Apparatus and method for controlling congestion in a wireless communication system

Abstract

The present disclosure relates to a pre-5G or 5G communication system, which is provided for supporting higher data rates of a fourth generation (4G) communication system beyond the long term evolution (LTE). The present disclosure is used to control channel congestion in a wireless communication system. According to an embodiment of the present disclosure, a method performed by a terminal in a wireless communication system includes: determining a plurality of authorized transmission resources for sidelink communication; performing transmission or retransmission using at least one transmission resource among the plurality of authorized transmission resources; receiving an acknowledgment (ACK) of the transmission or retransmission; releasing one or more transmission resources among the plurality of authorized transmission resources in response to the ACK; measuring channel occupancy (CR) from transmission resources other than the one or more released transmission resources among the plurality of authorized transmission resources and transmitting a physical sidelink shared channel (PSSCH) to satisfy a condition that the measured CR does not exceed a configured CR limit, thereby performing congestion control.

Description

Technical Field

[0001] The present disclosure relates to a wireless communication system, and more particularly, to an apparatus and method for controlling congestion in a wireless communication system. Background Art

[0002] To meet the increased demand for wireless data services since the deployment of the 4th generation (4G) communication system, efforts have been made to develop improved 5th generation (5G) or pre-5G communication systems. Therefore, 5G or pre-5G communication systems are also referred to as "beyond 4G networks" or "post-Long Term Evolution (LTE) systems."

[0003] 5G communication systems are expected to be implemented in higher frequency (mmWave) bands (e.g., the 60 GHz band) to achieve higher data rates. To reduce radio wave propagation losses and increase transmission distances, beamforming, massive multiple-input multiple-output (MIMO), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive antenna technologies are being discussed in 5G communication systems.

[0004] In addition, in 5G communication systems, development of system network improvements based on advanced small base stations, cloud radio access networks (RAN), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, mobile networks, cooperative communications, coordinated multi-point (CoMP), and receiving terminal interference cancellation is underway.

[0005] In 5G systems, hybrid FSK and QAM modulation (FQAM) and sliding window superposition coding (SWSC) as advanced coding modulation (ACM) and filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA) and sparse code multiple access (SCMA) as advanced access technologies have been developed.

[0006] The Internet, a human-centric network of connected devices where humans generate and consume information, is now evolving into the Internet of Things (IoT), in which distributed entities (e.g., things) exchange and process information without human intervention. The Internet of Everything (IoE), a combination of IoT technology and big data processing technology via cloud servers, has emerged. IoT implementation requires technological elements such as sensing technology, wired / wireless communication and network infrastructure, service interface technology, and security technology. Recently, research has focused on sensor networks, machine-to-machine (M2M) communication, and machine-type communication (MTC).

[0007] This IoT environment provides intelligent internet technology services that create new value for human life by collecting and analyzing data generated by connected things. By integrating existing information technology (IT) with various industrial applications, IoT can be applied to various fields such as smart homes, smart buildings, smart cities, smart cars or connected cars, smart grids, healthcare, smart appliances, and advanced medical services.

[0008] As wireless communication systems evolve, various technologies such as vehicle-to-everything (V2X) can be supported. A method for smoothly providing such V2X communication is needed.

[0009] The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with respect to the present disclosure. Summary of the Invention

[0010] Technical Solution

[0011] Aspects of the present disclosure address at least the above-mentioned problems and / or disadvantages and provide at least the advantages described below. Therefore, one aspect of the present disclosure provides an apparatus and method for controlling congestion when providing vehicle-to-everything (V2X) communication in a wireless communication system.

[0012] Additional aspects will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the presented embodiments.

[0013] According to one aspect of the present disclosure, a method performed by a terminal in a wireless communication system is provided. The method includes: determining multiple authorized transmission resources for sidelink communication; using at least one transmission resource from the multiple authorized transmission resources to perform transmission or retransmission; receiving an acknowledgment (ACK) for the transmission or retransmission; releasing one or more transmission resources from the multiple authorized transmission resources in response to the ACK; measuring channel occupancy (CR) of transmission resources other than the one or more transmission resources released from the multiple authorized transmission resources; and transmitting a physical sidelink shared channel (PSSCH) to satisfy a condition that the measured CR does not exceed a configured CR limit (CR limit), thereby performing congestion control.

