RLF may be declared when the CSI report is not received for a predetermined period of time after receiving the previous feedback.

** SL CSI report may include information such as Channel Quality Indicator (CQI) and Rank Indicator (RI). When the value of the CQI index is 0, it indicates that the current channel state is out-of-range. When determining the RLF as the CQI index indicating 0, a threshold value may be set, and the condition of the RLF declaration may be determined when a CQI of X≥1 or more indicates index 0 for a predetermined time. In addition, the CQI counts the number of indications for index 0 within a predetermined time, and when the predetermined time elapses, the accumulated counting may be reset.

In the above method, information on a threshold value and a predetermined time may be set. As one method for setting information on a threshold and a predetermined time, the information can be set as resource pool information, and the resource pool setting may be indicated by system information (SIB), (pre-)configuration, or overwritten by RRC information. have.

When it is determined as unicast transmission by the above and the prerequisites for performing RLM/RLF are satisfied, the following two cases can be considered to perform RLM/RLF. First of all, it is possible to consider a method to always perform RLM/RLF by assuming that all terminals corresponding to the prerequisite perform RLM/RLF as the default operation. You may also consider how is performed. In order for RLM/RLF to be performed as a default operation, the following conditions must be satisfied.

[When the receiving terminal performs RLM/RLF as a default operation when there is a received data signal]

* When a data signal is received, signals usable as RLM/RLF may include SSB, PSCCH DMRS, PSSCH DMRS, SL PTRS, and SL CSI-RS.

** In order for RLM/RLF to be performed as a default operation, when at least one of the signals is set to default and is transmitted periodically or is not transmitted periodically, at least one of the signals must be transmitted together with PSCCH/PSSCH transmission. For example, if the SL CSI-RS is used as RLM/RLF when the periodic SL CSI-RS is not supported, the SL CSI-RS should always be transmitted together when the PSSCH is transmitted.

* Even though the actual scheduling is not received, a method of transmitting a dummy signal through PSCCH or PSSCH or PSCCH/PSSCH may be considered.

[When there is no data signal received, when the transmitting terminal is performed as a default operation]

* Since HARQ ACK/NACK or SL CSI reporting cannot be used as a default operation in the sidelink, only AM (Acknowledged mode) at the RLC end can be used in this case.

Next, a case in which RLM/RLF is enabling/disabling by setting may be considered. In addition, when RLM/RLF is enabled, it may be interpreted that RLM/RLF operation is activated, and when RLM/RLF is enabled, additional signaling for activating RLM/RLF operation may be considered. First, as a method of enabling/disabling RLM/RLF, the information may be set as resource pool information, and resource pool configuration may be indicated by system information (SIB), (pre-)configuration, or overwritten by RRC information. In contrast, the following conditions in which RLM/RLF is enabled or activated in an indirect way as follows may be considered.

* When SL CSI-RS is used as RLM/RLF, it is determined that RLM/RLF is enabling/activation when SL CSI-RS is transmitted, or

* If SL CSI reporting is enabled, it is determined that RLM/RLF is enabling/activation, or

* When HARQ ACK/NACK reporting is enabled, it is determined that RLM/RLF is enabling/activation.

In other words, if the condition is not satisfied, it is determined that the RLM/RLF is disabling. The method can be applied to both the transmitting terminal and the receiving terminal. In other words, it can be applied to a transmitting terminal that cannot receive data in one-way communication. Similarly, the following conditions can be considered as a method in which RLM/RLF is enabled or activated.

* When SL CSI reporting is activated, it is determined that RLM/RLF is enabling/activation. or

* When HARQ ACK/NACK reporting is activated, it is determined that RLM/RLF is enabling/activation.

How the SL CSI report is activated or the HARQ ACK/NACK report is activated may be indicated through SCI, and it may be determined that RLM/RLF is activated through this. In other words, since the UE receives the SCI and determines that the RLM/RLF is enabling/activation due to the SL CSI report or the activation of HARQ ACK/NACK, it can be applied only to the receiving UE that has received the SCI.

Finally, when the UE declares RLF by performing an RLM/RLF operation, the following procedure may be considered for link recovery. The terminal corresponding to the receiving end may declare an RLF and perform one or more of the following procedures for link recovery.

* The terminal corresponding to the receiving end stops sidelink transmission.

** Sidelink transmission to be terminated (released) may include one or more of the following.

*** SPS (semi-persistent scheduling), CQI (Channel quality indicator), CSI (Channel state information) feedback, HARQ feedback, SRS (Sounding reference signal), SR (Scheduling request)

* The terminal corresponding to the receiving end may perform one or more of the following methods for sidelink recovery and re-establishment.

