KR20210003648A - A method and apparatus of resource selection for sidelink transmission - Google Patents

Abstract

The present invention relates to a method and an apparatus of resource selection for sidelink transmission in a wireless communication system and, more specifically, to a method and an apparatus for selecting transmission resources in a process in which a vehicle terminal uses another vehicle terminal, a terminal of a pedestrian, and a sidelink to transmit and receive information. The method in which a base station allocates resources for sidelink communication comprises: a step of transmitting a sidelink system information block (SL SIB) to a terminal if the terminal is in a camp-on state; a step of receiving a transmission resource request for sidelink communication from the terminal; and a step of transmitting downlink control information (DCI) including scheduling information to the terminal via a PDCCH based on the transmission resource request.

Description

Resource selection method and device for sidelink transmission {A METHOD AND APPARATUS OF RESOURCE SELECTION FOR SIDELINK TRANSMISSION}

The present disclosure relates to a method and apparatus for selecting resources for sidelink transmission in a wireless communication system. Specifically, the present disclosure relates to a method and apparatus for selecting a resource in a process in which a vehicle terminal supporting vehicle-to-everything (V2X) transmits and receives information using a sidelink with another terminal.

In order to meet the demand for wireless data traffic that is explosively increasing due to the commercialization of 4G communication systems and the increase in multimedia services, an improved 5G communication system or pre-5G communication system is being developed. 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 increase the data rate, the 5G communication system is being considered for implementation in an ultra high frequency (mmWave) band (eg, a 60 gigabyte (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 performance of the system, in 5G communication systems, advanced small cells, advanced small cells, cloud radio access networks (cloud RAN), and ultra-dense networks (ultra-dense networks) network), Device to Device communication (D2D), wireless backhaul, moving network, cooperative communication, CoMP (Coordinated Multi-Points), and interference cancellation (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.

Meanwhile, 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 disclosure relates to a wireless communication system, and relates to a method and apparatus for selecting a transmission resource in a process in which a vehicle terminal supporting V2X transmits and receives information using a sidelink with another vehicle terminal and a pedestrian terminal. Specifically, it relates to a resource selection criterion and operation of a base station and a terminal therefor when the base station allocates transmission resources in the sidelink and when the terminal directly allocates sidelink transmission resources through sensing.

A method of allocating resources for sidelink communication by a base station includes: when the terminal is in a camp on state, transmitting an SL Sidelink System Information Block (SIB) to the terminal; Receiving a transmission resource request for sidelink communication from the terminal; And transmitting Downlink Control Information (DCI) including scheduling information to the terminal through a PDCCH based on the transmission resource request.

1 is a diagram 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.
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 of allocating transmission resources in a sidelink by a base station 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 resource allocation information related to a time gap between initial transmission and retransmission according to an embodiment of the present disclosure.
7 is a flowchart of a method of reducing signaling overhead according to an embodiment of the present disclosure.
8A is a diagram illustrating that resource allocation of a PSSCH is performed in units of subchannels according to an embodiment of the present disclosure.
8B is a diagram illustrating a transmission location of a DMRS according to an embodiment of the present disclosure.
8C is a diagram illustrating a region in which a PSCCH is transmitted according to an embodiment of the present disclosure. FIG. 9 is a diagram illustrating a configuration of a sensing window for Mode 2 operation of a sidelink according to an embodiment of the present disclosure.
10A is a diagram for explaining a method of performing energy detection according to an embodiment of the present disclosure.
10B illustrates a method in which energy detection is performed in a specific area within a slot according to an embodiment of the present disclosure.
10C is a diagram illustrating a case in which all resource candidates left in the Resource selection window as a result of the Sensing window A according to an embodiment of the present disclosure are used in the Sensing window B.
10D is a diagram illustrating a case in which a resource candidate left in a resource selection window as a result of sensing in a sensing window A according to an embodiment of the present disclosure is reported to an upper level of a terminal and sensing is performed in a sensing window B.
10E is a diagram illustrating a final resource selection method according to an embodiment of the present disclosure.
11 is a diagram illustrating a mapping structure of physical channels mapped to one slot in a sidelink according to an embodiment of the present disclosure.
12 is a diagram illustrating that a resource for transmitting and receiving a PSFCH is set according to an embodiment of the present disclosure.
13 is a diagram illustrating a resource selection method according to an embodiment of the present disclosure.
14 is a block diagram illustrating an internal structure of a terminal according to an embodiment of the present disclosure.
15 is a block diagram illustrating an internal structure of a base station according to an embodiment of the present disclosure.
16 is a diagram illustrating a mapping structure of physical channels mapped to one slot in a sidelink according to an embodiment of the present disclosure.
17 is a diagram illustrating a resource selection and resource reselection method according to an embodiment of the present disclosure.
FIG. 18 is a diagram for describing a case in which triggering times of a resource selection and resource reselection method according to an embodiment of the present disclosure are different.

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 the detailed description of the embodiments of the present disclosure, the wireless access network New RAN (NR) in the 5G mobile communication standard specified by 3GPP, a mobile communication standard standardization body, and a packet core (5G System, or 5G Core Network, or NG Core: Next Generation Core) is the main target, but the main subject of the present disclosure is applicable to other communication systems having a similar technical background with a slight modification within the scope of the present disclosure. It will be possible at the judgment of a person with skilled technical knowledge in the technical field of the present disclosure.

In a 5G system, in order to support network automation, a Network Data Collection and Analysis Function (NWDAF), a network function that provides a function of analyzing and providing data collected from a 5G network network, may be defined. NWDAF can collect/store/analyze information from 5G networks and provide the results to unspecified network functions (NF), and the analysis results can be used independently by each NF.

For convenience of description below, some terms and names defined in the 3rd Generation Partnership Project Long Term Evolution (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 HARQ feedback is not supported in the sidelink based on the existing LTE system, when retransmission is performed in the sidelink, retransmission is necessarily performed regardless of whether the initial transmission is successfully received. Herein, a method of performing retransmission not based on HARQ feedback information is referred to as blind retransmission. In contrast, in the NR system-based sidelink, HARQ feedback may be supported in unicast and groupcast communication between the UE and the UE, and whether to retransmit may be determined based on an ACK/NACK feedback result. Specifically, retransmission may occur only when NACK is fed back. Here, a method of performing retransmission based on HARQ ACK/NACK feedback is referred to as HARQ feedback based retransmission. In NR V2X, a method in which a base station allocates sidelink transmission resources (Mode1) and a method in which a terminal directly allocates sidelink transmission resources through sensing (Mode2) are supported. In the case of Mode1, the base station may determine resource allocation for initial transmission and retransmission, and transmit information about this to the transmitting terminal through Downlink Control Information (DCI). The terminal receiving the DCI from the base station may allocate a sidelink resource based on the information thereon, and transmit the information about this by including it in Sidelink Control Information (SCI). In Mode1, the resource allocation information included in DCI and SCI may be initial transmission and retransmission transmission time and frequency allocation location information. In contrast, in the case of Mode2, the terminal determines time and frequency resource allocation for initial transmission and retransmission through direct sensing, and information about this may be included in SCI and transmitted. In Mode2, the resource allocation information included in the SCI may be initial transmission and retransmission transmission time and frequency allocation location information. In the existing LTE system-based sidelink, retransmission for one TB (Transport Block) was supported only up to two times. Specifically, when retransmission is set for one TB, only initial transmission and one retransmission for this are possible. However, in the NR system-based sidelink, not only blind retransmission and HARQ feedback-based retransmission are supported, but the maximum number of retransmissions for one TB may also be increased. In the case of transmitting resource allocation information for initial transmission and retransmission transmission time and frequency location information through SCI, it can be effectively used for the sensing operation of Mode2. Specifically, the sensing operation in Mode2 includes a process of performing SCI decoding for another terminal. At this time, after the transmitting terminal successfully decodes the SCI transmitted by the other terminal, the other terminal includes an operation of obtaining SCI information. The transmission time and frequency location information of the initial transmission and retransmission of the other terminal can be obtained from the SCI information of the other terminal, from which the transmitting terminal can determine whether to select the corresponding resource as the transmission resource. Therefore, when the SCI includes both transmission time and frequency location information of initial transmission and retransmission, it is possible to expect improvement in the sensing and resource selection performance of Mode2. However, when the maximum number of retransmissions for one TB is increased, signaling overhead for initial transmission and retransmission transmission time and frequency position information cannot be avoided. Accordingly, there is a need for a method that simultaneously considers the performance improvement of resource selection and signaling overhead included in DCI and SCI. In addition, since the blind retransmission method operates without HARQ feedback, a constraint may not occur in determining a transmission time point between initial transmission and retransmission. However, in the case of the HARQ feedback-based retransmission method, transmission resources are selected in consideration of the ACK/NACK feedback and possible retransmission timing in determining the transmission time between initial transmission and retransmission because transmission is based on the ACK/NACK feedback result. I need this. In the NR sidelink, the PSCCH and the PSSCH are multiplexed, as well as the structure of the PSCCH may be different from that in the LTE sidelink. Therefore, in order to perform sensing through SCI decoding in Mode2, a method for the UE to monitor the PSCCH of the NR sidelink is necessary in consideration of this point.

In this way, HARQ ACK/NACK feedback is supported in the NR sidelink, so that not only blind retransmission but also HARQ feedback based retransmission is supported, the maximum number of retransmissions may also be increased. Therefore, there is a need for a method that simultaneously considers an increase in signaling overhead related to resource allocation included in DCI and SCI and performance for resource selection. In addition, there is a need for a method of selecting a transmission resource in consideration of ACK/NACK feedback and possible retransmission timing. In addition, for SCI decoding in the Mode2 sensing process, a method for the UE to monitor the PSCCH of the NR sidelink is required. However, there is no discussion about this. Accordingly, in the present disclosure, a method and apparatus for selecting a resource for retransmission suitable for the transmission scenario in the sidelink are proposed. Also, a signaling method for DCI and SCI is proposed.

An embodiment of the present specification is proposed to support the above-described scenario, and a method of selecting a transmission resource in a process in which a vehicle terminal supporting V2X exchanges information using a sidelink with another vehicle terminal and a pedestrian mobile terminal, and It relates to the device. Specifically, it is intended to provide a resource selection criterion and a method and apparatus for operating a base station and a terminal therefor when the base station allocates transmission resources in the sidelink and when the terminal directly allocates sidelink transmission resources through sensing. To do.

According to an embodiment of the present disclosure, by providing a method of selecting a transmission resource in sidelink communication, resource selection in consideration of initial transmission and retransmission can be effectively performed.

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 a downlink (DL) or transmit data and control information to the base station through an 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 can 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). have.

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) shows a case where the 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). 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. V2X terminal (UE-1) can receive a V2X dedicated SIB (System Information Block) from the base station to which it is connected (or camping), and the V2X terminal (UE-2) is connected (or You can receive a V2X dedicated SIB from another base station (which you are camping). At this time, the information of the V2X-only SIB received by the V2X terminal (UE-1) and the information of the V2X-only SIB received by the V2X terminal (UE-2) may be different from each other. Therefore, in order to perform V2X communication between terminals (UE-1, UE-2) located in different cells, information can be unified, or parameter setting can be supported more flexibly through the method and apparatus for setting related parameters of the present disclosure. have.

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, 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, a terminal is a vehicle supporting vehicle-to-vehicular communication (Vehicular-to-Vehicular, 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 mean an RSU (Road Side Unit) equipped with a terminal function, an RSU equipped with a base station function, or an RSU equipped with a part of a base station function and a part of a 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 a road site unit (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. As shown in (a) of FIG. 2, the TX terminal and the RX terminal may perform one-to-one communication, and this may be referred to as unicast communication.

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

In Figure 2 (b), UE-1, UE-2, and UE-3 form one group (Group A) to perform groupcast communication, and UE-4, UE-5 , UE-6, and UE-7 may form another group (Group B) to perform groupcast communication. 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 that UE-1 is a transmitting terminal for broadcast in (b) of FIG. 2, all terminals (UE-2, UE-3, UE-4, UE-5, and UE- 6, and UE-7) may receive data and control information transmitted by UE-1.

In NR V2X, unlike in LTE V2X, support in the form of sending data to only one specific node through unicast and sending data to a number of specific nodes through groupcast can be considered. have. 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 for the purpose of simultaneously controlling a group consisting of a specific number of nodes. I can.

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. In addition, the resource granularity of the frequency axis may be one or more PRBs (Physical Resource Block).

When the resource pool is allocated on time and frequency (3-10), the colored area represents the area set as the resource pool on time and frequency. Although the present disclosure focuses on the case where the resource pool is non-contiguously allocated over time, the resource pool may be continuously allocated over time. In addition, although the present disclosure focuses on 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 where non-contiguous resource allocation is made in time (3-20) is shown. Referring to FIG. 3, a case where the granularity of resource allocation over time is made of slots (3-30) is illustrated. Specifically, one slot composed of 14 OFDM symbols may be a basic unit of resource allocation on the time axis. Referring to FIG. 3, a colored slot indicates a slot allocated to a resource pool in time, and may be indicated as resource pool configuration information in time in an SIB. Specifically, a slot set as a resource pool in time may be indicated through a bitmap. Referring to FIG. 3, physical slots 3-20 belonging to a non-contiguous resource pool in time may be mapped (3-21) to logical slots. In general, the set (set) of slots belonging to the PSSCH (Physical Sidelink Shared Channel) resource pool may be represented by (t ₀ ,t ₁ ,...,t _i ,...,tT _max ).

Referring to FIG. 3, a case where a resource pool is continuously allocated on a frequency (3-30) is shown.

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

startRB-Subchannel (3-32) may indicate the start position of the subchannel (3-31) on the frequency in the resource pool. When resource allocation is performed in units of sub-channels (3-31) on the frequency axis, the RB index (startRB-Subchannel, 3-32) where the sub-channel (3-31) starts, and the number of RBs in the sub-channel (3-31) A resource pool setting on a frequency may be made through information on whether it is composed of (sizeSubchannel) and setting information on the total number of subchannels (3-31) (numSubchannel). startRB-Subchannel, sizeSubchannel, and numSubchannel may be indicated as frequency resource pool configuration information in the SIB. In the present disclosure, when the UE is configured with related information as resource pool information, it may generally mean that the UE is configured through system information (SIB). However, for example, when the terminal does not receive system information from the base station, such as OOC (Out Of Converage), the resource pool related information may be pre-configuration. Here, the term pre-configuration may refer to information previously stored and set in the terminal, or may refer to information set when the terminal previously accessed the base station. In addition, when the UE receives the SIB from the base station and then receives resource pool information through the RRC after RRC connection with the base station is established, the resource pool information set through RRC may overwrite the information received through the SIB. In other words, resource pool information may be updated through RRC.

4 is a diagram illustrating a method of allocating transmission resources in a sidelink by a base station 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 the 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.

4, a transmitting terminal (4-01) and a receiving terminal (4-02) camping on (4-05) may receive SL SIB (Sidelink System Information Block) from the base station (4-03). Yes (4-10). Here, the receiving terminal 4-02 represents a terminal that receives the data transmitted by the transmitting terminal 4-01. The SL SIB information may include 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. have. When data traffic for V2X is generated in the transmitting terminal 4-01, the transmitting terminal 4-01 may be RRC connected to the base station 4-03 (4-20). Here, the RRC connection between the terminal and the base station may be referred to as Uu-RRC. The Uu-RRC connection process (4-20) may be performed before the transmission terminal 4-01 generates data traffic. In addition, in Mode 1, in a state in which the Uu-RRC connection process (4-20) between the base station (4-03) and the receiving terminal (4-02) is made, the transmitting terminal can transmit to the receiving terminal through a sidelink. . In contrast, in Mode 1, the transmitting terminal transmits to the receiving terminal through the sidelink even when the Uu-RRC connection process (4-20) between the base station (4-03) and the receiving terminal (4-02) is not performed. The transmitting terminal 4-01 may request a transmission resource capable of V2X communication with the receiving terminal 4-02 from the base station (4-30). At this time, the transmitting terminal 4-01 may request a sidelink transmission resource from the base station 4-03 using an uplink physical control channel (PUCCH), an RRC message, or a MAC CE. Meanwhile, the MAC CE may be a buffer status report (BSR, buffer status report) MAC CE of a new format (including at least an indicator indicating that the buffer status report is for V2X communication and information on the size of data buffered for D2D communication). have. In addition, a sidelink resource may be requested through a scheduling request (SR) bit transmitted through an uplink physical control channel. The base station 4-03 may allocate a V2X transmission resource to the transmitting terminal 4-01 through a dedicated Uu-RRC message. The dedicated Uu-RRC message may be included in a message (eg, RRCConnectionReconfiguration) that resets parameter information for RRC connection configuration. The resource allocation request information may be a V2X resource through Uu or a resource allocation request for PC5 according to the type of traffic requested by the terminal or whether the corresponding link is congested. In order to determine the resource allocation request, the transmitting terminal 4-01 may add and transmit PPPP (ProSe Per Packet Priority) or LCID (Logical Channel ID) information of V2X traffic through UEAssistanceInformation or MAC CE. The base station 4-03 may instruct the transmitting terminal 4-01 to perform final scheduling for sidelink communication with the receiving terminal 4-02 through DCI transmission through the PDCCH (4-40). 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.

Next, in the case of broadcast transmission, the transmitting terminal (4-01) broadcasts SCI (Sidelink Control Information) to the receiving terminal (4-02) through the PSCCH by broadcast without additional sidelink RRC setting (4-15). Can be cast (4-60). In addition, the transmitting terminal 4-01 may broadcast data to the receiving terminal 4-02 through the PSSCH (4-70).

In contrast, in the case of unicast or groupcast transmission, the transmitting terminal 4-01 may perform an RRC connection with other terminals on a one-to-one basis. In this case, the RRC connection between terminals may be referred to as PC5-RRC (4-15) separately from Uu-RRC. Even in the case of groupcast, the PC5-RRC (4-15) can be individually connected between the terminal and the terminal in the group. 4, the connection of the PC5-RRC (4-15) is shown as an operation after transmission of the SL-SIB (4-10), but before the transmission of the SL-SIB (4-10) or broadcast of the SCI ( 4-60) may be performed at any time before. If RRC connection between terminals is required, PC5-RRC connection of the sidelink is performed, and SCI can be transmitted to the receiving terminal 4-02 through PSCCH in unicast or groupcast (4-60). At this time, the groupcast transmission of SCI may be interpreted as a group SCI. In addition, the transmitting terminal 4-01 may transmit data to the receiving terminal 4-02 through the PSSCH through unicast or groupcast (4-70). In the case of Mode 1, the transmitting terminal 4-01 interprets the sidelink scheduling information included in the DCI received from the base station 4-03, performs scheduling for the sidelink through this, and sends the following scheduling information to the SCI. Can be transmitted including.

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

* NDI (New Data Indicator) field

* RV (Redundancy Version) field

* Information field indicating reservation interval

The information field indicating the reservation interval is indicated as a fixed value for an interval between TBs when selecting resources for a plurality of TBs (multiple MAC PDUs), and if a resource is selected for only one TB, the corresponding value is used. '0' may be indicated.

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 5-03 provides a pool of sidelink transmission/reception resources for V2X as system information, and the transmitting terminal 5-01 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 5-01 autonomously selects a resource and transmits data based on a resource pool previously received through system information. .

Referring to FIG. 5, a transmitting terminal 5-01 and a receiving terminal 5-02 camping on (5-05) may receive SL SIBs from the base station 5-03 ( 5-10). Here, the receiving terminal 5-02 represents a terminal that receives data transmitted by the transmitting terminal 5-01. The SL SIB information may include 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. have. The difference in operation between FIGS. 4 and 5 is that in FIG. 4, the base station 5-03 and the terminal 5-01 operate in a state in which RRC is connected, whereas in FIG. 5, the idle mode 5 in which RRC is not connected. -20) can also work. In addition, even in a state in which the RRC is connected (5-20), the base station 5-03 may operate so that the transmitting terminal 5-01 autonomously selects a transmission resource without being directly involved in resource allocation. Here, the RRC connection between the terminal 5-01 and the base station 5-03 may be referred to as a Uu-RRC 5-20. When data traffic for V2X is generated in the transmitting terminal 5-01, the transmitting terminal 5-01 receives a resource pool through the system information received from the base station 5-03 and receives the transmission terminal 5-01. Can select a time/frequency domain resource according to a set transmission operation within the set resource pool (5-30).

Next, in the case of broadcast transmission, the transmitting terminal (5-01) broadcasts SCI (Sidelink Control Information) to the receiving terminal (5-02) through the PSCCH by broadcast without additional sidelink RRC configuration (5-20). Can be cast (5-50). In addition, data may be broadcast to the receiving terminal 5-02 through the PSSCH (5-60).

In contrast, in the case of unicast and groupcast transmission, the transmitting terminal 5-01 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 is individually connected between the terminals in the group. In Figure 5, the PC5-RRC (5-15) connection is shown as an operation after transmission of SL SIB (5-10), but any time before transmission of SL SIB (5-10) or transmission of SCI (5-50) It can also be done. If RRC connection between terminals is required, sidelink PC5-RRC connection is performed (5-15) and SCI (Sidelink Control Information) can be transmitted to the receiving terminal (5-02) through unicast or groupcast through PSCCH. (5-50). At this time, the groupcast transmission of SCI may be interpreted as a group SCI. In addition, data may be transmitted to the receiving terminal 5-02 through the PSSCH through unicast or groupcast (5-60). In the case of Mode 2, the transmitting terminal 4-01 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 (New Data Indicator) field

* RV (Redundancy Version) field

* Information field indicating reservation interval

The information field indicating the reservation interval is indicated as a fixed value for an interval between TBs when selecting resources for a plurality of TBs (multiple MAC PDUs), and if a resource is selected for only one TB, the corresponding value is used. '0' may be indicated.

According to specific embodiments to be described later, a resource selection criterion and a base station for this when the base station allocates transmission resources in the sidelink (Mode 1) and when the terminal directly allocates sidelink transmission resources through sensing (Mode2). And the terminal operation method will be described in more detail.

[Example 1]

[Embodiment 1] of the present disclosure provides a method of simultaneously considering signaling overhead for resource allocation information and performance for resource selection that may occur due to an increased number of retransmissions in an NR sidelink. First, there is a blind retransmission method in which retransmission is performed without based on HARQ feedback information as a retransmission method. In contrast, there is a HARQ feedback-based retransmission method, which is a method of performing retransmission based on HARQ ACK/NACK feedback. Specifically, in the blind retransmission method, retransmission may be necessarily performed regardless of whether the initial transmission is successfully received. However, in the case of the HARQ feedback-based retransmission method, whether to retransmit may be determined based on an ACK/NACK feedback result transmitted from the receiving terminal to the transmitting terminal. When the HARQ feedback-based retransmission method is used and corresponds to the configured maximum retransmission, the receiving terminal may not perform ACK/NACK feedback to the transmitting terminal. As HARQ ACK/NACK feedback is supported in the NR sidelink, not only blind retransmission but also HARQ feedback based retransmission are both supported, so the maximum number of retransmissions may also be increased. Table 1 below shows examples of the maximum number of retransmissions and the number of resource reservations that can be considered for blind retransmission (Case 1) and HARQ feedback-based retransmission (Case 2).

