KR20210009261A - Apparatus and method for controlling congestion in wireless communication system - Google Patents

Abstract

The present invention relates to a fifth-generation (5G) or pre-5G communication system for supporting a higher data rate after a fourth-generation (4G) communication system such as long term evolution (LTE) and, more specifically, to a method for controlling congestion of a channel in a wireless communication system. According to the present invention, an operation method of a first terminal comprises the following processes: receiving a signal for requesting a channel state between the first terminal and a second terminal from the second terminal; measuring the channel state; and transmitting, to the second terminal, information on the channel state generated based on the result of the measurement, wherein the information on the channel state can include information for indicating the degree of congestion of the channel between the first terminal and the second terminal.

Description

Apparatus and method for controlling congestion in a wireless communication system {APPARATUS AND METHOD FOR CONTROLLING CONGESTION IN WIRELESS COMMUNICATION SYSTEM}

The present disclosure generally relates to a wireless communication system, and more particularly, to an apparatus and method for controlling congestion in a wireless communication system.

4G (4 ^th generation) to meet the traffic demand in the radio data communication system increases since the commercialization trend, efforts to develop improved 5G (5 ^th generation) communication system, or pre-5G communication system have been made. For this reason, the 5G communication system or the pre-5G communication system is called a beyond 4G network communication system or a long term evolution (LTE) system and a post LTE system.

In order to achieve a high data rate, 5G communication systems are being considered for implementation in the ultra-high frequency (mmWave) band (eg, such as the 28 giga (28 GHz) or 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 multiple-input multiple-output (MIMO), and full-dimensional multiple input/output (full dimensional MIMO, FD-MIMO), array antenna, analog beamforming, 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, coordinated multi-points (CoMP), and interference cancellation And other technologies are being developed.

In addition, in the 5G system, hybrid frequency shift keying and quadrature amplitude modulation (FQAM) and sliding window superposition coding (SWSC), which are advanced coding modulation (ACM) schemes, and filter bank multi-carrier (FBMC), an advanced access technology. ), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) have been developed.

The Internet is evolving from a human-centered network in which humans create and consume information, to an Internet of Things (IoT) network that exchanges and processes information between distributed components such as objects. Internet of Everything (IoE) 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.

With the development of wireless communication systems, various technologies such as vehicle-to-everything (V2X) may be supported. There is a need for a plan to provide such V2X communication smoothly.

Based on the above discussion, the present disclosure provides an apparatus and method for controlling congestion when vehicle-to-everything (V2X) communication is provided in a wireless communication system.

According to various embodiments of the present disclosure, a method of operating a first terminal in a wireless communication system includes a process of receiving a signal for requesting a channel state between the first terminal and the second terminal from a second terminal, and the channel A process of performing a state measurement, and a process of transmitting information about a channel state generated based on a result of the performed measurement to the second terminal, wherein the information about the channel state comprises the first It may include information for indicating the degree of congestion of the channel between the terminal and the second terminal.

According to various embodiments of the present disclosure, an apparatus of a first terminal in a wireless communication system includes a transmission/reception unit and at least one processor connected to the transmission/reception unit, and the at least one processor is The second terminal receives a signal for requesting a channel state between a terminal 1 and the second terminal, performs measurement on the channel state, and provides information on a channel state generated based on the result of the performed measurement. And the information on the channel state may include information for indicating a degree of congestion of a channel between the first terminal and the second terminal.

The apparatus and method according to various embodiments of the present disclosure enable stable V2X communication to be performed through congestion control in sidelink (SL) communication.

The effects obtainable in the present disclosure are not limited to the above-mentioned effects, and other effects not mentioned may be clearly understood by those of ordinary skill in the technical field to which the present disclosure belongs from the following description. will be.

1A to 1D illustrate examples of scenarios for sidelink communication in a wireless communication system according to various embodiments of the present disclosure.
2A and 2B illustrate examples of a method of transmitting sidelink communication in a wireless communication system according to various embodiments of the present disclosure.
3 illustrates an example of a sidelink resource pool in a wireless communication system according to various embodiments of the present disclosure.
4 illustrates an example of a signal flow for allocating a sidelink transmission resource in a wireless communication system according to various embodiments of the present disclosure.
5 illustrates another example of a signal flow for allocating sidelink transmission resources in a wireless communication system according to various embodiments of the present disclosure.
6 shows an example of a channel structure of a slot used for sidelink communication in a wireless communication system according to various embodiments of the present disclosure.
7A illustrates a first example of a distribution of a feedback channel in a wireless communication system according to various embodiments of the present disclosure.
7B illustrates a second example of a distribution of a feedback channel in a wireless communication system according to various embodiments of the present disclosure.
8 shows an example of a signal flow for measuring and reporting a sidelink channel state in a wireless communication system according to various embodiments of the present disclosure.
9 shows an example of a signal flow for measuring and transmitting a channel busy ratio (CBR) in a wireless communication system according to various embodiments of the present disclosure.
10 illustrates an example for setting a channel occupancy ratio (CR) limitation and a transmission parameter range in a wireless communication system according to various embodiments of the present disclosure.
11 illustrates an example for setting a CR limit and a feedback parameter range in a wireless communication system according to various embodiments of the present disclosure.
12 illustrates a configuration of a terminal in a wireless communication system according to various embodiments of the present disclosure.
13 illustrates a configuration of a base station in a wireless communication system according to various embodiments of the present disclosure.

Terms used in the present disclosure are used only to describe a specific embodiment, and may not be intended to limit the scope of other embodiments. Singular expressions may include plural expressions unless the context clearly indicates otherwise. Terms used herein, including technical or scientific terms, may have the same meaning as commonly understood by one of ordinary skill in the technical field described in the present disclosure. Among the terms used in the present disclosure, terms defined in a general dictionary may be interpreted as having the same or similar meaning as the meaning in the context of the related technology, and unless explicitly defined in the present disclosure, an ideal or excessively formal meaning Is not interpreted as. In some cases, even terms defined in the present disclosure cannot be interpreted to exclude embodiments of the present disclosure.

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

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

In the following description, a term referring to a signal, a term referring to a channel, a term referring to control information, a term referring to network entities, a term referring to a component of a device, etc. are for convenience of description. It is illustrated. Accordingly, the present disclosure is not limited to terms to be described later, and other terms having an equivalent technical meaning may be used.

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

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

In addition, in the present disclosure, in order to determine whether a specific condition is satisfied or satisfied, an expression exceeding or less than is used, but this is only a description for expressing an example, and more or less descriptions are excluded. Not to do. Conditions described as'greater than' may be replaced with'greater than', conditions described as'less than' may be replaced with'less than', and conditions described as'more and less' may be replaced with'greater than and less than'.

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

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

Various attempts are being made to apply the 5G communication system to the IoT network. For example, technologies such as sensor network, machine to nachine (M2M), and machine type communication (MTC) are 5G communication technologies such as beamforming, multiple-input multiple-output (MIMO), and It is implemented by techniques such as an array antenna. It can be understood that the application of a cloud radio access network (RAN) as a big data processing technology is an example of fusion of 5G technology and IoT technology. In this way, a plurality of services can be provided to a user in a communication system, and in order to provide such a plurality of services to users, a method for providing each service within the same time period according to characteristics and an apparatus using the same are required. . 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, based on a device-to-device (D2D) communication structure, the LTE-based vehicle to everything (V2X) system has been standardized in 3GPP Rel-14 and Rel-15, and now 5G NR (new radio) Efforts are being made to develop a V2X system based on it. In the NR V2X system, unicast communication, groupcast (or multicast) communication, and broadcast communication between the terminal and the terminal will be supported. In addition, NR V2X, unlike LTE V2X, which aims to transmit and receive basic safety information necessary for vehicle driving on the road, is group driving (platooning), advanced driving (advanced driving), extended sensor (extended sensor), remote driving (remote driving). It aims to provide more advanced services like this.

In the sidelink of V2X, whether the terminal accesses the channel and the setting range of the transmission parameter may be determined according to whether the corresponding channel is congested. This is a congestion control that allows the terminal to drop transmission when the channel is congested or control channel access through scheduling adjustment, and when accessing a channel, increase the transmission success probability by selecting transmission parameters according to the congestion situation of the channel. This is the (congestion control) function. The terminal measures the channel busy ratio (CBR) and can select a transmission parameter accordingly. CBR is an index indicating how much of the current channel is occupied by UEs, and a range of transmission parameters that can be selected may be determined according to the CBR value. In addition to CBR measurement, the UE may perform congestion control by measuring a channel occupancy ratio (CR). The CR is an index indicating how much the terminal occupies the channel, and the CR limit in which the terminal can occupy the channel may be determined according to the CBR value. For example, when the channel is congested (when the CBR value is measured to be high), the CR limit is set low, and the UE must perform congestion control so that the measured CR does not exceed the CR limit. For example, the terminal must drop transmission or satisfy the CR limitation through scheduling implementation.

In the NR sidelink, hybrid automatic repeat and request (HARQ) positive acknowledge (ACK)/negative acknowledge (NACK) feedback and channel state information (CSI) feedback are considered, so the operation of the transmitting terminal for congestion control compared to the LTE sidelink In addition, the operation of the receiving terminal may be considered with respect to the feedback for transmission. Therefore, an operation of exchanging CBR information between the transmitting terminal and the receiving terminal may be considered. In addition, in the NR sidelink, a retransmission method based on HARQ feedback, which is a method of performing retransmission based on HARQ ACK/NACK feedback as well as a blind retransmission method in which retransmission is performed without HARQ feedback information as a retransmission method, may be supported. When the terminal measures CR, not only a record of occupying and using a channel in the past based on the current point in time, but also a portion permitted to occupy and use the channel in the future may be reflected. In the case of the retransmission method based on HARQ ACK/NACK feedback, the resource reserved for the retransmission may not be performed when the transmitting terminal reserves the resource to occupy and use it in the future, but when an ACK is reported from the receiving terminal, the resource reserved for retransmission is released. Can be. Therefore, this should be reflected when measuring CR. Hereinafter, embodiments for performing congestion control in the NR sidelink will be described in detail in the present disclosure.

