KR20200116295A - Method and apparatus for transmitting and receiving feedback in wireless communication system - Google Patents

Abstract

The present disclosure relates to a communication technique for fusing a 5^th generation (5G) communication system with an Internet of things (IoT) technology to support a higher data transmission rate than that of a 4^th generation (4G) system and a system thereof. The present disclosure can be applied to an intelligent service (for example, smart home, smart building, smart city, smart car or connected car, healthcare, digital education, retail business, security and safety related services, etc.) based on a 5G communication technology and an IoT-related technology. According to the present invention, an effective feedback method in a vehicle to everything (V2X) system is disclosed. A control signal processing method of a vehicle to everything (V2X) transmission terminal in a wireless communication system comprises the steps of: receiving a first control signal transmitted from a base station; generating a second control signal based on the first control signal; and transmitting the second control signal to a V2X reception terminal.

Description

A method and apparatus for sending and receiving feedback in a wireless communication system {METHOD AND APPARATUS FOR TRANSMITTING AND RECEIVING FEEDBACK IN WIRELESS COMMUNICATION SYSTEM}

The present disclosure relates to a method and apparatus for transmitting and receiving feedback information in a wireless communication system, and more particularly, to a method and apparatus for feedback in a V2X (vehicle to everything) system.

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

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

Accordingly, various attempts have been made to apply a 5G communication system to an IoT network. For example, technologies such as sensor network, machine to machine (M2M), and MTC (Machine Type Communication) are implemented by techniques such as beamforming, MIMO, and array antenna, which are 5G communication technologies. will be. 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 addition, vehicle-to-everything (V2X) using a 5G communication system is being studied, and it is expected to be able to provide various services to users using V2X.

The above information is presented only as background information, and is provided to aid understanding of the present invention. No decision has been made and no claim has been made as to whether any of the above can be applied as prior art in connection with the present disclosure.

A technical problem to be achieved in an embodiment of the present invention relates to a method and an apparatus for feedback in a vehicle to everything (V2X) system of a next-generation mobile communication system.

The present invention for solving the above problem is a control signal processing method in a wireless communication system, comprising: receiving, by a V2X transmitting terminal, a first control signal transmitted from a base station; Processing the received first control signal by a V2X transmitting terminal; And transmitting a second control signal generated by the V2X transmitting terminal to the V2X receiving terminal based on the processing.

In addition, the present invention provides a method for processing a control signal for a wireless communication system, comprising: receiving, by a V2X receiving terminal, the second signal transmitted from a V2X transmitting terminal; Processing the received second control signal by a V2X receiving terminal; And transmitting a third control signal generated by the V2X receiving terminal to the V2X transmitting terminal based on the processing.

According to an embodiment of the present invention, an improved method and apparatus for transmitting and receiving feedback in a communication system can be provided. Further, according to an embodiment of the present invention, an improved feedback method and apparatus in a vehicle to everything (V2X) system may be provided.

1 is an example of a system for describing an embodiment of the present disclosure.
2 is an example of a V2X communication method for describing an embodiment of the present disclosure.
3 is an example of a protocol of a terminal for V2X communication according to an embodiment of the present disclosure.
4 is an example of a V2X communication procedure according to an embodiment of the present disclosure.
5 is another example of a V2X communication procedure according to an embodiment of the present disclosure.
6 is another example of a V2X communication procedure according to an embodiment of the present disclosure.
7 is an example of transmitting and receiving feedback information of a V2X terminal according to an embodiment of the present disclosure.
8 is a block diagram illustrating an internal structure of a transmitting terminal according to an embodiment of the present invention.
9 is a block diagram showing the internal structure of a receiving terminal according to an embodiment of the present invention.
10 is a block diagram illustrating an internal structure of a base station according to an embodiment of the present invention.

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 belongs 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 embodiments described later 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, only the present embodiments are intended to complete the present disclosure, and those of ordinary skill in the art to which the present disclosure pertains. It is provided to completely inform the scope of the present disclosure, 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 the case of vehicle communication, in the LTE system, standardization work on V2X technology based on device-to-device (D2D) communication structure was completed in 3GPP Release 14 and Release 15, and V2X technology is currently based on 5G NR. Efforts to develop are underway. 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.

V2X service can be divided into basic safety service and advanced service. The basic safety service may include detailed services such as vehicle notification (CAM or BSM) service, left turn notification service, front vehicle collision warning service, emergency vehicle approach notification service, front obstacle warning service, and intersection signal information service. , V2X information may be transmitted and received using a broadcast or unicast or groupcast transmission method. Advanced service not only strengthens QoS requirements than basic safety service, but also V2X using unicast and groupcast transmission methods in addition to broadcast so that V2X information can be transmitted and received within a specific vehicle group or V2X information between two vehicles. Request a way to transmit and receive information. Advanced services can include detailed services such as platoon driving service, autonomous driving service, remote driving service, and extended sensor-based V2X service.

Hereinafter, a sidelink (SL) refers to a signal transmission/reception path between the terminal and the terminal, which can be mixed with the PC5 interface. Hereinafter, a base station is a subject that performs resource allocation of a terminal, and may be a base station supporting both V2X communication and general cellular communication, or a base station supporting only V2X communication. That is, the base station may mean an NR base station (gNB), an LTE base station (eNB), or a road site unit (RSU). The terminal is a vehicle that supports vehicle-to-vehicle communication (Vehicular-to-Vehicular, V2V) as well as general user equipment and mobile stations, and vehicle-to-pedestrian communication (Vehicular-to-Pedestrian, V2P). ) Supporting vehicle or pedestrian's handset (e.g. smartphone), vehicle supporting communication between vehicle and network (Vehicular-to-Network, V2N), or communication between vehicle and transportation infrastructure (Vehicular-to-Infrastructure) , V2I) support vehicle and an RSU equipped with a terminal function, an RSU equipped with a base station function, or a part of the base station function and an RSU equipped with a part of the terminal function may be included. In addition, the V2X terminal used in the following description may be referred to as a terminal. That is, in relation to V2X communication, the terminal can be used as a V2X terminal.

The base station and the terminal are connected through the Uu interface. Uplink (UL) refers to a radio link through which the UE transmits data or control signals to the base station, and downlink (DL) refers to a radio link through which the base station transmits data or control signals to the UE.

Hereinafter, in various embodiments of the present invention, hybrid automatic repeat request (HARQ) feedback may be used in combination with feedback information and HARQ ACK/NACK.

1 is an example of a system for describing an embodiment of the present disclosure.

1A is an example of a case in which all V2X terminals (UE-1 and UE-2) are located within the coverage of a base station.

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. Alternatively, the data and control information may be data and control information for general cellular communication. In addition, V2X terminals may transmit/receive data and control information for V2X communication through a sidelink (SL).