[0014] According to another aspect of the present disclosure, a terminal in a wireless communication system is provided. The terminal includes a transceiver and at least one processor, the processor being configured to: determine a plurality of authorized transmission resources for sidelink communication; use at least one transmission resource of the plurality of authorized transmission resources to perform transmission or retransmission; receive an acknowledgment (ACK) for the transmission or retransmission; release one or more transmission resources of the plurality of authorized transmission resources in response to the ACK; measure channel occupancy (CR) of transmission resources other than the one or more transmission resources released from the plurality of authorized transmission resources; and transmit a physical sidelink shared channel (PSSCH) to satisfy a condition that the measured CR does not exceed a configured CR limit, thereby performing congestion control.

[0015] Apparatuses and methods according to various embodiments enable stable V2X communication to be performed via congestion control in sidelink (SL) communication.

[0016] Other aspects, advantages, and salient features of the disclosure will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the accompanying drawings, discloses various embodiments of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other aspects, features and advantages of certain embodiments of the present disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings, in which:

[0018] Figure 1A A scenario of side chain communication in a wireless communication system according to an embodiment of the present disclosure is shown;

[0019] Figure 1B A scenario of side chain communication in a wireless communication system according to an embodiment of the present disclosure is shown;

[0020] Figure 1C A scenario of side chain communication in a wireless communication system according to an embodiment of the present disclosure is shown;

[0021] Figure 1D A scenario of side chain communication in a wireless communication system according to an embodiment of the present disclosure is shown;

[0022] Figure 2A A transmission method for side chain communication in a wireless communication system according to an embodiment of the present disclosure is shown;

[0023] Figure 2B A transmission method for side chain communication in a wireless communication system according to an embodiment of the present disclosure is shown;

[0024] Figure 3 A sidelink resource pool in a wireless communication system according to an embodiment of the present disclosure is shown;

[0025] Figure 4A signal flow for allocating sidelink transmission resources in a wireless communication system according to an embodiment of the present disclosure is shown;

[0026] Figure 5 The present invention shows a signal flow for allocating transmission resources of a side link in a wireless communication system according to an embodiment of the present disclosure;

[0027] Figure 6 The invention shows a channel structure of a time slot for side chain communication in a wireless communication system according to an embodiment of the present disclosure;

[0028] Figure 7A shows the distribution of feedback channels in a wireless communication system according to an embodiment of the present disclosure;

[0029] Figure 7B shows the distribution of feedback channels in a wireless communication system according to an embodiment of the present disclosure;

[0030] Figure 8 A signal flow for measuring and reporting sidelink channel status in a wireless communication system according to an embodiment of the present disclosure is shown;

[0031] Figure 9 A signal flow for measuring and delivering a channel busy rate (CBR) in a wireless communication system according to an embodiment of the present disclosure is shown;

[0032] Figure 10 The present invention shows the configuration of channel occupancy rate (CR) limit and transmission parameter range in a wireless communication system according to an embodiment of the present disclosure;

[0033] Figure 11 The configuration of CR limit and feedback parameter range in a wireless communication system according to an embodiment of the present disclosure is shown;

[0034] Figure 12 shows a configuration of a terminal in a wireless communication system according to an embodiment of the present disclosure; and

[0035] Figure 13 The configuration of a base station in a wireless communication system according to an embodiment of the present disclosure is shown.

[0036] Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures. DETAILED DESCRIPTION

[0037] The following description, with reference to the accompanying drawings, is provided to facilitate a comprehensive understanding of the various embodiments of the present disclosure as defined by the claims and their equivalents. It includes various specific details to assist understanding, but these are to be regarded as exemplary only. Therefore, those skilled in the art will recognize that various changes and modifications may be made to the various embodiments described herein without departing from the scope and spirit of the present disclosure. Furthermore, descriptions of well-known functions and configurations may be omitted for clarity and brevity.