[Table 1]

Compared with the case where the maximum number of retransmissions is 2 in [Table 1] (Case 1-4, Case 2-4), when the maximum number of retransmissions is increased to 4, when the maximum number of retransmissions is considered and the resource is reserved and transmitted. (Case 1-1, Case 2-1, Case 2-3) If the resource allocation information for this is included in DCI and SCI, there is a problem that overhead for DCI and SCI increases.

6 is a diagram illustrating resource allocation information related to a time gap between initial transmission and retransmission according to an embodiment of the present disclosure.

Specifically, referring to FIG. 6, resource allocation information indicating a time gap between initial transmission and retransmission is shown in terms of an information field. However, the reservation information for resource allocation may include both initial transmission and retransmission transmission time and frequency allocation location information. In FIG. 6, SA (Scheduling Assignment) means that the terminal indicates information on resource allocation, and this may be interpreted as an operation in which the terminal signals resource allocation information to SCI through PSCCH in the sidelink. Referring to FIG. 6, when the maximum number of retransmissions is 2 (Case 1-4, Case 2-4), the case where the number of resource reservations is 2 (6-10) is shown. In this case, the SA may indicate a transmission time between initial transmission and retransmission through one time gap. In addition, when the maximum number of retransmissions is 4, the number of resource reservations for this may be 4 (6-20) (Case 1-1, Case 2-1, Case 2-3). In this case, the SA may indicate a transmission time between initial transmission and retransmission through three time gaps. In this way, after resource selection for initial transmission and retransmission, a method of signaling both transmission time and frequency allocation location information for initial transmission and retransmission through DCI and SCI may be referred to as a look-ahead reservation method. In the case of a look-ahead reservation scheme, the sensing and resource selection performance for Mode 2 may be improved. The sensing operation for Mode 2 may be defined as an operation of performing SCI decoding for another terminal and an operation of performing sidelink measurement. For a method for the UE to monitor the PSCCH for SCI decoding, refer to [Embodiment 2] to be described later. Also, for detailed operations of selecting resources by performing sensing in Mode 2, refer to [Example 3-7] to be described later. When SCI includes both transmission time and frequency allocation location information of initial transmission and retransmission, and failure to successfully receive and decode one of the two SAs indicated at the time of initial transmission and retransmission (6-30, 6-40) Also, the transmission time between initial transmission and retransmission can be identified by using one of the two SAs. In addition, the transmitting terminal may determine whether the initial transmission and retransmission resources occupied by other terminals may be used as transmission resources through the sidelink measurement result. However, when using the Look-ahead reservation method, referring to 6-20 of FIG. 6, the maximum number of retransmissions and the number of times of reservation and transmission of resources are increased, so that the transmission time and frequency allocation position of initial transmission and retransmission are increased. The overhead will increase.

In order to solve the signaling overhead problem, a chain reservation method can be considered. Referring to 6-50, 6-60, and 6-70 of FIG. 6, an example of a chain reservation scheme is shown. In the above [Table 1], when the maximum number of retransmissions is increased to 4, the DCI and SCI when the number of transmissions by reservation of resources is limited to 2 (Case 1-2, Case 2-2, Case 1-3) Resource allocation information included in may be reduced. Specifically, the chain reservation scheme is a method (6-50) of signaling both transmission time and frequency allocation location information for the current transmission and the next retransmission after resource selection for initial transmission and retransmission through DCI and SCI. However, unlike in 6-50 of FIG. 6, the interpretation of the time gap field may vary according to the time point at which SA is indicated in the chain reservation scheme. In 6-50 of FIG. 6, the SA at the last retransmission time point is shown to indicate only resource allocation information for the current time point. However, considering that the number of resource reservations is supported up to 2, a method of indicating resource allocation information for a previous retransmission time at the last retransmission time can be considered. For example, referring to 6-60 of FIG. 6, resource allocation information for the current and next retransmission is indicated at the initial transmission and intermediate retransmission time, but the resource allocation information for the current and previous retransmission time is indicated at the last retransmission time. I can instruct. However, in the case of the chain reservation method, compared to the look-ahead reservation method, the performance of sensing and resource selection for Mode 2 may be deteriorated. For example, referring to 6-70 of FIG. 6, when only the SA for initial transmission is successfully decoded in the chain reservation scheme, and all the SAs indicated at the 2nd, 3rd, and 4th retransmission times are not successfully received and decoded. The information on the 3rd and 4th retransmission times cannot be identified. However, referring to 6-80 of FIG. 6, in the case of the Look-ahead reservation scheme, only the SA for the initial transmission was successfully decoded, and all SAs indicated at the 2nd, 3rd, and 4th retransmission times were not successfully received and decoded. Even in this case, information on all transmission times can be obtained from the SA for initial transmission.

As described above, the overhead problem that occurs when signaling resource allocation information using a look-ahead reservation scheme according to an increase in the maximum number of retransmissions and the number of resource reservations has been described. In addition, in order to solve the signaling overhead problem, it has been described that when the chain reservation method is used, performance degradation of Mode 2 sensing and resource selection may occur. First of all, the present disclosure may provide a method for solving signaling overhead for resource allocation information when using a look-ahead reservation scheme. As described above, the reservation information for resource allocation may include initial transmission and retransmission transmission time and frequency allocation location information. In the look-ahead reservation scheme, the following method may be used to reduce signaling overhead for resource allocation information.

* The frequency allocation position selected for initial transmission is equally applied to all retransmissions, and only frequency allocation position information for the initial transmission may be signaled.

* Retransmission resources are allocated to maintain a constant time gap between initial transmission and retransmission, and only one fixed time gap information can be signaled.

** When there are two or more retransmissions, it can be allocated so that a constant time gap in time is maintained even between all retransmissions.

** As shown in Table 2, when resources allocated to the resource pool are not continuous in time, the time gap may not be constant based on the physical slot index. [Table 2] is an example of a case where initial transmission occurs in slot n and time gap is set to 4 slots. As shown in [Table 2], when a corresponding slot is a slot that cannot be transmitted through PSSCH after 4 slots, the corresponding resource may be transmitted in the first transmittable slot among time resources allocated to the resource pool.

** As a method of maintaining a constant time gap, the time gap selected for the initial transmission and the first retransmission can be applied equally to the remaining retransmissions.

[Table 2]

Next, in order to solve the overhead problem that occurs when signaling resource allocation information using the look-ahead reservation method according to the increase in the maximum number of retransmissions and resource reservations, the look-ahead reservation method and the chain reservation method are used. Can be used in combination. As described above, the reservation information for resource allocation may include initial transmission and retransmission transmission time and frequency allocation location information. The following method may be used to reduce signaling overhead for resource allocation information by combining the Look-ahead reservation method and the Chain reservation method. Of course, it is not limited to the following examples.

* The maximum number of resource reservations for retransmission is fixed to one.

** In this disclosure, there is no limit on the fixed maximum number of resource reservations. However, as the number of resource reservations increases, the overhead of signaling resource allocation information for this may increase. Therefore, as an appropriate value, the maximum number of resource reservations for retransmission including only the initial transmission and one retransmission may be set to 2.

* The maximum number of retransmissions can be set.

** The maximum number of retransmissions that can be set in the present disclosure may not be limited. When the maximum number of retransmissions that can be set is up to two, it can be expressed as three (A, B). When the maximum number of retransmissions that can be set is up to three, it can be expressed as three (A, B, C). When the maximum number of retransmissions that can be set is up to two, it can be set as set (A, B) = (2, 4) as an appropriate value.

** The maximum number of retransmissions can be set through the sidelink SIB. Specifically, the maximum number of retransmissions may be set in the resource pool setting in the SIB. When the maximum number of retransmissions is set in the resource pool, it can be understood that the maximum number of retransmissions is set equally to all terminals operating in the resource pool. In contrast, the maximum number of retransmissions may be set more dynamically through DCI and SCI. In this case, the maximum number of retransmissions of a terminal operating in the same resource pool may be set differently. In the case of Mode 1 operation, the base station determines the setting of the maximum number of retransmissions through DCI, and the transmitting terminal may signal the setting of the corresponding maximum number of retransmissions to another terminal through SCI. In the case of Mode 2 operation, the UE may directly determine the setting of the maximum number of retransmissions and indicate this through SCI. When the maximum number of retransmissions is set through SCI, in the sensing operation in Mode 2, the transmitting terminal can determine the maximum number of retransmissions of other terminals by decoding the SCI.

* You can decide whether to use the Look-ahead reservation method or the Chain reservation method according to the set maximum number of retransmissions.

** If the maximum number of retransmissions is determined and set in sets (A, B) = (2, 4) and the maximum number of retransmissions is set to 2, the look-ahead reservation method can be used. And accordingly, the resource allocation configuration signaling interpretation can be followed.

*** In this case, the following information may be included in the DCI for resource allocation setting. However, it is not limited to the following method in the present disclosure.

**** Frequency start position information field for initial transmission

**** Length of allocated subchannel and frequency start position information field for retransmission

**** Information field indicating the time gap between initial transmission and retransmission

*** In this case, the following information may be included in the SCI for resource allocation setting. However, it is not limited to the following method in the present disclosure.

**** Length of assigned subchannel and frequency start position information field for retransmission and previous transmission

**** Information field indicating the time gap between initial transmission and retransmission

** If the maximum number of retransmissions is determined and set in sets (A, B) = (2, 4), and the maximum number of retransmissions is set to 4, the chain reservation method can be used. And accordingly, the resource allocation configuration signaling interpretation can be followed.

*** In this case, the following information may be included in the DCI for resource allocation setting. However, it is not limited to the following method in the present disclosure.

**** Frequency start position information field for the current transmission (may be initial transmission days or retransmission days)

**** Length of assigned subchannel and frequency start position information field for next retransmission

**** Information field indicating the time gap between the current transmission (initial transmission days or retransmission days) and the next retransmission

*** In this case, the following information may be included in the SCI for resource allocation setting. However, it is not limited to the following method in the present disclosure.

**** Length of assigned subchannel and frequency start position information field for next retransmission

***** Only resource allocation information for the current time may be included as shown in 6-50 of FIG. 6 at the last retransmission time.

***** Alternatively, resource allocation information for the current time and the previous retransmission time may be included as shown in 6-60 of FIG. 6 at the last retransmission time.

**** Information field indicating the time gap between the current transmission (initial transmission days or retransmission days) and the next retransmission

In the above-described method, a method for analyzing resource allocation configuration signaling when there is a resource reservation for retransmission is described. If there is no resource reservation for retransmission and only initial transmission, only resource allocation information for initial transmission may be signaled. In [Embodiment 2] to be described later, a method of including resource allocation information in SCI will be described in more detail.

7 is a flowchart of a method of reducing signaling overhead according to an embodiment of the present disclosure.

Specifically, referring to FIG. 7, it shows a method of reducing signaling overhead for resource allocation information by combining the above-described look-ahead reservation method and chain reservation method.

[Example 2]

[Embodiment 2] of the present disclosure describes a method for a UE to monitor the PSCCH of the NR sidelink for SCI decoding. In the NR sidelink, the PSCCH and the PSSCH are multiplexed, as well as the structure of the PSCCH may be different from that in the LTE sidelink. Therefore, in order to perform sensing through SCI decoding in Mode 2, a method for the UE to monitor the PSCCH of the NR sidelink is required. The operation of the transmitting terminal performing SCI decoding for another terminal may include an operation of monitoring the PSCCH to successfully decode the SCI and then obtaining SCI information of the other terminal. First, the following method may be considered in a manner in which PSCCH and PSSCH are multiplexed in the NR sidelink.

* A part of PSCCH and the associated PSSCH are transmitted using overlapping time resources in non-overlapping frequency resources, but another part of the associated PSSCH and/or another part of the PSCCH are transmitted using non-overlapping time resources.

Here,'associated' means that the PSCCH contains at least information necessary to decode the PSSCH. FIG. 8 shows a method in which PSCCH and PSSCH are multiplexed according to the above-described method. Next, as described above with reference to FIG. 3, when resource allocation is performed in units of subchannels on the frequency axis, startRB-Subchannel, sizeSubchannel, and numSubchannel may be indicated as frequency setting information for the resource pool in the SIB. In the NR sidelink, subcarrier spacing according to the frequency range supported by the NR Uu system may be supported. [Table 3] and [Table 4] show the system transmission bandwidth, subcarrier width and channel bandwidth in a frequency band lower than 6 GHz (Frequency Range 1) and higher than 6 GHz (Frequency Range 2) in NR Uu, respectively. Channel bandwidth) may represent a part of the correspondence. In [Table 3] and [Table 4], N/A may be a bandwidth-subcarrier combination that is not supported by the NR system. When defining a subchannel unit in the sidelink, sizeSubchannel and numSubchannel may be determined based on the subcarrier width and the number of RBs available in the channel bandwidth. For example, an NR system having a 100 MHz channel bandwidth with a 30 kHz subcarrier width may have a transmission bandwidth of 273 RBs. Therefore, in this case, when sizeSubchannel is configured with 10RB, a maximum of 27 numSubchannels may be supported.

[Table 3]: Composition of FR1 (Frequency Range 1)

[Table 4]: Composition of FR2 (Frequency Range 2)

Accordingly, when the resource allocation of the PSSCH in the NR sidelink is performed on a subchannel basis, it may be necessary to determine whether to allow the PSCCH to be transmitted while being included in the subchannel or to allow the PSCCH to be transmitted across the subchannel.

8A is a diagram illustrating that resource allocation of a PSSCH is performed in units of subchannels according to an embodiment of the present disclosure.

In the present disclosure, a method in which the PSCCH is always included in the subchannel and transmitted in the NR sidelink may be considered. In this case, a method of transmitting the PSCCH in the subchannel may be determined according to the size of the set subchannel. In addition, a method of transmitting the PSCCH by repetition in the PSSCH region may be considered according to the subchannel size. Specifically, a method in which the PSCCH is included in the subchannel and transmitted is shown in 8-20 and 8-30 of FIG. 8A. Referring to 8-20 and 8-30 of FIG. 8A, the terminal may be configured with startRB-Subchannel, sizeSubchannel, and numSubchannel as frequency setting information for the resource pool. In the present disclosure, the PSCCH resource m may be included in the m-th subchannel based on the startRB-Subchannel and transmitted. As in the above-described [Embodiment 1], information on a transmission time point and frequency allocation location of initial transmission and retransmission as reservation information for PSSCH resource allocation may be included in the SCI. For the Look-ahead reservation scheme that indicates resource allocation by allowing retransmissions up to 2 times, when SCI is transmitted through PSCCH resource m in slot t _n allocated to the resource pool, the slot and subchannel corresponding to PSSCH transmission are as follows: It can be determined as:

* When the time gap (SF _gap ) between initial transmission and retransmission is 0 (when retransmission is not performed), the time and frequency allocation positions for the PSSCH are as follows (8-20).

** sub-channel(s) m, m+1,... ,m+LsubCH-1 in slot t _n

* If the time gap (SF _gap ) between initial transmission and retransmission is not 0 (corresponding to initial transmission), the time and frequency allocation positions for the PSSCH are as follows.

** sub-channel(s) m, m+1,... ,m+L _subCH -1 in slot t _n (8-20)

** sub-channel(s) n _subCHstart , n _subCHstart +1,... , n _subCHstart +L _subCH -1 in slot t _n+SFgap (8-30)

* If the time gap (SF _gap ) between initial transmission and retransmission is not 0 (corresponding to retransmission), the time and frequency allocation positions for PSSCH are as follows:

** sub-channel(s) n _subCHstart , n _subCHstart +1,... , n _subCHstart +L _subCH -1 in slot t _n-SFgap

** sub-channel(s) m, m+1,... ,m+L _subCH -1 in slot t _n

L _subCH represents the length of a subchannel allocated to PSSCH, n _subCHstart indicates the start position of the subchannel allocated to PSSCH, and this information is included in the SCI. In contrast, when SCI is transmitted through the PSCCH resource m in the slot t _n allocated to the resource pool for the Chain reservation scheme indicating resource allocation for the current transmission and the next retransmission, the slot and subchannel corresponding to PSSCH transmission are as follows: Can be determined as:

* When the time gap (SF _gap ) between the current transmission and the next retransmission is 0 (when retransmission is not performed), the time and frequency allocation positions for the PSSCH are as follows (8-20)

** sub-channel(s) m, m+1,... ,m+LsubCH-1 in slot t _n

* If the time gap (SF _gap ) between the current transmission and the next retransmission is not 0 (corresponding to the current transmission), the time and frequency allocation positions for the PSSCH are as follows

** sub-channel(s) m, m+1,... ,m+L _subCH -1 in slot t _n (8-20)

** sub-channel(s) n _subCHstart , n _subCHstart +1,... , n _subCHstart +L _subCH -1 in slot t _n+SFgap (8-30)

* If the time gap (SF _gap ) between the current transmission and the next retransmission is not 0 (corresponding to the next retransmission), the time and frequency allocation positions for the PSSCH are as follows

** sub-channel(s) n _subCHstart , n _subCHstart +1,... , n _subCHstart +L _subCH -1 in slot t _n-SFgap

** sub-channel(s) m, m+1,... ,m+L _subCH -1 in slot t _n and

In the above, L _subCH represents the length of a subchannel allocated to PSSCH, n _subCHstart indicates a start position of a subchannel allocated to PSSCH, and this information may be included in SCI. The difference in bit field interpretation according to the look-ahead reservation or chain reservation scheme is that the reservation scheme is different according to the maximum number of retransmissions as described above through [Example 1], and the bit field interpretation is different in the SCI signal for this. It could be an example.

Referring to FIGS. 8-20 and 8-30 of FIG. 8A, the PSCCH is transmitted on the subchannel corresponding to the lowest subchannel index in the subchannel allocated to the PSSCH. In the present disclosure, a method in which PSCCH repetition can be configured is provided. If PSCCH repetition is not supported, it is assumed that the PSCCH is transmitted in the subchannel corresponding to the lowest subchannel index in the subchannel allocated to the PSSCH, as shown in 8-20 and 8-30 of FIG. 8A. On the contrary, when PSCCH repetition is supported, PSSCH may be repetitioned in consecutive subchannels according to the set number of PSCCH repetition. PSCCH repetition may be set when the PSSCH is transmitted on one or more consecutive subchannels, and the maximum number of configurable PSCCH repetitions may be the number of subchannels to which the PSSCH is allocated. When PSCCH repetition is supported, the number of PSCCH repetition may be set in SCI and signaled. In addition, when the number of PSCCH repetition (length) R is set, the subchannel corresponding to the lowest subchannel index in the subchannel allocated to the PSSCH may be repeatedly transmitted at the same time and frequency position in consecutive R subchannels. Here, R may be set to an integer such as 1,2,3,4. R=1 means that the PSCCH is not repetitioned and is transmitted only in one subchannel. Alternatively, the maximum number (length) of PSCCH repetition may be set based on the resource pool information. In this case, the number of actually applied PSCCH repetitions may vary according to the channel conditions. Accordingly, the UE may attempt to detect the PSCCH in the consecutive R subchannels starting from the subchannel corresponding to the lowest subchannel index in the subchannel allocated to the PSSCH assuming the maximum length R of the PSCCH repetition. Referring to 8-40 of FIG. 8A, a case in which PSCCH repetition is supported and PSCCH repetition length R is set to 2 is illustrated. Considering the repetition of the PSCCH is that if the PSCCH is always included in the subchannel and transmitted, if the size of the subchannel is small, the frequency resource area in which the PSCCH can be transmitted is limited, so that the reliability of PSCCH transmission may not be guaranteed This is the way to consider. In addition, by considering the repetition of the PSCCH, a case in which the PSCCH is used for the purpose of Radio Link Monitoring (RLM) in the sidelink may be considered. When the PSCCH is transmitted only in a partial region of the frequency, accuracy for this may not be guaranteed when RLM is measured from the corresponding PSCCH. Specifically, the transmitting terminal transmits the PSCCH DMRS through the PSCCH, and the receiving terminal receiving it may monitor the link state. In addition, similarly to Uu, the receiving terminal may report a link state monitoring result to an upper layer through an indicator in the form of IC (In-Sync) or OOC (Out-of-Coverage). Therefore, when the PSCCH DMRS is used as a sidelink RLM, a method of forcing the PSCCH repetition number to be greater than or equal to X in this embodiment may be considered. Accordingly, the accuracy of the RLM of the sidelink can be guaranteed. In this way, the PSCCH repetition method is differentiated from the transmission structure of the NR PDCCH.

Next, use of the structure of the NR PDCCH can be considered as the structure of the PSCCH in the NR sidelink. The basic unit of time and frequency resources constituting the NR PDCCH may be referred to as REG (Resource Element Group) as shown in 8-50 of FIG. 8A, and REG is 1 OFDM symbol on the time axis and 1 PRB on the frequency axis ( Physical Resource Block), that is, it may be defined as 12 subcarriers. REG may include a region to which a demodulation reference signal (DMRS), which is a reference signal for decoding it, is mapped. As shown in 8-50 of FIG. 8A, three DMRSs may be transmitted within 1 REG. The base station may configure the allocation unit of the NR PDCCH by concatenating the REG. The basic unit to which the PDCCH is allocated in NR Uu is called a Control Channel Element (CCE), and 1 CCE may be composed of a plurality of REG bundles. Here, the REG bundle is composed of a number of REGs and becomes the minimum unit in which the PDCCH is interleaving. The structures of CCEs supported by NR Uu are shown in 8-60, 8-70, and 8-80 of FIG. 8A. Specifically, referring to 8-60, 8-70, and 8-80 of FIG. 8A, a structure of a CCE corresponding to a case in which the PDCCH symbol length is 1, 2, and 3, respectively, may be shown. In NR PDCCH, when the structure of 8-60 or 8-70 of FIG. 8A is used, the possible REG bundle is 2 or 6, and when the structure of 8-80 is used, the possible REG bundle may be 3 or 6. The structure of the CCE supported by NR Uu shown in 8-60, 8-70, and 8-80 of FIG. 8A may be utilized for the NR sidelink PSCCH. In other words, 8-60, 8-70, and 8-80 of FIG. 8A may be a structure of a CCE corresponding to a case where the PSCCH symbol length is 1, 2, and 3, respectively. In addition, the increased PSCCH symbol length may be considered to support extended coverage in the NR sidelink. Referring to 8-90 and 8-100 of FIG. 8A, a CCE structure that can be used when the PSCCH symbol length is 6 is shown. In the case of 8-90 of FIG. 8A, a case in which the REG bundle is 3 or 6 is an example, and in the case of 8-100 is an example in which the REG bundle is 2 or 6. When the PSCCH symbol length of 6 is supported in the NR sidelink, a CCE structure of 8-90 or 8-100 may be used. Therefore, when the PSCCH region of the sidelink is set, the corresponding region may be composed of a plurality of CCEs, and may be mapped to one or more CCEs according to an aggregation level (AL) and transmitted. CCEs in the PSCCH region are classified by number, and the number of CCEs may be assigned according to a logical mapping method. In the case of the NR PDCCH, the AL may be used to implement link adaptation of the downlink control channel, but in the NR PSCCH, the AL may not be used for link adaptation and may be set to the UE through resource pool configuration. In addition, in the case of the NR PDCCH, since the UE needs to detect a signal without knowing information on the downlink control channel, a search space indicating a set of CCEs may be defined for blind decoding. Here, the search space is a set of downlink control channel candidates consisting of CCEs that the terminal should attempt to decode on a given aggregation level, and there are various aggregation levels that make one bundle with multiple CCEs according to AL. May have a plurality of search spaces. Also, in the NR PDCCH, a search space set may be defined as a set of search spaces at all set aggregation levels. However, such a search space and a search space set may not be defined in the NR PSCCH. As shown in 8-20 and 8-30 of FIG. 8A, the NR PSCCH can be basically transmitted at a predetermined time and frequency position in a subchannel. Specifically, the time position for the PSCCH in the subchannel may be set or transmitted from the first OFDM symbol of the slot to the X symbol according to the fixed PSCCH length X. In addition, according to the CCE structure and AL in which the frequency position of the PSCCH in the subchannel is set, it may be mapped from the lowest or highest PRB index of the subchannel, or mapped to the center of the subchannel. Therefore, the following information may be set in the resource pool for PSCCH transmission of the sidelink. In addition, this configuration information may be transmitted through the SIB.