1B is an example of a case in which UE-1 is located within the coverage of the base station and UE-2 is located outside the coverage of the base station among V2X terminals. The example shown in FIG. 1(b) may be referred to as an example of partial coverage.

UE-1 located within the coverage of the base station 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).

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.

UE-2 can transmit/receive data and control information for V2X communication with UE-1 through a sidelink.

1C is an example of a case where all V2X terminals are located outside the coverage of a base station.

Accordingly, UE-1 and 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.

UE-1 and UE-2 may transmit/receive data and control information for V2X communication through a sidelink.

1D is an example of a scenario for performing V2X communication between terminals located in different cells. Specifically, in FIG. 1d, the V2X transmitting terminal and the V2X receiving terminal are connected to different base stations (RRC connection state) or camping (RRC connection release state, that is, RRC idle state). At this time, UE-1 may be a V2X transmitting terminal and UE-2 may be a V2X receiving terminal. Alternatively, UE-1 may be a V2X receiving terminal, and UE-2 may be a V2X transmitting terminal. UE-1 can receive a V2X-only SIB (System Information Block) from the base station to which it is connected (or it is camping), and UE-2 is It is possible to receive a V2X dedicated SIB from the base station. At this time, the information of the V2X-only SIB received by UE-1 and the information of the V2X-only SIB received by UE-2 may be different from each other. Therefore, it is necessary to unify information in order to perform V2X communication between terminals located in different cells.

1 illustrates a V2X system consisting of two terminals (UE-1 and UE-2) for convenience of description, but is not limited thereto. 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, the terminal is a vehicle supporting vehicle-to-vehicle communication (Vehicular-to-Vehicular: V2V), a vehicle supporting vehicle-to-pedestrian communication (Vehicular-to-Pedestrian: V2P), or a handset of a pedestrian (ie, smart Phone), a vehicle supporting communication between a vehicle and a network (Vehicular-to-Network: V2N), or a vehicle supporting communication between a vehicle and a traffic infrastructure (Vehicular-to-Infrastructure: V2I). 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.

In addition, in the present disclosure, it is predefined that the base station may be a base station supporting both V2X communication and general cellular communication, or a base station supporting only V2X communication. In this case, the base station may mean a 5G base station (gNB), a 4G base station (eNB), or a road site unit (RSU). Therefore, unless otherwise specified in the present disclosure, the base station and the RSU may be used in the same concept and may be used interchangeably.

2 is an example of a V2X communication method performed through a sidelink.

As shown in FIG. 2A, the TX terminal and the RX terminal may perform one-to-one communication, which may be referred to as unicast communication.

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

In FIG. 2B, UE-1, UE-2, and UE-3 form a group (group A) to perform groupcast communication, and UE-4, UE-5, and UE-6 And UE-7 is a diagram showing that another group (group) is formed (group B) to perform groupcast communication. Each terminal performs groupcast communication only within a group to which it belongs, and communication with terminals in different groups may be performed by unicast, groupcast, or broadcast communication methods. Although it is shown that two groups are formed in FIG. 2B, the present invention is not limited thereto. Each group may include at least one terminal, and one terminal may belong to two or more groups.

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. For example, if it is assumed that UE-1 is a transmitting terminal for broadcast in FIG. 2B, all terminals (UE-2, UE-3, UE-4, UE-5, UE-6, and UE -7) may receive data and control information transmitted by UE-1.

Sidelink broadcast, groupcast, and unicast communication methods according to an embodiment of the present invention may be supported in in-coverage, out-of-coverage, and partial-coverage scenarios.

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

Resource allocation in the V2X system can use the following methods.

-Mode 1 resource allocation

It refers to a method of resource allocation scheduled by the base station. More specifically, in mode 1 resource allocation, the base station may allocate resources used for sidelink transmission to RRC-connected terminals in a dedicated scheduling scheme. The scheduled resource allocation method can be effective for interference management and resource pool management (dynamic allocation and/or semi-persistent transmission) because the base station can manage the resources of the sidelink. When there is data to be transmitted to other terminal(s), the RRC connected mode terminal may transmit information notifying the base station that there is data to be transmitted to the other terminal(s) using an RRC message or a MAC control element (CE). have. For example, such an RRC message may be a sidelink terminal information (SidelinkUEInformation), a terminal assistance information (UEAssistanceInformation) message, and the MAC CE is an indicator indicating that the buffer status report (BSR) for V2X communication and sidelink A BSR MAC CE, SR (scheduling request), etc. including at least one of information on the size of data buffered for communication may correspond. The above method is applicable only when the V2X transmitting terminal is within the coverage of the base station because the sidelink transmitting terminal is scheduled for resources by the base station.

-Mode 2 resource allocation

Mode 2 allows the sidelink transmitting terminal to autonomously select resources (UE autonomous resource selection). More specifically, in mode 2, the base station provides a sidelink transmission/reception resource pool for V2X to the terminal as system information or an RRC message (for example, an RRC reconfiguration message, a PC5-RRC message), and the transmitting terminal This is a method of selecting a resource pool and a resource according to a set rule. In the above example, since the base station provides configuration information on the sidelink transmission/reception resource pool, it can be applied when the V2X transmission/reception terminal is in the coverage of the base station. When the V2X transmission/reception terminal exists outside the coverage of the base station, the V2X transmission/reception terminal may perform a mode 2 operation in a preset transmission/reception resource pool. The terminal autonomous resource selection method may include zone mapping, sensing-based resource selection, and random selection.

-In addition, even if it exists in the coverage of the base station, resource allocation or resource selection may not be performed in a scheduled resource allocation or terminal autonomous resource selection mode, in which case the terminal is a preconfigured sidelink transmission/reception resource pool (preconfiguration resource pool). V2X sidelink communication can also be performed through.

3 is an example of a protocol of a terminal for V2X communication according to an embodiment of the present disclosure.

Although not shown in FIG. 3, the application layers of UE-A and UE-B may perform service discovery. In this case, the service discovery may include a discovery of which V2X communication method (ie, unicast, groupcast, broadcast communication method) each terminal will perform. In FIG. 3, it may be assumed that terminal-A and terminal-B recognize that they will perform a unicast communication method through a service discovery process performed in an application layer. NR V2X terminals may obtain information on source ID and destination ID for NR V2X communication in the aforementioned service discovery process.

When the service discovery process is completed, the PC5 signaling protocol layer shown in FIG. 3 may perform a direct link setup procedure between the terminal and the terminal. At this time, security setting information for direct communication between the terminal and the terminal can be exchanged.

When the direct link setup procedure is completed, the PC5 RRC setup procedure between terminals may be performed in the PC5 RRC layer of FIG. 3. At this time, information on the capabilities of UE-A and UE-B may be exchanged, and AS (access stratum) layer parameter information for unicast communication may be exchanged.