Various embodiments of the present disclosure are intended to perform congestion control in a process in which a vehicle terminal supporting V2X transmits and receives information using a side link with another vehicle terminal and a pedestrian portable terminal. Specifically, the transmitting terminal may determine whether the channel is congested by measuring the CBR and CR, and determine whether the terminal accesses the channel and the setting range of the transmission parameter according to the determination result. In addition, in the present disclosure, an operation of a base station and an operation of a terminal according to various embodiments will be described in detail.

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

1A illustrates an in-coverage (IC) scenario in which sidelink terminals 120 and 125 are located within the coverage 110 of the base station 100. The sidelink terminals 120 and 125 may receive data and control information from the base station through downlink (DL) or transmit data and control information to the base station through uplink (UL). In this case, the data and control information may be data and control information for sidelink communication, or data and control information for general cellular communication other than sidelink communication. In addition, in FIG. 1A, the sidelink terminals 120 and 125 may transmit and receive data and control information for sidelink communication through the sidelink.

1B shows partial coverage in which the first terminal 120 is located within the coverage 110 of the base station 100 and the second terminal 125 is located outside the coverage 110 of the base station 100 among sidelink terminals. , PC). The first terminal 120 located within the coverage 110 of the base station 100 may receive data and control information from the base station through downlink or transmit data and control information to the base station through uplink. The second terminal 125 located outside the coverage of the base station 100 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 second terminal 125 may transmit and receive data and control information for sidelink communication through the sidelink with the first terminal 120.

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

1D shows that the first terminal 120 and the second terminal 125 performing sidelink communication are connected to different base stations (eg, the first base station 100, the second base station 105), or : RRC connection state) or when camping (eg, RRC connection release state, that is, RRC idle state), inter-cell sidelink communication is performed. In this case, the first terminal 120 may be a sidelink transmitting terminal, and the second terminal 125 may be a sidelink receiving terminal. Alternatively, the first terminal 120 may be a sidelink receiving terminal, and the second terminal 125 may be a sidelink transmitting terminal. The first terminal 120 may receive a sidelink dedicated system information block (SIB) from the base station 100 to which it is connected (or camping), and the second terminal 125 is It is possible to receive a sidelink-only SIB from another base station 105 (or it is camping). In this case, the information of the sidelink-only SIB received by the first terminal 120 and the information of the sidelink-only SIB received by the second terminal 125 may be different from each other. Accordingly, in order to perform sidelink communication between terminals located in different cells, information may be unified or an assumption and interpretation method thereof may be additionally required.

In the examples of FIGS. 1A to 1D, for convenience of explanation, a sidelink system consisting of two terminals (eg, a first terminal 120 and a second terminal 125) has been described as an example. It is not limited and may be applied to a sidelink system in which three or more terminals participate. Further, the uplink and downlink between the base station 100 and the sidelink terminals may be referred to as a Uu interface, and a sidelink between the sidelink terminals may be referred to as a PC5 interface. In the following description, uplink or downlink and Uu interface, sidelink, and PC5 may be mixed.

Meanwhile, in the present disclosure, the 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 (eg: 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 an infrastructure (vehicular-to-infrastructure, V2I). . In addition, in the present disclosure, the terminal may mean a road side unit (RSU) equipped with a terminal function, an RSU equipped with a base station function, or an RSU equipped with a part of the base station function and a part of the terminal function.

In addition, in the present disclosure, 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 be a 5G base station (gNB), a 4G base station (eNB), or an RSU. Therefore, in this disclosure, the base station may be referred to as an RSU.

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

As shown in FIG. 2A, the transmitting terminal 200 and the receiving terminal 205 may perform one-to-one communication. The transmission scheme shown in FIG. 2A may be referred to as unicast communication. As shown in FIG. 2B, the transmitting terminal 230 or 245 and the receiving terminals 235, 240, 250, 255, and 260 may perform one-to-many communication. The transmission scheme shown in FIG. 2B may be referred to as groupcast or multicast. In FIG. 2B, the first terminal 230, the second terminal 235, and the third terminal 240 form a group, perform groupcast communication, and the fourth terminal 245, 5 The terminal 250, the sixth terminal 255, and the seventh terminal 260 form different groups and perform groupcast communication. Terminals may perform groupcast communication within a group to which they belong, and may perform unicast, groupcast, or broadcast communication with at least one other terminal belonging to different groups. In FIG. 2B, two groups are illustrated, but the present invention is not limited thereto and may be applied even when a larger number of groups are formed.

Meanwhile, although not shown in FIGS. 2A or 2B, sidelink terminals may perform broadcast communication. Broadcast communication refers to a method in which all sidelink terminals receive data and control information transmitted by a sidelink transmission terminal through a sidelink. For example, if the first terminal 230 in FIG. 2B is a transmitting terminal, the remaining terminals 235, 240, 245, 250, 255, 260 receive data and control information transmitted by the first terminal 230. can do.

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

In the case of the NR sidelink, unlike in the LTE sidelink, 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 are supported. Can be considered. For example, when considering a service scenario such as platooning, which is a technology that connects two or more vehicles to one network and moves in a cluster form, such unicast and groupcast technologies can be usefully used. Specifically, unicast communication may be used for the purpose of a group leader terminal connected by platooning to control one specific terminal, and groupcast for the purpose of simultaneously controlling a group consisting of a plurality of specific terminals. Communication can be used.

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

A resource allocation unit on the time axis within the resource pool may be one or more orthogonal frequency division multiplexing (OFDM) symbols. In addition, resource granularity on the frequency axis may be one or more physical resource blocks (PRBs).

When a resource pool is allocated in the time domain and the frequency domain, a region composed of shaded resources indicates a region set as a resource pool in time and frequency. In the present disclosure, a case in which a resource pool is non-contiguously allocated in time is described, but the present invention is not limited thereto and may be applied even when a resource pool is continuously allocated in time. In addition, in the present disclosure, a case in which a resource pool is continuously allocated on a frequency will be described, but the present invention is not limited thereto and may be applied even when a resource pool is non-consecutively allocated on a frequency.

Referring to FIG. 3, the time domain 300 of the set resource pool exemplifies a case in which resources are non-contiguously allocated in the time domain. In the time domain 300 of the resource pool, a granularity of resource allocation on the time axis may be a slot. Specifically, one slot composed of 14 OFDM symbols may be a basic unit of resource allocation on the time axis. Referring to the time domain 300 of the set resource pool, the shaded slots represent slots allocated to the resource pool in time, and slots allocated to the resource pool in time may be indicated using system information. For example, slots allocated to the resource pool in time may be indicated using resource pool configuration information in time within the SIB. Specifically, at least one slot set as a resource pool in time may be indicated through a bitmap. Referring to FIG. 3, physical slots 300 belonging to a non-contiguous resource pool on the time axis may be mapped to logical slots 325. In general, a set of slots belonging to a resource pool for a physical sidelink shared channel (PSSCH) may be expressed as (t ₀ , t ₁ , ??, t _i , ??, tT _max ).

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

Referring to FIG. 3, the start position of the subchannel 3-31 on the frequency in the resource pool may be indicated by the startRB-Subchannel 315. When resource allocation is performed in units of subchannels 310 in the frequency axis, an RB index (startRB-Subchannel) 315 at which the subchannel 310 starts, indicating how many RBs the subchannel 310 is composed of A resource pool setting on a frequency may be performed through information for (sizeSubchannel) and configuration information on the total number of subchannels 310 (numSubchannel). According to various embodiments, subchannels allocated to a resource pool on a frequency may be indicated using system information. For example, at least one of startRB-Subchannel, sizeSubchannel, and numSubchannel may be indicated as frequency resource pool configuration information in the SIB. When the subchannel for the PSFCH is defined independently from the PSSCH, subchannel configuration information of the PSFCH and PSSCH may be indicated, respectively.

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

As described below, a method in which the base station allocates transmission resources for sidelink communication may be referred to as mode 1. Mode 1 is a scheme based on scheduled resource allocation 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 according to a dedicated scheduling scheme. Since the base station can manage the resources of the sidelink, scheduled resource allocation is advantageous for interference management and resource pool management (eg, dynamic allocation and/or semi-persistent transmission).

Referring to FIG. 4, in step 407, the transmitting terminal 401 camping on 405 may receive a sidelink SIB from the base station 403. In step 409, the receiving terminal 402 may receive a sidelink system information block (SIB) from the base station 403. Here, the receiving terminal 402 refers to a terminal that receives data transmitted by the transmitting terminal 401. The sidelink SIB can be transmitted periodically or on demand. In addition, the sidelink SIB is among sidelink resource pool information for sidelink communication, parameter setting information for sensing operation, information for setting sidelink synchronization, or carrier information for sidelink communication operating at different frequencies. It may include at least one. Steps 407 and 409 have been sequentially described above, but this is for convenience of description, and steps 407 and 409 may be performed in parallel.

In step 413, when data traffic for sidelink communication is generated in the transmitting terminal 401, the transmitting terminal 401 may be RRC connected to the base station 403. Here, the RRC connection between the transmitting terminal 401 and the base station 403 may be referred to as Uu-RRC. The Uu-RRC connection may be performed before the transmission terminal 401 generates data traffic. In addition, in the case of mode 1, in a state in which a Uu-RRC connection is established between the base station 403 and the receiving terminal 402, the transmitting terminal 401 may perform transmission to the receiving terminal 402 through a sidelink. In addition, in the case of mode 1, the transmitting terminal 401 can transmit to the receiving terminal 402 through a sidelink even when a Uu-RRC connection is not established between the base station 403 and the receiving terminal 402. have.

In step 415, the transmitting terminal 401 may request a transmission resource for performing sidelink communication with the receiving terminal 402 from the base station 403. At this time, the transmitting terminal 401 transmits the sidelink to the base station 403 by using at least one of an uplink physical uplink control channel (PUCCH), an RRC message, or a media access controller (MAC) control element (CE). You can request a transmission resource for. For example, when the MAC CE is used, the MAC CE is at least one of an indicator for indicating that the buffer status report for sidelink communication and information on the size of data buffered for device-to-device (D2D) communication It may be MAC CE for a buffer status report (BSR) having a new format including one. In addition, when PUCCH is used, the transmitting terminal 401 may request a sidelink resource through a bit of a scheduling request (SR) transmitted through an uplink physical control channel.