* Time resource pool setting information for PSSCH

** PSCCH may be transmitted in a set (set) of slots belonging to the PSSCH resource pool (t ₀ ,t ₁ ,...,t _i ,...,tT _max ).

* Frequency resource pool setting information for PSSCH (subchannel setting information): startRB-Subchannel, sizeSubchannel, numSubchannel

* PSCCH information set in the subchannel

** PSCCH length X

*** When X=1 is set, the structure of the CCE of FIGS. 8-60 may be used.

*** When X=2 is set, the CCE structure of FIGS. 8-70 may be used.

*** When X=3 is set, the CCE structure of FIGS. 8-80 may be used.

*** When X=6 is set, the CCE structure of FIGS. 8-90 or 8-100 may be used.

*** The structure of the CCE that can be used may be limited according to the size of the set subchannel (sizeSubchannel). For example, if the size of the subchannel is smaller than 6RB, the CCE structure of FIGS. 8-60 cannot be used.

** Aggregation Level (AL) L

*** If L=1 is set, it means no aggregation.

*** When L>1 is set, the CCE structure can be continuously aggregated in frequency. The number of CCEs that can be aggregated may be limited according to the set subchannel size (sizeSubchannel). For example, when the size of the subchannel is 10RB and X=1 is set and the CCE structure of FIGS. 8-60 is used, only L=1 is possible.

As described above, when the size of a subchannel (sizeSubchannel) is set with the frequency setting information for the resource pool in the SIB, the available CCE structure or the number of CCEs that can be aggregated may be limited and set according to the size of the subchannel.

According to the above-described PSCCH transmission method in the NR sidelink, the UE can monitor the PSCCH region located in each subchannel from information set in the resource pool. In addition, it is possible to determine the resource allocation information of the PSSCH by decoding the SCI transmitted through the PSCCH. In addition, when PSCCH repetition information is included in the SCI, the resource allocation information of the PSSCH may be determined by reflecting it. Specifically, in the PSSCH region, the PSSCH may be decoded by identifying the subchannel including the PSCCH and the subchannel not including the PSCCH. The PSCCH structure and PSCCH monitoring method in the NR sidelink proposed in the above-described embodiment provides an example for performing SCI decoding in the process of the UE performing sensing, and is not limited to the above-described method.

[Example 2-1]

In [Embodiment 2-1] of the present disclosure, the structure of the PSCCH will be described in more detail. The structure of the control channel proposed here is considering the use of the sidelink, but is not limited thereto. For example, for the purpose of supporting coverage extension in a communication system between a base station and a terminal, a control channel having a long symbol length proposed in Embodiment 2-1 may be used. In general, the basic unit to which the PSCCH is allocated in the sidelink may be a control channel element (CCE), and the PSCCH may be transmitted by being mapped to one or more CCEs according to an aggregation level (AL). CCEs in the PSCCH area are classified by number, and the number of CCEs may be assigned according to a logical mapping method. In addition, one CCE may consist of a plurality of REG bundles. Here, the REG bundle is composed of a plurality of REGs, and CCE-to-REG mapping is interleaved to be the minimum unit in which the PSCCH is interleaved. Here, the CCE-to-REG mapping may or may not be interleaving, and corresponding information in the sidelink may be set as resource pool information. According to the supported PDCCH symbol length, a structure of a CCE corresponding thereto may be used. In general, a CCE composed of REGs of L(N) can be made for the symbol length N. REG (Resource Element Group) may be defined as 1 OFDM symbol on the time axis and 1 Physical Resource Block (PRB) on the frequency axis, that is, 12 subcarriers. REG may include a region to which a demodulation reference signal (DMRS), which is a reference signal for decoding it, is mapped.

8B is a diagram illustrating a transmission location of a DMRS according to an embodiment of the present disclosure.

Specifically, an example of a location in which three DMRSs are transmitted in 1 REG is shown in 8-110 of FIG. 8B. Next, referring to 8-120, 8-130, 8-140, 8-150, and 8-160 of FIG. 8B, the structure of CCE corresponding to the case where the PSCCH symbol length is 1, 2, 3, 4, 6, respectively Examples of each are shown. More specifically,

* Referring to 8-120 of FIG. 8B, an example of the CCE structure for the case where the PSCCH symbol length is 1 is shown, and 6 REGs constitute one CCE. Also, L={2, 6} is shown as a possible REG bundle size. In this case, the DMRS pattern for the PSCCH symbol length of 1 may be assumed to be a pattern 8-110 of FIG. 8B.

* Referring to 8-130 of FIG. 8B, an example of the CCE structure for the case where the PSCCH symbol length is 2 is shown, and 6 REGs constitute one CCE. Also, L={2, 6} is shown as a possible REG bundle size. In this case, as for the DMRS pattern for the PSCCH symbol length of 2, it may be assumed that the patterns 8-110 of FIG. 8B are repeated for each symbol.

* Referring to 8-140 of FIG. 8B, an example of the CCE structure for the case where the PSCCH symbol length is 3 is shown, and 6 REGs constitute one CCE. In addition, L={3, 6} is shown as a possible REG bundle size. In this case, as for the DMRS pattern for the PSCCH symbol length of 3, it may be assumed that the patterns 8-110 of FIG. 8B are repeated for each symbol.

* Referring to FIGS. 8-150, an example of a CCE structure for a case where the PSCCH symbol length is 4 is shown, and 6 REGs constitute one CCE. Also, L={4, 6} is shown as a possible REG bundle size. When the PDCCH symbol length is 4, as shown in 8-151 of FIG. 8B, two CCEs may be always transmitted in a bundling structure. Therefore, AL>1 can be supported. At this time, the DMRS pattern for the PSCCH symbol length of 4 may be assumed that the patterns 8-110 of FIG. 8B are repeated for each symbol, and the DMRS is transmitted only to the first symbol and the fourth symbol, and the second symbol and the third symbol are It may be assumed that the DMRS is not transmitted. The latter method may be a method for reducing DMRS overhead.

* Referring to 8-160 of FIG. 8B, an example of the CCE structure for the case where the PSCCH symbol length is 6 is shown, and 6 REGs constitute one CCE. Also, L=6 is shown as a possible REG bundle size. At this time, the DMRS pattern for the PSCCH symbol length of 6 may be assumed to be repeated for each symbol, and the DMRS is transmitted only to the first/third/sixth symbol and the second/fourth/fifth symbol It may be assumed that the DMRS is not transmitted. The latter method may be a method for reducing DMRS overhead.

이고 심볼수가

라고 할 때, CCE for the structure of the CCE corresponding to the case where the PSCCH symbol length shown through 8-120, 8-130, 8-140, 8-150 and 8-160 of FIG. 8B is 1, 2, 3, 4, 6 Describe the -to-REG mapping. Specifically, the number of RBs in the control region (Control Resource Set, CORESET) in which the PSCCH can be transmitted

And the number of symbols

When I say,

EG들로 정의될 수 있다. 여기서 L은 REG bundle의 크기이고,

이다.* REG bundle i

It can be defined as EGs. Where L is the size of the REG bundle,

to be.

의 REG bundle들로 정의될 수 있다. 여기서

는 interleaver를 나타낸다.* CCE j is

It can be defined as REG bundles. here

Stands for interleaver.

이고

가 될 수 있다. If CCE-to-REG mapping is not interleaving

ego

Can be.

는 다음과 같이 정의 될 수 있다. In contrast, when CCE-to-REG mapping is interleaving, the PSSCH symbol length and REG bundle size L described above are

Can be defined as

[Equation 1]

는 interleaving을 random화 하기 위해서 사용되는 파라미터이다. 상기의 파라미터는 정보는 자원 풀 정보로 설정될 수 있다. 구체적으로, 전술한 자원 풀에 설정되는 정보는 다음을 포함 할 수 있다.Where R represents the interleaver size.

Is a parameter used to randomize interleaving. The above parameter information may be set as resource pool information. Specifically, information set in the aforementioned resource pool may include the following.

* PSCCH control area information

)와 심볼 수 (

)의 설정을 나타낸다.** Number of RBs in the control region in which PSCCH is transmitted (

) And the number of symbols (

).

** This may have a limitation in the setting range according to the structure of the PSCCH and the multiplexing scheme of the PSCCH and PSCCH.

*** According to the method of [Embodiment 2], the number of RBs in the control region in which the PSCCH is transmitted may be set to the size of the subchannel or smaller.

* REG bundle size

** This may determine the available REG bundle size according to the PSCCH structure. In this embodiment, the CCE structure for the case where the number of symbols in the control region is 1,2,3,4,6 is shown in 8-120, 8-130, 8-140, 8-150 and 8-160 of FIG. 8B. Accordingly, examples of available REG bundle sizes were presented. However, it is not limited to the REG bundle size presented in the present invention.

* Whether CCE-to-REG mapping is interleaving

** It can be set not to interleaving or to interleaving. In case of interleaving, refer to [Equation 1]. However, the present disclosure is not limited to the method of [Equation 1].

* Interleaver size R

로 설정될 수 있다. 하지만 본 개시에서 R로 설정할 수 있는 값이 이에 한정되는 것은 아니다.**

Can be set to However, a value that can be set as R in the present disclosure is not limited thereto.

*

의 값 중에 선택될 수 있다. 또한 해당 값은 SCS와 BW에 따라 설정 가능한 RB수의 최대값의 범위로 한정될 수도 있다. 하지만 본 개시에서

로 설정할 수 있는 값이 이에 한정되는 것은 아니다.**

It can be selected from among the values of. Also, the corresponding value may be limited to a range of the maximum value of the number of RBs that can be set according to the SCS and BW. But in this disclosure

The value that can be set to is not limited thereto.

In addition, when the terminal does not receive system information from the base station, such as OOC, the above-described parameter information may be pre-configurated as resource pool information. Here, the term pre-configuration may refer to information previously stored and set in the terminal, or may refer to information set when the terminal previously accessed the base station. Alternatively, the assumed parameter information at this time may be a predetermined value. Hereinafter, an example of information on a predetermined value will be described. The following values may be used as the pre-configuration value for the resource pool information. However, the present disclosure is not limited to setting the promised values below.

* PSCCH control area information

)와 심볼 수 (

)의 설정 값으로 TS38.213 13절에 정의된 값을 사용한다.** Number of RBs in the control region in which PSCCH is transmitted (

) And the number of symbols (

), use the value defined in TS38.213 clause 13.

* REG bundle size: can be assumed to be 6.

* Whether to interleaving CCE-to-REG mapping: It may be assumed to be interleaving.

* Interleaver size R: 2 can be assumed.

: sidelink synchronization ID로 가정될 수 있다. sidelink synchronization ID라 함은 사이드링크에서 동기를 맞출 때 사용된 ID를 의미한다.*

: Can be assumed as a sidelink synchronization ID. The sidelink synchronization ID means the ID used when synchronizing in the sidelink.

In the above-described embodiment, it has been described that configuration information for the PSCCH can be set in the resource pool. In addition, the configuration information for the PSCCH may be information set in the corresponding sidelink BWP. If a plurality of sidelink BWPs are supported to be set, the UE may transmit the PSCCH by setting corresponding information only in the active sidelink BWP. In other words, the UE may not transmit PSCCH in a BWP other than the active sidelink BWP. The PSCCH structure proposed in the above-described embodiment provides an example for performing SCI decoding while the UE performs sensing and is not limited to the above-described method.

[Example 2-2]

In [Embodiment 2-2] of the present disclosure, a method different from the method of multiplexing PSCCH and PSSCH proposed in [Embodiment 2] described above will be described. [Embodiment 2] considers a case in which the aggregation level (AL) is fixed according to the size of the subchannel through resource pool configuration, but the AL is used to implement link adaptation of the sidelink control channel. I can. Accordingly, in [Embodiment 2], the maximum value of AL is set in the resource pool setting, and an operation of adapting the actually used AL value according to channel conditions may be considered. However, if the AL is not fixed, there may be a burden for the UE to blindly decode the actually used AL. In addition, in [Embodiment 2], since the PSCCH is limited to being included in the subchannel, it may be difficult to freely set the size of the AL when the size of the subchannel set in the resource pool is small.

8C is a diagram illustrating a region in which a PSCCH is transmitted according to an embodiment of the present disclosure.

However, according to an embodiment of the present disclosure, it is not limited to a case in which the PSCCH is included in a subchannel, and as shown in FIG. 8C, a method in which a region in which the PSCCH is transmitted is determined in a resource pool configuration region is proposed. Specifically, startRB-Subchannel, sizeSubchannel, and numSubchannel, which are resource pool configuration information on frequency, are shown in 8-210 of FIG. 8C, and accordingly, a method of setting a frequency domain in which the PSCCH is transmitted in the resource pool domain is shown. Referring to 8-210 of FIG. 8C, as the subchannel position (n _{SubCHstartPSCCH} ) at which PSCCH transmission _starts and the number of subchannels through which PSCCH is transmitted (numSubCH-PSCCH) are set in the resource pool region, PSCCH can be transmitted. The frequency position at which the control region (Control Resource Set, CORESET) is transmitted may be determined. Also, referring to 8-220, 8-230, and 8-240 of FIG. 8C, different examples of the PSSCH region indicated by the PSCCH and the resource allocation for the PSSCH are determined. Specifically, referring to 8-220 of FIG. 8C, a region of a PSSCH on a frequency may include a PSCCH. Referring to 8-230 of FIG. 8C, the region of the PSSCH on the frequency may include only a part of the PSCCH. Referring to 8-240 of FIG. 8C, the region of the PSSCH on the frequency may not include the PSCCH. In contrast, in the case of the multiplexing structure of the PSCCH and PSSCH proposed in [Embodiment 2], the PSCCH may always be included in the PSSCH frequency domain.

In addition, in the case of the method in which the PSCCH and the PSSCH are multiplexed according to an embodiment of the present disclosure according to FIG. 8C, unlike the method proposed in [Embodiment 2], since the location at which the PSCCH is transmitted is not fixed, CCE for blind decoding A search space representing a set of data may be defined. Here, the search space is a set of sidelink control channel candidates consisting of CCEs that the terminal should attempt to decode on a given aggregation level, and there are various aggregation levels that make one bundle with multiple CCEs according to AL. May have a plurality of search spaces. Also, in the PSCCH, a search space set may be defined as a set of search spaces at all set aggregation levels. Specifically, the search space of the control region p in the PSCCH of the sidelink and the search space of the aggregation level L in the search space set s may be expressed as [Equation 2] below. Here, the control area p and the search space set s may be set as resource pool information.

[Equation 2]

* L: Aggregation Level (AL)

** This value can be set as resource pool information.

* n _CI : Carrier index

** When cross carrier scheduling is used, the value may be set as resource pool information. When cross carrier scheduling is not used, a corresponding value may be set to 0.

* N _CCE,p : Total number of CCEs in control area p

** If a structure in which two CCEs are always aggregated is used for the case where the PSCCH symbol length is 4 as shown in 8-150 of FIG. 8B (refer to 8-151 of FIG. 8B), the corresponding value is not the total number of CCEs. It can be defined as the total number of bundling units of two CCEs in the control region p. In other words, in this case, CCE shifting of a search space occurs in units in which two CCEs are bundling.

* n ^μ _s,f : slot index

* M ^(L) _p,s,max : Number of PSCCH candidates at aggregation level L

** This value can be set as resource pool information.

* m _snCI = 0, ..., M ^(L) _p,s,max -1: PSCCH candidate index of aggregation level L

* i = 0, ..., L-1

* For the value of Y_(p,n ^μ _s,f ), one of the following methods may be used.

** Method 1:

*** n _RNTI : In the case of Mode1 as the terminal identifier, SL-V-RNTI may be used for the dynamic grant method, and SL-SPS-V-RNTI may be used for the configured grant method. In this case, the value of Y_(p,n ^μ _s,f ) may be a value that changes according to the identity of the terminal (C-RNTI or an ID set by the base station to the terminal) and a time index. Meanwhile, in Mode2, a value of Y_(p,n ^μ _s,f ) may be 0. In addition, in the case of using pre-configurated resource pool information, a value of Y_(p,n ^μ _s,f ) may be assumed to be 0.

** Method 2: Regardless of Mode1 or Mode2, the value of Y_(p,n ^μ _s,f ) can always be 0.

When the terminal does not receive system information from the base station, such as OOC, the above-described parameter information may be pre-configurated as resource pool information. Here, the term pre-configuration may refer to information previously stored and set in the terminal, or may refer to information set when the terminal previously accessed the base station.

In addition, according to an embodiment of the present disclosure, the PSCCH and PSSCH multiplexing method is different from the PSCCH and PSSCH multiplexing structure proposed in [Embodiment 2], since the start time for the PSSCH may be different. It is necessary to additionally consider signaling that indicates. In the case of the multiplexing structure of PSCCH and PSSCH proposed in [Embodiment 2], since the location and region of the PSCCH are fixed, the region for the PSSCH may also be fixed. However, as described with reference to 8-220, 8-230, and 8-240 of FIG. 8C, according to an embodiment of the present disclosure, information on the starting position of the PSSCH because the position and region for the PSCCH may not be fixed. It is necessary to indicate through SCI. Also, as in [Embodiment 1], information on a transmission time point and frequency allocation location of initial transmission and retransmission may be included as SCI in reservation information for PSSCH resource allocation. However, in this case, unlike in [Embodiment 2], since it cannot be assumed that the starting position of the PSSCH for the current transmission starts from the subchannel assigned to the PSCCH, resources are allocated for all transmissions including initial transmission and retransmission. Additional overhead of signaling the start position for the PSSCH may occur. Specifically, in the case where SCI is transmitted through PSCCH in slot t _n allocated to the resource pool for the Look-ahead reservation scheme indicating resource allocation for retransmission up to 2 times, the slot and subchannel corresponding to PSSCH transmission are as follows: It can be determined as:

* When the time gap (SF _gap ) between initial transmission and retransmission is 0 (when retransmission is not performed), the time and frequency allocation positions for the PSSCH are as follows (8-20 of FIG. 8A).

** sub-channel(s) n _subCHstart , n _subCHstart +1,... , n _subCHstart +L _subCH -1 in slot t _n

* If the time gap (SF _gap ) between initial transmission and retransmission is not 0 (corresponding to initial transmission), the time and frequency allocation positions for the PSSCH are as follows.

** sub-channel(s) n _subCHstart , n _subCHstart +1,... , n _subCHstart +L _subCH -1 in slot t _n (8-20 in FIG. 8A)

** sub-channel(s) n _{subCHstart(RE)} , n _{subCHstart(RE)} +1,... , n _{subCHstart(RE)} +L _subCH -1 in slot t _n+SFgap (8-30 in FIG. 8A)

* If the time gap (SF _gap ) between initial transmission and retransmission is not 0 (corresponding to retransmission), the time and frequency allocation positions for PSSCH are as follows:

** sub-channel(s) n _subCHstart , n _subCHstart +1,... , n _subCHstart +L _subCH -1 in slot t _n-SFgap

** sub-channel(s) n _{subCHstart(RE)} , n _{subCHstart(RE)} +1,... , n _{subCHstart(RE)} +L _subCH -1 in slot t _n

L _subCH represents the length of the subchannel allocated to the _PSSCH , n _subCHstart and n _{subCHstart (RE)} indicate the start position of the subchannel allocated to the PSSCH for initial transmission and retransmission, and this information may be included in the SCI. In contrast, when SCI is transmitted through the PSCCH in the slot t _n allocated to the resource pool for the Chain reservation scheme indicating resource allocation for the current transmission and the next retransmission, the slot and subchannel corresponding to PSSCH transmission will be determined as follows. Can be:

* When the time gap (SF _gap ) between the current transmission and the next retransmission is 0 (when retransmission is not performed), the time and frequency allocation positions for the PSSCH are as follows (8-20)

** sub-channel(s) n _subCHstart , n _subCHstart +1,... , n _subCHstart +L _subCH -1 in slot t _n

* If the time gap (SF _gap ) between the current transmission and the next retransmission is not 0 (corresponding to the current transmission), the time and frequency allocation positions for the PSSCH are as follows

** sub-channel(s) n _subCHstart , n _subCHstart +1,... , n _subCHstart +L _subCH -1 in slot t _n (8-20 in FIG. 8A)

** sub-channel(s) n _{subCHstart(RE)} , n _{subCHstart(RE)} +1,... , n _{subCHstart(RE)} +L _subCH -1 in slot t _n+SFgap (8-30 in FIG. 8A)

* If the time gap (SF _gap ) between the current transmission and the next retransmission is not 0 (corresponding to the next retransmission), the time and frequency allocation positions for the PSSCH are as follows

** sub-channel(s) n _subCHstart , n _subCHstart +1,... , n _subCHstart +L _subCH -1 in slot t _n-SFgap

** sub-channel(s) n _{subCHstart(RE)} , n _{subCHstart(RE)} +1,... , n _{subCHstart(RE)} +L _subCH -1 in slot t _n and

L _subCH represents the length of the subchannel allocated to the _PSSCH , n _subCHstart and n _{subCHstart (RE)} indicate the start position of the subchannel allocated to the PSSCH for initial transmission and retransmission, and this information may be included in the SCI. The difference in bit field interpretation according to the look-ahead reservation or chain reservation scheme is that the reservation scheme is different according to the maximum number of retransmissions as described above through [Example 1], and the bit field interpretation is different in the SCI signal for this. It could be an example.

According to the aforementioned method of transmitting PSCCH in the NR sidelink, the UE can monitor the PSCCH region from information set in the resource pool. In addition, it is possible to determine the resource allocation information of the PSSCH by decoding the SCI transmitted through the PSCCH. The PSCCH structure and PSCCH monitoring method in the NR sidelink proposed in the above-described embodiment provides an example for performing SCI decoding in the process of the UE performing sensing, and is not limited to the above-described method.

[Example 3]

In [Embodiment 3] of the present disclosure, a detailed operation of the UE performing sensing and selecting a transmission resource in Mode 2 will be described. First, sensing may be defined as an operation in which a transmitting terminal performs Sidelink Control Information (SCI) decoding for another terminal and an operation in which sidelink measurement is performed. The operation of performing SCI decoding on another terminal may include an operation of obtaining SCI information of another terminal after successfully decoding the SCI. Sidelink measurement is to determine whether another terminal occupies the time and frequency resources that the transmitting terminal intends to transmit, and for this purpose, the following measurement methods may be considered in the sidelink.

* PSCCH RSRP (Reference Signal Received Power): The average reception power (in [W]) for the DMRS included in the PSCCH can be measured.

* PSSCH RSRP (Reference Signal Received Power): The average reception power (in [W]) for the DMRS included in the PSSCH can be measured.