When the PC5 RRC setup procedure is completed, UE-A and UE-B may perform unicast communication.

In the above example, unicast communication has been described as an example, but it can be extended to groupcast communication. For example, when UE-A, UE-B, and UE-C perform groupcast communication, the aforementioned service discovery, direct link setup, and PC5 RRC setup procedure between UE-A and UE-B It can be performed in terminal-B and terminal-C, and terminal-A and terminal-C.

4 is an example of a V2X communication procedure according to an embodiment of the present disclosure.

More specifically, it is a diagram for a V2X communication procedure based on mode 1 resource allocation described in FIG. 2. In FIG. 4, the base station may set parameters for V2X communication to V2X transmission/reception terminals in the cell through system information. For example, the base station may set information on a resource pool in which V2X communication can be performed in its cell. In this case, the resource pool may refer to a transmission resource pool for V2X transmission or a reception resource pool for V2X reception. The V2X terminal may receive information on one or more resource pools from the base station. The base station can configure unicast, groupcast, and broadcast communication to be performed in different resource pools through system information or RRC configuration. For example, resource pool 1 may be used for unicast communication, resource pool 2 may be used for groupcast, and resource pool 3 may be used for broadcast communication. As another example, the base station may be configured to perform unicast, groupcast, and broadcast communication within the same resource pool. At least one of the following information may be included in the resource pool information set by the base station.

- Information on the time axis of the resource pool in which the sidelink control channel (PSCCH) and the sidelink data channel (PSSCH) can be transmitted: (Specifically, the slot index in which the PSCCH and PSSCH are transmitted or A slot index in which the PSCCH and PSSCH are transmitted and a symbol index within a corresponding slot) may be included.

- Information on the frequency resource of the sidelink feedback channel (PSFCH: physical sidelink feedback channel): refers to information on the frequency axis in a resource pool in which PSCCH and PSSCH can be transmitted, and specifically a resource block constituting a resource pool It may include an index or an index of a sub-channel composed of two or more resource blocks.

- Information on whether or not sidelink HARQ-ACK is operated may be included in the resource pool configuration information.

● At least one of the following information may be included for a case in which sidelink HARQ-ACK is operated.

□ Maximum number of retransmissions

□ HARQ-ACK timing: It refers to the time from the time when the V2X receiving terminal receives the sidelink control information and data information from the V2X transmitting terminal to the time when the V2X receiving terminal transmits HARQ-ACK/NACK information to the V2X transmitting terminal. do. In this case, the unit of time may be a slot or one or more OFDM symbols.

□ Format of PSFCH: When two or more PSFCH formats are operated, one PSFCH format may be used to transmit HARQ-ACK/NACK information consisting of 1 bit or 2 bits. Another PSFCH format may be used to transmit HARQ-ACK/NACK information consisting of 3 or more bits. Meanwhile, when the aforementioned HARQ-ACK/NACK information is transmitted through PSFCH, ACK information and NACK information may be transmitted through PSFCH, respectively. At this time, when the NR V2X receiving terminal succeeds in decoding the PSSCH transmitted from the NR V2X transmitting terminal, the NR V2X receiving terminal may transmit an ACK to the PSFCH. When decoding fails, NACK can be transmitted through PSFCH. As another example, when the NR V2X receiving terminal succeeds in decoding the PSSCH transmitted from the NR V2X transmitting terminal, it does not transmit an ACK, and only when the decoding fails, the NACK can be transmitted through the PSFCH.

□ A time/frequency/code resource or a set of resources constituting the PSFCH: In the case of a time resource, it may include a slot index or symbol index and period in which the PSFCH is transmitted. In the case of frequency resources, it may include a starting point and an ending point (or a starting point and a length of a frequency resource) of a frequency block (RB) through which the PSFCH is transmitted or a sub channel composed of two or more consecutive blocks.

- Information on whether or not blind retransmission is operated may be included in the resource pool configuration information.

● Blind retransmission, unlike HARQ-ACK/NACK-based retransmission, may mean that the V2X transmitting terminal does not receive feedback information for ACK or NACK from the V2X receiving terminal, and the V2X transmitting terminal repeatedly transmits. When blind retransmission is operated, the number of blind retransmissions may be included in the resource pool information. For example, when the number of blind retransmissions is set to 4, the transmitting terminal may always transmit the same information 4 times when transmitting the PSCCH/PSSCH to the receiving terminal. In this case, a redundancy version (RV) value may be included in sidelink control information (SCI) transmitted through the PSCCH.

- Information on DMRS patterns that can be used in PSSCH transmitted from the corresponding resource pool

● The DMRS pattern that can be used in the PSSCH may be different depending on the speed of the terminal. For example, when the speed is high, it is necessary to increase the number of OFDM symbols used for DMRS transmission in the time axis in order to improve the accuracy of channel estimation. In addition, when the speed of the terminal is slow, since the accuracy of channel estimation can be guaranteed even when a small number of DMRS symbols are used, the number of OFDM symbols used for DMRS transmission in the time axis needs to be reduced to reduce DMRS overhead. . Therefore, the information on the resource pool may include information on the DMRS pattern that can be used in the corresponding resource pool. At this time, two or more DMRS patterns are set in one resource pool, and the V2X transmitting terminal may select and use one DMRS pattern from DMRS patterns set according to its own speed. In addition, the V2X transmitting terminal may transmit information on the DMRS pattern selected by it to the V2X receiving terminal through the SCI of the PSCCH. The V2X receiving terminal may receive this to obtain DMRS pattern information, perform channel estimation for PSSCH, and obtain sidelink data information through demodulation and decoding processes.

- Whether sidelink CSI-RS is operated

● When the sidelink CSI-RS is operated, at least one of the following information may be included.

□ CSI-RS transmission start time: It may mean a start time at which the V2X transmitting terminal should transmit the CSI-RS to the V2X receiving terminal. This start point may refer to an index of a slot through which CSI-RS is transmitted, or may refer to an index of a symbol through which CSI-RS is transmitted, or both a slot and an index of a symbol.

□ CSI reporting (CSI reporting) timing: From the time when the V2X receiving terminal receives the CSI-RS to the V2X transmitting terminal (ie, the received slot index or the symbol index in the received slot) V2X receiving terminal CSI to the V2X transmitting terminal It means the time to the time point at which the report is transmitted (ie, the slot index at which the CSI report is transmitted or the symbol index within the transmitted slot index). In this case, the unit representing time may be a slot or one or more OFDM symbols.

- Parameters for sidelink transmission power control

Although the above-mentioned information is illustrated to be included in the resource pool setting for V2X communication, it is not limited thereto. That is, the above-mentioned information may be set to a V2X transmitting terminal or a V2X receiving terminal independently of a resource pool setting.