[0038] The terms and words used in the following description and claims are not limited to the literal meanings, but are merely used by the inventor to enable a clear and consistent understanding of the present disclosure. Therefore, it should be clear to those skilled in the art that the following description of various embodiments of the present disclosure is for illustration purposes only and is not intended to limit the present disclosure as defined by the appended claims and their equivalents.

[0039] It is to be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a component surface" includes reference to one or more of such surfaces.

[0040] Hereinafter, various embodiments of the present disclosure will be described based on hardware. However, various embodiments of the present disclosure include technologies using both hardware and software, and therefore, various embodiments of the present disclosure do not exclude the viewpoint of software.

[0041] 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 terminals, and relates to an apparatus and method for performing congestion control based on a result of determining whether a channel is congested based on a channel busy rate (CBR) and a channel occupancy rate (CR).

[0042] In the following description, for the convenience of description, terms used for signals, terms referring to channels, terms referring to control information, terms referring to network entities, terms referring to device components, etc. are exemplified. Therefore, the present disclosure is not limited to the terms described below, and other terms with equivalent technical meanings may be used.

[0043] In the following description, physical channels and signals may be used in conjunction with data or control signals. For example, the term "physical downlink shared channel" (PDSCH) refers to a physical channel over which data is transmitted, but PDSCH may also be used to refer to data. For example, in this disclosure, the expression "transmitting a physical channel" may be interpreted as equivalent to expressing "transmitting data or signals via a physical channel."

[0044] Hereinafter, in the disclosure, "upper layer signaling" refers to a signal transmission method in which a signal is transmitted from a base station to a terminal using a downlink data channel of the physical layer, or a signal is transmitted from a terminal to a base station using an uplink data channel of the physical layer. Upper layer signaling can be understood as radio resource control (RRC) signaling or media access control (MAC) control element (CE).

[0045] In addition, in this disclosure, expressions such as "more" or "less" are used to determine whether a certain condition is satisfied or met. However, this is merely an example and does not exclude the use of "more" or "less." A condition described as "equal to or greater than" can be replaced with "exceeds," a condition described as "equal to or less than" can be replaced with "lower than," and a condition described as "lower than" or "equal to or greater than or equal to or less than" can be replaced with "lower than" or "lower than."

[0046] In addition, the present disclosure describes various embodiments using terms used in some communication standards (eg, the 3rd Generation Partnership Project (3GPP)), but this is merely an example for illustration. Various embodiments can be easily modified and applied to other communication systems.

[0047] In this 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 this disclosure, a receiving terminal refers to a terminal that receives sidelink data and control information or a terminal that transmits sidelink feedback information.

[0048] Various attempts have been made to apply 5G communication systems to IoT networks. Technologies such as sensor networks, machine-to-machine (M2M) communications, and machine-type communications (MTC) are implemented through technologies such as beamforming, multiple-input multiple-output (MIMO), and array antennas, which are 5G communication technologies. It can be understood that the application of cloud radio access network (RAN) as a big data processing technology is an example of the integration of 5G technology and IoT technology. As described above, in a communication system, a method and an apparatus using the method are needed, in which a plurality of services can be provided to a user based on characteristics and each service can be provided within the same time period to provide a plurality of services to the user. Various services provided in the 5G communication system are under study, one of which is a service that meets the requirements of low latency and high reliability.

[0049] In the case of vehicle communications, LTE-based vehicle-to-everything (V2X) systems have been standardized in 3GPP Rel-14 and Rel-15 based on a device-to-device (D2D) communication structure, and efforts are currently underway to develop V2X systems based on 5G New Radio (NR). In NR systems, unicast, groupcast (or multicast), and broadcast communications between terminals will be supported. Furthermore, unlike LTE V2X, which is designed to transmit and receive basic safety information required for vehicles to operate on the road, NR V2X aims to provide more advanced services such as grouping, advanced driving, extended sensors, and remote driving.