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

In the case of the dynamic grant scheme, the base station 403 transmits the DCI to the transmitting terminal 401 to allocate resources for one TB (transport block) transmission. The sidelink scheduling information included in the DCI may include a parameter related to an initial transmission time point and/or a transmission time point of retransmission, and a parameter related to a frequency allocation location information field. The DCI for the dynamic grant scheme may be scrambled with a cyclic redundancy check (CRC) based on a sidelink-v2x-radio network temporary identifier (SL-V-RNTI) to indicate that the transmission resource allocation scheme is a dynamic grant scheme.

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

When broadcast transmission is performed between the terminals 401 and 402, in step 419, the transmitting terminal 401 broadcasts the SCI to the receiving terminal 402 through the PSCCH without additional sidelink RRC setting (step 411). can do. Further, in step 421, the transmitting terminal 401 may broadcast data to the receiving terminal 402 through the PSSCH.

When unicast or groupcast transmission is performed between the terminals 401 and 402, in step 411, the transmitting terminal 401 may perform a one-to-one RRC connection with other terminals (eg, the receiving terminal 402). have. In this case, in order to distinguish from the Uu-RRC, the RRC connection between the terminals 401 and 402 may be referred to as PC5-RRC. In the case of the groupcast transmission method, the PC5-RRC connection may be individually established between the terminal and the terminal in the group. Referring to FIG. 4, the connection of PC5-RRC (step 411) is shown as an operation after transmission of the sidelink SIB (steps 407 and 409), but before transmission of the sidelink SIB or broadcast of the SCI (step 419) ) May be done before. If the RRC connection between the terminals is required, the PC5-RRC connection of the sidelink is performed, and in step 419, the transmitting terminal 401 can transmit the SCI to the receiving terminal 402 through PSCCH by unicast or groupcast. have. At this time, the groupcast transmission of SCI may be understood as a group SCI. In addition, in step 421, the transmitting terminal 401 may transmit data to the receiving terminal 402 through the PSSCH through unicast or groupcast. In the case of mode 1, the transmitting terminal 401 may identify sidelink scheduling information included in the DCI received from the base station 403, and perform sidelink scheduling based on the sidelink scheduling information. SCI may include the following scheduling information.

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

* New data indicator (NDI) field

* Redundancy version (RV) field

* Information field for indicating reservation interval

In the information field for indicating the reservation interval, when resources for a plurality of TBs (ie, a plurality of media access controller (MAC) protocol data units (PDUs)) are selected, an interval between TBs is fixed. It is indicated as one value, and when a resource for one TB is selected, '0' may be indicated as a value of an interval between TBs.

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

As described below, a method in which the UE directly allocates sidelink transmission resources through sensing in the sidelink may be referred to as mode 2. Mode 2 may also be referred to as UE autonomous resource selection. Specifically, according to mode 2, the base station 503 provides the sidelink transmission/reception resource pool for the sidelink to the terminal as system information or an RRC message (eg, RRC reconfiguration (RRCReconfiguration) message, PC5 RRC message), and the transmitting terminal (501) selects a resource pool and a resource according to a set rule. Unlike mode 1 in which the base station is directly involved in resource allocation, mode 2 described in FIG. 5 may autonomously select resources and transmit data based on a resource pool previously received by the transmitting terminal 501 through system information. .

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

In the case of FIG. 4 described above, the base station 503 and the transmitting terminal 501 operate in a state in which the RRC is connected, whereas in FIG. 5, the base station 503 and the transmitting terminal 501 have the base station 503 in step 513. And it can operate regardless of whether the RRC is connected between the transmitting terminal 501. That is, the base station 503 and the transmitting terminal 501 may operate in an idle mode 513 in which RRC is not connected. In addition, even in a state in which the RRC is connected, the base station 503 may operate so that the transmitting terminal 501 autonomously selects a transmission resource without being directly involved in resource allocation. In this case, the RRC connection between the transmitting terminal 501 and the base station 503 may be referred to as Uu-RRC.

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

When broadcast transmission is performed between the terminals 501 and 502, in step 519, the transmitting terminal 501 broadcasts the SCI to the receiving terminal 502 through the PSCCH without additional sidelink RRC setup (step 513). can do. Further, in step 521, the transmitting terminal 501 may broadcast data to the receiving terminal 502 through the PSSCH.

When unicast and groupcast transmission is performed between the terminals 501 and 502, in step 511, the transmitting terminal 501 may perform a one-to-one RRC connection with other terminals (eg, the receiving terminal 502). have. In this case, in order to distinguish from the Uu-RRC, the RRC connection between the terminals 501 and 502 may be referred to as PC5-RRC. In the case of the groupcast transmission method, PC5-RRC connection is individually established between terminals in the group. In FIG. 5, the PC5-RRC connection (step 511) is shown as an operation after transmission of the sidelink SIB (steps 507 and 509), but is performed before transmission of the sidelink SIB or before transmission of the SCI (step 519). It could be. If the RRC connection between the terminals is required, the PC5-RRC connection of the sidelink is performed, and in step 519, the transmitting terminal 501 can transmit the SCI to the receiving terminal 502 through PSCCH by unicast or groupcast. have. At this time, the groupcast transmission of SCI may be understood as a group SCI. In addition, in step 521, the transmitting terminal 501 may transmit data to the receiving terminal 502 through the PSSCH through unicast or groupcast. In the case of mode 2, the transmitting terminal 501 may directly perform sidelink scheduling by performing sensing and transmission resource selection operations. SCI may include the following scheduling information.

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

* New data indicator (NDI) field

* Redundancy version (RV) field

* Information field for indicating reservation interval

The information field for indicating the reservation interval is indicated as one value in which an interval between TBs is fixed when a resource for a plurality of TBs (ie, a plurality of MAC PDUs) is selected, and one When a resource for TB is selected, '0' may be indicated as a value of an interval between TBs.

6 shows an example of a channel structure of a slot used for sidelink communication in a wireless communication system according to various embodiments of the present disclosure. 6 illustrates physical channels mapped to a slot for sidelink communication. Referring to FIG. 6, a preamble 615 is mapped before the start of the slot 600, that is, to the rear end of the previous slot 605. Thereafter, from the start of the slot 600, the PSCCH 620, the PSSCH 625, the gap 630, the PSFCH 635, and the gap 640 are mapped.

Before transmitting a signal in the corresponding slot 600, the transmitting terminal transmits a preamble 615 in one or more symbols. The preamble may be used to correctly perform automatic gain control (AGC) for adjusting the intensity of amplification when the receiving terminal amplifies the power of the received signal. In addition, the preamble may or may not be transmitted depending on whether the transmission terminal transmits the previous slot 605. That is, when the transmitting terminal transmits a signal to the same terminal in a previous slot (eg, slot 605) of the corresponding slot (eg, slot 600), transmission of the preamble 615 may be omitted. The preamble 615 is a'sync signal', a'sidelink sync signal', a'sidelink reference signal', a'midamble', a'initial signal', a'wake-up signal', or It may be referred to as other terms having an equivalent technical meaning.

The PSCCH 620 including control information is transmitted using symbols transmitted at the beginning of the slot, and the PSSCH 625 scheduled by the control information of the PSCCH 620 may be transmitted. At least a part of SCI, which is control information, may be mapped to the PSSCH 625. Thereafter, a gap 630 exists, and a PSFCH 635, which is a physical channel for transmitting feedback information, is mapped.

In the case of FIG. 6, the PSFCH 635 is illustrated as being located at the last part of the slot. By securing a gap 630, which is an empty time of a predetermined time between the PSSCH 625 and the PSFCH 635, the terminal transmitting or receiving the PSSCH 625 prepares for transmitting or receiving the PSFCH 635 (e.g. : Transmit/receive conversion) can be performed. After the PSFCH 635, a gap 640 that is an empty period for a predetermined time exists.

The UE may receive a position of a slot capable of transmitting the PSFCH in advance. The preset reception may be determined in advance during the process of making the terminal, or may be transmitted when accessing a sidelink-related system, or transmitted from the base station when accessing the base station, or may be transmitted from another terminal.

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

7A illustrates a first example of a distribution of a feedback channel in a wireless communication system according to various embodiments of the present disclosure. 7A illustrates a case in which a resource capable of transmitting and receiving PSFCH is allocated in every slot. In FIG. 7A, an arrow indicates a slot of a PSFCH in which HARQ-ACK feedback information corresponding to a PSSCH is transmitted. Referring to FIG. 7A, HARQ-ACK feedback information for the PSSCH 711 transmitted in the slot 701 is transmitted in the PSFCH 722 of the slot 702. Since the PSFCH is allocated to every slot, the PSFCH may correspond 1:1 to the slot including the PSSCH. For example, when configuring a period of a resource capable of transmitting and receiving PSFCH by a parameter such as periodicity_PSFCH_resource, in the case of FIG. 7A, periodicity_PSFCH_resource indicates 1 slot. Alternatively, the period may be set in units of msec, and the period may be indicated as a value allocated for every slot according to a subcarrier spacing (SCS).

7B illustrates a second example of a distribution of a feedback channel in a wireless communication system according to various embodiments of the present disclosure. 7B illustrates a case in which resources are allocated to transmit/receive PSFCH in every 4 slots. In FIG. 7B, an arrow indicates a slot of a PSFCH through which HARQ-ACK feedback information corresponding to a PSSCH is transmitted. Referring to FIG. 7B, only the last slot 754 of the four slots 751, 752, 753 and 754 includes the PSFCH 774. Similarly, only the last slot 758 of the next four slots 755, 756, 757, 758 contains the PSFCH 778. Accordingly, HARQ-ACK feedback information for the PSSCH 761 of the slot 751, the PSSCH 762 of the slot 752, and the PSSCH 763 of the slot 753 is in the PSFCH 774 of the slot 754 Is sent. Similarly, the HARQ-ACK feedback information for the PSSCH 765 of the slot 755, the PSSCH 766 of the slot 756, and the PSSCH 767 of the slot 757 is the PSFCH 778 of the slot 758. Is sent from Here, the index of the slot may be an index of slots included in the resource pool. That is, the four slots are not actually consecutive slots, but may be consecutively listed slots among slots included in a resource pool (or slot pool) used for sidelink communication between terminals. The reason that the HARQ-ACK feedback information of the PSSCH transmitted in the fourth slot is not transmitted in the PSFCH of the same slot may be due to insufficient time for the UE to finish decoding the PSSCH transmitted in the corresponding slot and transmit the PSFCH in the same slot. . That is, it may be because the minimum processing time required to process the PSSCH and prepare the PSFCH is not sufficiently small.