* SL RSSI (Sidelink Received Signal Strength Indicatior): Average reception power (in [W]) can be measured. The area for measuring the received power may be variously defined. For example, it may be defined as the average reception power of OFDM symbols in which the PSSCH is transmitted. It may also be defined as an average reception power in a specific OFDM symbol region in which the PSSCH is transmitted. In addition, it may be defined as the average reception power of OFDM symbols in a specific region of a slot other than the PSSCH transmission region. It may also be an average reception power in a time interval smaller than the OFDM symbol. Accordingly, the SL RSSI may be the average reception power in the time/frequency domain defined according to the purpose of use.

The UE can measure the PSCCH RSRP by monitoring the PSCCH region. The UE may perform SCI decoding and determine PSSCH information connected thereto from SCI information to measure PSSCH RSRP or SL RSSI. PSCCH RSRP or PSSCH RSRP may be referred to as SL RSRP. Transmission resource selection may be defined as an operation of determining resources for sidelink transmission using a sensing result. In addition, a process of reselecting transmission resources may be performed according to the state of the sidelink.

In the present disclosure, a Sensing window A and a Sensing window B are defined to effectively perform sensing in a situation in which periodic and aperiodic traffic coexist.

9 is a diagram illustrating a setting of a sensing window for a Mode 2 operation of a sidelink according to an embodiment of the present disclosure.

Referring to FIG. 9, the sensing section is divided into Sensing window A (9-02) and Sensing window B (9-08), but these are Sensing window A (9-02) and Sensing window B (9-08). Does not mean that is always used separately. As in the following embodiment, only one of Sensing window A (9-02) and Sensing window B (9-08) can be set and used, and both Sensing window A (9-02) and Sensing window B (9-08) are set. It can also be used. When only one of the Sensing window A (9-02) and the Sensing window B (9-08) is set and used, the Sensing window A (9-02) or the Sensing window B (9-08) may be referred to as a Sensing window. When both Sensing window A (9-02) and Sensing window B (9-08) are set and used, Sensing window A (9-02) and Sensing window B (9-08) may be referred to as one Sensing window. have. When data to be transmitted is generated, the terminal performs sensing during a set sensing window period and may select a transmission resource based on the result.

As shown in FIG. 9, when triggering for selecting a transmission resource occurs in slot n (9-01), the Sensing window A (9-02) may be defined as follows.

* Sensing window A(9-02) can be defined as a slot section of [n-T0, n-1]. Here, T0 may be a fixed value or a settable value.

** As an example of the case where T0 is determined to be a fixed value, it may be expressed as T0=1000*2 ^μ for periodic traffic. Alternatively, a fixed value of T0 = 100 * 2 ^μ may be set for aperiodic traffic. As such, the fixed T0 value may be changed to a different value according to the traffic characteristics to be considered. Unlike this, the fixed T0 value may be fixed to the same value for periodic and aperiodic traffic. Here, μ is an index corresponding to numerology and may be set to the following values according to SCS (Subcarrier Spacing).

*** SCS=15kHz, μ=0

*** SCS=30kHz, μ=1

*** SCS=60kHz, μ=2

*** SCS=120kHz, μ=3

** For a case where T0 is determined to be configurable, the configuration may be indicated through SL SIB (Sidelink System Information Block) or UE-specific higher level signaling. When indicated through SL SIB, a corresponding value may be set in resource pool information among corresponding system information. The information for allocating a resource pool may consist of many parameters, and a value corresponding to T0 may be included among them. If T0 is set in the resource pool information, it means that a constant T0 is always used in the resource pool.

** When T0 is set, the UE _monitors the slots (t _n'-T0 , t _n'-T0+1 ,..., t _n'-1 ) excluding the slot in which _sidelink transmission occurs. Here, if slot n is included in the set of slots belonging to the PSSCH resource pool (t ₀ ,t ₁ ,...,t _i ,...,tT _max ), t _n' = n, otherwise slot t _{n 'is} the first slot in the slot after the n belongs to the set of _{(t 0, t 1, ...} , t, ..., tT max) of the slots belong to the resource pool PSSCH.

* SCI decoding and sidelink measurement for other terminals may be performed in the sensing window A (9-02). In this case, the sensing operation may be performed in units of slots.

** Resource allocation information for other terminals and QoS information for packets may be obtained from SCI information obtained after successfully decoding the SCI in the sensing window A (9-02). The resource allocation information may be information on a transmission time point and frequency allocation position of initial transmission and retransmission. The NR sidelink defines a PQI (PC5 5G QoS Indicator) for QoS, and the PQI may include a default priority level, a packet delay budget, a packet error rate, a default maximum date burst volume, and a default averaging window. Therefore, a value defined in PQI may be included in SCI. For example, priority information may be information included in SCI for QoS. Also, when distance information is included in the SCI, location information for another terminal may be obtained from the received SCI. The TX-RX distance can be calculated from the location information of the receiving terminal and the location information of the transmitting terminal. Distance information included in SCI may be a Zone ID.

** PSSCH RSRP may be measured from SCI information obtained after successfully decoding SCI within the sensing window A (9-02). As another method, PSCCH RSRP for PSCCH including SCI may be measured.

*** The PSSCH RSRP and PSCCH RSRP may be used as a metric for determining whether to exclude a resource that is determined to be ineffective due to occupied by another terminal within the Resource selection window. At this time, it may be determined whether or not to exclude resources based on whether the PSSCH RSRP and PSCCH RSRP exceed the (pre-)configuration threshold. When the PSSCH RSRP and PSCCH RSRP exceed the threshold, the corresponding resource may be excluded from the resource candidate. In this case, the (pre-)configuration threshold may be a value determined according to a priority of the terminal and a channel busy ratio (CBR) value.

** SL RSSI can be measured within the sensing window A (9-02). Here, the SL RSSI can be observed by valid OFDM symbol positions in a slot in which the PSSCH can be transmitted and a set subchannel.

*** SL RSSI may be used for the purpose of ordering and sorting resource candidates that can be allocated resources within the Resource selection window (9-03).

It is not effective to identify resource allocation information of other terminals through SCI decoding in Sensing Window A (9-02) and allocate transmission resources to resources to be used by other terminals by using sidelink measurement results such as SL RSRP or SL RSSI. If determined, the resource may be excluded from the Resource selection window (9-03).

As shown in FIG. 9, when triggering for selecting a transmission resource occurs in slot n (9-01), the Resource selection window (9-03) may be defined as follows.

* Resource selection window (9-03) may be defined as a slot section of [n+T1, n+T2]. Here, T1 and T2 may be fixed values or may be settable values. Alternatively, T1 and T2 are determined in a fixed range, and the UE may set an appropriate value within the fixed range in consideration of implementation.

** For example, when T1 and T2 are determined as a fixed range and the terminal sets an appropriate value within a fixed range considering implementation, 0≤T1≤4*2 ^μ and 20*2 ^μ ≤T2≤100*2 ^μ It can be set by the terminal implementation in the range. Where μ is the index corresponding to numerology.

** The section of the resource selection window (9-03) may be set in consideration of the maximum number of retransmissions. For example, when the maximum number of retransmissions is 4 compared to the case where the maximum number of retransmissions is 2, the section of the Resource selection window needs to be selected longer to select a corresponding resource.

* In the Resource selection window (9-03), one resource candidate for PSSCH transmission can be defined as Rx,y (9-06). A resource pool on time and frequency used for transmission and reception of a sidelink has been described with reference to FIG. 3. Rx,y(9-06) represents one resource candidate composed of consecutive subchannels of x+j in a subchannel region set as a resource pool for slot ty(9-04) belonging to the resource pool. Where j=0,... ,LsubCH-1, LsubCH (9-05) is a subchannel length for resource allocation, and may be selected within a resource allocation range that is down as system information. The number of all resource candidates in the Resource selection window (9-03) can be determined as M. Resource candidates judged that it is not effective to allocate PSSCH transmission resources in S _A using the sensing result may be excluded, and X (≦M) of resource candidates for which resource allocation is possible may be left.

* The final transmission resource (9-07) may be selected in the Resource selection window (9-03) by using the sensing result performed in the Sensing window A (9-02) and the Sensing window B (9-08). In this case, the final transmission resource may be selected in consideration of only the initial transmission and may be selected in consideration of both initial transmission and retransmission. For details on this, refer to the following examples.

Next, as shown in FIG. 9, when triggering for selecting a transmission resource occurs in slot n (9-01), Sensing window B (9-08) may be defined as follows.

* Sensing window B(9-08) may be defined as a slot section of [n+T1', n+T2']. Here, T1' and T2' may be fixed values or settable values. In contrast, T1' and T2' are determined in a fixed range, and the UE may set an appropriate value within the fixed range in consideration of implementation. And when k indicates that the resource is the last selected slot, the sensing window B (9-08) may be stopped in the slot k. Therefore, the final Sensing window B(9-08) becomes [n+T1', k].

** T1' and T2' may be set to be the same as the values of T1 and T2 of the Resource selection window (9-03), respectively, or may be set to different values.

** For example, when T1'=0 is set, it means that sensing is performed from triggering slot n for selecting a transmission resource.

** Sensing window B (9-08) may be set to one slot or one or more slots by the set values of T1' and T2'.

* Sensing in the sensing window B (9-08) may be operated by one or a combination of one or more of the methods to be described later. For details, refer to [Embodiment 4].

** Sidelink measurement such as Listen Before Talk (LBT) may be performed in the sensing window B (9-08). The LBT can determine whether the current resource is idle (when not occupied by another terminal) or busy (when occupied by another terminal) through energy detection. Here, the LBT is only an example, and is not limited thereto, and other methods may be used as long as it is a sidelink measurement method. Therefore, in the following embodiments, the term LBT is not separately used. As described above, sensing in the sensing window B (9-08) may be interpreted as an operation of additionally sensing aperiodic traffic that cannot be predicted in the sensing window A (9-02). Specifically, the method can be classified as follows according to the setting of the time unit and location at which energy detection is performed in the sensing window B (9-08).

*** The first method is when energy detection is performed in units of slots.

*** The second method is when energy detection is performed in units of symbols.

*** The third method is when energy detection is performed in a time unit smaller than a symbol.

** Similar to the sensing operation defined in Sensing window B (9-02) in Sensing window B (9-08), SCI decoding and Sidelink measurement for other terminals are performed within the Resource selection window (9-03). Resources occupied by other terminals and determined to be ineffective for use may be additionally excluded.

As described above, the Sensing window A (9-02) and the Sensing window B (9-08) may be classified based on a time when triggering for selecting a transmission resource comes down. In more detail, a sensing period previously set based on a triggering slot n for selecting a transmission resource may be defined as a sensing window A (9-02), and a sensing period set later as a sensing window B (9-08). Sensing window A (9-02) can be interpreted for long-term sensing and Sensing window B (9-08) can be interpreted for the purpose of short-term sensing. Here, Sensing window A (9-02) and Sensing window B (9-08) may be referred to as different terms. In addition, only one of Sensing window A (9-02) and Sensing window B (9-08) may be used, or both Sensing window A (9-02) and Sensing window B (9-08) may be used. It can also be operated so that the method of using the sensing window can be set. For example, the base station can set this. Specifically, it is connected to a resource pool, so that how to use the sensing window for each resource pool (pre-)configuration can be made. For example, you can set methods in which only Sensing window A is used, only Sensing window B is used, or both Sensing window A and Sensing window B are used. When corresponding information is set in a resource pool, all terminals in the corresponding pool may be able to operate using the same Sensing window setting. Information related to the configuration of the sensing window may be indicated through SL SIB (Sidelink System Information Block) or UE-specific higher level signaling. When information related to the setting of the sensing window is indicated through the SL SIB, a corresponding value may be set in the resource pool information among corresponding system information. When it is set through an upper layer, it can indicate which Sensing window is set with Uu-RRC or PC5-RRC.

In the above-described sidelink, the sensing of Mode 2 and the operation of selecting a transmission resource may be implemented in various ways. For example, when Sensing window A (9-02) and Sensing window B (9-08) are set at the same time, the terminal always performs sensing for Sensing window A (9-02) and then selects a transmission resource. When triggering to occur in slot n, a final transmission resource can be selected by performing sensing for the sensing window B (9-08). However, the operation in which the terminal always senses the sensing window A (9-02) can use the sensing result of the sensing window A (9-02) at any time, so there is an advantage in terms of latency when selecting a transmission resource. However, it may be a disadvantage in terms of terminal energy consumption. Therefore, as another method, when the traffic to be transmitted occurs, the terminal immediately performs sensing on the sensing window A (9-02) and triggering to select the transmission resource occurs in slot n, and then the sensing window B (9-08). The final transmission resource can be selected by sensing for. The latter method has the advantage of minimizing the energy consumption of the terminal by performing sensing only when necessary, but it can be a disadvantage in terms of latency for selecting a transmission resource.

[Example 4]

In [Embodiment 4] of the present disclosure, various methods of performing sensing in the sensing window B (9-08) will be described in detail. As described above through [Embodiment 3], the Sensing window A (9-02) and the Sensing window B (9-08) may be classified based on the time when triggering for selecting a transmission resource comes down, and the Sensing window A ( 9-02) and Sensing window B (9-08) can be considered, or both Sensing window A (9-02) and Sensing window B (9-08) can be considered. Through [Example 3], in the sensing window B (9-08), energy detection may be performed for the purpose of additionally sensing unpredictable aperiodic traffic in the sensing window A (9-02). It has been explained that there are three methods depending on the time unit and location setting. If only the sensing window B (9-08) is set and used, it can be interpreted as an operation of simultaneously sensing periodic and aperiodic traffic. Through energy detection, it is possible to determine whether the current resource is idle (when not occupied by another terminal) or busy (when occupied by another terminal). Specifically, when the energy detection result exceeds the (pre-)configuration threshold value, it may be determined as busy, and when the energy detection result does not exceed the threshold value, it may be determined as idle. In addition, similar to the sensing operation defined in Sensing window A (9-02) in Sensing window B (9-08), SCI decoding and Sidelink measurement for other terminals are performed to perform the Resource selection window (9-03). ), a resource occupied by another terminal and determined to be ineffective in use may be additionally excluded. In contrast, similar to the sensing operation defined in Sensing window A (9-02) in Sensing window B, SCI decoding and Sidelink measurement for other terminals are performed to select a resource, and the Resource selection window (9-03). ) May be defined as an operation of additionally exclusion of resources that are occupied by other terminals and are determined to be ineffective. Therefore, when operating together with Sensing window A, it may not be necessary to set Sensing window A and Sensing window B separately. The operation in the sensing window A may be interpreted as an operation that continues even after the time when triggering for selecting a transmission resource comes down. However, in the sensing window B section, SCI decoding and sidelink measurement are not performed for the resource candidates that are excluded from the sensing result in the sensing window A, and sidelink measurement is not performed on the resource candidate in the sensing window B area. ) Is limited to the case of being performed in one slot unit. Therefore, it may correspond to a case where the energy detection interval X=1 is fixed and set in Method 1 of the three methods in which energy detection is performed below. Hereinafter, three methods according to a time unit and a location in which energy detection is performed will be described in more detail. In the above-described [Embodiment 3], it has been proposed that the method of using the sensing window can be operated to be settable. In addition, one of the various sensing methods in the sensing window B described below may be selected and operated, but one or more of the various sensing methods in the sensing window B may be operated to be settable. For example, the base station can set this. Specifically, it is connected to the resource pool, and the sensing method in the sensing window B for each resource pool may be (pre-)configurated. When the corresponding information is set in the resource pool, all terminals in the corresponding pool may be able to operate with the sensing method in the same sensing window B. Information related to the sensing method configuration in the sensing window B may be indicated through SL SIB (Sidelink System Information Block) or UE-specific upper signaling. When information related to the sensing method setting in the sensing window B is indicated through the SL SIB, a corresponding value may be set in the resource pool information among corresponding system information. When it is set through an upper layer, it is possible to indicate which sensing method is set in the sensing window B with Uu-RRC or PC5-RRC.

10A is a diagram for explaining a method of performing energy detection according to an embodiment of the present disclosure.

Method 1 is a case where energy detection is performed in units of slots. In Method 1, a slot interval for energy detection may be determined within [0 X]. Here, when '0' is set, it means that energy detection is not performed, and in this case, it may be determined that sensing is not performed. When X=1, it means that energy detection is performed in units of one slot. Here, X means the number of slots in the resource pool, not the number of physical slots. The value of X is a fixed value or it can be set and operated. If the value of X is configurable, the value of X can be set by connecting to the resource pool. When the value of X is set in the resource pool, UEs in the same resource pool perform energy detection in the same X slot interval. Alternatively, terminals in the resource pool may be supported to select the value of X. At this time, it is possible to allow the terminals to randomly select the value of X within the maximum value that can be set as X, and a method of concatenating the value of X with the priority value for packet transmission of the terminal so that the value of X is selected may be considered. have. Specifically, it is possible to support faster transmission by setting a higher priority to have a shorter X value. A method of allowing terminals to select different values of X may have an effect of reducing a probability of occurrence of packet collision. In Method 1, when the UE performs energy detection in a slot interval of X and it is determined that the corresponding resource is currently idle, resource transmission may be performed in the next slot belonging to the resource pool.

Hereinafter, Method 1 will be described in more detail with reference to FIG. 10A. First, consider a case in which sensing is performed using only the sensing window B (10A-2). When only the sensing window B (10A-2) is used without the sensing window A (9-02), sensing can be performed without the resources excluded from the resource selection window (10A-1) through sensing in the sensing window A. . Referring to FIG. 10A, when Method 1 is used, a slot period 10A-4 for energy detection may be set. In FIG. 10A, the section [n+T1, n+T2]=[n+1, n+6] of the resource selection window 10A-1 and the section [n+T1', n] of the sensing window B(10A-2) A case where +T2'] = [n+1, n+6] is set equally is shown. In FIG. 10A, an example in which the slot interval for energy detection is set to X=2 is shown (10A-4). As described above, since X means the number of slots belonging to the resource pool, not the number of physical slots, 10A-9 and 10A-10 in FIG. 10A are slot intervals in which energy detection is performed by X=2. As described above through [Embodiment 3], Rx,y(10A-3) selects one resource candidate composed of consecutive subchannels of x+j in the subchannel region set as the resource pool for slot ty belonging to the resource pool. Show. Where j=0,... Rx,y(10A-3) as ,LsubCH-1 is an example of a case where LsubCH=2, and in fact, LsubCH is a subchannel length for resource allocation and may be selected within a resource allocation range descending as system information. In FIG. 10A, the number of all resource candidates in slots 10A-9 and 10A-10 belonging to the first slot interval for energy detection may be determined as N by X=2. The UE may determine which resource candidate is suitable for transmission by performing energy detection on N resource candidates. At this time, for energy detection, the UE measures SL RSSI for each resource candidate to determine whether the corresponding value exceeds the (pre-)configuration threshold value. In this case, SL RSSI values for all resource candidates may be sequentially ordered. In Method 1, the SL RSSI may be defined as the average reception power measured in the frequency domain of the corresponding resource candidate for all OFDM symbols in the PSSCH region in the slot belonging to the resource pool. In addition, the (pre-)configuration threshold may be a value determined according to a priority of the terminal and a channel busy ratio (CBR) value. If the slot interval X is greater than 1, there may be a method of determining idle resources with one shot or a method of determining idle resources using a contention method. Referring to FIG. 10A, a method of determining an idle resource with one shot is a method of selecting a resource determined to be the most idle among all corresponding resource candidates in a slot interval X for energy detection. Through this, when the idle resource is selected (10A-7), the transmission resource 10A-8 in the same frequency domain as 10A-7 in the next slot belonging to the resource pool may be selected. In contrast, in the method of determining idle resources by the contention method, referring to FIG. 10A, resources determined to be the most idle in slots 10A-9 and 10A-10 belonging to the first slot interval for energy detection by X=2. It is determined that the corresponding time/frequency domain is idle only when the resource is in the same frequency domain, and the same frequency domain may be selected as a transmission resource in a next slot belonging to the resource pool. If X=1 is set, only the method of determining idle resources with one shot can be used. When a resource to perform transmission is selected as shown in 10A-8, the sensing window B (10A-2) is stopped in the 10A-11 slot. If it is determined that all resources are busy in the slot period in which energy detection has been performed, a method of performing back-off within the resource selection window 10A-1 may be considered. Back-off may be defined as an operation in which the UE recognizes idle resources through sensing during an energy detection slot period of length X again and selects a resource to be transmitted again. When performing back-off, X may be the same value as before. If the terminal randomly selects X, when performing back-off, the X value may be randomly reselected. If the UE continues sensing and no idle transmission resources are found during the last energy detection slot interval before the end of the resource selection window 10A-1, the SL RSSI is a result of energy detection of all resource candidates in the last energy detection slot interval. By selecting the lowest resource candidate, the same frequency domain of the next slot belonging to the resource pool may be selected as the transmission resource. For example, in FIG. 10A, when it is determined that all resources are busy in the slot period for energy detection of 10A-4, energy detection may be performed by moving to the next slot 10A-11 belonging to the resource pool. As shown in FIG. 10A, the last energy detection slot period before the end of the resource selection window 10A-1 is the previous energy according to the setting period of the resource selection window 10A-1, the energy detection slot period set as X, and the slot set as the resource pool. It may not be able to maintain the same size as the detection slot interval. As shown in FIG. 10A, when it is determined that all resources are busy in the slot period for energy detection of 10A-4, the next slot 10A-11 belonging to the resource pool is the last energy detection slot before the end of the resource selection window 10A-1. Since it is a period, when all resource candidates in the slots 10A-11 are busy, the same frequency domain of the next slot in the resource pool may be selected as a transmission resource by selecting a resource candidate having the lowest SL RSSI.

Method 2 is a case where energy detection is performed in units of symbols. In Method 2, the symbol interval for energy detection may be determined in the PSSCH symbol region [0 Y] of a slot belonging to the resource pool. Here, when '0' is set, it means that energy detection is not performed, and in this case, it may be determined that sensing is not performed. When Y=4, it means that energy detection is performed in a symbol interval from the first symbol to the fourth symbol of the PSSCH region of the slot. Therefore, the maximum value that can be set as Y may be determined by the number of OFDM symbols occupied by the PSSCH. Here, the value of Y may be a fixed value or it may be operated by enabling it to be set. If Y is fixed to the maximum number of OFDM symbols occupied by the PSSCH, it is the same as the case where the slot interval X for energy detection is fixed to 1 in Method 1. When the value of Y is configurable, the value of Y can be set by being connected to a resource pool. When a corresponding value is set in the resource pool, UEs in the same resource pool may perform energy detection in the same Y symbol interval. Alternatively, terminals in the resource pool may be supported to select the value of Y. At this time, it is possible to allow the terminals to randomly select the value of Y within the maximum value that can be set to Y, and a method of concatenating the value of Y with the priority value for packet transmission of the terminal to select the Y value may be considered. . Specifically, it is possible to support faster transmission by setting a higher priority to have a shorter Y value. A method of allowing terminals to select different values of Y may have an effect of reducing a probability of occurrence of packet collision. In Method 2, when the UE performs energy detection in the symbol interval of Y and it is determined that the corresponding resource is currently idle, resource transmission may be performed in the remaining PSSCH symbol interval of the current slot or in the next slot belonging to the resource pool. When resource transmission is performed in the remaining PSSCH symbol period of the current slot, it may be supported only when it is allowed to start PSSCH transmission at an arbitrary position in the PSSCH region of the slot.