As shown in FIG. 4, when data to be transmitted to the V2X transmitting terminal to the V2X receiving terminal occurs, the V2X transmitting terminal uses a scheduling request (SR) or/and a buffer status report (BSR) to the base station to transmit a sidelink to the V2X receiving terminal. You can request resources. The base station receiving the BSR may confirm that the terminal has data for sidelink transmission, and may determine a resource required for sidelink transmission based on the BSR.

The base station transmits a sidelink scheduling grant including at least one of resource information for sidelink control information (SCI) transmission and resource information for sidelink data transmission to the V2X transmitting terminal. The sidelink scheduling grant is information for granting dynamic scheduling in the sidelink, and is downlink control information (DCI) transmitted on a physical downlink control channel (PDCCH). I can. In the sidelink scheduling grant, when the base station is an NR base station, information indicating a bandwidth part (BWP) in which sidelink transmission is performed and a carrier indicator field (CIF) in which sidelink transmission is performed, or a carrier A carrier frequency indicator may be included, and when the base station is an LTE base station, only CIF may be included. In addition, the sidelink scheduling grant may further include information related to resource allocation of a PSFCH that transmits feedback information (A/N information) on the sidelink data. Such resource allocation information may include information for allocating a plurality of PSFCH resources to a plurality of terminals in a group when sidelink transmission is a groupcast. In addition, the resource allocation related information of the feedback information may be information indicating at least one of a plurality of feedback information resource candidate sets set by higher layer signaling.

The V2X transmitting terminal receiving the sidelink scheduling grant transmits the SCI for scheduling sidelink data according to the sidelink scheduling grant to the V2X transmitting terminal over a physical sidelink control channel (PSCCH), and the side Link data is transmitted on a physical sidelink shared channel (PSSCH). The SCI includes resource allocation information used for sidelink data transmission, modulation and coding scheme (MCS) information applied to the sidelink data, group destination ID information, source ID information, and unicast Destination ID (unicast destination ID) information, power control information for controlling sidelink power, timing advance (TA) information, DMRS configuration information for sidelink transmission, information related to packet repetition transmission (for example, It may further include at least one of the number of times, information related to resource allocation during repeated packet transmission, redundancy version (RV), and HARQ process ID. In addition, the SCI includes feedback information (A/N information) for the sidelink data. It may further include information indicating the transmitted resource.

Upon receiving the SCI, the V2X receiving terminal receives the sidelink data. Thereafter, the V2X receiving terminal transmits ACK/NACK information indicating success or failure of decoding the sidelink data to the V2X transmitting terminal over a physical sidelink feedback channel (PSFCH). The transmission of feedback information on the sidelink may be applied to unicast transmission or groupcast transmission, but broadcast transmission is not excluded. If sidelink transmission corresponds to groupcast transmission, each terminal that has received groupcast data may transmit feedback information using different PSFCH resources. Alternatively, each terminal that has received the groupcast data may transmit feedback information using the same PSFCH resource with each other, and in this case, it may feed back only NACK information (that is, the terminal receiving the data does not perform feedback in case of ACK). In this case, the PSFCH resource means not only resources classified in the time or/and frequency domain, but also resources classified using codes such as scrambling code and orthogonal cover code, and different sequences (and sequences). Resources that are classified by using the applied cyclic shift (cyclic shift) may be included.

4 is a state in which the V2X transmitting terminal establishes an uplink connection with the base station (ie, an RRC connection state), and assumes a scenario in which both the V2X transmitting terminal and the V2X receiving terminal exist within the coverage of the base station. Although not shown in Figure 4, when the V2X transmitting terminal has not set uplink connection with the base station (i.e., RRC idle state), the V2X transmitting terminal can perform a random access procedure for setting uplink connection with the base station have. In addition, although not shown in FIG. 4, in a scenario in which the V2X transmitting terminal exists within the coverage of the base station and the V2X receiving terminal exists outside the coverage of the base station, the V2X receiving terminal can use the information for V2X communication previously set. . Meanwhile, the V2X transmitting terminal may receive information for V2X communication from the base station as shown in FIG. 4. When both the V2X transmitting terminal and the V2X receiving terminal exist outside the coverage of the base station, the V2X transmitting terminal and the V2X receiving terminal may receive and use the information for the aforementioned V2X communication in advance. In this case, the meaning of being set in advance may be interpreted as using a value built into the terminal when the terminal is shipped. In another sense, if the V2X transmitting terminal or the receiving terminal has previously obtained information on V2X communication through RRC setting by accessing the base station, or has experience in obtaining information on V2X communication through system information of the base station, It may mean the most recently acquired information.

Although not shown in FIG. 4, it is assumed that before the V2X transmitting terminal transmits the SR/BSR to the base station, the V2X receiving terminal and service discovery, direct link setup procedure, and PC5 RRC configuration have been completed through the procedure mentioned in FIG. can do.

In FIG. 4, unicast communication in which only one V2X receiving terminal exists is described as an example, but the same can be applied to groupcast communication and broadcast communication in which two or more V2X receiving terminals exist.

5 is another example of a V2X communication procedure according to an embodiment of the present disclosure.

More specifically, FIG. 5 is a diagram for a V2X communication procedure based on mode 2 resource allocation described in FIG. 2. In FIG. 5, the base station may set parameters for V2X communication to V2X transmission/reception terminals in the cell through system information. In this case, the parameter may include at least one of the parameter information illustrated in FIG. 4.

As shown in FIG. 5, when data to be transmitted to the V2X receiving terminal is generated from the V2X transmitting terminal, the V2X transmitting terminal transmits the SCI to the V2X transmitting terminal over the PSCCH, and transmits the sidelink data over the PSSCH. The SCI includes resource allocation information used for sidelink data transmission, MCS information applied to the sidelink data, group destination ID information, sender ID information, unicast destination ID information, power control information for controlling sidelink power, timing Advance information, DMRS configuration information for sidelink transmission, packet repetition transmission-related information (for example, at least one of the number of repetitive packet transmissions, resource allocation-related information during packet repetition transmission, redundancy version (RV), and HARQ process ID) In addition, the SCI may further include information indicating a resource through which feedback information (A/N information) for the sidelink data is transmitted.