Therefore, the UE receiving the PSSCH in slot n uses the smallest x among integers greater than or equal to K when the resource for transmitting the PSFCH in slot n+x is set or given, and the HARQ-ACK feedback of the PSSCH. Information is transmitted using the PSFCH of slot n+x. K may be a value preset from the transmitting terminal, or may be a value set in a resource pool through which the corresponding PSSCH or PSFCH is transmitted. In order to set K, each terminal can exchange its capability information with the transmitting terminal in advance. For example, K may be determined according to at least one of a subcarrier interval, a terminal capability, a setting value with a transmitting terminal, or a resource pool setting.

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

In step 805, the transmitting terminal 801 transmits a sidelink channel state information reference signal (CSI-RS) to the receiving terminal 802. That is, the transmitting terminal 801 transmits the sidelink CSI-RS to obtain channel information from the receiving terminal 802, and the receiving terminal 802 receives the sidelink CSI-RS. In addition, the transmitting terminal 801 may request the receiving terminal 802 to report sidelink channel state information (CSI). Sidelink CSI reporting may be enabled or disabled.

In step 807, the receiving terminal 802 measures the channel state of the sidelink between the transmitting terminal 801 and the receiving terminal 802 by using the received sidelink CSI-RS.

In step 809, the receiving terminal 802 generates information on the sidelink CSI by using the channel state measurement result. That is, when sidelink CSI reporting is enabled, the receiving terminal 802 may generate information about the CSI measurement result for reporting to the transmitting terminal 801.

In step 811, the receiving terminal 802 may transmit the sidelink CSI to the transmitting terminal 801. In the present invention, sidelink CSI-RS transmission and sidelink CSI reporting are considered when unicast transmission is performed between a terminal and a terminal in the sidelink. That is, in the case of broadcast transmission, sidelink CSI-RS transmission and sidelink CSI reporting may not be supported. In addition, in the case of groupcast transmission, the sidelink CSI-RS transmission and sidelink CSI reporting method for groupcast are not considered. Therefore, when the terminal does not operate in unicast through the PC5-RRC connection, the transmitting terminal of the sidelink cannot receive the SL CSI report from the receiving terminal. In addition, in the case of unicast transmission between terminals of the sidelink, only the aperiodic sidelink CSI report is considered.

The present disclosure is for performing congestion control in the sidelink of V2X communication, and according to whether the corresponding channel of the sidelink is congested, it is determined whether the terminal accesses the channel, and through a limitation on the setting range of the transmission parameter Congestion control is performed. That is, when the channel is congested, the terminal drops transmission or controls channel access through scheduling adjustment, and when the terminal accesses the channel, the transmission success probability is selected by selecting a transmission parameter based on the congestion situation of the channel. This can be improved.

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

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

** CBR measurement from a transmission point of view may be performed for the PSSCH region. Referring to FIG. 6, it is assumed that the PSSCH region and the PSCCH region are located in adjacent resource regions. Here, when the frequency resource region to which the PSSCH is allocated and the frequency region in which the PSCCH is transmitted overlap, the PSSCH region and the PSCCH region are interpreted as adjacent. When the PSSCH region and the PSCCH region are not located in adjacent resource regions, CBR measurement may be performed in the PSCCH region.

According to another embodiment, CBR measurement from a transmission point of view may be performed simultaneously for both the PSSCH region and the PSCCH region. 6, a PSSCH related to a part of the PSCCH is transmitted on a non-overlapping frequency resource and a temporal resource that overlaps, but according to another example, there may be a case where a related PSSCH and at least a part of the PSCCH are transmitted on a non-overlapping time resource. I can. Here, the meaning of “related” means that the PSCCH includes at least information necessary to decode the PSSCH. As described above, when the PSCCH and the PSSCH are multiplexed, the transmission power of the PSCCH region and the PSSCH region is constant. Accordingly, under the assumption that the RSSI can be measured in the same manner in the PSCCH region and the PSSCH region, the CBR measurement can be simultaneously performed in both regions without discriminating between the PSSCH region and the PSCCH region. Specifically, RSSI may be measured in symbols of the PSCCH region and the PSSCH region in FIG. 6. When the PSCCH and PSSCH are multiplexed as shown in FIG. 6, it may be difficult for the UE to distinguish between the PSCCH region and the PSSCH region when measuring CBR. Accordingly, the CBR measurement can be performed in both symbols of the PSCCH region and the PSSCH region without distinguishing between the PSCCH region and the PSSCH region.

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

** CBR measurement in terms of feedback for transmission may be performed for the PSFCH region. The above measurement can be described with reference to the PSFCH region shown in FIGS. 6 and 7.

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

** X is a value of the size of a window in which CBR is measured, and X may be a fixed value or a settable value.

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

**** SCS=15kHz, μ=0

**** SCS=30kHz, μ=1

**** SCS=60kHz, μ=2

**** SCS=120kHz, μ=3

Among the above two setting methods, when X=100·2 ^μ is set, the CBR window is fixed at 100 ms regardless of the SCS. When X=100 is set, the CBR window is displayed according to the SCS. This is how the measurement time (ms) can vary.

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

*** Here, the configured subchannel may mean a subchannel allocated as a resource pool. Also, the subchannel may be set differently according to the corresponding channel. For example, the PSSCH has a minimum configurable subchannel size of 4 RB and a maximum of 20 subchannels may be allocated. The PSFCH has a minimum configurable subchannel size of 2 RB, and a maximum of 40 subchannels can be allocated. The present invention is not limited thereto, and the size of the subchannel or the maximum number of subchannels may vary according to the SCS.

It may be determined whether the corresponding channel is congested based on the CBR value measured by the definition of the CBR. The terminal may report the measured CBR to the base station. Specifically, when the base station and the terminal are connected by Uu-RRC, the CBR value measured by the terminal may be reported to the base station through Uu-RRC. In mode 1 of the sidelink resource allocation schemes, when the transmitting terminal requests a transmission resource for performing sidelink communication with the receiving terminal from the base station, the base station can allocate the transmission resource using the reported CBR information. In addition, the base station may determine transmission parameter information such as pattern information of PSSCH demodulation reference signal (DMRS), modulation and coding scheme (MCS) configuration, and the number of transport layers, and instruct the determined transmission parameter information to the terminal. have. As described above, the base station may signal allocation information for transmission resources to the transmitting terminal through DCI. The base station may indicate transmission parameter information such as PSSCH DMRS pattern information, MCS configuration, and the number of transport layers through an upper layer. For example, the base station may transmit transmission parameter information to the terminal through Uu-RRC. However, the present invention does not exclude that transmission parameter information such as pattern information of PSSCH DMRS, MCS configuration, and number of transport layers is signaled through DCI. When the sidelink CSI report is transmitted from the receiving terminal, it is necessary to dynamically change the transmission parameter based on the sidelink CSI. In this case, the transmitting terminal does not follow transmission parameters such as PSSCH DMRS pattern information, MCS configuration, and number of transport layers signaled by the base station, but directly based on sidelink CSI, PSSCH DMRS pattern information, MCS configuration, and transport layer. Transmission parameters such as the number of can be determined.

Meanwhile, in mode 2 of the sidelink resource allocation schemes, the terminal must not only perform direct resource allocation through sensing, but also determine channel access and transmission parameters by reflecting the CBR measured by the terminal. Accordingly, in mode 2, the terminal may perform congestion control by measuring a channel occupancy ratio (CR) together with a CBR measurement. In this case, the priority of the packet may be reflected. When the transmitting terminal transmits a packet, a value for indicating the priority of the packet may be transmitted to the receiving terminal through SCI. The CR is an index indicating how much the terminal occupies the channel, and the CR limit that the terminal can occupy the channel may be determined according to the CBR value. For example, when the channel is congested (that is, when the CBR value is measured to be high), the CR limit is set low, and the UE must perform congestion control so that the measured CR does not exceed the CR limit. In order to perform congestion control, the UE must drop transmission or make the CR measured through scheduling implementation satisfy the CR limit. When the channel is not congested (i.e., when the CBR value is measured to be low), the CR limit is set high, and the possibility that the measured CR does not exceed the CR limit is increased.Therefore, it is better for the terminal to occupy and use the channel. It could be possible.

Hereinafter, various embodiments of an operation of a terminal for performing congestion control in the NR sidelink will be described.

<First embodiment>

According to the first embodiment of the present disclosure, in mode 2, the terminal may measure the CR for congestion control. Among the sidelink resource allocation schemes, when the terminal selects a resource through sensing in mode 2, the terminal can reserve a resource for transmission of one TB or reserve a resource for transmission of a plurality of TBs. have. The setting of whether to reserve a resource for transmission of one TB or a plurality of TBs may be determined from a higher level. In addition, in mode 2, the terminal may reserve resources for not only initial transmission of the TB, but also retransmission of the corresponding TB. When the terminal reserves a transmission resource through sensing in mode 2, when the terminal measures CR, assuming that transmission occurs from the reserved resource, not only the record used by occupying the channel in the past but also the future The portion that is to be used by occupying the channel can be calculated. Accordingly, the CR measured for PSSCH transmission in slot n may be defined as follows.

Definition of CR measured for PSSCH transmission

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

** Here, the channel corresponds to the PSSCH.

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

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

N의 조건을 만족시키도록 단말 구현에 의해 결정된 값일 수 있다. 여기서, M=1000 및 N=500이 사용될 수 있으나 이에 한정되지 않는다. M 및 N의 값들이 설정 가능한 경우에, M 및 N의 값들은 자원 풀 설정 정보에 포함될 수 있다. 단말이 기지국과 RRC 연결되기 전에는 단말에서 해당 값들이 미리 구성되거나 기지국으로부터 SIB을 통해 설정 받을 수 있다. 단말이 기지국과 RRC 연결된 이후에는 단말-특정된(UE specific) 값으로 설정 받을 수 있다. 예를 들어, M은 {1000·2^μ, 1000} 슬롯들 중 하나의 값으로, N은 {500·2^μ, 500} 슬롯들 중 하나의 값으로 자원 풀 설정 정보를 통해 설정 가능할 수 있다. 여기서, μ는 뉴머랄러지(numerology)에 해당하는 인덱스(index)이며 SCS (subcarrier spacing)에 따라 다음과 같은 값으로 설정된다.*** M and N are a+b+1=M and a

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

**** SCS=15kHz, μ=0

**** SCS=30kHz, μ=1

**** SCS=60kHz, μ=2

**** SCS=120kHz, μ=3

Among the above two setting methods, when M=1000·2 ^μ and N=500·2 ^μ are set, the CBR window is fixed at 100 ms regardless of SCS, and when M=1000 and N=500 are set. , This is a method in which the measurement time (ms) of the CBR window may vary depending on the SCS.