Method 3 is a case where energy detection is performed in a time unit smaller than a symbol. In Method 3, an interval for energy detection may be determined within [0 Z]. Here, when '0' is set, it means that energy detection is not performed, and in this case, it may be determined that sensing is not performed. Z is the time interval set for energy detection. For example, it is possible to perform energy detection in a short time unit such as 16 μsec or 4 μsec. OFDM symbol length (T) according to subcarrier spacing (SCS) is as follows.

* SCS=15kHz, T=66.67μsec

* SCS=30kHz, T=33.33μsec

* SCS=60kHz, T=16.67μsec

* SCS=120kHz, T=8.33μsec

Therefore, the energy detection interval of 16 μsec is included in a time unit smaller than the symbol except for SCS=120 kHz, and the energy detection interval of 4 μsec may be included in a time unit smaller than the symbol in all SCSs. Method 3 will be described in more detail through FIG. 10A. First, consider a case in which sensing is performed using only the sensing window B (10A-2). When only the sensing window B (10A-2) is used without the sensing window A, sensing can be performed without the resources excluded from the resource selection window (10A-1) through sensing in the sensing window A. Referring to FIG. 10A, when Method 3 is used, an interval Z for energy detection may be set (10A-6). In FIG. 10A, the section [n+T1, n+T2]=[n+1, n+6] of the resource selection window 10A-1 and the section [n+T1', n] of the sensing window B(10A-2) A case where +T2']=[n+1, n+6] is set equally is shown. An example of a section for energy detection in FIG. 10A is shown in 10A-6. In 10A-6, it is shown that a partial region in the first symbol of slot 10A-9 can be used as an energy detection interval. However, it is not limited to the region corresponding to the start position of the slot as shown in 10A-6, and examples of various time regions in which Method 3 can be utilized will be described with reference to FIG. 10B. As described above through [Embodiment 3], Rx,y(10A-3) selects one resource candidate composed of consecutive subchannels of x+j in the subchannel region set as the resource pool for slot ty belonging to the resource pool. Can be indicated. Where j=0,... ,LsubCH-1, 10A-3 is an example of a case where LsubCH=2, and in fact, LsubCH is a subchannel length for resource allocation, and may be selected within a resource allocation range descending as system information. Referring to FIG. 10A, the number of all resource candidates in a slot 10A-9 to which a period Z set as an energy detection period belongs may be determined as N. The UE may determine which resource candidate is suitable for transmission by performing energy detection on N resource candidates. In this case, energy detection may determine whether the corresponding value exceeds the (pre-)configuration threshold value by measuring the SL RSSI for each resource candidate. In this case, SL RSSI values for all resource candidates may be sequentially ordered. In Method 3, the SL RSSI may be defined as the first predetermined time period in a specific area in the slot and the average reception power measured in the frequency domain of the corresponding resource candidate. In this case, the energy detection interval may be performed in a time unit smaller than a symbol. As in Method 3, when performed in a time unit Z smaller than a symbol, energy detection may be performed in the time domain. Energy detection for Method 1, Method 2, or Method 3 may be performed in both time and frequency domains, and is not limited to energy detection in a specific domain of the present disclosure. In addition, the (pre-)configuration threshold may be a value determined according to a priority of the terminal and a Channel Busy Ratio (CBR) value. Referring to FIG. 10A, energy detection is the same frequency as 10A-14 in the slot 10A-9 when the idle resource is selected as a result of energy detection measured in the time period Z (10A-6). The transmission resource 10A-15 of the region may be selected. As described above, Method 3 has an advantage of being able to select a transmission resource directly from a slot in which energy detection has been performed. Even in Method 2, if the symbol length for energy detection is fixed and set in a specific region other than a region in which the PSSCH is transmitted, it may be possible to select a transmission resource directly from the slot in which energy detection is performed. When a resource to perform transmission is selected as shown in 10A-15, sensing window B (10A-2) may be stopped in slot 10A-9. If it is determined that all resources are busy in the time interval Z in which energy detection is performed, a method of performing back-off within the resource selection window 10A-1 may be considered. Back-off may be defined as an operation of reselecting a resource to be transmitted by recognizing idle resources through sensing during an energy detection period of length Z at a predetermined location of the next slot belonging to the resource pool. When performing back-off, Z may be the same value as before. If the terminal randomly selects Z, the Z value may be randomly reselected when performing back-off. In FIG. 10B below, it will be described that the Z value may be differently selected through setting of an offset value. If the UE continues sensing and no idle transmission resources are found during the last energy detection interval before the end of the resource selection window 10A-1, the result of energy detection of all resource candidates in the slot to which the last energy detection interval belongs SL By selecting a resource candidate having the lowest RSSI, the same frequency domain of the corresponding slot may be selected as a transmission resource. For example, in the case of using Method 3, in FIG. 10A, 10A-16 becomes a slot in which the last energy detection interval is located before the end of the resource selection window 10A-1. As a result of energy detection, when it is determined that all resources in this slot are busy, a resource candidate having the lowest SL RSSI may be selected and the same frequency domain may be selected as a transmission resource in the corresponding slot.

Next, there is a method in which energy detection is performed in a specific area within the slot. In this way, the above-described energy detection method 3 may be used. In addition, this method can be used even when the region in which energy detection is performed in Method 2 is applied not in the PSSCH region but in another specific region in the slot with a fixed symbol length.

10B illustrates a method in which energy detection is performed in a specific area within a slot according to an embodiment of the present disclosure.

Referring to FIG. 10B, the last symbol 10B-1 of the previous slot of the slot to be transmitted and the previous symbol 10B-2 of the slot to be transmitted are illustrated. In the sidelink, the last symbol area of a slot can be used as an area for GP (Guard Period) and AGC (Automatic Gain Control). Also, the first symbol area of the slot may be used as a symbol area for AGC. In 10B-1 and 10B-2, a corresponding region is illustrated as one OFDM symbol, but the present disclosure is not limited thereto. Two symbols or more symbol regions may be used to perform the purpose of the AGC in the NR sidelink. In the present disclosure, the AGC region may be used to perform sensing in the sensing window B. When the AGC area is located in the last area of the slot as in 10B-1, the terminal transmits a preamble in the AGC area of the previous slot for data transmission, or when the AGC area is located in the first area of the slot as in 10B-2. The UE may transmit the preamble in the AGC region of the current slot in which data is transmitted. At this time, the UE may determine whether a corresponding slot to be attempted transmission is idle or busy by performing energy detection on the preamble transmitted in the AGC region. Specifically, when the energy detection result exceeds the (pre-)configuration threshold value, it may be determined as busy, and when the energy detection result does not exceed the threshold value, it may be determined as idle. Various methods of performing sensing in the AGC region will be described through 10B-3, 10B-4, and 10B-5. In 10B-3, 10B-4, and 10B-5, it is shown that the AGC area may be composed of one or more symbols. In addition, according to 10B-3, 10B-4, and 10B-5, the UE may perform energy detection in slots and frequency resource locations to perform sensing within a sensing window. In 10B-3, 10B-4, and 10B-5, the portion indicated by the sensing area 10B-6 is an AGC section connected to the slot to which the resource candidate corresponding to Rx,y (10A-3) in FIG. 10A belongs. Can represent some of the. For example, when the AGC is transmitted in the first region of the slot, it may correspond to a portion corresponding to 10A-6 of FIG. 10A. First, in the method of 10B-3, all areas set as the AGC area can be used as a sensing section. A terminal performing sensing may only perform energy detection without transmitting a preamble in the AGC region. However, the method of 10B-3 has a problem in that when one or more terminals transmit a preamble in a corresponding section, all sensing terminals may determine that the corresponding slot is busy. Therefore, in order to solve this, the methods of FIGS. 10B-4 and 10B-5 can be used. The methods of 10B-4 and 10B-5 are a method of supporting differently setting the start position at which the AGC preamble 10B-7 is transmitted for each terminal. Compared with 10B-4, the start position at which the preamble 10B-7 is transmitted in 10B-5 may be further behind. The terminal may perform energy detection in a time interval prior to the start position where the preamble is transmitted. In the case of using the methods of 10B-4 and 10B-5, the offset value for the preamble transmission start position may be indicated to the terminal. Candidate values that can be set as the corresponding offset value may be preset through an upper layer such as RRC, and the terminal may randomly select one of the set offset candidate values. Alternatively, a method of selecting an offset value in connection with a priority value for packet transmission of the terminal may be considered. Specifically, it is possible to support faster transmission by setting a higher priority to have a shorter offset value. In addition, as an example of a possible method, when a plurality of candidate values for offset values are set from low to high values, it is possible to place restrictions on candidate values for offsets that can be selected according to priority. Therefore, when the pritority is high, it can be limited to select randomly among low offset values, and when the pritority is low, it can be limited to select randomly among high offset values. As an example of another method, a method of setting an additional offset value according to priority so that an additional offset value is added to the offset value for the start position of the preamble may be considered. Here, an additional offset value according to the priority may also be determined as a preset fixed value, and may be adjusted so as not to exceed the set preamble transmission period.

In FIGS. 10A and 10B, only the case of sensing using only the sensing window B is considered. When only the sensing window B is used without the sensing window A, sensing can be performed without the resources excluded from the resource selection window through sensing in the sensing window A. However, when Sensing window A and Sensing window B are used at the same time, and when SCI decoding and sidelink measurement are performed in Sensing window B, resources that are occupied by other terminals within the Resource selection window are considered to be ineffective. In the case of performing an additional exclusion operation, the sensing operation and the operation of selecting the final transmission resource may be different. Hereinafter, a sensing operation in this case will be described with reference to FIGS. 10C and 10D.

10C is a diagram illustrating a case in which all resource candidates left in the Resource selection window as a result of the Sensing window A according to an embodiment of the present disclosure are used in the Sensing window B. In contrast, in FIG. 10D, when a method of reporting the resource candidate left in the Resource selection window as a result of the Sensing window A to the upper level of the terminal and selecting the transmission resource candidate from the upper level of the terminal is used, the resource candidates that can be selected in the sensing window B are limited. The problem is shown.

Referring to FIG. 10C, first, the resource candidates left in the resource selection window 10C-1 as a result of sensing in the sensing window A may be used in the sensing window B 10C-2 as it is. 10C-7 may be a resource that is excluded from the sensing result in the sensing window A. In this case, an operation such as down-selecting a resource candidate left in the Resource selection window 10C-1 again at an upper level of the terminal or selecting a final transmission resource candidate may be excluded. 10C is an additional resource that is determined to be ineffective because other terminals occupy the resource selection window 10C-1 by performing SCI decoding and sidelink measurement in the sensing window B (10C-2). The same may be considered when performing the exclusion operation 10C-7. For example, the UE performs SCI decoding in the Sensing window B (10C-2) and identifies information on whether another UE is reserving a resource in the Resource selection window (10C-1), and determines the corresponding resource according to the sidelink measurement result. It can be excluded from resource candidates in the Resource selection window (10C-1). In FIG. 10C, a resource region that is not usable for resource selection in the Resource selection window 10C-1 because the resource exclusion operation is performed as described above is shown through 10C-7. Therefore, when sensing and resource selection in the sensing window B (10C-2), sensing is not performed in a resource region that is not available for resource selection such as 10C-7, and the corresponding resource region cannot be selected as a transmission resource. Even in this case, as shown in FIG. 10C, as a method of setting a section for energy detection in the sensing window B (10C-2), the aforementioned method 1 (10C-4), method 2 (10C-5), and method All 3(10C-6) can be used. In FIG. 10C, the section [n+T1, n+T2]=[n+1, n+6] of the Resource selection window (10C-1) and the section [n+T1', n] of the Sensing window B(10C-2) A case where +T2'] = [n+1, n+6] is set equally is shown. In FIG. 10C, when Method 1 is used, unlike in FIG. 10A, an example in which a slot interval for energy detection is set to X=1 is shown (10C-4). As described above, X means the number of slots belonging to the resource pool, not the number of physical slots. Here, X=1 is fixed and used, SCI decoding and Sidelink measurement are performed in Sensing window B along with Sensing window A, so that other terminals occupy it within the Resource selection window (10C-1), and the use will not be effective. In the case of performing the operation of additionally exclusion of the determined resource, it is not necessary to distinguish between the sensing window A and the sensing window B as described above, and the operation in the sensing window A is performed even after the triggering for selecting the transmission resource comes down. It can last. A resource candidate that is not usable in 10C-7 may be a resource that is excluded from the sensing result in the Sensing window A or the Sensing window B. As described through [Embodiment 3], Rx,y(10C-3) represents one resource candidate consisting of consecutive subchannels of x+j in a subchannel region set as a resource pool for slot ty belonging to the resource pool. . Where j=0,... ,LsubCH-1 and 10C-3 is an example of the case where LsubCH=2, and in fact, LsubCH is a subchannel length for resource allocation, and may be selected within a resource allocation range down as system information. In the example of FIG. 10C, the number of all resource candidates in the slot 10C-10 belonging to the first slot interval for energy detection may be determined as N by X=1. The UE may determine which resource candidate is suitable for transmission by performing energy detection on N resource candidates. In this case, energy detection may determine whether the corresponding value exceeds the (pre-)configuration threshold value by measuring the SL RSSI for each resource candidate. In this case, SL RSSI values for all resource candidates may be sequentially ordered. As described above, when X=1 in Method 1, only a method of determining idle resources with one shot can be used. Referring to FIG. 10C, for energy detection with one shot, in a slot interval X=1, a resource determined to be the most idle among all corresponding resource candidates may be selected. Through this, when an idle resource is selected (10C-8), transmission may be attempted in the next slot (10C-11) belonging to the resource pool. However, at this time, the same frequency region as 10C-8 of the next slot 10C-11 belonging to the resource pool may be a resource region that is not usable for resource selection, as illustrated by 10C-7. In this case, two methods can be considered. The first method is to attempt transmission in the next slot (10C-12) belonging to the resource pool (10C-9). The same frequency domain as 10C-8 in the slot 10C-12 can be selected as the transmission resource 10C-9 because it can be used as a resource selection. Another second method is that when the idle resource is selected in slot 10C-10 (10C-8), the same frequency domain as 10C-8 of the next slot 10C-11 belonging to the resource pool is shown in FIG. 10C-7. As described above, in the case of a resource region that is not usable due to resource selection, energy detection is performed in another region of the slot 10C-11 to find idle resources again. Using this method, when the idle resource is selected again in the slot 10C-11 (10C-13), transmission may be attempted in the next slot 10C-12 belonging to the resource pool. The same frequency domain as 10C-13 in the slot 10C-12 can be selected as the transmission resource 10C-14 because it can be used as a resource selection. Sensing window B can be stopped when the transmission resource is finally selected in both methods. In addition, if it is determined that all resources are busy in the slot period in which energy detection is performed, a method of performing back-off in the resource selection window 10C-1 may be considered. For a detailed method of performing back-off, refer to the descriptions in the above Energy detection methods 1, 2, and 3. 10C has been described based on Method 1, but can be applied to both Method 2 and Method 3.

10D is a diagram illustrating a case in which a resource candidate left in a resource selection window as a result of sensing in a sensing window A according to an embodiment of the present disclosure is reported to an upper level of a terminal and sensing is performed in a sensing window B.

Unlike in FIG. 10C, referring to FIG. 10D, the sensing result in the sensing window A reports the resource candidate left in the resource selection window 10D-1 to the upper level of the terminal, and after selecting the resource candidate from the upper level of the terminal, Sensing window B (10D A case in which sensing is performed in -2) is shown. In FIG. 10D, the number X of resource candidates left in the Resource selection window (10D-1) as a result of sensing in the sensing window A as described above is reported as higher, and Y (1≦Y<X) of these from the upper terminal are down-selected ( 10D-7) A case in which a resource should be selected among Y resource candidates 10D-7 through sensing in the Sensing window B (10D-2) is shown. Therefore, when sensing and selecting a resource in the sensing window B (10D-2), sensing must be performed only in the resource region that can be used for resource selection as in 10C-7 and the transmission resource must be selected. Therefore, it may be difficult to sense and select resources according to the energy detection method. 10D shows an example in which the above-described energy detection method 1 (10D-4) is used. In FIG. 10D, when Method 1 is used, an example in which the slot interval for energy detection is set to X=1 is shown (10D-4). As described above, X means the number of slots belonging to the resource pool, not the number of physical slots. As described above, in the example of FIG. 10D, the number of all resource candidates in the slot 10D-9 belonging to the first slot interval for energy detection may be determined as N by X=1. The UE may determine which resource candidate is suitable for transmission by performing energy detection on N resource candidates. At this time, when it is determined that all resources are busy through energy detection in slot 10D-9, and the idle resource is selected by performing energy detection by moving to the next slot (10D-10) corresponding to the resource pool (10D-7), Transmission may be attempted in the next slot 10D-11 belonging to the resource pool. In the example of FIG. 10D, there may be a problem that transmission resources that can be selected in slots after 10D-7 do not exist. That is, method 1 may cause a problem in the sensing and resource selection method as in FIG. 10D. In contrast, as described with reference to FIG. 10B, when the method of setting the energy detection interval in a specific region such as an AGC region is applied, the problem with Method 1 can be solved to some extent. In order to set the energy detection interval in a specific area such as the AGC area, as described in FIG. 10B, in the symbol area occupied by the AGC area, as in Method 2, a fixed symbol length is set as the energy detection period, or the symbol occupied by the AGC area. In the region, as in Method 3, a method of setting and using an energy detection interval having a length less than the symbol length may be used. In FIG. 10D, when Method 3 is used (10D-6), when the section Z set as the energy detection section is set in a partial section of the first symbol of the slot, not the PSSCH region as in the slot 10D-10, the corresponding region is When an idle resource region is selected among resource candidates in the slot 10D-10 by energy detection (10D-8), a resource corresponding to the same frequency region as 10D-8 is transmitted to the corresponding slot 10D-10. It may be possible to select and send immediately. However, as shown in FIG. 10D, when a method of reporting a resource candidate left in the resulting Resource selection window (10D-1) as a result of the Sensing window A to the upper level of the UE and selecting a transmission resource candidate from the upper level of the UE is used, the Sensing window B (10D-2) ), the resource candidates that can be selected are limited, and thus sensing and resource selection may be restricted.

[Example 5]

[Embodiment 5] of the present disclosure provides a method and an apparatus for selecting a transmission resource in consideration of ACK/NACK feedback timing and possible retransmission timing accordingly when HARQ feedback-based retransmission is performed.

11 is a diagram illustrating a mapping structure of physical channels mapped to one slot in a sidelink according to an embodiment of the present disclosure.

Referring to FIG. 11, a transmitting terminal may transmit a preamble signal 11-02 in one or more symbols before transmitting a corresponding slot 11-01. The preamble signal 11-02 may be used to enable the receiving terminal to correctly perform automatic gain control (AGC) for adjusting the intensity of amplification when amplifying the power of the received signal. In addition, for the preamble signal 11-02, transmission of the preamble signal 11-02 may be determined according to whether the transmitting terminal transmits a previous slot of the corresponding slot 11-01. That is, when the corresponding transmitting terminal transmits a signal to the same terminal in the previous slot of the corresponding slot 11-01, transmission of the preamble signal 11-02 may be omitted. A PSCCH 11-03 including control information may be transmitted in initial symbols of a slot, and a PSSCH 11-04 scheduled by control information of the PSCCH 11-03 may be transmitted. A part of sidelink control information (SCI), which is control information, may be mapped to the PSSCH 11-04 and transmitted. In addition, FIG. 11 shows that a physical sidelink feedback channel (PSFCH 11-05), which is a physical channel for transmitting feedback information, is located at the end of a slot. A certain amount of free time is secured between the PSSCH (11-04) and the PSFCH (11-05), so that the terminal that has transmitted/received the PSSCH (11-04) is prepared to transmit or receive the PSFCH (11-05). You can do it. After transmission and reception of the PSFCH (11-05), an empty section can be secured for a predetermined time.

The terminal may receive a position of a slot capable of transmitting the PSFCH (11-05) in advance. The preset reception may be determined in advance in the process of creating the terminal, or may be transmitted when a sidelink-related system is accessed, or transmitted from the base station when connected to the base station, or may be transmitted from another terminal.

12 is a diagram illustrating that a resource for transmitting and receiving a PSFCH is set according to an embodiment of the present disclosure.

Specifically, referring to 12-10 of FIG. 12, a diagram illustrating an example in which a resource capable of transmitting and receiving a PSFCH is set in every slot. For example, when a period of a resource capable of transmitting and receiving PSFCH can be set by a parameter such as periodicity_PSFCH_resource, in the case of 12-01, periodicity_PSFCH_resource = 1 slot. Alternatively, the period may be set in units of msec (milliseconds), and resources may be set for each slot belonging to the resource pool according to a subcarrier spacing (SCS). 12-20 are diagrams illustrating an example in which resources are configured to transmit and receive PSFCH every 4 slots. Referring to FIG. 12, only the last slot 12-24 among the four slots 12-21, 12-22, 12-23, and 12-24 may be configured to transmit and receive the PSFCH 12-29. Similarly, only the last slot 12-28 among the four slots 12-25, 12-26, 12-27, and 12-28 may be configured to transmit and receive the PSFCH 12-30. The slot may be a slot determined in the resource pool. Referring to FIG. 12, the slot index may be an index set in a slot determined in a resource pool. That is, the four slots (12-21, 12-22, 12-23, 12-24) are not actually contiguous slots, but slots belonging to the resource pool (or slot pool) used by the transceiver It may be a slot that appears continuously among the. The arrow of FIG. 12 may indicate a slot of the PSFCH through which HARQ feedback information of the PSSCH is transmitted. For example, the HARQ feedback information of the PSSCH transmitted in slots 12-21, 12-22, and 12-23 may be included in the PSFCH that may be transmitted in slots 12-24 and transmitted/received. Similarly, HARQ feedback information of the PSSCH transmitted in slots 12-25, 12-26, and 12-27 may be included in the PSFCH that may be transmitted in slots 12-28 and transmitted and received. The reason that the HARQ feedback information of the PSSCH transmitted in slots 12-24 is not transmitted in the same slot 12-24 is because the UE finishes decoding the PSSCH transmitted in slots 12-24 and transmits the PSFCH in the same slot 12-24. It may be because you are running out of time. That is, it may be because the minimum processing time required to process the PSSCH and prepare the PSFCH is not small enough. Therefore, the UE receiving the PSSCH uses the smallest x among integers greater than or equal to K when the PSSCH is received in slot n, when resources for transmitting PSFCH in slot n+x are set or given, The information of the HARQ-ACK feedback of the PSSCH may be mapped to the PSFCH of slot n+x and transmitted. K may be a value set in advance from the transmitting terminal, or may be a value set in the resource pool in which the corresponding PSSCH or PSFCH is transmitted, and for setting, each terminal may exchange its capabilities with the transmitting terminal in advance. K may be a value determined according to at least one or more of a subcarrier spacing (SCS), a terminal capability, a setting value with a transmitting terminal, or a resource pool setting.

For example, when N=1 and K=2, that is, when a PSFCH transmission resource is configured for every slot in the resource pool, and when a PSSCH is transmitted and HARQ feedback of a PSSCH can be transmitted from at least 2 slots later, HARQ feedback is provided. The slot in which the PSFCH that can be transmitted can be transmitted may be determined as shown in [Table 5].