[0050] In the V2X sidelink, whether the channel is congested can determine whether the channel is connected to the terminal and the configuration range of the transmission parameters. This is a congestion control function that controls the terminal's channel access by discarding the transmission or adjusting the schedule when the channel is congested, and by selecting the transmission parameters according to the congestion status of the channel when the channel is accessed, thereby increasing the probability of successful transmission. The terminal can measure the channel busy rate (CBR) and select the transmission parameters. CBR is an indicator that indicates how much of the current channel is occupied by the terminal, and the range of selectable transmission parameters can be determined based on the CBR value. Together with the CBR measurement, the terminal can perform congestion control by measuring the channel occupancy rate (CR). CR is an indicator that indicates how much of the channel is occupied by the terminal, and the CR limit of the terminal's channel occupation can be determined based on the CBR value. For example, if the channel is congested (when the CBR value is measured as high), the CR limit is configured to be low, and the terminal should perform congestion control so that the measured CR does not exceed the CR limit. For example, the terminal should abandon the transmission or meet the CR limit through scheduling implementation.

[0051] In the NR sidelink, since hybrid automatic repeat and request (HARQ) acknowledgement (ACK) / negative acknowledgement (NACK) feedback and channel state information (CSI) feedback are considered, compared to the LTE sidelink, the operations of the transmitting terminal for congestion control and the operations of the receiving terminal can be considered for transmission feedback. Therefore, the operations of the transmitting and receiving terminals exchanging CBR information can be considered. In addition, the NR sidelink supports retransmission methods based on HARQ feedback (a method that performs retransmission based on HARQ ACK / NACK feedback) and blind retransmission (a method that supports retransmission without HARQ feedback information). When measuring CR, the terminal can reflect both the record of past channel occupation and use based on the current time point and the portion of the channel authorized for future occupation and use. In the case of retransmission methods based on HARQ ACK / NACK feedback, if the transmitting terminal reserves resources for future occupation and use, but an ACK is reported from the receiving terminal, the resources occupied for retransmission may be released, as retransmission may not be possible. Therefore, this portion should be reflected in the CR measurement. Hereinafter, in this disclosure, an embodiment of performing congestion control in the NR side chain will be described.

[0052] Various embodiments implement congestion control when a V2X-enabled vehicle-mounted terminal uses a side link to transmit and receive information with another vehicle-mounted terminal and a pedestrian portable terminal. Specifically, the transmitting terminal can determine whether the channel is congested by measuring the CBR and CR. Based on this determination, the transmitting terminal determines whether the channel is connected to the terminal and the configuration range of transmission parameters. Furthermore, in the present disclosure, the operations of the base station and terminal according to various embodiments are described below.

[0053] Figure 1A A scenario of side chain communication in a wireless communication system according to an embodiment of the present disclosure is shown. Figure 1B A scenario of side chain communication in a wireless communication system according to an embodiment of the present disclosure is shown. Figure 1C A scenario of side chain communication in a wireless communication system according to an embodiment of the present disclosure is shown. Figure 1D A scenario of side chain communication in a wireless communication system according to an embodiment of the present disclosure is shown.

[0054] refer to Figure 1A , shows an in-coverage (IC) scenario, where the sidelink terminals 120 and 125 are located within the coverage 110 of the base station 100. The sidelink terminals 120 and 125 can receive data and control information from the base station via a downlink (DL) or send data and control information to the base station via an uplink (UL). In this case, the data and control information can be data and control information for sidelink communication or data and control information for general cellular communication rather than sidelink communication. In addition, in Figure 1A In the embodiment, the side chain terminals 120 and 125 can send and receive data and control information for side chain communication via the side chain.

[0055] refer to Figure 1B , shows a partial coverage (PC) situation, in which the first terminal 120 of the sidelink terminals is located within the coverage range 110 of the base station 100 and the second terminal 125 is located outside the coverage range 110 of the base station 100. The first terminal 120 located within the coverage range 110 of the base station 100 can receive data and control information from the base station via a downlink or send data and control information to the base station via an uplink. The second terminal 125 located outside the coverage range of the base station 100 cannot receive data and control information from the base station via a downlink, and cannot send data and control information to the base station via an uplink. The second terminal 125 can send and receive data and control information for sidelink communication with the first terminal 120 via a sidelink.