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

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

** As described through the third embodiment below, CR may be measured for a priority level.

** Depending on whether the above-described transmission type such as broadcast, unicast, and groupcast can be simultaneously set in one resource pool or separately set for each resource pool, the CR measurement method may be different. According to the definition of CR, when different transmission types can be simultaneously set in one resource pool, the CR can be measured simultaneously for all transmission types. When different transmission types are defined to be divided into resource pools and configured, the CR may be classified and measured for each transmission type. Here, broadcast may be referred to as a first transmission type, unicast may be referred to as a second transmission type, and groupcast may be referred to as a third transmission type.

According to the CR value measured based on the above definition, the degree of channel occupancy of the terminal may be determined by reflecting how many channels have been occupied by the terminal in the past and how many channels will be occupied in the future. In addition, the terminal must perform congestion control so that the CR value measured as described above does not exceed the CR limit determined by the CBR. Therefore, it is necessary to accurately measure CR. According to the above description, when the terminal reserves a transmission resource through sensing in mode 2, the CR is defined under the assumption that transmission occurs from the reserved resource. However, depending on the retransmission scheme supported by the NR sidelink, this assumption cannot always be satisfied. Therefore, in order to solve the above-described problem, a method of always setting the b value to 0 may be considered. When b is set to 0, it means that the CR calculation is not applied to the resource allowed to occupy and use the channel at the time slot [n, n+b], that is, the reserved transmission resource. However, setting b to 0 does not take into account the fairness of channel occupancy between a terminal allowed to use a large number of resources at a time slot [n, n+b] and a terminal that does not. Therefore, in the following, a method in which transmission is not performed on the reserved transmission resource is considered.

Specifically, in the NR sidelink, HARQ feedback-based retransmission that performs retransmission based on HARQ-ACK/NACK feedback as well as blind retransmission not based on HARQ-ACK feedback information as a retransmission method will be supported. I can. In the case of the blind retransmission method, retransmission is necessarily performed regardless of whether the initial transmission and reception of the retransmission are successful. However, in the case of the HARQ feedback-based retransmission method, whether to retransmit may be determined based on the ACK/NACK feedback result. In addition, in mode 2 of the NR sidelink, the UE may reserve transmission resources through sensing for blind retransmission and HARQ feedback-based retransmission methods. In addition, in the case of the HARQ feedback-based retransmission method, reserved transmission resources may be released based on the HARQ ACK/NACK feedback. For example, when the transmitting terminal receives an ACK for a previous transmission, a resource reserved for a next retransmission may be released. That is, in the definition of the above-described CR, when the terminal reserves a transmission resource through sensing, the assumption that transmission must occur in the reserved resource is not satisfied. Therefore, in order to accurately measure CR, a case in which the reserved resources can be released must be considered. When the case in which the reserved resource can be released is not considered, the greater the maximum number of HARQ feedback-based retransmissions and the greater the number of resource reservations for transmission of a plurality of TBs, the greater the accuracy of the CR measurement. I can. To solve this problem, in the definition of the above-described CR, in the case of calculating the sum of the number of subchannels allowed to occupy and use the channel at the time of slot [n, n+b], the following retransmission method The calculation method can be applied.

Method of applying weighted sum when HARQ feedback-based retransmission is used

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

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

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

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

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

** Method 5: It is defined as W(i)=0(i>1). In other words, no weighted sum is applied.

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

In the case where the definition of the CR measured for the PSSCH transmission and retransmission based on HARQ feedback are used, the measurement value of the CR to which the weighted sum is applied may be expressed by <Equation 1> below.

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

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

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

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

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

* NumMAXReTX: Maximum number of retransmissions supported for one TB

<Equation 1> represents the CR calculation method proposed by the present invention when HARQ feedback-based retransmission is used, and may be modified into other expressions having the same meaning. In addition, in Equation 1, when W(i)=1 is applied to all i, the weighted sum can be applied to the blind retransmission method.

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

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

In evaluating SL CR, the UE shall assume the transmission parameter used at slot n is reused according to the existing grant(s) in slot [n+1, n+b] without packet dropping if SL HARQ feedback is disabled.
In evaluating SL CR, the UE shall assume the transmission parameter used at slot n is reused according to the existing grant(s) in slot [n+1, n+b] and the existing grant(s) can be released by the UE if SL HARQ feedback is enabled.

Referring to <Table 1>, when evaluating the SL CR, when the SL HARQ feedback is deactivated, the UE transmits the transmission parameter used in slot n to the existing grant(s) of slot [n+1, n+b] without dropping packets. Can be assumed to be reused accordingly. In addition, when evaluating the SL CR, the UE reuses the transmission parameter used in slot n according to the existing grant(s) of slot [n+1, n+b], and if SL HARQ feedback is deactivated, the existing grant(s) May be released by the UE. As described above, a blind retransmission method for performing retransmission without based on HARQ feedback information and a HARQ feedback-based retransmission method for performing retransmission based on HARQ ACK/NACK feedback It is considered in this NR sidelink. The two retransmission schemes described above may be classified and used according to a transmission type. In the case of broadcast communication, since HARQ feedback is not supported, blind retransmission may be used. In the case of unicast or groupcast communication, since HARQ feedback is supported, at least one of blind retransmission or HARQ feedback-based retransmission method may be configured and used.

In the above-described embodiment, the case of blind retransmission and the case of HARQ feedback-based retransmission have been described separately. However, the present invention is not limited thereto, and blind retransmission and HARQ feedback-based retransmission may be simultaneously configured and used in mode 2 of the NR sidelink. For example, when up to 4 retransmissions are allowed, blind retransmission is used up to 2 retransmissions, and whether additional retransmission is performed may be determined based on HARQ feedback. That is, based on the HARQ feedback result, whether or not additional retransmission may be determined. For example, blind retransmission is performed until the first two retransmissions, and when NACK is continuously received, additional HARQ feedback-based retransmission may be performed or two blind retransmissions may be performed. In general, by considering the above method, when the number of blind retransmissions is set to A, the number of HARQ feedback-based retransmissions is set to B, and a maximum of four retransmissions are allowed, examples in which A and B are set as follows: Can be considered.

* Example 1: A=0, B=4

* Example 2: A=1, B=1

* Example 3: A=1, B=2

* Example 4: A=2, B=0

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

<Second Example>

According to a second embodiment of the present disclosure, an operation for a terminal to measure CBR for congestion control in a sidelink of V2X and a method for a transmitter and a receiver to exchange CBR information are proposed. In the NR sidelink, not only CBR measurement for transmission but also CBR measurement for feedback of transmission may be considered. In the case of LTE sidelink, HARQ ACK/NACK feedback or sidelink CSI feedback is not considered. However, in the case of the NR sidelink, since HARQ ACK/NACK feedback and sidelink CSI feedback are considered, not only the operation of the transmitting terminal but also the operation of the receiving terminal with respect to the transmission feedback may be considered for congestion control. Accordingly, the transmitting terminal can measure the CBR from the viewpoint of transmission, and the receiving terminal can measure the CBR from the viewpoint of feedback for transmission. The CBR measurement of the terminal in the sidelink may be defined as a default feature or may be defined as an optional feature. In addition, a case in which CBR is not used through setting by an upper layer regardless of CBR measurement capability may also be considered. When CBR measurement is set as a selectable operation, the CBR measurement capability can be classified into four cases as shown in Table 2 below according to the CBR measurement capability of the transmitting terminal and the receiving terminal.

Referring to <Table 2>, when the CBR measurement of the terminal is determined as a basic operation in the sidelink, the CBR measurement capability of the terminal may correspond to the fourth case.

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

The transmitting end may be understood as a subject that transmits a signal, and the receiving end may be understood as a subject receiving the signal. Accordingly, in the V2X system, transmitting terminals can operate as a transmitting end and a receiving terminal can operate as a receiving end. That is, the CBR measurement according to the CBR measurement capability of the transmitting terminal and the receiving terminal and, if necessary, an operation of transmitting the CBR measured by the transmitting terminal to the receiving terminal or transmitting the CBR measured by the receiving terminal to the transmitting terminal are described in FIG. 9.

Referring to FIG. 9, in step 905, the transmitting end 901 and the receiving end 902 exchange information on CBR capability. As described above, when the transmitting terminal measures CBR from the viewpoint of transmission and the receiving terminal measures CBR from the viewpoint of transmission feedback, the transmitting terminal and the receiving terminal may need information on each other's CBR capabilities. For example, when a transmitting terminal and a receiving terminal obtain information on each other's CBR capability, when the transmitting terminal requests sidelink CSI, it may be instructed to feed back the sidelink CSI by reflecting the CBR to the receiving terminal. As another example, if the receiving terminal has CBR capability, assuming that it is the default operation for the receiving terminal to report the sidelink CSI based on CBR, the transmitting terminal may determine whether the CBR is reflected in the SL CSI reported by the receiving terminal. I can. In addition, the difference between the CBR measured by the transmitting terminal and the CBR measured by the receiving terminal may increase according to the environment of the transmitting terminal and the receiving terminal. Therefore, when the transmitting terminal and the receiving terminal know each other's CBR capabilities, they can request each other's CBR information if necessary. Information on the CBR capability of the sending terminal and the receiving terminal can be exchanged during the PC5-RRC connection process. As described in FIGS. 4 and 5, in the case of unicast transmission of the sidelink, PC5-RRC connection may be performed between terminals.