Upon receiving the SCI, the V2X receiving terminal receives the sidelink data. Thereafter, the V2X receiving terminal transmits ACK/NACK information indicating success or failure of decoding the sidelink data to the V2X transmitting terminal over the PSFCH. The transmission of feedback information on the sidelink may be applied to unicast transmission or groupcast transmission, but broadcast transmission is not excluded. If sidelink transmission corresponds to groupcast transmission, each terminal that has received groupcast data may transmit feedback information using different PSFCH resources. Alternatively, each terminal that has received the groupcast data may transmit feedback information using the same PSFCH resource with each other, and in this case, it may feed back only NACK information (that is, if the terminal receiving the data determines ACK, feedback is not performed). . In this case, the PSFCH resource means not only resources classified in the time or/and frequency domain, but also resources classified using codes such as scrambling code and orthogonal cover code, and different sequences (and sequences). Resources that are classified by using the applied cyclic shift (cyclic shift) may be included.

5 assumes a scenario in which all V2X transmitting and receiving terminals exist within the coverage of the base station. Although not shown in FIG. 5, it may be applied even when all the V2X transmission/reception terminals exist outside the coverage of the base station. In this case, the V2X transmission/reception terminals may receive pre-set information for the aforementioned V2X communication. In addition, although not shown in FIG. 5, one of the V2X transmission/reception terminals may be applied to a scenario in which one terminal exists in the coverage of the base station and the other terminal exists outside the coverage of the base station. In this case, a terminal existing within the coverage of the base station receives information for V2X communication from the base station, and a terminal outside the coverage of the base station may receive information for V2X communication in advance. In the above example,'information for V2X communication' may be interpreted as information on at least one or more of the parameters for V2X communication mentioned in FIG. 4. In addition, in the above example, the meaning of being set in advance can be interpreted as using a value built into the terminal when the terminal is shipped. In another sense, if the V2X transmitting terminal or the receiving terminal has previously obtained information on V2X communication through RRC setting by accessing the base station, or has experience in obtaining information on V2X communication through system information of the base station, It may mean the most recently acquired information.

Although not shown in FIG. 5, before the V2X transmitting terminal transmits the PSCCH/PSSCH to the V2X receiving terminal, the V2X transmitting terminal through the procedure mentioned in FIG. 3 searches for a V2X receiving terminal and a service, a direct link setup procedure, and PC5. It can be assumed that the RRC setting has been completed.

In FIG. 5, unicast communication in which only one V2X receiving terminal exists is described as an example, but the same can be applied to groupcast communication and broadcast communication in which two or more V2X receiving terminals exist.

6 is another example of a V2X communication procedure according to an embodiment of the present disclosure.

More specifically, FIG. 6 is a diagram for a V2X communication procedure based on mode 1 resource allocation described in FIG. 2. Therefore, it may be similar to the V2X communication procedure shown in FIG. 4. However, the difference between FIG. 6 and FIG. 4 is that the base station in FIG. 4 shows a method of transmitting resource allocation information for a sidelink control channel, a sidelink data channel, and a sidelink feedback channel to a V2X transmitting terminal through DCI. However, in FIG. 6, the base station transmits the resource allocation information of the sidelink control channel and the sidelink data channel to the V2X transmitting terminal by using DCI format A, and side by side to the V2X transmitting terminal using another DCI format (DCI format B). A method of transmitting resource allocation information for a link feedback channel is illustrated.

Upon receiving the DCI format B from the base station, the V2X transmitting terminal may transmit at least one of parameter information for SFCI and PSFCH transmission illustrated in FIG. 4 in SCI information transmitted to the V2X receiving terminal. The parameter information for SFCI and PSFCH transmission may include resource allocation information of PSFCH. Upon receiving the SCI, the V2X receiving terminal may transmit the PSFCH to the V2X transmitting terminal using resource allocation information of PSFCH and/or parameter information for SFCI and PSFCH transmission. At this time, HARQ-ACK feedback of all PSSCHs received so far may be multiplexed and transmitted through PSFCH. That is, the PSCCH/PSSCH triggered by DCI format B and transmitted by the V2X transmitting terminal may indirectly trigger multiplexing of HARQ-ACK feedback for the PSSCH received so far from the V2X receiving terminal.

In the above example, DCI format B may mean group common DCI rather than UE-specific DCI. That is, among the V2X transmitting terminals within the coverage of the base station, the DCI is provided to the terminals that are in an RRC connection state with the base station and require SFCI (ie, HARQ-ACK information, CSI feedback information, or both information) transmission. Can be transmitted.

The above embodiment can also be applied to CSI feedback. That is, DCI format B may include CSI triggering information, and the V2X transmitting terminal receiving it includes information on the CSI report of the V2X receiving terminal in the SCI transmitted through the PSCCH, and a reference signal for CSI reporting through the PSSCH. Can be transmitted. In this case, the reference signal for CSI reporting may mean a DMRS transmitted through a PSSCH or a separate sidelink CSI-RS for CSI measurement.

The information for CSI reporting may include information on timing at which CSI is reported (eg, a slot index and a symbol index at which CSI is reported). Meanwhile, the CSI report information reported by the V2X receiving terminal to the V2X transmitting terminal may be transmitted through PSFCH or through PSSCH. When the CSI report information is transmitted to the V2X transmitting terminal through the PSFCH, the information for the CSI report may include information on SFCI and PSFCH transmission parameters as illustrated in FIG. 3 (e.g., bit of SFCI Number, format of PSFCH, time and/or frequency, etc.). In contrast, when the CSI report information is transmitted to the V2X transmitting terminal through the PSSCH, the information for the CSI report may include information on the time and/or frequency resources of the PSSCH transmitted by the V2X receiving terminal to the V2X transmitting terminal. have.

Meanwhile, in FIG. 6, DCI format B is transmitted to the V2X transmitting terminal, and the V2X transmitting terminal receiving the DCI format B was able to transmit the PSCCH and PSSCH to the V2X receiving terminal. In addition, the V2X receiving terminal receiving this was able to transmit the PSFCH to the V2X transmitting terminal after receiving the PSCCH and PSSCH from the V2X transmitting terminal. However, it may not be limited to this. For example, the DCI format B may be directly transmitted to the V2X receiving terminal rather than the V2X transmitting terminal, and the V2X receiving terminal receiving the DCI format B from the base station may transmit the PSFCH to the transmitting terminal. At this time, as in the above example, HARQ-ACK/NACK information for the PSSCH received by the V2X receiving terminal so far may be multiplexed and transmitted through one PSFCH channel.

As another example, DCI format B may trigger CSI reporting, as illustrated above. For example, the base station directly transmits DCI format B to the V2X receiving terminal, and the V2X receiving terminal receiving it may report the CSI to the V2X transmitting terminal. At this time, the DCI format B transmitted by the base station to the V2X receiving terminal may include a parameter for SFCI and PSFCH transmission (when a CSI report is transmitted through PSFCH), or a parameter for PSSCH transmission (CSI report is a PSSCH). If transmitted). In this scenario, it may be assumed that the V2X transmitting terminal transmits a reference signal prior to CSI reporting so that the receiving terminal can measure CSI. For example, DCI format A in FIG. 6 may trigger a V2X transmitting terminal to transmit a reference signal for CSI reporting of a V2X receiving terminal. The V2X transmitting terminal receiving this may transmit a reference signal to the V2X receiving terminal through the PSSCH. The V2X receiving terminal may generate CSI report information using a reference signal for CSI reporting received from the V2X transmitting terminal until DCI format B is received from the base station.