[0056] refer to Figure 1C , shows a situation where sidelink terminals (e.g., first terminal 120 and second terminal 125) are located outside the coverage (OOC) 110 of base station 100. Therefore, first terminal 120 and second terminal 125 cannot receive data and control information from the base station via the downlink, nor can they transmit data and control information to the base station via the uplink. First terminal 120 and second terminal 125 can transmit and receive data and control information for sidelink communication via the sidelink.

[0057] refer to Figure 1D , shows a case where inter-cell sidelink communication is performed, wherein the first terminal 120 and the second terminal 125 performing the sidelink communication are connected to different base stations (e.g., the first base station (i.e., base station 100) and the second base station 105) (e.g., RRC connected state) or are camping (e.g., RRC connection released state, i.e., RRC idle state). In this case, the first terminal 120 can be a sidelink transmitting terminal and the second terminal 125 can be a sidelink receiving terminal. Alternatively, the first terminal 120 can be a sidelink receiving terminal and the second terminal 125 can be a sidelink transmitting terminal. The first terminal 120 can receive a sidelink dedicated system information block (SIB) from the base station 100 to which the first terminal 120 is connected (or camping), and the second terminal 125 can receive a sidelink dedicated SIB from the second base station 105 to which the second base station is connected (or camping). In this case, the sidelink dedicated SIB information received by the first terminal 120 and the sidelink dedicated SIB information received by the second terminal 125 can be different from each other. Therefore, in order to perform sidelink communication between terminals located in different cells, information may need to be unified, or additional assumptions and interpretation methods may be required.

[0058] exist Figures 1A to 1DIn the example, for convenience of description, a sidelink system including two terminals (e.g., a first terminal 120 and a second terminal 125) has been described as an example, but the present disclosure is not limited thereto and is applicable to a sidelink system in which three or more terminals participate. In addition, the uplink and downlink between the base station 100 and the sidelink terminal may be referred to as a Uu interface, and the sidelink between the sidelink terminals may be referred to as a PC5 interface. In the following description, uplink or downlink is used interchangeably with Uu interface, sidelink, and PC5.

[0059] At the same time, in this disclosure, a terminal may refer to a vehicle that supports vehicle-to-vehicle (V2V) communication, a vehicle that supports vehicle-to-pedestrian (V2P) communication or a pedestrian mobile phone (e.g., a smartphone), a vehicle that supports vehicle-to-network (V2N) communication, or a vehicle that supports vehicle-to-infrastructure (V2I) communication. In addition, in this disclosure, a terminal may refer to a roadside unit (RSU) equipped with terminal functions, an RSU equipped with base station functions, or an RSU equipped with partial base station functions and partial terminal functions.

[0060] Furthermore, in this disclosure, a base station can be a base station that supports both V2X communication and ordinary cellular communication, or a base station that only supports V2X communication. In this case, the base station can be a 5G base station (gNB), a 4G base station (eNB), or an RSU. Therefore, in this disclosure, a base station can be referred to as an RSU.

[0061] Figure 2A A transmission method for side link communication in a wireless communication system according to an embodiment of the present disclosure is shown. Figure 2B A transmission method for side link communication in a wireless communication system according to an embodiment of the present disclosure is shown. Figure 2A shows a unicast scenario, while Figure 2B A multicast scenario is shown.

[0062] refer to Figure 2A , the sending terminal 200 and the receiving terminal 205 can perform one-to-one communication 210. Figure 2A The transmission scheme shown may be referred to as unicast communication 210 .