[Table 5] N=1, K=2

As another example, when N=2 and K=2, that is, when the PSFCH transmission resource is configured for every two slots in the resource pool, and when the PSSCH is transmitted and HARQ feedback of the PSSCH can be transmitted from at least 2 slots later, HARQ A slot in which the PSFCH capable of transmitting the feedback can be transmitted may be determined as shown in [Table 6].

[Table 6] N=2, K=2

As another example, when N=4 and K=2, that is, when PSFCH transmission resources are configured for every 4 slots in the resource pool, and when PSSCH is transmitted and HARQ feedback of PSSCH can be transmitted from at least 2 slots later, HARQ A slot in which a PSFCH capable of transmitting feedback can be transmitted may be determined as shown in [Table 7].

[Table 7] N=4, K=2

As another example, when N=4 and K=1, that is, when the PSFCH transmission resource is configured for every 4 slots in the resource pool, and when the PSSCH is transmitted and HARQ feedback of the PSSCH can be transmitted from the next slot, HARQ feedback is provided. The slot in which the PSFCH that can be transmitted can be transmitted can be determined as shown in [Table 8].

[Table 8] N=4, K=1

According to [Table 5] to [Table 8], the setting value of the period (N) of the resource capable of transmitting and receiving PSFCH and the setting value of the offset value (K) between the slot transmitting the PSFCH from the slot receiving the PSSCH Accordingly, the slot in which the PSFCH can be transmitted may be different. Therefore, when HARQ feedback-based retransmission is performed, the transmission resource should be selected in consideration of the following parameters.

* Cycle of resources that can transmit and receive PSFCH (N)

* Offset value (K) between slots transmitting PSFCH in slots receiving PSSCH

According to a parameter, a position of a slot capable of performing HARQ ACK/NACK feedback for a corresponding PSSCH may be determined for a slot in which a PSSCH is transmitted. If a preparation time for PSSCH retransmission is additionally required, including a time for the transmitting terminal to receive and decode HARQ ACK/NACK, the following parameters may be additionally considered and used to select transmission resources for initial transmission and retransmission. have.

* Preparation time for PSSCH retransmission (including time to receive HARQ ACK/NACK and decode it)

If the preparation time for PSSCH retransmission is not required, the parameter may not be considered as a parameter for selection of a transmission resource when HARQ feedback-based retransmission is performed. When the proposed HARQ feedback-based retransmission is performed, the parameters to be considered for selecting a transmission resource are when the base station allocates transmission resources in the sidelink (Mode 1) and the terminal directly allocates sidelink transmission resources through sensing. It can be applied to all resource selection criteria for the case (Mode 2). For example, in Mode 1, the base station may select a resource selection for HARQ feedback-based retransmission by applying a proposed parameter, and signal transmission time information for this to the transmitting terminal as resource allocation reservation information through DCI. In Mode 2, when the UE directly selects a resource for HARQ feedback-based retransmission through sensing, it is determined by applying a proposed parameter, and transmission time information for this may be signaled to another UE as resource allocation reservation information through SCI. In the following embodiment, a method in which a terminal selects a transmission resource based on parameters N and K in Mode 2 will be described in detail.

[Example 6]

[Embodiment 6] of the present disclosure provides a method and apparatus for selecting a transmission resource based on parameters N and K when a UE performs HARQ feedback-based retransmission in Mode 2 as proposed in [Embodiment 5]. . In addition, a method of selecting a transmission resource for a case where blind retransmission is performed is also described. The transmission resource selection method may vary depending on whether only one of the Sensing window A and the Sensing window B is used or both the Sensing window A and the Sensing window B are used as described above through [Embodiment 3] and [Embodiment 4]. . In addition, in the embodiment of the present disclosure, a case in which mode 2 resource selection is performed only for one MAC PDU (Protocol Data Unit) and a case in which a plurality of MAC PDUs is performed through a reservation interval setting will be described separately. Here, the MAC PDU may be a unit corresponding to one TB in the physical layer. First, according to an embodiment of the present disclosure, when sensing is performed using only the sensing window A in Mode 2 and transmission resource selection is performed through this, a transmission resource selection method may be used. In addition, an embodiment of the present disclosure is a case in which the sensing result of the sensing window A is reported to the upper terminal of the terminal and a method of finally selecting a transmission resource from the upper terminal is used. The sensing result of the sensing window A is not reported to the upper level of the terminal, and a method of finally selecting a transmission resource at the physical layer may be considered. However, when the sensing result of the sensing window A is reported to the upper level of the UE, and the method of finally selecting the transmission resource from the upper level of the UE is used, the resource selection may be more randomized to avoid collisions between UEs.

When resource selection is made for one MAC PDU, the following resource selection method may be used.

* Step 1: Based on the resource pool information set in the resource selection window (refer to the definition of the Resource selection window in [Example 3]), the sensing result in the sensing window A among the number of resource candidates M that can be allocated resources ([Example 3] (Refer to the sensing operation in Sensing window A of), the resource candidates that are judged to be ineffective to allocate PSSCH transmission resources are excluded, leaving X (≤M) of the resource candidates available for resource allocation. have.

** When the resource selection method of the terminal is set to random resource selection, a procedure for excluding a resource candidate may be omitted. In this case, it could be X=M.

* Step 2: A resource candidate list consisting of X resources may be reported as a higher layer of the terminal.

* Step 2-1: In the upper layer of the terminal, a transmission resource for one transmission opportunity among X candidates may be randomly selected.

If retransmission is set (if the number of times set for retransmission is not 0), you can move to the step below. Here, the number of additionally selected transmission opportunities may be one or more depending on the maximum number of retransmissions.

If the retransmission method is set to blind retransmission, you can move to the step below.

* Step 2-2: Among the X candidates reported to the upper layer of the terminal, one transmission opportunity may be selected in Step 2-1, and a transmission resource for another transmission opportunity may be randomly selected from the remaining resource candidates. Step 2-2 may be repeated to additionally select a transmission opportunity according to the maximum number of times set for retransmission.

If the retransmission method is set to HARQ-based retransmission, it may move to the step below.

* Step 2-2: Transmission resources for other transmission opportunities may be selected in consideration of parameters (N, K, etc.) related to HARQ ACK/NACK feedback and retransmission proposed in [Embodiment 5]. Step 2-2 may be repeated to select an additional transmission opportunity according to the maximum number of retransmissions set. For this, various Alt 1/2/3/4 as follows can be considered. However, the present disclosure is not limited to Alt 1/2/3/4.

** Alt 1) One transmission opportunity may be selected in Step 2-1 among the X candidates reported to the upper layer of the terminal, and another transmission opportunity may be selected based on the transmission opportunity previously selected in Step 2-1 among the remaining resource candidates. . Specifically, another transmission opportunity is randomly selected from the remaining available resource candidates after a time gap in consideration of parameters (N, K, etc.) related to HARQ ACK/NACK feedback and retransmission in [Embodiment 5]. I can. The method for Alt 1 will be described in more detail with reference to FIG. 13 as follows.

13 is a diagram illustrating a resource selection method according to an embodiment of the present disclosure.

*** Referring to 13-10 of FIG. 13, after selecting one transmission opportunity in Step 2-1 according to Alt 1 (13-11), parameters related to HARQ ACK/NACK feedback and retransmission (N, K , Etc.) is shown an example of randomly selecting another transmission opportunity from the remaining resource candidates (13-13, 13-14) available in the region after the time gap (13-12) in consideration of). When it is assumed that the resource candidate 13-13 is selected among the resource candidates 13-13 and 13-14 in 13-10, an example of a case in which an additional transmission opportunity should be selected is shown through 13-20. . It is assumed that the time gap between the transmission opportunity 13-11 and 13-13 at 13-20 is not guaranteed enough to be able to select another transmission opportunity. Therefore, the additional transmission opportunity is based on transmission opportunities 13-11 and 13-13, as shown in Fig. 13-20, in consideration of parameters related to HARQ ACK/NACK feedback and retransmission (N, K, etc.). 21) Can be randomly selected from the remaining resource candidates (13-22, 13-23) that can be used in a subsequent area.

** Alt 2) One transmission opportunity may be selected in Step 2-1 from among the X candidates reported to the upper layer of the terminal, and another transmission opportunity may be randomly selected from the remaining resource candidates. If the additionally selected transmission opportunity is based on the transmission opportunity previously selected in Step 2-1, the time gap in consideration of parameters related to HARQ ACK/NACK feedback and retransmission proposed in [Example 5] (N, K, etc.) may not be guaranteed. In the case, another transmission opportunity may perform the selection again until this is satisfied. The method for Alt 2 will be described in more detail as follows through FIG. 13.

*** An example of selecting one transmission opportunity (13-31) in Step 2-1 according to Alt 2 and randomly selecting another transmission opportunity (13-32) from the remaining resource candidates is shown through 13-30. do. However, as in 13-30, another transmission opportunity (13-32) takes into account the transmission opportunity (13-10) previously selected in Step 2-1 and parameters related to HARQ ACK/NACK feedback and retransmission (N, K, etc.). If the time gap (13-33) is not guaranteed, the transmission opportunity in Step 2-2 may need to be reselected. Therefore, an example in which the transmission opportunity in Step 2-2 is reselected is shown through 13-40. In 13-40, one transmission opportunity is selected in Step 2-1 (13-41), and another transmission opportunity (13-42) randomly selected from the remaining resource candidates may be considered for HARQ ACK/NACK feedback and retransmission. have. Further, referring to 13-40, a case of satisfying the time gap 13-43 in consideration of parameters (N, K, etc.) related to transmission opportunity (13-42) and HARQ ACK/NACK feedback and retransmission is shown. . In this way, in Alt 2, the reselection process may be repeated until conditions for other transmission opportunities are satisfied.

** Alt 3) The operation of selecting one transmission opportunity in Step 2-1 is omitted, and transmission opportunities of the maximum number of times set for initial transmission and retransmission among X candidates in the upper layer of the terminal may be simultaneously randomly selected. If the time gap between the selected transmission opportunities does not guarantee the time gap in consideration of parameters (N, K, etc.) related to HARQ ACK/NACK feedback and retransmission proposed in [Embodiment 5], all transmissions until they are satisfied. You can select opportunitie again. The method for Alt 3 will be described in more detail as follows through FIG. 13.

*** In accordance with Alt 3, the operation of selecting one transmission opportunity in Step 2-1 is omitted, and transmission opportunities set for initial transmission and one retransmission among X candidates in the upper layer of the terminal are simultaneously randomly selected. Examples are shown through 13-50 and 13-50. In the case of 13-50, the time gap of transmission opportunities (13-51) selected for initial transmission and one retransmission is a time gap (13-52) that considers HARQ ACK/NACK feedback and parameters related to retransmission (N, K, etc.) ) Is not satisfied. In this case, the transmission opportunities selected for the initial transmission and for one retransmission should be reselected. In the case of 13-60, the time gap of the transmission opportunities (13-61) selected for initial transmission and one retransmission is the time gap considering parameters (N, K, etc.) related to HARQ ACK/NACK feedback and retransmission (13-62 ) Is shown. As described above, in Alt 3, the reselection process may be repeated until conditions for all transmission opportunities are satisfied.

** Alt 4) Another transmission opportunity selected for retransmission is one transmission opportunity selected in Step 2-1 from among the X candidates reported to the upper layer of the terminal and not selected from the remaining resource candidates. Based on the transmission opportunity, it may be selected after a time gap in consideration of parameters (N, K, etc.) related to HARQ ACK/NACK feedback and retransmission proposed in [Embodiment 5]. In this case, another transmission opportunity may be selected from the same frequency resource as the transmission opportunity selected in Step 2-1. In the case of Alt-4, the section of the Resource selection window may be selected in consideration of only one transmission opportunity in Step 2-1. The method for Alt 3 will be described in more detail as follows through FIG. 13.

*** For the case of selecting 4 retransmission resources according to Alt 4, different transmission opportunities (13-72, 13-73, 13-74) are provided with one transmission opportunity (13-71) selected in Step 2-1. An example in which a time gap 13-75 in consideration of parameters (N, K, etc.) related to HARQ ACK/NACK feedback and retransmission as a reference is subsequently sequentially selected is shown through FIGS. 13-70. In 13-70, other transmission opportunities (13-72, 13-73, 13-74) are shown to be selected from the same frequency resource as the transmission opportunity (13-71) selected in Step 2-1.

* Step 2-3: In the transmission opportunities selected in Step 2-2, the transmission opportunity that comes first in time is used for initial transmission, and the transmission opportunity that comes later can be a transmission resource for sequential retransmission.

* Step 3: Selected transmission opportunities can be selected sidelink grant.

If retransmission is not set (the number of times set for retransmission is 0), you can move to Step 3 below.

* Step 3: One selected transmission opportunity may be the selected sidelink grant.

If the selected sidelink grant is available through Step3, you can move to the step below.

* Step 4: By using the selected sidelink grant, the UE can determine the time and frequency location at which the PSCCH and PSSCH are transmitted.

* Step 5: The selected sidelink grant may be the configured sidelink grant.

Even though the Resource selection window is set in consideration of retransmission, selecting the transmission opportunity in the Resource selection window in the process of selecting the transmission opportunity for HARQ-based retransmission using one of Alt1 to Alt4 described above. If there are no resources available for the purpose, the following two methods can be considered.

First of all, the first method is a method in which the UE cancels reservation for some resources for HARQ-based retransmission when there is no available resource for selecting a transmission opportunity in the Resource selection window. For example, when the transmission opportunity is selected in consideration of up to 4 retransmissions, two transmission opportunities are selected, but when the other two transmission opportunities cannot be selected in the Resource selection window, transmission resources are reserved for only 2 retransmissions. The remaining retransmissions can be canceled. Also, information about this may be signaled directly or indirectly through SCI.

The second method is a method of selecting a transmission opportunity outside of T2 beyond the Resource selection window when there is no available resource to select a transmission opportunity in the Resource selection window [n+T1, n+T2]. When using this method, Step 2-3 is first applied to the transmission opportunity selected in the Resource selection window, and the next transmission opportunity based on the transmission opportunity located at the end in the Resource selection window at the time point is proposed in [Example 5]. It may be randomly selected at a time gap in consideration of parameters (N, K, etc.) related to HARQ ACK/NACK feedback and retransmission.

When the retransmission method is set to HARQ-based retransmission as described above, transmission resources for other transmission opportunities in consideration of parameters (N, K, etc.) related to HARQ ACK/NACK feedback and retransmission in [Embodiment 5] This method of choice can be used. In addition, for this, the aforementioned Alt 1/2/3/4 may be considered. When the retransmission method is set to HARQ-based retransmission, a method of selecting a transmission resource in another method may be applied without applying the method proposed in Step 2-2. The method of selecting a transmission resource by a method other than the method proposed in Step 2-2 is the same as in the case of blind retransmission even when the retransmission method is set to HARQ-based retransmission, in Step 2-2 (above). If blind retransmission is set, transmission resources can be selected through the same procedure as in Step 2-2).

* Step 2-2: Among the X candidates reported to the upper layer of the terminal, one transmission opportunity may be selected in Step 2-1, and a transmission resource for another transmission opportunity may be randomly selected from the remaining resource candidates. Step 2-2 may be repeated to additionally select a transmission opportunity according to the maximum number of times set for retransmission.

That is, in this method, when the retransmission method is set to blind retransmission and when the HARQ-based retransmission method is set, the transmission resource selection method does not change. In this method, when HARQ-based retransmission is configured, the HARQ ACK/NACK feedback and timing gap to be considered for retransmission are not considered, and when a transmission resource is selected, the receiving terminal cannot transmit the HARQ ACK/NACK feedback. Further, the transmitting terminal also does not expect HARQ ACK/NACK feedback from the receiving terminal. As described above through [Embodiment 2] and [Embodiment 3], the transmitting terminal may select a transmission resource and transmit resource reservation information for this to the receiving terminal through SCI. Accordingly, the transmitting terminal receiving this may determine whether the time gap is guaranteed or not guaranteed from the transmission time information of the initial transmission and retransmission included in the SCI field. Accordingly, only when the selected transmission resource satisfies the timing gap to be considered for HARQ ACK/NACK feedback and retransmission, the transmitting terminal can receive the HARQ ACK/NACK feedback from the receiving terminal. In the case of using such a method, there is an advantage that it is not necessary to consider Alt 1/2/3/4 for selecting a transmission resource considering HARQ ACK/NACK feedback and retransmission in the Resource selection window, but the transmission resource is HARQ ACK/NACK feedback. And when the timing gap to be considered for retransmission is selected not to be satisfied, a situation in which the transmitting terminal cannot receive the HARQ ACK/NACK feedback from the receiving terminal may occur.

When resource selection is made for a plurality of MAC PDUs, the following resource selection method may be used.

If retransmission is set (if the number of times set for retransmission is not 0), the resource selection method for one MAC PDU above is applied and a transmission opportunity different from the one selected transmission opportunity (resource for initial transmission) is applied. On the basis of opportunity (resource for retransmission), a set for transmission opportunity for a plurality of MAC PDUs may be selected according to the number of reservations set at intervals indicated by each reservation interval. Each set can be a set classified according to the initial transmission and the set number of retransmissions. These sets can be selected sidelink grants. Also, in this case, Steps 4 and 5 described above may be performed.

If retransmission is not set (when the number of retransmission is set to 0), the resource selection method for one MAC PDU described above is applied and selected based on one transmission opportunity (resource for initial transmission). Transmission opportunities for a plurality of MAC PDUs are selected according to the number of reservations set at an interval indicated by the reservation interval, and one set for the transmission opportunity can be configured. This set can be a selected sidelink grant. Also, in this case, Steps 4 and 5 described above may be performed.

[Example 6-1]

[Embodiment 6-1] of the present disclosure additionally performs SCI decoding and sensing until the final resource is selected even after triggering for resource selection occurs in slot n based on the method proposed in the above-described [Embodiment 6]. We propose a method to determine the resource selection. According to the above, after triggering for resource selection occurs in slot n, that is, even in the sensing window B, similarly to the sensing operation defined in the sensing window A, SCI decoding and sidelink measurement for other terminals are performed. Resources occupied by other terminals within the selection window and determined to be ineffective for use may be additionally excluded.

10E is a diagram illustrating a final resource selection method according to an embodiment of the present disclosure.

Specifically, the related operation will be described in detail with reference to FIG. 10E. Referring to FIG. 10E, the section [n+T1, n+T2]=[n+1, n+6] of the resource selection window 10E-1 is set, and the section [n] of the sensing window B(10E-2) It may be set as +T1', n+T2']=[n, n+2]. In the resource selection window, T1 and T2 may be determined in units of slots. It can be determined by the terminal implementation under the following conditions.

Also, in the sensing window B, T1' and T2' may be determined in units of slots. In addition, T1' and T2' may be settable values. In general, when the present embodiment is applied, T1' in the section of the sensing window B 10E-2 may be set to a slot n in which triggering for resource selection has occurred for continuous connection in the sensing window A. In addition, in the sensing window B (10E-2) interval, T2' may be determined by a time Tsel (10E-3) required for reselection except for a resource according to a time when a resource for initial transmission is selected. Here, Tsel (10E-3) may be determined in units of slots. As described in [Embodiment 6], when a resource for initial transmission is selected through the result of the sensing window A, the sensing window B from the time point for the initial transmission to before Tsel may be used. More specifically, as shown in 10E-3 of FIG. 10E, the initial transmission resource selection (10E-5) may be determined as slot n+4 (10E-9) and the value of Tsel may be determined as 2 slots. Accordingly, the section of the sensing window B (10E-2) may be set as [n+T1', n+T2']=[n, n+2]. Here, Tsel (10E-3) may indicate a processing time required to select a resource after the sensing window is terminated, as well as determining the section of the sensing window B in the present embodiment. Therefore, it can also be used to determine the start point T1 of the resource selection window 10E-1. And this can be applied to all of the Resource selection window start time T1 of Figs. 10A, 10C, 10D, and 10E.

Hereinafter, an operation of modifying the resource selection result except for the resource selected in the Resource selection window as needed through the sensing result of the Sensing window B through FIG. 10E will be described in more detail. First, in FIG. 10E, Rx,y (10E-4) is one composed of consecutive subchannels of x+j in the subchannel region set as the resource pool for slot ty belonging to the resource pool as described above through [Embodiment 3]. Can represent a resource candidate of. Where j=0,... Rx,y(10E-4) as ,LsubCH-1 is an example of a case where LsubCH=2, and in fact, LsubCH is a subchannel length for resource allocation and may be selected within a resource allocation range that is down as system information. In addition, it is assumed that the initial transmission resource 10E-5 and the retransmission resource 10E-6 are selected according to the sensing result of the Sensing Window A in the resource selection method proposed in [Embodiment 6] in FIG. 10E. However, in the case of [Example 6-1], additional sensing may be performed in the section [n+T1', n+T2']=[n, n+2] of the sensing window B (10E-2). If, as a result of performing SCI decoding and sidelink measurement in the section of the sensing window B (10E-2), the occupancy of another terminal is observed in the transmission resource that has already been selected, and it is determined that it is inappropriate to perform the transmission on the resource. In this case, it may be necessary to perform the resource selection again except for the selected resource. In the example of FIG. 10E, the following case may be considered as a result of sensing the sensing window B 10E-2.

* Case 1: Initial transmission resource (10E-5) is determined to be inappropriate for transmission

* Case 2: Retransmission resource (10E-6) is determined to be inappropriate for transmission

* Case 3: It is determined that transmission is inappropriate for both the initial transmission resource (10E-5) and the retransmission resource (10E-6)

* Case 4: It is determined that both the initial transmission resource (10E-5) and the retransmission resource (10E-6) are suitable for transmission

Case 4 is a case in which both the initial transmission resource 10E-5 and the retransmission resource 10E-6 are determined to be suitable for transmission, and thus may be excluded from consideration of the present embodiment. In addition, although FIG. 10E considers only one initial transmission and one retransmission resource, a case of indicating up to two resource allocation information as SCI is considered, but is not limited thereto. For example, a case in which four resource allocation information is indicated by SCI may also be included in the scope of an embodiment of the present disclosure. In addition, FIG. 10E shows a case in which both the initial transmission and retransmission resources are selected, but when only the resource for the initial resource is selected, the initial transmission resource 10E-5 is determined to be suitable for transmission or is determined to be inappropriate as in case 1. May be limited to cases. In addition, various methods of performing resource selection again excluding resources selected for case 1, case 2, and case 3 may be considered below. First of all, for case 1, the following methods can be considered.* Method 1-1: Exclusion of the already selected initial transmission resource (10E-5) and replacing the retransmission resource (10E-6) with the initial transmission resource, and not selecting the retransmission resource

** In the case of Method 1-1, although the UE is configured to select a retransmission resource, the retransmission resource may be lost. In this case, the transmitting terminal may inform the receiving terminal that there is only the initial transmission by indicating the time gap (SF _gap ) between initial transmission and retransmission as 0 through SCI.

* Method 1-2: Reselecting the initial transmission resource among remaining resource candidates

** When only the resource for the initial resource is selected during the resource selection process, the initial transmission resource may be reselected through method 1-2.

** When the initial resource and the retransmission resource are selected during the resource selection process, the initial resource and the retransmission resource may be determined again according to the temporal position of the transmission resource reselected through method 1-2. If the reselected transmission resource is located in front of the already selected retransmission resource, only the initial transmission resource can be reselected, but if the reselected transmission resource is located behind the already selected retransmission resource, the resource located in front of the time is initially transmitted. It becomes a resource and a resource located behind it can be selected as a retransmission resource.