As shown in FIG. 9, a transmitting terminal or a receiving terminal having CBR measurement capability may perform CBR measurement (steps 907 and 909). In addition, a situation in which the transmitting terminal or the receiving terminal is unable to measure the CBR may occur despite the ability to measure CBR according to the situation of the sidelink. In addition, the difference between the CBR measured by the transmitting terminal and the CBR measured by the receiving terminal may increase according to the environment of the transmitting terminal and the receiving terminal. In this case, in step 911, the transmitting end may transmit the CBR measurement result to the receiving end, or in step 913, the receiving end may transmit the CBR measurement result to the transmitting end. In FIG. 9, steps 911 and 913 are shown to be sequentially performed, but this is for convenience of description, and steps 911 and 913 may be performed regardless of the order.

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

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

In addition, when both the transmitting terminal and the receiving terminal have CBR measurement capability, steps 911 to 913 may be performed.

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

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

Alternatively, the CBR measurement result may be transmitted according to an indicator for instructing transmission of the CBR measurement result. For example, the transmitting terminal receiving the CBR measurement capability of the receiving terminal may transmit an indicator for instructing the receiving terminal to transmit the CBR measurement result. Accordingly, the transmitting terminal can receive the CBR measurement result from the receiving terminal.

When the transmitting end and the receiving end have CBR information of each other, the transmitting end and the receiving end can more accurately determine the congestion situation of the channel. Specifically, the CBR level may be determined using both the CBR level (RX (receive)) of the receiving end and the CBR level (TX) of the transmitting end. For example, the CBR level may be determined based on Max (CBR level (TX), CBR level (RX)), which is a maximum value among the CBR level of the transmitting end and the CBR level of the receiving end. In this case, the worst case for the CBR of each of the transmitting end and the receiving end may be considered. Hereinafter, CBR information of the transmitting end and the receiving end described in the second embodiment may be reflected in order to set the CR limit reflecting the CBR and the range of the transmission and feedback parameters.

<Third Example>

According to the third embodiment of the present disclosure, congestion control may be performed so that the CR value measured based on the CR defined in the first embodiment does not exceed the CR limit determined by the CBR. When the terminal receives the CR restriction using the higher parameter and the terminal transmits the PSSCH in slot n, the priority value k must satisfy the condition of Equation 2 below.

는 SCI에 우선 순위 필드의 우선 순위 레벨(priority level)이 i로 설정된 PSSCH 전송에 대해서 슬롯 n-Y에서 측정된 CR값을 의미한다. 여기서, Y의 값은 CR을 측정하고 슬롯 n에서 PSSCH 전송을 하기 전까지 필요한 프로세싱 시간으로서, 슬롯의 단위로 정의될 수 있으며, Y의 값은 고정된 값이거나 설정 가능한 값일 수 있다. here,

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

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

μ (in slot) 0 2 One 2 2 3 3 4

는 n-Y에서 측정된 CR값과 우선 순위의 값 k에 대응하도록 결정되는 CR 제한 값으로서, 상위 파라미터를 이용하여 설정될 수 있다. 구체적으로, 슬롯 n-Y에서 측정된 CBR값에 의해서 CR 제한 값이 결정될 수 있다. 이하 도 10에서 상세하게 설명된다. 단말은 슬롯 n에서 PSSCH의 전송을 드롭(drop)하거나, 단말 구현을 통해 <수학식 2>의 CR 제한을 만족시켜야 한다. <수학식 2>는 사이드링크 CSI가 PSSCH를 통해 전송되는 경우에 사이드링크 CSI를 전송하는 단말에도 적용될 수 있다. 사이드링크 CSI를 전송하는 단말이 PSSCH를 통해 사이드링크 CSI를 보고하는 경우, 단말이 측정한 CR이 <수학식 2>의 조건을 만족시키지 못하면, 단말이 사이드링크 CSI의 보고를 드롭하거나 단말 구현을 통해 <수학식 2>의 CR 제한을 만족시키도록 하는 동작이 고려될 수 있다.In <Table 3>, the value of Y that varies depending on the SCS is proposed based on the PSSCH preparation time in the NR system. Specifically, in the NR system, it is assumed that the PUSCH preparation time is 10 symbols when μ=0, 12 symbols when μ=1, 23 symbols when μ=2, and 36 symbols when μ=3. For example, When the value of Y is one fixed value, it can be Y=4. In addition, when the value of Y can be set, information for indicating the value of Y may be included in the resource pool setting information. Before the terminal is RRC-connected with the base station, corresponding values may be pre-configured in the terminal and may be set from the base station through the SIB. After RRC connection with the base station, it may be set to a terminal-specific value. In addition, the value of Y may be set through the PC5-RRC connection between the terminal and the terminal. Also,

Is a CR limit value determined to correspond to the CR value measured in nY and the priority value k, and may be set using an upper parameter. Specifically, the CR limit value may be determined by the CBR value measured in slot nY. It will be described in detail in FIG. 10 below. The UE must drop the transmission of the PSSCH in slot n or satisfy the CR limitation of Equation 2 through UE implementation. <Equation 2> can also be applied to a terminal transmitting the sidelink CSI when the sidelink CSI is transmitted through the PSSCH. When the terminal transmitting the sidelink CSI reports the sidelink CSI through the PSSCH, if the CR measured by the terminal does not satisfy the condition of <Equation 2>, the terminal drops the report of the sidelink CSI or implements the terminal. Through this, an operation to satisfy the CR limit of Equation 2 may be considered.

In the above-described <Equation 2>, the performance of congestion control by the transmitting terminal is described through the CR measurement for the PSSCH. However, in the NR sidelink, performance of congestion control by the receiving terminal may be considered through the CR measurement for the PSFCH. As described above, when the HARQ feedback-based retransmission method is used, HARQ feedback information is transmitted to the PSFCH, and as described in FIGS. 6 and 7, CBR may be measured in a region in which the PSFCH is transmitted. Accordingly, congestion control can be performed so that the CR limit determined by the CBR measured in the region in which the PSFCH is transmitted is not exceeded. When the terminal receives the CR restriction through the higher parameter and the receiving terminal transmits the HARQ ACK/NACK feedback to the transmitting terminal through the PSFCH in slot n, the priority value k is expressed by <Equation 3>. The following conditions must be satisfied.

Here, CR ^FB (i) refers to a CR value measured in slot nZ for a PSFCH through which HARQ ACK/NACK feedback for PSSCH transmission in which the priority level of the field is set to i in SCI is transmitted. Here, the value of Z is a processing time required before measuring CR and transmitting PSFCH in slot n, and may be defined in units of slots. The value of Z may be a fixed value or a settable value.

는 n-Z에서 측정된 CR값과 우선 순위의 값 k에 대응하도록 결정되는 CR 제한 값으로 상위 파라미터를 통해 설정될 수 있다. 구체적으로, 슬롯 n-Z에서 측정된 CBR값에 의해서 CR 제한 값이 결정될 수 있다. 이에 대해 도 11에서 상세히 설명된다. 단말은 슬롯 n에서 PSFCH에 HARQ ACK/NACK 전송을 드롭하거나 단말 구현을 통해 <수학식 3>의 CR 제한을 만족시켜야 한다. Alternatively, unlike this, the value of Z may be determined according to the SCS as shown in Table 3 above. For example, when the value of Z is one fixed value, Z=4. In addition, when the value of Z is configurable, information for indicating the value of Z may be included in the resource pool configuration information. Before the terminal is RRC-connected with the base station, corresponding values may be pre-configured in the terminal and may be set from the base station through the SIB. After RRC connection with the base station, it may be configured to be UE-specific. In addition, the value of Y may be set through a PC5-RRC connection between the terminal and the terminal. Also, refer to the definition of the CR measured for PSFCH transmission by the receiving terminal below. Also,

Is a CR limit value determined to correspond to the CR value measured in nZ and the priority value k, and may be set through an upper parameter. Specifically, the CR limit value may be determined by the CBR value measured in slot nZ. This will be described in detail in FIG. 11. The UE must drop HARQ ACK/NACK transmission on the PSFCH in slot n or satisfy the CR limitation of Equation 3 through UE implementation.

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

Definition of CR measured for PSFCH transmission

* CR is defined as a value obtained by dividing the number of subchannels used by the UE by occupying the channel at the time point of slot [n-a, n-1] by the total number of subchannels set as PSCFH at the time point of slot [n-a, n-1].

** Here, the channel corresponds to the PSFCH.

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

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

*** For example, when a is determined to be a fixed value, a value of a=500 may be considered. However, the value of a may be determined as another value. Alternatively, when the value of a can be set, information for indicating the value of a may be included in the resource pool configuration information. Before the terminal is RRC-connected with the base station, corresponding values may be pre-configured in the terminal and may be set from the base station through the SIB. After RRC connection with the base station, the value of a may be set to UE-specifically.

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

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

In the case where the UE performs HARQ ACK/NACK feedback through the PSFCH through Equation 3, the performance of congestion control using CBR and CR has been described. In the above-described embodiment, even when the HARQ ACK/NACK feedback is deactivated and the HARQ feedback-based retransmission method is used, when the condition of <Equation 3> is not satisfied for congestion control, the receiving terminal transmits to the transmitting terminal. This is for an operation that does not perform HARQ ACK/NACK feedback. In addition, other congestion control methods may be considered for HARQ ACK/NACK feedback. That is, the CBR measurement value for the PSFCH channel may be used without using the CR measurement of Equation 3>. In this case, the CBR measurement value for the PSFCH channel can be used by both the transmitting terminal and the receiving terminal. When HARQ ACK/NACK feedback is deactivated and the HARQ feedback-based retransmission method is used, the transmitting terminal measures the CBR for the PSFCH channel, and when the measured value is greater than the set threshold, the transmitting terminal requests HARQ ACK/NACK feedback from the receiving terminal. Can be canceled. Specifically, the transmitting terminal may indicate HARQ ACK/NACK feedback cancellation information by including 1 bit information in the SCI. In contrast, when HARQ ACK/NACK feedback is deactivated and the HARQ feedback-based retransmission method is used, when the receiving terminal measures the CBR for the PSFCH channel and the measured value is greater than the set threshold, HARQ ACK/NACK to the receiving terminal No feedback can be used. Here, the threshold value may be included in the resource pool setting information. Before the terminal is RRC-connected with the base station, corresponding values may be pre-configured in the terminal and may be set by the base station through the SIB. After the terminal is RRC connected to the base station, the threshold value may be set terminal-specifically. Also, the threshold may be set through a PC5-RRC connection between the terminal and the terminal.