6 is a state in which the V2X transmitting terminal establishes an uplink connection with the base station (ie, an RRC connection state), and assumes a scenario in which both the V2X transmitting terminal and the V2X receiving terminal exist within the coverage of the base station. Although not shown in FIG. 6, when the V2X transmitting terminal has not established an uplink connection with the base station (i.e., RRC idle state), the V2X transmitting terminal can perform a random access procedure for setting uplink connection with the base station. have. In addition, although not shown in FIG. 6, in a scenario in which the V2X transmitting terminal exists within the coverage of the base station and the V2X receiving terminal exists outside the coverage of the base station, the V2X receiving terminal can use the information for the aforementioned V2X communication in advance. . Meanwhile, the V2X transmitting terminal may receive information for V2X communication from the base station as shown in FIG. 6. When both the V2X transmitting terminal and the V2X receiving terminal exist outside the coverage of the base station, the V2X transmitting terminal and the V2X receiving terminal may receive and use the information for the aforementioned V2X communication in advance. In this case, the meaning of being set in advance may be interpreted as using a value built into the terminal when the terminal is shipped. In another sense, if the V2X transmitting terminal or the receiving terminal has previously obtained information on V2X communication through RRC setting by accessing the base station, or has experience in obtaining information on V2X communication through system information of the base station, It may mean the most recently acquired information.

Although not shown in FIG. 6, it is assumed that before the V2X transmitting terminal transmits the SR/BSR to the base station, the V2X receiving terminal and service discovery, direct link setup procedure, and PC5 RRC configuration have been completed through the procedure mentioned in FIG. can do.

In FIG. 6, unicast communication in which only one V2X receiving terminal exists is described as an example, but the same may be applied to groupcast communication and broadcast communication in which two or more V2X receiving terminals exist.

7 is an example of transmitting and receiving feedback information of a V2X terminal according to an embodiment of the present disclosure.

In FIG. 7, the terminal transmitting feedback information may refer to a V2X receiving terminal illustrated in FIGS. 4 and 5 to 6. The V2X terminal may receive information for transmitting the feedback information from the base station or the V2X transmitting terminal. At this time, the information for transmitting the feedback information may include at least information related to the HARQ-ACK operation illustrated in FIGS. 4 and 5 to 6, information regarding the blind retransmission operation, and information for transmitting SFCI and PSFCH. have.

As illustrated in FIGS. 4 and 5 to 6, the information may be set from the base station or the V2X transmitting terminal or may be indicated by the base station or the V2X transmitting terminal. In addition, when the V2X terminal is outside the coverage of the base station, it may be information previously set in the V2X terminal.

Upon receiving the information, the V2X terminal may operate HARQ-ACK or/and blind retransmission using at least one of the following methods.

Method 1) As shown in FIG. 7, blind retransmission may be automatically activated only when HARQ-ACK-based retransmission operation is deactivated. At this time, when HARQ-ACK-based retransmission operation is activated, blind retransmission may be automatically deactivated.

Whether to operate HARQ-ACK-based retransmission may be set or indicated by the base station. As an example, the base station may set the HARQ-ACK-based retransmission enable (enable) or disable (disable) to the V2X transmitting and receiving terminal through system information or RRC configuration.

As another example, the base station may instruct the V2X transceiver terminal to enable or disable HARQ-ACK-based retransmission through DCI. At this time, the DCI information indicating the enable or disable of HARQ-ACK-based retransmission is a 1-bit field or a DCI field used for other purposes is a specific value (for example, all bits are '0'). Alternatively, it may mean that all bits are set to '1').

As another example, the base station sets the activation (enable) or disable (disable) of HARQ-ACK-based retransmission to the V2X transmitting and receiving terminal through the system information or RRC configuration, and the HARQ-ACK-based to the V2X transmitting and receiving terminal through the DCI. Activation or deactivation of retransmission may be indicated again.

As another example, the base station sets the enable (enable) or disable (disable) of HARQ-ACK-based retransmission to the V2X transmitting terminal through RRC configuration, and the activation of HARQ-ACK-based retransmission to the V2X transmitting terminal through the DCI ( activation) or deactivation. In this case, the V2X transmitting terminal may additionally instruct the V2X receiving terminal to activate or deactivate HARQ-ACK-based retransmission.

As another example, as described in FIG. 3, activation or deactivation of HARQ-ACK-based retransmission may be configured from a V2X transmitting terminal through PC5 RRC configuration between terminals.

As another example, the V2X transmitting terminal may instruct the V2X receiving terminal to activate or deactivate HARQ-ACK-based retransmission through sidelink control information (SCI). At this time, the SCI information indicating activation or deactivation of HARQ-ACK-based retransmission is a 1-bit field or a field of SCI used for other purposes has a specific value (for example, all bits are '0'). Alternatively, it may mean that all bits are set to '1').

In the above examples, the base station or the V2X transmitting terminal may determine activation or deactivation of HARQ-ACK-based retransmission through at least one of the following methods.

For example, specific sidelink traffic may have high requirements for V2X communication delay time. Since such traffic requires fast processing, HARQ-ACK-based retransmission may not be desirable. In order to satisfy these requirements, HARQ-ACK based retransmission may be disabled. In this case, blind retransmission may be activated. On the contrary, if the requirement for the delay time of the sidelink traffic is not high, HARQ-ACK-based retransmission may be activated, and at this time, blind retransmission may be deactivated.

As another example, when the amount of resources of the feedback channel for operating HARQ-ACK-based retransmission is insufficient, HARQ-ACK-based retransmission may be deactivated. For example, when the number of group members forming a group in groupcast communication is greater than or equal to a predetermined value, HARQ-ACK-based retransmission may be deactivated. This is because it is necessary to allocate feedback resources for HARQ-ACK operation to each group member. Therefore, when the number of group members is greater than a certain value (or greater than a certain value), HARQ-ACK-based retransmission may be deactivated and blind retransmission may be automatically activated. Otherwise (ie, when the number of group members is less than a certain value or when the number of group members is less than a certain value), HARQ-ACK-based retransmission may be activated and blind retransmission may be deactivated.

Method 2) Although not shown in FIG. 7, blind retransmission may always be activated regardless of activation or deactivation of HARQ-ACK operation.

For example, in broadcast communication, HARQ-ACK-based retransmission may always be disabled. Therefore, only blind retransmission can always be activated in broadcast communication.