** When method 1-2 is used when the initial resource and the retransmission resource are selected in the resource selection process, there is a problem in that it is difficult to guarantee a time gap between the initial transmission and the retransmission resource, especially for the HARQ feedback-based retransmission method. Therefore, in the case of the HARQ feedback-based retransmission method, the exclusion of Method 1-2 may be considered.

* Method 1-3: Reselecting all of the remaining resource candidates for the initial transmission resource and the retransmission resource

** The resource reselected earlier in time becomes the initial transmission resource, and the resource reselected later becomes the retransmission resource.

** In the HARQ feedback-based retransmission method through Method 1-3, it may be advantageous to select resources again to maintain a time gap between initial transmission and retransmission resources.

Alternatively, for case 2, the following methods may be considered.

* Method 2-1: Use only the initial transmission resource (10E-5), exclude the retransmission resource, and do not select again

** In the case of Method 2-1, although the UE is configured to select a retransmission resource, the retransmission resource may be lost. In this case, the transmitting terminal may inform the receiving terminal that there is only the initial transmission by indicating the time gap (SF _gap ) between initial transmission and retransmission as 0 through SCI.

* Method 2-2: Re-selecting only the retransmission resource from among the remaining resource candidates

** In method 2-2, the initial resource and the retransmission resource may be determined again according to the time position of the reselected transmission resource. If the reselected transmission resource is located behind the previously selected initial transmission resource, only the retransmission resource can be reselected, but if the reselected transmission resource is located in front of the already selected initial transmission resource, the resource located in front of the time It becomes a transmission resource, and a resource located behind can be selected as a retransmission resource.

** When Method 2-2 is used, there is a problem in that it is difficult to guarantee a time gap between the initial transmission and the retransmission resource, especially for the HARQ feedback-based retransmission method. Therefore, in the case of the HARQ feedback-based retransmission method, the exclusion of Method 2-2 may be considered.

* Method 2-3: Reselect all of the remaining resource candidates for the initial transmission resource and the retransmission resource

** The resource reselected earlier in time becomes the initial transmission resource, and the resource reselected later becomes the retransmission resource.

** Even in the HARQ feedback-based retransmission method through Method 2-3, it may be advantageous to select resources again to maintain a time gap between initial transmission and retransmission resources.

For case 3, the following methods can be considered.

* Method 3-3: Re-select all of the remaining resource candidates for the initial transmission resource and the retransmission resource

** The resource reselected earlier in time becomes the initial transmission resource, and the resource reselected later becomes the retransmission resource.

** Even in the HARQ feedback-based retransmission method through Method 3-3, it may be advantageous to re-select resources to maintain a time gap between initial transmission and retransmission resources.

The content of the resource selection in [Example 6-1] will be omitted here because the methods proposed in [Embodiment 2] can be used. Whether to use any of the above-described methods may be set with resource pool information or higher layer information. In addition, one method suitable for each case among the above-described methods may be used. When one of the above-described methods is to be determined, if the initial resource must be reselected, a method of reselecting the remaining resource candidates (Method 1-2), one or both of the initial resource and the retransmission resource are reselected Even if it is necessary, a method of reselecting both the initial transmission resource and the retransmission resource (method 1-3, method 2-3, method 3-3) may be advantageous. Also, as pointed out in Method 1-2, Method 2-2, and Method 3-2, in the case of HARQ feedback-based retransmission, when one of the initial resource and the retransmission resource is reselected, there is a problem in maintaining the time gap between the initial transmission and the retransmission. May occur, the resource selection result can be modified, excluding the selected resource in the Resource selection window, if necessary through the sensing result of the Sensing window B. Excluding the resource selected in the resource selection window, the operation of modifying the resource selection result applies only to the blind retransmission method, and when the HARQ feedback-based retransmission method is used, the method of using only the sensing window A as in [Embodiment 6] May be considered.

[Example 6-2]

In Example 6-1, a resource selection method (a method of reselecting and reselecting a selected resource) when sensing is continuously performed before and after the triggering point n has been described. 10 illustrates a case in which an initial transmission resource and one retransmission resource are reserved and transmitted, but the present disclosure is not limited thereto. Specifically, Nmax resources may be reserved for one TB. The value of Nmax can be set in the resource pool. If the value of Nmax is set to 3, 3 resources including initial transmission may be reserved. Therefore, as the value of Nmax increases, sensing is continuously performed after triggering n, and when a method of modifying and reselecting an already selected resource is used, the resource selection operation in Mode2 may be very complicated. When reselecting an already selected resource, the following cases may be considered.

* Case 1: Reselection of a resource requiring reselection among all resources is allowed.

* Case 2: Reselection of resources is allowed only when reselection is required for initial transmission among all resources.

When case 1 is considered, the operation of selecting a resource in Mode2 may become very complicated as described above. In other words, the complexity of the operation for selecting the maximum resource may increase more than twice. In addition, in the case of HARQ feedback-based retransmission, since HARQ ACK/NACK needs to be received, it is necessary to ensure a time gap between selected resources as proposed in the present disclosure. When case 1 is used, for example, if Nmax=3 is set and 3 resources including initial transmission are reserved after triggering n, it is determined that only the second resource should be reselected through additional sensing, and the second resource In the case of reselection, if this resource cannot guarantee the time gap between the initial transmission and the last retransmission, other transmission resources need to be selected again. Specifically, when the reselection triggering time is before the initial transmission, even though only the second resource needs to be reselected, there may be a case in which all three resources must be selected again to ensure a time gap. In contrast, case 2 is a method of limiting resource reselection only to initial transmission. Through case 2, it is possible to prevent an increase in the complexity of resource selection occurring in case 1. In addition, since initial transmission is the most important and in the case of HARQ feedback-based retransmission, retransmission resources may be released when the initial transmission is successful, which may be an effective method. As another method, a method in which case 1 is allowed only when blind retransmission is used can be considered. Specifically, the retransmission resource selection method may be configured by distinguishing whether it is a HARQ feedback-based retransmission method or a blind retransmission method. For example, a corresponding method may be set in the resource pool information. If the configured retransmission resource selection method is a HARQ feedback-based retransmission method, case 2 is used, and when the retransmission resource selection method is a blind retransmission method, case 1 or case 2 may be used. At this time, when the blind retransmission method is always, a method of supporting case 1 may be considered, and when the retransmission resource selection method is the blind retransmission method, a method of supporting whether to use case 1 or 2 may be considered. In the latter case, whether the retransmission resource selection method is the blind retransmission method in the resource pool information, and whether the case 1 is supported or the case 2 is supported may be set.

[Example 6-3]

In the above embodiment, a resource selection method when sensing is continuously performed before and after the triggering point n (a method of reselecting a selected resource by modifying it) has been described.

17 is a diagram illustrating a resource selection and resource reselection method according to an embodiment of the present disclosure. Specifically, in FIG. 17, when triggering for resource selection is performed at time n and triggering for re-evaluation is performed at n'(n'>n) by continuously sensing before and after triggering time n Is shown. Referring to FIG. 17, when triggering for resource selection is performed at time n, the sensing window may be defined as [n-T0, n-Tproc,0). Here, T0 is a (pre-)configuration value, and corresponding information may be configured in the resource pool. In addition, Tproc,0 may be defined as a time required to process the sensing result, and the required Tproc,0 may vary according to the set T0 value. Specifically, when a long T0 value is set, a long Tproc,0 may be required. Conversely, when a short T0 value is set, a short Tproc,0 may be required. Accordingly, the value of Tproc,0 may be fixed to one value, but another value adjusted by the set T0 value may be (pre-)configuration. Next, when triggering for resource selection is performed at time n, the resource selection window may be determined as [n+T1, n+T2]. Here, T1 may be selected as a terminal implementation for T1≦Tproc,1. Tproc,1 is the maximum reference value in which the processing time required to select a resource is considered, and since this processing time may vary according to the terminal implementation, T1 may be selected as a value less than Tproc,1 by the terminal implementation. In addition, assuming that T2 is set to select Nmax resources for one TB, the resources of Nmax may include initial transmission and retransmission resources. In this case, the UE selects T2 within a range that satisfies the T2≦Packet delay budget (PDP). Next, when triggering for re-evaluation occurs at n'(n'>n) by continuously performing sensing even after triggering, referring to FIG. 17, this means that at least an already selected resource is in slot m. If present, triggering for reselection must be performed before m-T3. Here, T3 may be a processing time required for reselection. Therefore, in the case of FIG. 17 described above, a method of setting T3 = Tproc,1 may be considered. As described above, Tproc,1 is the maximum reference value in which the processing time required to select a resource is considered, so if triggering for reselection is performed before the corresponding value, it may be possible to change the selected resource to another resource. . In this case, in determining the value of Tproc,1, not only the dropping time of the previously selected resource can be considered, but also the time required to process it in the case of overlapping the previous resource and the new resource can be considered. . Alternatively, a method of setting T3=T0 may be considered. This is a method of using the resource selection processing time T0 already selected according to the terminal implementation as T3. As shown in Fig. 17, when triggering for re-evaluation occurs at n'(n'>n), the sensing window for this is set to [n'-T0, n'-Tproc,0). The resource selection widow for this may be determined as [n'+T1, n'+T2]. At this time, the value of T0 and Tproc,0 may be the same value as the value used when triggering for resource selection is performed at time n. However, for T1 and T2, although the UE may select the same value as at time n when triggering for resource selection is performed by the UE, different values may be selected.

FIG. 18 is a diagram for describing a case in which triggering times of a resource selection and resource reselection method according to an embodiment of the present disclosure are different.

Specifically, in FIG. 18, unlike in FIG. 17, a case in which triggering for resource selection and re-evaluation is simultaneously performed at time n is illustrated. According to FIG. 18, when resource selection and reselection are simultaneously triggered at time n, the sensing window may be defined as [n-T0, n-Tproc,0). Here, T0 is a (pre-)configuration value, and corresponding information may be configured in the resource pool. In addition, Tproc,0 may be defined as a time required to process the sensing result, and the required Tproc,0 may vary according to the set T0 value. Specifically, when a long T0 value is set, a long Tproc,0 may be required. Conversely, when a short T0 value is set, a short Tproc,0 may be required. Accordingly, the value of Tproc,0 may be fixed to one value, but another value adjusted by the set T0 value may be (pre-)configuration. Next, when resource selection and reselection triggering are simultaneously performed at time n, the resource selection window may be determined as [n+T1, n+T2]. Here, T1 may be selected as a terminal implementation for T1≦Tproc,1. Tproc,1 is a maximum reference value in which the processing time required to select a resource is considered, and since this processing time may vary depending on the terminal implementation, T1 may be selected as a value less than Tproc,1 by the terminal implementation. In addition, assuming that T2 is set to select Nmax resources for one TB, the resources of Nmax may include initial transmission and retransmission resources. In this case, the UE selects T2 within a range that satisfies the T2≦Packet delay budget (PDP). Next, the terminal may continuously perform sensing after triggering at time n to reselect an already selected resource when re-evaluation is required. However, this reselection should be performed before m-T3 at least when the already selected resource is in slot m (shown in blue in FIG. 18) with reference to FIG. 18. Here, T3 may be a processing time required for reselection. Accordingly, in the case of FIG. 18 described above, a method of setting T3=Tproc,0+Tproc,1 may be considered. As described above, Tproc,0 is the time required to process the sensing result, and Tproc,1 is the maximum reference value considering the processing time required to select a resource, so if triggering for reselection is performed before T3 with that value It may be possible in implementation to change the selected resource to another resource. In this case, in determining the value of Tproc,1, not only the dropping time of the previously selected resource may be considered, but also the time required to process the dropping of the previously selected resource may be considered. Alternatively, a method of setting T3=T0+Tproc,0 may be considered. This is a method of using by reflecting the resource selection processing time T0 already selected according to the terminal implementation as the resource selection processing time.

[Example 6-4]

In the above embodiment, it has been described that Nmax resources can be reserved for one TB. The number of resources that can be actually reserved for Nmax can be (pre-)configuratoned as resource pool information. For example, when Nmax is determined to be 3, the number of resources that can be actually reserved for one TB is 3 or 2 can be set. When the corresponding value is set to 3, the initial transmission resource and two retransmission resources may be reserved, and when the corresponding value is set to 2, the initial transmission and one retransmission resource may be reserved. Information on the finally selected resource through the sensing and resource selection process may be signaled through SCI. In this case, the number of bits of the following equation may be included in the SCI field indicating frequency resource location information in consideration of the case where the number of resources that can be actually reserved for one TB is 3.

[Equation 3]

는 서브채널의 수를 나타낸다.

에 대한 정보는 자원 풀 정보로 (pre-)configuration될 수 있다. 또한 수학식 3에서

는 조합을 나타내는 수식으로서

에 대해서 시작점과 끝점을 찾는 방법으로 사용된다. 상기 [수학식 3]에서는 하나의 TB에 대한 3개의 자원에 대해서 주파수상 할당된 서브채널의 길이는 동일하다고 가정하고, 초기 전송에 대한 시작 위치는 SCI가 전송되는 PSCCH가 시작되는 서브채널 위치라고 가정하고 하나의 TB에 대한 3개의 자원에 대해서 주파수 시작 위치는 모두 다르게 설정될 수 있음을 가정하고 제안된 수식이다.In [Equation 3] above

Represents the number of subchannels.

Information about may be (pre-)configuration as resource pool information. Also in Equation 3

Is a formula representing a combination

It is used as a method of finding the starting and ending points for. In [Equation 3], it is assumed that the lengths of subchannels allocated on the frequency for three resources for one TB are the same, and the start position for initial transmission is the subchannel position where the PSCCH through which SCI is transmitted starts. Assuming that the frequency start positions for three resources for one TB are all set differently, this is the proposed equation.

[Equation 3] can be expressed by Equation 4 below.

[Equation 4]

[Example 7]

Embodiment 7 of the present disclosure proposes a transmission resource selection method when sensing is performed using only the sensing window B in Mode 2 and transmission resource selection is performed through this.

When resource selection is made for one MAC PDU, the following resource selection method may be used.

* Step 1: Based on the resource pool information set in the resource selection window (refer to the definition of the Resource selection window in [Example 3]), the interval set in the Sensing window B to select the PSSCH transmission resource among the number of resource candidates M that can be allocated resources Energy detection for (refer to the sensing operation in the sensing window B of [Example 4]) may be performed. In addition, it is possible to search for idle resources among resource candidates N in the energy detection region. At this time, SCI decoding and sidelink measurement in the sensing window B may be performed, and an operation of excluding a resource that is determined to be ineffective due to occupancy by another terminal in the resource selection window may be included.

** When the resource selection method of the terminal is set to random resource selection, a procedure for excluding sensing and resource candidates may be omitted. In this case, X=M is set and the operation of the following embodiment is not performed, and a procedure other than Step 1 in [Example 6] can be performed.

If retransmission is set (if the number of times set for retransmission is not 0), you can move to the step below. Here, the number of additionally selected transmission opportunities may be one or more depending on the maximum number of retransmissions.

If the retransmission method is set to blind retransmission, you can move to Step 2 below.

* Step 2: When an idle resource is detected among resource candidates N in the energy detection area by performing energy detection for the section set in the sensing window B, one transmission opportunity is selected and energy detection is performed again to perform energy detection. When an idle resource is found among candidate N, a transmission resource for another transmission opportunity may be selected. In the selected transmission opportunities, a transmission opportunity that comes first in time is used for initial transmission, and a transmission opportunity that comes later may be a transmission resource for sequential retransmission. Step 2 may be repeated to additionally select a transmission opportunity according to the maximum number of times set for retransmission. For details of a method of selecting a resource through energy detection in the sensing window B, refer to [Example 4].

If the retransmission method is set to HARQ-based retransmission, it may move to Step 2 below.

* Step 2: When an idle resource is found among resource candidates N in the energy detection area by performing energy detection for a section set in the sensing window B, one transmission opportunity can be selected. In addition, energy detection may be performed at a time point at which a transmission time point for another transmission opportunity is satisfied in consideration of parameters (N, K, etc.) related to HARQ ACK/NACK feedback and retransmission in [Embodiment 5]. In this case, when an idle resource is found among resource candidates N in the energy detection region, a transmission resource for another transmission opportunity may be selected. In the selected transmission opportunities, a transmission opportunity that comes first in time is used for initial transmission, and a transmission opportunity that comes later may be a transmission resource for sequential retransmission. Step 2 may be repeated to select an additional transmission opportunity according to the maximum number of retransmissions set. For details of a method of selecting a resource through energy detection in the sensing window B, refer to [Example 4].

* Step 3: Selected transmission opportunities can be selected sidelink grant.

If retransmission is not set (the number of times set for retransmission is 0), you can move to Step 2 below.

* Step 2: When an idle resource is found among resource candidates N in the energy detection area by performing energy detection for a section set in the sensing window B, one transmission opportunity can be selected. For details of a method of selecting a resource through energy detection in the sensing window B, refer to [Example 4].

* Step 3: One selected transmission opportunity may be the selected sidelink grant.

If the selected sidelink grant is available through Step3, you can move to the step below.

* Step 4: By using the selected sidelink grant, the UE can determine the time and frequency location at which the PSCCH and PSSCH are transmitted.

* Step 5: The selected sidelink grant may be the configured sidelink grant.

When the retransmission method is set to HARQ-based retransmission as described above, transmission resources for other transmission opportunities in consideration of parameters (N, K, etc.) related to HARQ ACK/NACK feedback and retransmission in [Embodiment 5] This method of choice can be used. When the retransmission method is set to HARQ-based retransmission, a method of selecting a transmission resource in another method may be applied without applying the method proposed in Step 2. The method of selecting a transmission resource by a method other than the method proposed in Step 2 is the same as in the case of blind retransmission even when the retransmission method is set to HARQ-based retransmission, Step 2 below (set by the blind retransmission) If yes, you can select the transmission resource through Step2).

* Step 2: When an idle resource is detected among resource candidates N in the energy detection area by performing energy detection for the section set in the sensing window B, one transmission opportunity is selected and energy detection is performed again to perform energy detection. When an idle resource is found among candidate N, a transmission resource for another transmission opportunity may be selected. In the selected transmission opportunities, a transmission opportunity that comes first in time is used for initial transmission, and a transmission opportunity that comes later may be a transmission resource for sequential retransmission. Step 2 may be repeated to additionally select a transmission opportunity according to the maximum number of times set for retransmission. For details of a method of selecting a resource through energy detection in the sensing window B, refer to [Example 4].

That is, in this method, when the retransmission method is set to blind retransmission and when the HARQ-based retransmission method is set, the transmission resource selection method does not change. In this method, when HARQ-based retransmission is configured, the HARQ ACK/NACK feedback and timing gap to be considered for retransmission are not considered, and when a transmission resource is selected, the receiving terminal cannot transmit the HARQ ACK/NACK feedback. Further, the transmitting terminal also does not expect HARQ ACK/NACK feedback from the receiving terminal. As described above through [Embodiment 2] and [Embodiment 3], the transmitting terminal may select a transmission resource and transmit resource reservation information for this to the receiving terminal through SCI. Accordingly, the transmitting terminal receiving this may determine whether the time gap is guaranteed or not guaranteed from the transmission time information of the initial transmission and retransmission included in the SCI field. Accordingly, only when the selected transmission resource satisfies the timing gap to be considered for HARQ ACK/NACK feedback and retransmission, the transmitting terminal can receive the HARQ ACK/NACK feedback from the receiving terminal. In the case of using this method, there is an advantage that it is not necessary to consider a transmission resource selection method in consideration of HARQ ACK/NACK feedback and retransmission in the Resource selection window, but the timing gap that the transmission resource should be considered for HARQ ACK/NACK feedback and retransmission. If it is selected not to satisfy the transmission terminal, a situation in which the transmitting terminal cannot receive the HARQ ACK/NACK feedback from the receiving terminal may occur.

When resource selection is made for a plurality of MAC PDUs, the following resource selection method may be used.

If retransmission is set (if the number of times set for retransmission is not 0), the resource selection method for one MAC PDU is applied and the selected one transmission opportunity (resource for initial transmission) and the other transmission opportunity ( A set of transmission opportunities for a plurality of MAC PDUs may be selected according to the number of reservations set at intervals indicated by the reservation interval, respectively, based on resources for retransmission). Each set can be a set classified according to the initial transmission and the set number of retransmissions. These sets can be selected sidelink grants. In addition, steps 4 and 5 described above may be performed.

If retransmission is not set (if the number of retransmission is set to 0), the resource selection method for one MAC PDU is applied and the reservation interval is based on one selected transmission opportunity (resource for initial transmission). Transmission opportunities for multiple MAC PDUs are selected according to the number of reservations set at intervals indicated by this indication, and one set for transmission opportunity may be configured. This set can be a selected sidelink grant. In addition, Steps 4 and 5 described above may be performed.

[Example 8]

Embodiment 8 of the present disclosure proposes a transmission resource selection method when sensing is performed using both the Sensing window A and the Sensing window B in Mode 2 and transmission resource selection is performed through this. In addition, in the present embodiment, the sensing result of the sensing window A is not reported to the upper level of the terminal, and a method of finally selecting a transmission resource in the physical layer is used.

When resource selection is made for one MAC PDU, the following resource selection method may be used.

* Step 1: Based on the resource pool information set in the resource selection window (refer to the resource selection window definition in [Example 3]), the sensing result in the sensing window A among the number of resource candidates M that can be allocated resources ([Example 3] (Refer to the sensing operation in Sensing window A of), the resource candidates that are judged to be ineffective to allocate PSSCH transmission resources are excluded, leaving X (≤M) of the resource candidates available for resource allocation. have. In order to select a PSSCH transmission resource from among the number of resource candidates X capable of resource allocation, energy detection for a section set in the sensing window B (refer to the sensing operation in the sensing window B in [Example 4]) may be performed. It is possible to search for idle resources among resource candidates N in the energy detection region. At this time, by performing SCI decoding and sidelink measurement in the sensing window B, an operation of additionally exclusion of a resource that is determined to be ineffective due to occupancy by another terminal within the resource selection window may be included.

** When the resource selection method of the terminal is set to random resource selection, a procedure for excluding sensing and resource candidates may be omitted. In this case, X=M is set and the operation of the following example is not performed, and operations other than Step 1 in [Example 6] may be performed.

If retransmission is set (if the number of times set for retransmission is not 0), move to the step below. Here, the number of additionally selected transmission opportunities may be one or more depending on the maximum number of retransmissions.

If the retransmission method is set to blind retransmission, you can move to Step 2 below.

* Step 2: When an idle resource is found among resource candidates N in the energy detection region by performing energy detection for a section set in the sensing window B, one transmission opportunity may be selected and energy detection may be performed again. At this time, when an idle resource is found among resource candidates N in the energy detection region, a transmission resource for another transmission opportunity may be selected. In the selected transmission opportunities, a transmission opportunity that comes first in time is used for initial transmission, and a transmission opportunity that comes later may be a transmission resource for sequential retransmission. Step 2 may be repeated to additionally select a transmission opportunity according to the maximum number of times set for retransmission. For details of a method of selecting a resource through energy detection in the sensing window B, refer to [Example 4].

If the retransmission method is set to HARQ-based retransmission, it moves to Step2 below.