<Fourth embodiment>

According to the fourth embodiment of the present disclosure, congestion control may be performed by setting a CR limit according to CBR and determining a range of a settable transmission parameter according to CBR. CBR can be measured as a value between 0 and 100, but can be quantized according to the CBR range. For example, X CBR levels may be classified, and a CBR measurement result may be mapped to a CBR level corresponding to a corresponding CBR range. Accordingly, in the sidelink, the CR limit and the range of transmission parameters that can be set may be determined according to the CBR level and the priority of the packet to be transmitted. The terminal may perform congestion control through the CBR and the CR limit mapped to the highest priority of the packet to be transmitted and a range of transmission parameters. Hereinafter, in FIG. 10, an example in which the CR limit and the transmission parameter range are set according to the priority of CBR and packet in the sidelink is shown.

Referring to FIG. 10, through a resource pool setting 1010, a CR limit 1060 corresponding to a CBR level 1030 and a priority 1020 of a packet to be transmitted and a range of transmission parameters 1070 are set. Here, the range of the CR limit and transmission parameter corresponding to the CBR level determined through the resource pool setting and the priority of the packet to be transmitted can be configured in advance in the terminal before the terminal is RRC connected to the base station, and is set through the SIB from the base station. I can receive it. After the terminal is RRC-connected to the base station, the terminal may receive the above-described values terminal-specifically. In addition, the CR limit corresponding to the CBR level and the priority of the packet to be transmitted and the range of transmission parameters may be set through a PC5-RRC connection between the terminal and the terminal. According to FIG. 10, the measured CBR may be mapped to a minimum value and a maximum value of a CBR range set according to a corresponding CBR level and used. According to Fig. 10, the CBR level is. It can be divided into up to X CBR levels. Details of the range of transmission parameters (tx-Parameters) are described in detail in Table 4 below.

As described above, congestion control may be performed through the setting of the transmission parameter range. For example, when the channel is congested (when the CBR value is measured to be high), the size of the subchannel to which the PSSCH is allocated is reduced, the maximum value of the transmission power is decreased, and the number of retransmissions is reduced, thereby allowing the terminals to Interference can be minimized. At the same time, it may be possible to adjust the transmitted signal to be successfully received by setting the MCS low and reducing the number of transport layers. Therefore, setting the range of the transmission parameter by reflecting the CBR is advantageous in order to select a parameter suitable for the channel condition along with congestion control. A method of setting a transmission parameter range will be described in detail through an example of <Table 4> below. The transmission parameter set (SL-PSSCH-TxParameters) described in <Table 4> is the MCS setting range (minMCS-PSSCH, maxMCS-PSSCH), PSSCH DMRS pattern information (additional-dmrsPSSCH), and the number of transport layers (Txlayer-NumberPSSCH). ), as well as the subchannel allocation range (minSubChannel-NumberPSSCH, maxSubchannel-NumberPSSCH), and the number of retransmissions (allowedRetxNumberPSSCH). In addition, under the assumption that CBR measurement is used, the transmission parameter set (SL-PSSCH-TxParameters) may include maximum transmission power information (maxTxPower). Some of the parameters included in the transmission parameter set (SL-PSSCH-TxParameters) described in Table 4 below may not be used or other parameters may be additionally considered.

In <Table 4>, minMCS-PSSCH and maxMCS-PSSCH may be used to indicate the MCS configuration range. Alternatively, a method of configuring only maxMCS-PSSCH to select an MCS in a range smaller than maxMCS-PSSCH may also be considered. In addition, in <Table 4>, Txlayer-NumberPSSCH represents the number of transport layers, n1 represents layer 1 transmission, and n2 represents layer 2 transmission. In addition, both means that the terminal can autonomously set the setting for the 1/2 layer. In <Table 4>, allowedRetxNumberPSSCH means the setting of the number of retransmissions of the terminal, n0 means no retransmissions, and n1, n2, n3 each means 2, 3, and 4 retransmissions including initial transmission. Also, all means that the terminal can autonomously set the corresponding value. In <Table 4>, a subchannel allocation range may be indicated through minSubChannel-NumberPSSCH and maxSubchannel-NumberPSSCH. Here, the maximum number of subchannels (maxSubChannel) may vary according to the channel bandwidth and SCS. In <Table 4>, maxTxPower indicates the maximum transmission power value limited for congestion control when CBR is used. In <Table 4>, the additional-dmrsPSSCH is pattern information of the PSSCH DMRS and means the number of additional DMRS symbols. When the additional-dmrsPSSCH is set to 0, only the front-loaded DMRS is transmitted, and when the additional DMRS symbol is set to 3, the maximum 4 DMRS symbols including the front-loaded DMRS are transmitted. DMRS pattern information other than the number of additional DMRS symbols may be included. Here, the density of the DMRS may be increased through the additional-dmrsPSSCH, thereby improving the channel estimation performance in a low SNR region, thereby improving the reception performance.

The transmission parameter set (SL-PSSCH-TxParameters) of <Table 4> may be set regardless of CBR. As described in the second embodiment, an operation in which CBR is not used through higher-level configuration may also be considered. The case in which the transmission parameter set (SL-PSSCH-TxParameters) is set regardless of CBR may be applicable only when there is no SL CSI report. In other words, when there is an SL CSI report, the transmission parameter set (SL-PSSCH-TxParameters) cannot be set regardless of the CBR. When there is an SL CSI report, the transmitting terminal determines the channel state through SL CSI and selects a transmission parameter. In this case, whether there is an SL CSI report or not may be determined by one of the following conditions.

Conditions for determining whether there is an SL CSI report

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

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

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

Condition 1 is a method of determining that SL CSI reporting exists when SL CSI reporting is deactivated. Condition 2 is a method of determining that there is an SL CSI report when the SL CSI report is deactivated and the SL CSI report is activated. Condition 1 and condition 2 may be the same or different depending on how the SL CSI report is triggered and/or activated. For example, when SL CSI reporting is deactivated, a case in which SL CSI reporting is triggered/activated corresponds to a case where condition 1 and condition 2 are the same. In addition, condition 3 is a method of determining that there is an SL CSI report when the actual transmitting terminal receives the CSI report from the receiving terminal. If there is no SL CSI report under condition 3, a transmission parameter set (SL-PSSCH-TxParameters) may be set regardless of CBR. If there is no SL CSI report, since the transmitting terminal cannot know the terminal-to-terminal channel state, it may be difficult to select a transmission parameter so that the receiving terminal successfully receives the data transmitted by the transmitting terminal. Accordingly, in this case, a set of transmission parameters (SL-PSSCH-TxParameters) may be determined for each synchronization source of the terminal according to the absolute speed of the transmitting terminal. Here, the synchronization source may be at least one of a base station or a global navigation satellite system (GNSS). In the case of a terminal that is not connected to the base station and Uu-RRC, at least one of the GNSS or the terminal may be a synchronization source. By setting a threshold for the absolute speed of the terminal and comparing the absolute speed and the threshold of the transmitting terminal, a selectable transmission parameter set (SL-PSSCH-TxParameters) may be determined according to whether the speed is greater than or less than the threshold. . In this case, the threshold value may be included in the resource pool configuration information. Before the terminal is RRC-connected with the base station, corresponding values may be pre-configured in the terminal and may be set from the base station through SIB. After the terminal is RRC connected to the base station, the corresponding values may be terminal-specifically set. In addition, the terminal may receive a threshold setting through a PC5-RRC connection between the terminal and the terminal.

Accordingly, a method for the transmitting terminal to select transmission parameters may be determined according to the following cases.

* Case 1: When there is no SL CSI report, when only the transmission parameter set (SL-PSSCH-TxParameters) irrelevant to CBR is set, the transmitting terminal may select a transmission parameter within the transmission parameter set.

** Case 1 corresponds to a case in which CBR is not used by the higher level setting.

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

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

* Case 2: When there is no SL CSI report, the first transmission parameter set (SL-PSSCH-TxParameters) irrelevant to CBR is set, and the second transmission parameter set (SL-PSSCH-TxParameters) reflecting CBR is set through the upper setting. In this case, the transmitting terminal selects a transmission parameter within a range of parameters overlapping between the two transmission parameter sets. If there is no overlapping parameter, the transmission parameter is selected by the terminal implementation.

** Case 2 corresponds to a case where CBR is set to be used by a higher level setting.

** Case 2 corresponds to a case in which a set of transmission parameters according to an absolute speed of a transmitting terminal and a transmission parameter set reflecting CBR are used.

** For example, in the case of the MCS setting range described in <Table 4>, the MCS setting range of the first transmission parameter set is 0~5 and the MCS setting range of the second transmission parameter set is 3~9. The transmission parameter is selected in the range 3 to 5.

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

* Case 3: When there is an SL CSI report and it is set not to use CBR by higher configuration, a parameter in the transmission parameter set (SL-PSSCH-TxParameters) is selected by the UE implementation.

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

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

** Case 4 corresponds to a case where CBR is set to be used by higher level settings.

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

Hereinafter, an operation after the transmitting terminal selects a transmission parameter from the transmission parameter set (SL-PSSCH-TxParameters) of Table 4 will be described.

* The transmitting terminal may transmit based on the selected MCS and transmit corresponding information to the receiving terminal through SCI.

* The transmitting terminal may transmit based on the number of selected transport layers and transmit corresponding information to the receiving terminal through SCI.

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

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

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

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

<Fifth embodiment>

According to the fifth embodiment of the present disclosure, a method of performing congestion control on feedback for transmission according to CBR is proposed. As described above, since CSI feedback and HARQ ACK/NACK feedback are considered in the NR sidelink, the operation of the receiving terminal can be considered for feedback on transmission as well as the operation of the transmitting terminal for congestion control compared to the LTE sidelink. have. CBR can be measured as a value between 0 and 100, but can be quantized according to the CBR range. For example, X CBR levels may be classified, and a CBR measurement result may be mapped to a CBR level corresponding to a corresponding CBR range. Accordingly, in the sidelink, the CR limit and the range of the feedback parameters that can be set may be determined according to the CBR level and the priority of the packet to be transmitted. The terminal may perform congestion control through a range of a CR limit and a feedback parameter mapped to the CBR and the priority of the received packet. Hereinafter, in FIG. 11, an example in which the CR limit and the feedback parameter range are set according to the priority of the CBR and the packet in the sidelink is shown.