As another example, in unicast and groupcast communication, HARQ-ACK-based retransmission may be activated or deactivated. Even when HARQ-ACK-based retransmission is activated, blind retransmission may always be activated. In this case, the V2X transmitting terminal may transmit sidelink control information and data information based on the blind transmission parameters illustrated in FIG. 3 and the HARQ-ACK-based retransmission parameters illustrated in FIG. 3. For example, it may be assumed that the number of blind retransmissions is set to 4 and the maximum number of retransmissions based on HARQ-ACK is set to 2. The V2X transmitting terminal may repeatedly transmit sidelink control information and data information to the V2X receiving terminal 4 times (initial transmission). Upon receiving this, the V2X terminal may receive, combine, and decode sidelink control information and data information. When the result of performing the decoding is ACK, the V2X receiving terminal may transmit HARQ-ACK to the V2X transmitting terminal based on the SFCI and PSFCH parameters mentioned in FIG. 3. If the result of performing the decoding is NACK, the V2X receiving terminal may transmit HARQ-NACK to the V2X transmitting terminal based on the SFCI and PSFCH parameters mentioned in FIG. 3. The V2X transmitting terminal receiving this may repeatedly transmit sidelink control information and data information to the V2X receiving terminal 4 times (retransmission). Upon receiving this, the V2X terminal may receive, combine, and decode sidelink control information and data information. When the result of performing the decoding is ACK, the V2X receiving terminal may transmit HARQ-ACK to the V2X transmitting terminal based on the SFCI and PSFCH parameters mentioned in FIG. 3. When the result of performing the decoding is NACK, the V2X receiving terminal may transmit HARQ-NACK to the V2X transmitting terminal based on the SFCI and PSFCH parameters mentioned in FIG. 3. In the above example, since the maximum number of HARQ retransmissions is assumed to be 2, the V2X transmitting terminal and the V2X receiving terminal may delete the sidelink data information from the buffer. In addition, the aforementioned operation may be repeated using a new HARQ process ID. In the above example, the PSFCH transmitted from the V2X receiving terminal to the V2X transmitting terminal was illustrated to be transmitted without blind retransmission, but blind retransmission may be applied to the PSFCH in the same manner as the sidelink control channel and the data channel. That is, the PSFCH may be repeatedly transmitted 4 times.

Method 3) Although not shown in FIG. 7, if a specific condition is satisfied, blind retransmission may be activated.

For example, when information on the operation of HARQ-ACK-based retransmission is not set from the base station or the V2X transmitting terminal, blind retransmission may be automatically activated. For example, the embodiment may mean that there is no setting of a parameter for operating the HARQ-ACK-based retransmission illustrated in FIG. 4.

As another example, when information on activation of HARQ-ACK-based retransmission is not configured from a base station or a V2X transmitting terminal, blind retransmission may be automatically activated.

As another example, when information on deactivation of HARQ-ACK-based retransmission is configured from a base station or a V2X transmitting terminal, blind retransmission may be automatically activated.

As another example, blind retransmission may be activated from retransmission of HARQ-ACK. More specifically, as in the above example, it may be assumed that the number of blind retransmissions is set to 4 and the maximum number of retransmissions based on HARQ-ACK is set to 2. In this case, sidelink control information and data information initially transmitted by the V2X transmitting terminal may be transmitted without activation of blind retransmission. Upon receiving this, the V2X receiving terminal may receive and decode sidelink control information and data information (because there is no blind retransmission, the combining process is not performed at the receiving end). When the result of performing the decoding is ACK, the V2X receiving terminal may transmit HARQ-ACK to the V2X transmitting terminal based on the SFCI and PSFCH parameters mentioned in FIG. 3. If the result of performing the decoding is NACK, the V2X receiving terminal may transmit HARQ-NACK to the V2X transmitting terminal based on the SFCI and PSFCH parameters mentioned in FIG. 3. The V2X transmitting terminal receiving this may activate blind retransmission and repeatedly transmit sidelink control information and data information to the V2X receiving terminal 4 times (blind retransmission is activated from retransmission). Upon receiving this, the V2X terminal may receive, combine, and decode sidelink control information and data information. When the result of performing the decoding is ACK, the V2X receiving terminal may transmit HARQ-ACK to the V2X transmitting terminal based on the SFCI and PSFCH parameters mentioned in FIG. 3. If the result of performing the decoding is NACK, the V2X receiving terminal may transmit HARQ-NACK to the V2X transmitting terminal based on the SFCI and PSFCH parameters mentioned in FIG. 3. In the above example, since the maximum number of HARQ retransmissions is assumed to be 2, the V2X transmitting terminal and the V2X receiving terminal may delete the sidelink data information from the buffer. In addition, the aforementioned operation may be repeated using a new HARQ process ID. In the above example, the PSFCH transmitted from the V2X receiving terminal to the V2X transmitting terminal was illustrated to be transmitted without blind retransmission, but blind retransmission may be applied to the PSFCH in the same manner as the sidelink control channel and the data channel. That is, the PSFCH may be repeatedly transmitted 4 times.

As another example, in the case of groupcast communication, each group member may feed back ACK information and NACK information to the V2X transmitting terminal. At this time, when receiving NACK information from a certain number of group members or more, the V2X transmitting terminal may activate blind retransmission. For example, one group may assume groupcast communication consisting of 11 people, and one V2X transmitting terminal may receive ACK information and NACK information from 10 V2X receiving terminals, respectively. At this time, when NACK is received from 5 or 5 or more V2X receiving terminals, the V2X transmitting terminal may activate blind retransmission. In this case, the activation information may be included in SCI information transmitted by the V2X transmitting terminal to the V2X receiving terminal. Such activation information is an explicit 1-bit indicating activation of blind retransmission, a field indicating the number of blind retransmissions in SCI information, or when a field of SCI defined for other purposes is set to a specific value (e.g., the corresponding field May include all 0s or all 1s). In addition, the activation information may include information on a slot or symbol to which blind retransmission is applied. Upon receiving the information, the V2X receiving terminal may receive sidelink control information and data information as many times as the number of blind retransmissions, and combine them to perform decoding. In the above example, when blind retransmission is activated, blind retransmission may be applied to the PSFCH transmitted by the V2X receiving terminal to the V2X transmitting terminal.