* Step 2: When an idle resource is found among resource candidates N in the energy detection area by performing energy detection for a section set in the sensing window B, one transmission opportunity can be selected. In addition, energy detection may be performed at a time point at which a transmission time point for another transmission opportunity is satisfied in consideration of parameters (N, K, etc.) related to HARQ ACK/NACK feedback and retransmission in [Embodiment 5]. At this time, when an idle resource is found among resource candidates N in the energy detection region, a transmission resource for another transmission opportunity may be selected. In the selected transmission opportunities, a transmission opportunity that comes first in time is used for initial transmission, and a transmission opportunity that comes later may be a transmission resource for sequential retransmission. Step 2 may be repeated to select an additional transmission opportunity according to the maximum number of retransmissions set. For details of a method of selecting a resource through energy detection in the sensing window B, refer to [Example 4].

* Step 3: Selected transmission opportunities can be selected sidelink grant.

If retransmission is not set (the number of times set for retransmission is 0), you can move to Step 2 below.

* Step 2: When an idle resource is found among resource candidates N in the energy detection region by performing energy detection for a section set in the sensing window B, one transmission opportunity is selected. For details of a method of selecting a resource through energy detection in the sensing window B, refer to [Example 4].

* Step 3: One selected transmission opportunity may be the selected sidelink grant.

If the selected sidelink grant is available through Step3, you can move to the step below.

* Step 4: By using the selected sidelink grant, the UE can determine the time and frequency location at which the PSCCH and PSSCH are transmitted.

* Step 5: The selected sidelink grant may be the configured sidelink grant.

When the retransmission method is set to HARQ-based retransmission as described above, transmission resources for other transmission opportunities in consideration of parameters (N, K, etc.) related to HARQ ACK/NACK feedback and retransmission in [Embodiment 5] This method of choice can be used. When the retransmission method is set to HARQ-based retransmission, a method of selecting a transmission resource in another method may be applied without applying the method proposed in Step 2. The method of selecting a transmission resource by a method other than the method proposed in Step 2 is the same as in the case of blind retransmission even when the retransmission method is set to HARQ-based retransmission, Step 2 below (set by the blind retransmission) If yes, you can select the transmission resource through Step2).

* Step 2: When an idle resource is found among resource candidates N in the energy detection region by performing energy detection for a section set in the sensing window B, one transmission opportunity may be selected and energy detection may be performed again. At this time, when an idle resource is found among resource candidates N in the energy detection region, a transmission resource for another transmission opportunity may be selected. In the selected transmission opportunities, a transmission opportunity that comes first in time is used for initial transmission, and a transmission opportunity that comes later may be a transmission resource for sequential retransmission. Step 2 may be repeated to additionally select a transmission opportunity according to the maximum number of times set for retransmission. For details of a method of selecting a resource through energy detection in the sensing window B, refer to [Example 4].

That is, in this method, when the retransmission method is set to blind retransmission and when the HARQ-based retransmission method is set, the transmission resource selection method does not change. In this method, when HARQ-based retransmission is configured, the HARQ ACK/NACK feedback and timing gap to be considered for retransmission are not considered, and when a transmission resource is selected, the receiving terminal cannot transmit the HARQ ACK/NACK feedback. Further, the transmitting terminal also does not expect HARQ ACK/NACK feedback from the receiving terminal. As described above through [Embodiment 2] and [Embodiment 3], the transmitting terminal may select a transmission resource and transmit resource reservation information for this to the receiving terminal through SCI. Accordingly, the transmitting terminal receiving this may determine whether the time gap is guaranteed or not guaranteed from the transmission time information of the initial transmission and retransmission included in the SCI field. Accordingly, only when the selected transmission resource satisfies the timing gap to be considered for HARQ ACK/NACK feedback and retransmission, the transmitting terminal can receive the HARQ ACK/NACK feedback from the receiving terminal. In the case of using this method, there is an advantage that it is not necessary to consider a transmission resource selection method in consideration of HARQ ACK/NACK feedback and retransmission in the Resource selection window, but the timing gap that the transmission resource should be considered for HARQ ACK/NACK feedback and retransmission. If it is selected not to satisfy the transmission terminal, a situation in which the transmitting terminal cannot receive the HARQ ACK/NACK feedback from the receiving terminal may occur.

When resource selection is made for a plurality of MAC PDUs, the following resource selection method may be used.

If retransmission is set (if the number of times set for retransmission is not 0), the resource selection method for one MAC PDU is applied and the selected one transmission opportunity (resource for initial transmission) and the other transmission opportunity ( A set of transmission opportunities for a plurality of MAC PDUs may be selected according to the number of reservations set at intervals indicated by the reservation interval, respectively, based on resources for retransmission). Each set may be a set classified according to an initial transmission and a set number of retransmissions. These sets can be selected sidelink grants. In addition, Steps 4 and 5 described above may be performed.

If retransmission is not set (if the number of retransmission is set to 0), the resource selection method for one MAC PDU is applied and the reservation interval is based on one selected transmission opportunity (resource for initial transmission). Transmission opportunities for multiple MAC PDUs are selected according to the number of reservations set at intervals indicated by this indication, and one set for transmission opportunity may be configured. This set can be a selected sidelink grant. In addition, Steps 4 and 5 described above may be performed.

[Example 9]

[Embodiment 9] of the present disclosure proposes a transmission resource selection method when sensing is performed using both the Sensing window A and the Sensing window B in Mode 2, and transmission resource selection is performed through this. In addition, the present embodiment is a case in which a resource candidate left in the Resource selection window as a result of sensing in the sensing window A is reported to the upper level of the terminal, and after the resource candidate is selected from the upper level of the terminal, sensing is performed in the sensing window B.

When resource selection is made for one MAC PDU, the following resource selection method may be used.

* Step 1: Based on the resource pool information set in the resource selection window (refer to the definition of the Resource selection window in [Example 3]), the sensing result in the sensing window A among the number of resource candidates M that can be allocated resources ([Example 3] (Refer to the sensing operation in Sensing window A of), the resource candidates that are judged to be ineffective to allocate PSSCH transmission resources are excluded, leaving X (≤M) of the resource candidates available for resource allocation. have.

** When the resource selection method of the terminal is set to random resource selection, a procedure for excluding sensing and resource candidates may be omitted. In this case, X=M is set and the operation of the following example is not performed, and a procedure other than Step 1 in [Example 6] may be performed.

* Step 2: A resource candidate list consisting of X resources may be reported as a higher layer of the terminal. In addition, transmission resources for Y (Y<X) transmission opportunities among X candidates in the upper layer of the UE may be randomly selected. In the present embodiment, Y=1 is not excluded, but when the size of Y is set to be small as described with reference to FIG. 10D in [Embodiment 4], resource candidates for sensing and resource selection are limited and a problem may occur. Therefore, it may be desirable to ensure that the size of Y is greater than or equal to a predetermined value. For example, a method of setting X=0.2M and Y=0.1M can be considered.

* Step 3: In order to select a PSSCH transmission resource among the number of resource candidates Y for which resource allocation is possible, energy detection for a section set in the sensing window B (refer to the sensing operation in the sensing window B in [Example 4]) may be performed. . In addition, it is possible to search for idle resources among resource candidates N in the energy detection region. At this time, by performing SCI decoding and sidelink measurement in the sensing window B, an operation of additionally exclusion of a resource that is determined to be ineffective due to occupancy by another terminal within the resource selection window may be included.

If retransmission is set (if the number of times set for retransmission is not 0), you can move to the step below. Here, the number of additionally selected transmission opportunities may be one or more depending on the maximum number of retransmissions.

If the retransmission method is set to blind retransmission, you can move to Step 4 below.

* Step 4: When an idle resource is detected among resource candidates N in the energy detection region by performing energy detection for a section set in the sensing window B, one transmission opportunity may be selected and energy detection may be performed again. In this case, when an idle resource is found among resource candidates N in the energy detection region, a transmission resource for another transmission opportunity may be selected. In the selected transmission opportunities, a transmission opportunity that comes first in time is used for initial transmission, and a transmission opportunity that comes later may be a transmission resource for sequential retransmission. Step 2 may be repeated to additionally select a transmission opportunity according to the maximum number of times set for retransmission. For details of a method of selecting a resource through energy detection in the sensing window B, refer to [Example 4]. In [Embodiment 4], when the size of Y is set to be small as described with reference to FIG. 10D, a problem may occur because resource candidates for sensing and resource selection are limited.

If the retransmission method is set to HARQ-based retransmission, it may move to Step 4 below.

* Step 4: When an idle resource is searched among resource candidates N in the energy detection area by performing energy detection for a section set in the sensing window B, one transmission opportunity can be selected. In addition, a transmission resource may be selected in consideration of parameters (N, K, etc.) related to HARQ ACK/NACK feedback and retransmission in [Embodiment 5]. Specifically, when energy detection is performed at a time point at which a transmission time point for another transmission opportunity is satisfied, and an idle resource is found among resource candidate N in the energy detection region, a transmission resource for another transmission opportunity may be selected. In the selected transmission opportunities, a transmission opportunity that comes first in time is used for initial transmission, and a transmission opportunity that comes later may be a transmission resource for sequential retransmission. Step 2 may be repeated to select an additional transmission opportunity according to the maximum number of retransmissions set. For details of a method for selecting a resource through energy detection in the sensing window B, refer to [Embodiment 4] described above. In [Embodiment 4], when the size of Y is set to be small as described with reference to FIG. 10D, a problem may occur because resource candidates for sensing and resource selection are limited.

* Step 5: Selected transmission opportunities can be selected sidelink grant.

If retransmission is not set (the number of times set for retransmission is 0), you can move to Step 4 and Step 5 below.

* Step 4: When an idle resource is found among resource candidates N in the energy detection region by performing energy detection for a section set in the sensing window B, one transmission opportunity can be selected. For details of a method of selecting a resource through energy detection in the sensing window B, refer to [Example 4].

* Step 5: One selected transmission opportunity may be the selected sidelink grant.

If the selected sidelink grant is available through Step3, it can move to the step below.

* Step 6: By using the selected sidelink grant, the UE can determine the time and frequency location at which the PSCCH and PSSCH are transmitted.

* Step 7: The selected sidelink grant may be the configured sidelink grant.

When the retransmission method is set to HARQ-based retransmission as described above, transmission resources for other transmission opportunities in consideration of parameters (N, K, etc.) related to HARQ ACK/NACK feedback and retransmission in [Embodiment 5] This method of choice can be used. When the retransmission method is set to HARQ-based retransmission, a method of selecting a transmission resource in another method may be applied without applying the method proposed in Step 4. The method of selecting a transmission resource by a method other than the method proposed in Step 4 is the same as in the case of blind retransmission even when the retransmission method is set to HARQ-based retransmission, Step 4 below (set by the blind retransmission) If yes, you can select the transmission resource through Step4).

* Step 4: When an idle resource is detected among resource candidates N in the energy detection region by performing energy detection for a section set in the sensing window B, one transmission opportunity may be selected and energy detection may be performed again. In this case, when an idle resource is found among resource candidates N in the energy detection region, a transmission resource for another transmission opportunity may be selected. In the selected transmission opportunities, a transmission opportunity that comes first in time is used for initial transmission, and a transmission opportunity that comes later may be a transmission resource for sequential retransmission. Step 2 may be repeated to additionally select a transmission opportunity according to the maximum number of times set for retransmission. For details of a method of selecting a resource through energy detection in the sensing window B, refer to [Example 4]. In [Embodiment 4], when the size of Y is set to be small as described with reference to FIG. 10D, a problem may occur because resource candidates for sensing and resource selection are limited.

That is, in this method, when the retransmission method is set to blind retransmission and when the HARQ-based retransmission method is set, the transmission resource selection method does not change. In this method, when HARQ-based retransmission is configured, the HARQ ACK/NACK feedback and timing gap to be considered for retransmission are not considered, and when a transmission resource is selected, the receiving terminal cannot transmit the HARQ ACK/NACK feedback. Further, the transmitting terminal also does not expect HARQ ACK/NACK feedback from the receiving terminal. As described above through [Embodiment 2] and [Embodiment 3], the transmitting terminal may select a transmission resource and transmit resource reservation information for this to the receiving terminal through SCI. Accordingly, the transmitting terminal receiving this may determine whether the time gap is guaranteed or not guaranteed from the transmission time information of the initial transmission and retransmission included in the SCI field. Accordingly, only when the selected transmission resource satisfies the timing gap to be considered for HARQ ACK/NACK feedback and retransmission, the transmitting terminal can receive the HARQ ACK/NACK feedback from the receiving terminal. In the case of using this method, there is an advantage that it is not necessary to consider a transmission resource selection method in consideration of HARQ ACK/NACK feedback and retransmission in the Resource selection window, but the timing gap that the transmission resource should be considered for HARQ ACK/NACK feedback and retransmission. If it is selected not to satisfy the transmission terminal, a situation in which the transmitting terminal cannot receive the HARQ ACK/NACK feedback from the receiving terminal may occur.

When resource selection is made for a plurality of MAC PDUs, the following resource selection method may be used.

If retransmission is set (if the number of times set for retransmission is not 0), the resource selection method for one MAC PDU is applied and the selected one transmission opportunity (resource for initial transmission) and the other transmission opportunity ( A set of transmission opportunities for a plurality of MAC PDUs may be selected according to the number of reservations set at intervals indicated by the reservation interval, respectively, based on resources for retransmission). Each set can be a set classified according to the initial transmission and the set number of retransmissions. These sets can be selected sidelink grants. Also, Steps 6 and 7 described above can be performed.

If retransmission is not set (if the number of retransmission is set to 0), the resource selection method for one MAC PDU is applied and the reservation interval is based on one selected transmission opportunity (resource for initial transmission). Transmission opportunities for multiple MAC PDUs are selected according to the number of reservations set at intervals indicated by this indication, and one set for transmission opportunity may be configured. This set can be a selected sidelink grant. Also, Steps 6 and 7 described above can be performed.

[Example 10]

In Embodiment 10 of the present disclosure, a resource selection method when blind retransmission and HARQ feedback-based retransmission are simultaneously configured and used in Mode 2 will be described. As described above, retransmission methods considered in the NR sidelink include a blind retransmission method that performs retransmission without based on HARQ feedback information, and a HARQ feedback-based retransmission method that performs retransmission based on HARQ ACK/NACK feedback. . The use of these two retransmission schemes can be used separately by transmission type. First, in the case of broadcast communication, since HARQ feedback is not supported, only blind retransmission can be used. In contrast, in the case of unicast or groupcast communication, since HARQ feedback is supported, either blind retransmission or HARQ feedback-based retransmission method may be configured and used. In general, blind retransmission and HARQ feedback-based retransmission do not need to be configured and used at the same time. Therefore, in the above-described embodiment, the case of blind retransmission and the case of HARQ feedback-based retransmission have been described separately. However, in this embodiment, a case where blind retransmission and HARQ feedback-based retransmission are simultaneously configured and used will be described.

As a representative example of a case where blind retransmission and HARQ feedback-based retransmission are simultaneously configured and used, when up to 4 retransmissions are allowed, blind retransmission is used up to 2 retransmissions, and whether additional retransmissions are performed may be determined based on HARQ feedback. That is, it may be determined whether or not additional retransmission is based on the HARQ feedback result. For example, when blind retransmission is performed until the first two retransmissions and NACK is continuously received, additional HARQ feedback-based retransmission may be performed or two blind retransmissions may be performed. In general, the number of blind retransmissions and the number of retransmissions based on HARQ feedback may be set. When the number of blind retransmissions is set to A and the number of HARQ feedback-based retransmissions is set to B, examples in which A and B are set as follows when a maximum of 4 retransmissions are allowed can be considered.

* A=0, B=4

* A=1, B=1

* A=1, B=2

* A=2, B=0

A=0 means when blind retransmission is turned off, A=1 means 2 consecutive blind retransmissions, and A=2 means 4 consecutive blind retransmissions. In addition, B=0 is a case in which HARQ feedback-based retransmission is turned off, and B=1 is a case in which first two blind retransmissions are generated, and whether or not to perform two subsequent blind retransmissions may be determined based on HARQ feedback. In addition, B=2 is a case in which the first two blind retransmissions are generated, and whether the third or fourth retransmission is determined based on HARQ feedback. And B=4 is a case where all 4 retransmissions are determined based on HARQ feedback. The present disclosure is not limited only to the above-described embodiments. In the case of blind retransmission, there is no restriction on the time gap between the previous transmission time and the retransmission time, but when HARQ feedback-based retransmission is performed, parameters related to HARQ ACK/NACK feedback and retransmission in [Example 5] described above (N , K, etc.), the time gap between the previous transmission time and the retransmission time should be guaranteed. Therefore, when blind retransmission and HARQ feedback-based retransmission are configured and used at the same time, when resource selection is performed for this, in the case of HARQ feedback-based retransmission, resource selection must be performed to ensure a time gap between the previous transmission time and the retransmission time. This can be applied to both Mode 1 and Mode 2 transmission methods. In the case of HARQ feedback-based retransmission, if resource selection is not supported so that the time gap between the previous transmission time and the retransmission time is guaranteed, a situation in which the transmitting terminal cannot receive the HARQ ACK/NACK feedback from the receiving terminal may occur. Specifically, when the selected resource does not guarantee the time gap between the previous transmission time and the retransmission time, the receiving terminal does not feedback HARQ ACK/NACK. Also, the transmitting terminal does not expect HARQ ACK/NACK feedback from the receiving terminal. The receiving terminal may signal the transmission time information of the resource selected by SCI to the receiving terminal, and the receiving terminal may determine whether to give HARQ ACK/NACK feedback through this.

[Example 11]

16 is a diagram illustrating a mapping structure of physical channels mapped to one slot in a sidelink according to an embodiment of the present disclosure.

Referring to FIG. 16, a transmitting terminal may transmit a preamble signal 16-02 in one or more symbols before transmitting a corresponding slot 16-01. The preamble signal 16-02 may be used to enable the receiving terminal to correctly perform automatic gain control (AGC) to adjust the amplification strength when amplifying the power of the received signal. It is also possible to consider a method in which the transmitting terminal repetitively transmits a signal of another channel instead of a preamble for AGC in one or more symbols before transmitting the corresponding slot 16-01. In this case, a part of a PSCCH symbol or a PSSCH symbol may be considered for the repeated signal of another channel. However, in the case of using a preamble signal than a method of performing AGC through this method, there is an advantage in that the AGC execution time can be further shortened. When a preamble signal is transmitted for AGC, a specific sequence may be used as the preamble signal 16-02, and in this case, a sequence such as PSSCH DMRS, PSCCH DMRS, CSI-RS, etc. may be used as the preamble. The sequence used as the preamble in the present disclosure is not limited to the above example. However, PSSCH DMRS may be a suitable alternative as the above-described preamble sequence. Specifically, in the case of the PSSCH DMRS, since the PSCCH is transmitted in all frequency domains in which the PSCCH is transmitted, it will be easier to duplicate the DMRS sequence in the actual PSSCH transmission region and use it as a preamble sequence compared to other alternatives. Additionally, according to FIG. 16, a PSCCH 16-03 including control information is transmitted in initial symbols of a slot, and a PSSCH 16-04 scheduled by control information of the PSCCH 16-03 may be transmitted. A part (1 ^st stage SCI) of sidelink control information (SCI), which is control information, may be mapped to the PSCCH 16-03 and transmitted. PSSCH (16-04) has been mapped to the other part (2 ^nd stage SCI) of the SCI control information with the data information can be transmitted. In addition, in FIG. 16, a physical sidelink feedback channel (PSFCH 16-05), which is a physical channel for transmitting feedback information, is located at the end of a slot. By securing a predetermined free time between the PSSCH (16-04) and the PSFCH (16-05), the terminal that has transmitted/received the PSSCH (16-04) is prepared to transmit or receive the PSFCH (16-05). I can. In addition, after transmission and reception of the PSFCH (16-05), an empty section for a predetermined time can be secured.

14 is a block diagram illustrating an internal structure of a terminal according to an embodiment of the present disclosure.

Specifically, as shown in FIG. 14, the terminal of the present disclosure may include a processor 1410, a transceiver 1420, and a memory 1430.

However, the components of the base station are not limited to the above-described example. For example, the terminal may include more or fewer components than the above-described components. In addition, the processor 1410, the transceiver 1420, and the memory 1430 may be implemented in the form of a single chip. According to the above-described communication method of the base station, the transceiver 1420 and the processor 1410 It can work.

The transceiving unit 1420 may transmit and receive signals with the terminal. Here, the signal may include control information and data. To this end, the transceiver 1420 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. However, this is only an embodiment of the transmission/reception unit 1420, and components of the transmission/reception unit 1420 are not limited to the RF transmitter and the RF receiver.

Also, the transceiver 1420 may receive a signal through a wireless channel and output it to the processor 1410, and transmit a signal output from the processor 1410 through a wireless channel.

The processor 1410 may control a series of processes so that the base station can operate according to the above-described embodiment of the present disclosure. According to an embodiment of the present disclosure, the processor 1410 may set resources for sidelink communication. For example, the processor 1410 may self-set resources for sidelink communication or may be assigned resource settings from the base station based on information received from the base station through the transceiver 1420.

The memory 1430 may store programs and data necessary for the operation of the terminal. In addition, the memory 1430 may store control information or data included in a signal acquired from the terminal. The memory 1430 may include a storage medium such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD, or a memory formed of a combination of storage media. Also, the memory 1430 may be formed of a plurality of memories.

15 is a block diagram illustrating an internal structure of a base station according to an embodiment of the present disclosure.

As shown in FIG. 15, the base station of the present disclosure may include a processor 1510, a transceiver 1520, and a memory 1530.

However, the components of the terminal are not limited to the above-described example. For example, the terminal may include more or fewer components than the above-described components. In addition, the processor 1510, the transceiver 1520, and the memory 1530 may be implemented in the form of a single chip.

The transceiving unit 1520 may transmit and receive signals with a terminal. The above-described signal may include control information and data. To this end, the transceiving unit 1520 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. Also, the transceiver 1520 may receive a signal through a wireless channel and output it to the processor 1510, and transmit a signal output from the processor 1510 through a wireless channel.

The processor 1510 may control a series of processes so that the terminal may operate according to the above-described embodiment of the present disclosure. For example, the processor 1510 may receive a data signal including a control signal through the transceiver 1520 and may determine a reception result of the data signal. The processor 1510 transmits a SL SIB (Sidelink System Information Block) to the terminal when the terminal is in a camp on state, and when a transmission resource request for sidelink communication is received from the terminal, the received transmission resource request On the basis of, downlink control information (DCI) including scheduling information may be controlled to be transmitted to the terminal through the PDCCH.

In the above-described specific embodiments of the present disclosure, components included in the disclosure are expressed in the singular or plural according to the presented specific embodiments. However, the singular or plural expression is selected appropriately for the situation presented for convenience of explanation, and the present disclosure is not limited to the singular or plural constituent elements, and even constituent elements expressed in plural are composed of the singular or expressed Even if it is a component, it can be composed of a plurality.

Meanwhile, although specific embodiments have been described in the detailed description of the present disclosure, various modifications are possible without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure is limited to the described embodiments and should not be defined, 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 (1)

In the method of allocating resources for sidelink communication by a base station, the method comprising: when a terminal is in a camp on state, transmitting an SL Sidelink System Information Block (SIB) to the terminal;
Receiving a transmission resource request for sidelink communication from the terminal; And
And transmitting Downlink Control Information (DCI) including scheduling information to the terminal through a PDCCH based on the transmission resource request.

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