** The terminal corresponding to the receiving end informs the base station of the RLF state.

** The terminal corresponding to the receiving end requests the base station to terminate the link.

** The UE corresponding to the receiving end attempts to transmit the SL SS/PBCH block.

In contrast, the terminal corresponding to the transmitting end may declare an RLF and perform one or more of the following procedures for the next link recovery.

* The terminal corresponding to the transmitting end stops sidelink transmission.

** At this time, it is possible to instruct a request to send a keep alive message to an upper layer before stopping transmission.

* The terminal corresponding to the transmission end performs sidelink transmission in Fallback mode.

* The terminal corresponding to the transmitting end may perform one or more of the following methods for sidelink recovery and re-establishment.

** The terminal corresponding to the transmitting end informs the base station of the RLF state.

** The terminal corresponding to the transmitting end requests the base station to terminate the link.

*** In the case of group driving (Platooning), it is possible to request replacement of the reader terminal.

** The UE corresponding to the receiving end attempts to transmit the SL SS/PBCH block.

In order to carry out the above embodiments of the present invention, a transmitting unit, a receiving unit, and a processing unit of the terminal and the base station are shown in FIGS. 11 and 12, respectively. In the above embodiment, when a vehicle terminal supporting vehicle communication exchanges information using a sidelink with another vehicle terminal and a pedestrian portable terminal, the receiving terminal measures the channel state and reports it to the transmitting terminal, and the operation of the terminal. Is shown, and in order to perform this, the receiving unit, the processing unit, and the transmitting unit of the base station and the terminal must operate according to the embodiments.

Specifically, FIG. 11 is a block diagram showing the internal structure of a terminal according to an embodiment of the present invention.

As shown in FIG. 11, the terminal of the present invention may include a terminal receiving unit 1100, a terminal transmitting unit 1104, and a terminal processing unit 1102. The terminal receiving unit 1100 and the terminal collectively refer to the transmitting unit 1104 and may be referred to as a transmitting/receiving unit in the embodiment of the present invention.

The transceiver may transmit and receive signals with the base station. The signal may include control information and data. To this end, the transceiver unit may include an RF transmitter that up-converts and amplifies a frequency of a transmitted signal, and an RF receiver that amplifies a received signal with low noise and down-converts a frequency. In addition, the transmission/reception unit may receive a signal through a wireless channel, output it to the terminal processing unit 1102, and transmit a signal output from the terminal processing unit 1102 through the wireless channel.

The terminal processing unit 1102 may control a series of processes so that the terminal can operate according to the embodiment of the present invention described above.

12 is a block diagram showing an internal structure of a base station according to an embodiment of the present invention.

As shown in FIG. 12, the base station of the present invention may include a base station receiving unit 1201, a base station transmitting unit 1205, and a base station processing unit 1203. The base station receiving unit 1201 and the base station transmitting unit 1205 may be collectively referred to as a transmission/reception unit in an embodiment of the present invention.

The transceiver may transmit and receive signals with the terminal. The signal may include control information and data. To this end, the transceiver unit may include an RF transmitter that up-converts and amplifies a frequency of a transmitted signal, and an RF receiver that amplifies a received signal with low noise and down-converts a frequency. In addition, the transmission/reception unit may receive a signal through a wireless channel, output it to the base station processing unit 1203, and transmit the signal output from the base station processing unit 1203 through the wireless channel.

The base station processing unit 19203 may control a series of processes so that the base station can operate according to the above-described embodiment of the present invention.

On the other hand, in the drawings for explaining the method of the present invention, the order of description does not necessarily correspond to the order of execution, and the relationship between precedence and subsequent changes or may be executed in parallel.

Alternatively, in the drawings for explaining the method of the present invention, some components may be omitted and only some components may be included within the scope not impairing the essence of the present invention.

In addition, the method of the present invention may be implemented by combining some or all of the contents included in each embodiment within the scope not impairing the essence of the invention.

In the specific embodiments of the present invention described above, the constituent elements included in the invention are expressed in the singular or plural according to the presented specific embodiment. However, the singular or plural expression is selected appropriately for the situation presented for convenience of explanation, and the present invention is not limited to the singular or plural constituent elements, and even constituent elements expressed in plural are composed of the singular or singular. Even the expressed constituent elements may be composed of pluralities.

Meanwhile, although specific embodiments have been described in the detailed description of the present invention, various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention is limited to the described embodiments and should not be determined, and should be determined by the scope of the claims and equivalents as well as the scope of the claims to be described later.