As another example, in the case of groupcast communication, each group member may feed back only NACK information to the V2X transmitting terminal. As in the above example, one group consisting of 11 people may be assumed. At this time, 10 V2X receiving terminals may feed back NACK information to the V2X transmitting terminal using the same resource. Therefore, the V2X transmitting terminal may not know how many V2X receiving terminals have transmitted NACK information. However, the V2X transmitting terminal may activate blind retransmission when the NACK information is greater than a specific value (or greater than a specific value). Such activation information is an explicit 1-bit indicating activation of blind retransmission, a field indicating the number of blind retransmissions in SCI information, or when a field of SCI defined for other purposes is set to a specific value (e.g., the corresponding field May include all 0s or all 1s). In addition, the activation information may include information on a slot or symbol to which blind retransmission is applied. Upon receiving the information, the V2X receiving terminal may receive sidelink control information and data information as many times as the number of blind retransmissions, and combine them to perform decoding. In the above example, when blind retransmission is activated, blind retransmission may be applied to the PSFCH transmitted by the V2X receiving terminal to the V2X transmitting terminal.

Method 4) Although not shown in FIG. 7, blind retransmission is always activated and may be deactivated according to specific conditions.

For example, when ACK information is received from the V2X receiving terminal, blind retransmission may be deactivated. More specifically, as in the above example, it may be assumed that the number of blind retransmissions is set to 4 and the maximum number of retransmissions based on HARQ-ACK is set to 2. The V2X transmitting terminal may repeatedly transmit sidelink control information and data information to the V2X receiving terminal 4 times (initial transmission). Upon receiving this, the V2X terminal may receive, combine, and decode sidelink control information and data information. When the result of performing the decoding is ACK, the V2X receiving terminal may transmit HARQ-ACK to the V2X transmitting terminal based on the SFCI and PSFCH parameters mentioned in FIG. 3. The V2X transmitting terminal receiving this may deactivate HARQ-ACK-based retransmission. In contrast, when the result of the decoding performed by the V2X receiving terminal is NACK, the V2X receiving terminal may transmit HARQ-NACK to the V2X transmitting terminal based on the SFCI and PSFCH parameters mentioned in FIG. 3. The V2X transmitting terminal receiving this may repeatedly transmit sidelink control information and data information to the V2X receiving terminal 4 times (retransmission). Upon receiving this, the V2X terminal may receive, combine, and decode sidelink control information and data information. When the result of performing the decoding is ACK, the V2X receiving terminal may transmit HARQ-ACK to the V2X transmitting terminal based on the SFCI and PSFCH parameters mentioned in FIG. 3. And the V2X transmitting terminal receiving this can deactivate the HARQ-ACK-based retransmission. However, if the result of the decoding performed by the V2X receiving terminal is NACK again, the V2X receiving terminal may transmit HARQ-NACK to the V2X transmitting terminal based on the SFCI and PSFCH parameters mentioned in FIG. 3. In the above example, since the maximum number of HARQ retransmissions is assumed to be 2, the V2X transmitting terminal and the V2X receiving terminal may delete the sidelink data information from the buffer. In addition, the aforementioned operation may be repeated using a new HARQ process ID. In the above example, the PSFCH transmitted from the V2X receiving terminal to the V2X transmitting terminal was illustrated to be transmitted without blind retransmission, but blind retransmission may be applied to the PSFCH in the same manner as the sidelink control channel and the data channel. That is, the PSFCH may be repeatedly transmitted 4 times.

As another example, the base station may disable blind retransmission based on the congestion state of the sidelink resource pool. In the mode 2 resource allocation scheme described in FIG. 3, the V2X transmitting terminal may perform sensing to select its own transmission resource. At this time, sensing may mean decoding of sidelink control information transmitted from a V2X resource pool set by a base station or preset and/or measuring a reference signal received power (RSRP) of a DMRS transmitted through a sidelink data channel. The V2X transmitting terminals may report the sensing result to the base station to help the base station determine the congestion state of the resource pool. Alternatively, other information capable of determining the congestion state (eg, reference signal strength indicator (RSSI), reference signal received quality (RSRQ), interference information, etc.) may be transmitted to the base station. The base station receiving this may deactivate blind retransmission in the corresponding resource pool. In this case, the base station may deactivate blind retransmission of all V2X transmitting and receiving terminals using the corresponding resource pool, or deactivating blind retransmission of a specific V2X transmitting terminal or a specific V2X transmitting and receiving terminal.

An apparatus for performing embodiments according to the present invention is shown in FIGS. 8, 9 and 10.

8 is a block diagram illustrating an internal structure of a transmitting terminal according to an embodiment of the present invention.

Referring to FIG. 8, the transmitting terminal 800 of the present invention may include a transceiver 810, a control unit 820 and a storage unit 830. The transceiver 810 may transmit and receive signals with a base station or other terminal. The signal may include a synchronization signal, a reference signal, control information, and data. To this end, the transceiver may include an RF transmitter that up-converts and amplifies a frequency of a transmitted signal, and an RF receiver that amplifies a received signal with low noise and down-converts a frequency. In addition, the transceiving unit may receive a signal through a wireless channel, output it to the control unit 820, and transmit a signal output from the control unit 820 through the wireless channel. The controller 820 may control a series of processes so that the transmitting terminal 800 can operate according to the above-described embodiment of the present invention. The control unit 820 may include at least one processor.

9 is a block diagram showing the internal structure of a receiving terminal according to an embodiment of the present invention.

Referring to FIG. 9, the receiving terminal 900 of the present invention may include a transceiver 1910, a control unit 920, and a storage unit 930. The transceiver 910 may transmit and receive signals with a base station or another terminal. The signal may include a synchronization signal, a reference signal, control information, and data. To this end, the transceiver may include an RF transmitter that up-converts and amplifies a frequency of a transmitted signal, and an RF receiver that amplifies a received signal with low noise and down-converts a frequency. In addition, the transceiver may receive a signal through a wireless channel, output it to the control unit 920, and transmit a signal output from the control unit 920 through a wireless channel. The controller 920 may control a series of processes so that the receiving terminal 900 can operate according to the above-described embodiment of the present invention. The control unit 920 may include at least one processor.

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

Referring to FIG. 10, the transmission terminal 1000 of the present invention may include a transmission/reception unit 1010, a control unit 1020, and a storage unit 1030. The transceiver 1010 may transmit and receive signals with a base station or other terminal. The signal may include a synchronization signal, a reference signal, control information, and data. To this end, the transceiver may include an RF transmitter that up-converts and amplifies a frequency of a transmitted signal, and an RF receiver that amplifies a received signal with low noise and down-converts a frequency. In addition, the transceiver may receive a signal through a wireless channel, output it to the control unit 1020, and transmit a signal output from the control unit 1020 through the wireless channel. The controller 1020 may control a series of processes so that the terminal can operate according to the above-described embodiment of the present invention. The control unit 1020 may include at least one processor.

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

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

Claims (1)

In a control signal processing method of a V2X (vehicle to everything) transmitting terminal in a wireless communication system,
Receiving a first control signal transmitted from a base station;
Generating a second control signal based on the first control signal; And
And transmitting the second control signal to a V2X receiving terminal.

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