Referring to FIG. 11, through a resource pool setting 1110, a CR limit 1160 corresponding to a CBR level 1130 and a priority 1120 of a packet to be transmitted and a range 1170 of a feedback parameter are set. Here, the range of the CR limit and the feedback parameter corresponding to the CBR level determined through the resource pool setting and the priority of the received packet can be configured in advance in the terminal before the terminal is RRC connected to the base station, and the SIB from the base station It can be set through. After the terminal is RRC-connected to the base station, the terminal may receive the above-described values terminal-specifically. In addition, the range of the CR limit and the feedback parameter corresponding to the CBR level and the priority of the received packet may be set through a PC5-RRC connection between the terminal and the terminal. Referring to FIG. 11, the measured CBR may be mapped to a minimum value and a maximum value of a CBR range set according to a corresponding CBR level and used. According to FIG. 11, the CBR level may be divided into a maximum of X CBR levels. Details on the range of feedback parameters (CSI-Parameters) are described in detail in Table 5 below.

In this embodiment, a method of determining a CSI feedback parameter according to CBR is described. A method of performing congestion control for HARQ-ACK/NACK feedback according to CBR may be described with reference to the third embodiment. As described above, the CBR refers to a value obtained by the UE measuring whether the channel is congested in a certain time interval, and the UE may perform congestion control using the CBR value. In addition, when the receiving terminal generates SL CSI information, it is used as more effective information for the transmitting terminal to select the transmission parameter when selecting a parameter suitable for the channel situation in consideration of the congestion situation and feeding back the selected parameter to the transmitting terminal. Can be. For SL CSI reporting in the sidelink, the following method may be considered.

SL CSI transmission channel

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

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

* Method 3: SL CSI is transmitted through PSFCH

In the case of Method 1 and Method 2, since the SL CSI is transmitted through the PSSCH, the CBR measured for the aforementioned PSSCH region may be used. In the case of Method 3, since the SL CSI is transmitted through the PSFCH, the CBR measured for the aforementioned PSFCH region may be used. In this embodiment, a case in which a channel quality indicator (CQI) and a rank indicator (RI) are fed back as SL CSI information is considered. A method of setting a range of a feedback parameter will be described in detail through <Table 5> below. The feedback parameter set (SL-CBR-CSI-Config) of Table 5 may include a CQI configuration range (minCQI, maxCQI) and an RI configuration range (allowedRI). In addition to the parameters included in the feedback parameter set (SL-CBR-CSI-Config) of Table 5, other parameters may be additionally considered.

Referring to <Table 5>, the RI setting range (allowedRI) may be determined in the range of the maximum number of transport layers supported by the transmitting terminal. In <Table 5>, allowedRI indicates a reportable RI, and n1 indicates rank 1 and n2 indicates rank 2. And both means that the UE can autonomously set the settings for ranks 1 and 2. In addition, the CQI setting range (minCQI, maxCQI) may be determined by a used SL CQI table. For example, when the SL CQI table reuses the CQI table used in NR Uu, the CQI setting range (minCQI, maxCQI) may be determined among up to 16 levels. In contrast, when the SL CQI table is designed based on the MCS table used in NR Uu, the CQI setting range (minCQI, maxCQI) may be determined among up to 32 levels. As shown in <Table 5>, when CQI and RI are reported as SL CSI information, the receiving terminal sets a feedback parameter within the CQI configuration range (minCQI, maxCQI) and RI configuration range (allowedRI) set by the CBR level. You can choose.

12 illustrates a configuration of a terminal in a wireless communication system according to various embodiments of the present disclosure. Terms such as'?? unit' and'?? group' used hereinafter refer to units that process at least one function or operation, which may be implemented as hardware or software, or a combination of hardware and software.

Referring to FIG. 12, the terminal includes a communication unit 1210, a storage unit 1220, and a control unit 1230.

The communication unit 1210 performs functions for transmitting and receiving signals through a wireless channel. For example, the communication unit 1210 performs a function of converting between a baseband signal and a bit stream according to the physical layer standard of the system. For example, when transmitting data, the communication unit 1210 generates complex symbols by encoding and modulating a transmission bit stream. In addition, when receiving data, the communication unit 1210 restores the received bit stream through demodulation and decoding of the baseband signal. In addition, the communication unit 1210 up-converts the baseband signal to an RF band signal, transmits it through an antenna, and down-converts the RF band signal received through the antenna into a baseband signal. For example, the communication unit 1210 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, and the like.

In addition, the communication unit 1210 may include a plurality of transmission/reception paths. Further, the communication unit 1210 may include at least one antenna array composed of a plurality of antenna elements. In terms of hardware, the communication unit 1210 may include a digital circuit and an analog circuit (eg, radio frequency integrated circuit (RFIC)). Here, the digital circuit and the analog circuit may be implemented in one package. In addition, the communication unit 1210 may include a plurality of RF chains. Furthermore, the communication unit 1210 may perform beamforming.

The communication unit 1210 transmits and receives signals as described above. Accordingly, all or part of the communication unit 1210 may be referred to as a'transmitting unit', a'receiving unit', or a'transmitting/receiving unit'. In addition, in the following description, transmission and reception performed through a wireless channel is used in a sense including the processing as described above is performed by the communication unit 1210.

The storage unit 1220 stores data such as a basic program, an application program, and setting information for the operation of the terminal. The storage unit 1220 may be formed of a volatile memory, a nonvolatile memory, or a combination of a volatile memory and a nonvolatile memory. In addition, the storage unit 1220 provides stored data according to the request of the control unit 1230.

The controller 1230 controls overall operations of the terminal. For example, the control unit 1230 transmits and receives signals through the communication unit 1210. Also, the control unit 1230 writes and reads data in the storage unit 1220. In addition, the controller 1230 may perform functions of a protocol stack required by a communication standard. To this end, the controller 1230 may include at least one processor or a micro processor, or may be a part of a processor. In addition, a part of the communication unit 1210 and the control unit 1230 may be referred to as a communication processor (CP).

According to various embodiments, the control unit 1230 may control the terminal to perform operations according to the various embodiments described above.

13 illustrates a configuration of a base station in a wireless communication system according to various embodiments of the present disclosure. Terms such as'?? unit' and'?? group' used hereinafter refer to units that process at least one function or operation, which may be implemented as hardware or software, or a combination of hardware and software.

Referring to FIG. 13, the base station includes a communication unit 1310, a backhaul communication unit 1320, a storage unit 1330, and a control unit 1340.

The communication unit 1310 performs functions for transmitting and receiving signals through a wireless channel. For example, the communication unit 1310 performs a function of converting between a baseband signal and a bit stream according to the physical layer standard of the system. For example, when transmitting data, the communication unit 1310 generates complex symbols by encoding and modulating a transmission bit stream. In addition, when receiving data, the communication unit 1310 restores the received bit stream through demodulation and decoding of the baseband signal.

In addition, the communication unit 1310 up-converts the baseband signal into a radio frequency (RF) band signal and then transmits it through an antenna, and down-converts the RF band signal received through the antenna into a baseband signal. To this end, the communication unit 1310 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a digital to analog convertor (DAC), an analog to digital convertor (ADC), and the like. In addition, the communication unit 1310 may include a plurality of transmission/reception paths. Further, the communication unit 1310 may include at least one antenna array including a plurality of antenna elements.

In terms of hardware, the communication unit 1310 may be composed of a digital unit and an analog unit, and the analog unit is divided into a plurality of sub-units according to operating power and operating frequency. Can be configured. The digital unit may be implemented with at least one processor (eg, a digital signal processor (DSP)).

The communication unit 1310 transmits and receives signals as described above. Accordingly, all or part of the communication unit 1310 may be referred to as a'transmitter', a'receiver', or a'transceiver'. In addition, in the following description, transmission and reception performed through a wireless channel is used in a sense including the processing as described above is performed by the communication unit 1310.

The backhaul communication unit 1320 provides an interface for performing communication with other nodes in the network. That is, the backhaul communication unit 1320 converts a bit stream transmitted from the base station to another node, for example, another access node, another base station, an upper node, a core network, etc., into a physical signal, and converts the physical signal received from the other node. Convert to bit string.

The storage unit 1330 stores data such as a basic program, an application program, and setting information for the operation of the base station. The storage unit 1330 may be formed of a volatile memory, a nonvolatile memory, or a combination of a volatile memory and a nonvolatile memory. In addition, the storage unit 1330 provides stored data according to the request of the control unit 1340.

The controller 1340 controls overall operations of the base station. For example, the control unit 1340 transmits and receives signals through the communication unit 1310 or through the backhaul communication unit 1320. In addition, the control unit 1340 writes and reads data in the storage unit 1330. In addition, the control unit 1340 may perform functions of a protocol stack required by a communication standard. According to another implementation example, the protocol stack may be included in the communication unit 1310. To this end, the control unit 1340 may include at least one processor.

According to various embodiments, the controller 1340 may control the base station to perform operations according to the various embodiments described above.

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

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

These programs (software modules, software) include random access memory, non-volatile memory including flash memory, read only memory (ROM), and electrically erasable programmable ROM. (electrically erasable programmable read only memory, EEPROM), magnetic disc storage device, compact disc-ROM (CD-ROM), digital versatile discs (DVDs) or other forms of It may be stored in an optical storage device or a magnetic cassette. Alternatively, it may be stored in a memory composed of a combination of some or all of them. In addition, a plurality of configuration memories may be included.

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

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 description, 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 in the 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 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 determined, and should be determined by the scope of the claims as well as the equivalents of the claims to be described later.

Claims (2)

In the operating method of the first terminal in a wireless communication system,
Receiving a signal for requesting a channel state between the first terminal and the second terminal from a second terminal, and
A process of measuring the channel state, and
And transmitting information on a channel state generated based on a result of the performed measurement to the second terminal,
The information on the channel state includes information for indicating a degree of congestion of a channel between the first terminal and the second terminal.
In the device of the first terminal in a wireless communication system,
A transceiver; And
Including at least one processor connected to the transceiver,
The at least one processor,
Receiving a signal for requesting a channel state between the first terminal and the second terminal from a second terminal,
Perform a measurement on the channel state,
It is configured to transmit information on a channel state generated based on a result of the performed measurement to the second terminal,
The information on the channel state includes information for indicating a degree of congestion of a channel between the first terminal and the second terminal.

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