Claims (20)

In the method of the transmission terminal,
Receiving channel state information (CSI) and the CBR information determined based on channel busy ratio (CBR) information from a receiving terminal;
Determining a transmission parameter based on the CSI;
And transmitting the transmission parameter to a receiving terminal. The method of claim 1,
The CBR is determined as the ratio of the subchannel in which the received signal strength exceeds a predetermined threshold value in the resource pool,
The CBR information comprises a CBR level determined based on the CBR measurement result. The method of claim 1,
The step of determining the transmission parameter,
Including the step of determining an MCS value corresponding to a channel quality indicator (CQI) included in the CSI and the number of transport layers corresponding to a rank indicator (RI),
The CQI and RI are determined based on a range of CQI and a range of RI determined by the CBR information. The method of claim 1,
Receiving the CSI,
Before receiving the CSI, measuring CBR when the transmitting terminal has CBR measurement capability; And
And transmitting the CBR measurement result,
The CBR information is determined based on a CBR measurement result of the transmitting terminal and a CBR measurement result of the receiving terminal. The method of claim 4,
The CBR information is determined based on at least one of a CBR level corresponding to a CBR measurement result of the transmitting terminal and a maximum, minimum, or average value of a CBR level corresponding to a CBR measurement result of the receiving terminal. Way. In the method of the receiving terminal,
determining channel state information (CSI) based on channel busy ratio (CBR) information;
Transmitting the CSI; And
And receiving a transmission parameter determined based on the CSI. The method of claim 6,
The CBR is determined as the ratio of the subchannel in which the received signal strength exceeds a predetermined threshold value in the resource pool,
The CBR information comprises a CBR level determined based on the CBR measurement result. The method of claim 6,
The transmission parameter includes an MCS value corresponding to a channel quality indicator (CQI) included in the CSI and the number of transport layers corresponding to a rank indicator (RI),
The CQI and RI are determined based on a range of CQI and a range of RI determined by the CBR information. The method of claim 6,
The step of determining the CSI,
In case the transmitting terminal has CBR measurement capability, receiving a CBR measurement result,
The CBR information is determined based on a CBR measurement result of the transmitting terminal and a CBR measurement result of the receiving terminal. The method of claim 9,
The CBR information is determined based on at least one of a CBR level corresponding to a CBR measurement result of the transmitting terminal and a maximum, minimum, or average value of a CBR level corresponding to a CBR measurement result of the receiving terminal. Way. In the transmission terminal,
A transceiver; And
Receiving channel state information (CSI) and the CBR information determined based on channel busy ratio (CBR) information from a receiving terminal,
Determine a transmission parameter based on the CSI,
And a control unit for transmitting the transmission parameter to a receiving terminal. The method of claim 11,
The CBR is determined as the ratio of the subchannel in which the received signal strength exceeds a predetermined threshold value in the resource pool,
The CBR information includes a CBR level determined based on a result of the CBR measurement. The method of claim 11,
The control unit,
Determine the number of transport layers corresponding to an MCS value and a rank indicator (RI) corresponding to a channel quality indicator (CQI) included in the CSI,
The CQI and RI are determined based on the range of the CQI and the range of RI determined by the CBR information. The method of claim 11,
The control unit,
Before receiving the CSI, if the transmitting terminal has CBR measurement capability, the CBR is measured,
Transmits the CBR measurement result,
The CBR information is determined based on a CBR measurement result of the transmitting terminal and a CBR measurement result of the receiving terminal. The method of claim 14,
The CBR information is determined based on at least one of a CBR level corresponding to a CBR measurement result of the transmitting terminal and a maximum, minimum, or average value of a CBR level corresponding to a CBR measurement result of the receiving terminal. Transmitting terminal. In the receiving terminal,
A transceiver; And
Channel state information (CSI) is determined based on channel busy ratio (channel busy ratio: CBR) information,
Transmit the CSI, and
And a control unit for receiving a transmission parameter determined based on the CSI. The method of claim 16,
The CBR is determined as the ratio of the subchannel in which the received signal strength exceeds a predetermined threshold value in the resource pool,
The CBR information includes a CBR level determined based on a result of the CBR measurement. The method of claim 16,
The transmission parameter includes an MCS value corresponding to a channel quality indicator (CQI) included in the CSI and the number of transport layers corresponding to a rank indicator (RI),
The CQI and RI are determined based on a range of CQI and a range of RI determined by the CBR information. The method of claim 16,
The control unit,
When the transmitting terminal has CBR measurement capability, it receives the CBR measurement result,
The CBR information is determined based on a CBR measurement result of the transmitting terminal and a CBR measurement result of the receiving terminal. The method of claim 19,
The CBR information is determined based on at least one of a CBR level corresponding to a CBR measurement result of the transmitting terminal and a maximum, minimum, or average value of a CBR level corresponding to a CBR measurement result of the receiving terminal. Receiving terminal.

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