[0063] refer to Figure 2B , the transmitting terminal 230 or 245 and the receiving terminal 235 , 240 , 250 , 255 or 260 may perform one-to-many communications 270 , 272 , 274 , 276 and 278 . Figure 2B The transmission scheme shown may be referred to as multicast or multicast. Figure 2B, the first terminal 230, the second terminal 235, and the third terminal 240 form a group and perform multicast communication, and the fourth terminal 245, the fifth terminal 250, the sixth terminal 255, and the seventh terminal 260 form another group and perform multicast communication. The terminals can perform multicast communication within the group to which they belong, and perform unicast, multicast, or broadcast communication with at least one other terminal belonging to a different group. Figure 2B , two groups are shown, but the present disclosure is not limited thereto and can be applied even when a larger number of groups are formed.

[0064] At the same time, although Figure 2A or Figure 2B Not shown, but the side chain terminal can perform broadcast communication. Broadcast communication refers to a method in which all side chain terminals receive data and control information sent by the side chain sending terminal via the side chain. For example, Figure 2B In the embodiment, if the first terminal 230 is a transmitting terminal, the remaining terminals 235 , 240 , 245 , 250 , 255 , and 260 may receive data and control information transmitted by the first terminal 230 .

[0065] The above-mentioned side chain unicast communication, multicast communication and broadcast communication can be supported in the in-coverage scenario, partial coverage scenario or out-of-coverage scenario.

[0066] In the case of the NR side link, unlike the LTE side link, it is possible to consider supporting a vehicle terminal in which data is transmitted only to one specific terminal via unicast and a transmission type in which data is transmitted to a specific plurality of terminals via multicast. For example, when considering a service scenario such as queuing, which is a technology in which two or more vehicles are connected to a single network and move in a cluster, such unicast and multicast technologies can be used. Specifically, unicast communication can be used for the purpose of controlling one specific terminal by a leader terminal of a flatly connected group, while multicast communication can be used for the purpose of simultaneously controlling a group of multiple terminals.

[0067] Figure 3 The sidelink resource pool in the wireless communication system according to an embodiment of the present disclosure is shown. The resource pool can be defined as a collection of resources used for sidelink transmission and reception in the time domain and frequency domain.

[0068] The resource granularity of the time axis in the resource pool can be one or more Orthogonal Frequency Division Multiplexing (OFDM) symbols. In addition, the resource granularity of the frequency axis can be one or more Physical Resource Blocks (PRBs).

[0069] When allocating resource pools in the time and frequency domains, an area including shaded resources indicates an area configured as a resource pool in those time and frequency domains. This disclosure describes the case of discontinuous allocation of resource pools in the time domain, but is not limited thereto and can be applied even when resource pools are allocated continuously in the time domain. Furthermore, this disclosure describes the case of discontinuous allocation of resource pools in the frequency domain, but is not limited thereto and can also be applied when resource pools are allocated discontinuously in the frequency domain.

[0070] refer to Figure 3 , the time domain 300 of the configured resource pool illustrates the case of non-continuous allocation of resources in the time domain. In the time domain 300 of the resource pool, the resource granularity on the time axis may be a time slot. Specifically, a time slot including 14 OFDM symbols may be the basic resource granularity on the time axis. Referring to the time domain 300 of the configured resource pool, the shaded time slots represent time slots allocated as resource pools in the time domain, and system information may be used to indicate time slots allocated as resource pools in the time domain. For example, the resource pool configuration information on the time domain in the SIB may be used to indicate time slots allocated as resource pools in the time domain. Specifically, at least one time slot configured as a resource pool in the time domain may be indicated by a bitmap. Reference Figure 3 , the physical time slots (e.g., time domain 300) belonging to the non-contiguous resource pool on the time axis can be mapped to the logical time slot 325. Generally, a group of time slots belonging to the resource pool of the physical sidelink shared channel (PSSCH) can be represented as t0, t1, ..., t i ,...,t Tmax .

[0071] refer to Figure 3 , the frequency domain 305 of the configured resource pool illustrates a case where resources are continuously allocated in the frequency domain. In the frequency domain 305 of the resource pool, the resource granularity on the frequency axis may be a subchannel 310. Specifically, a subchannel 310 including one or more resource blocks (RBs) may be defined as a basic resource granularity on the frequency. For example, a subchannel 310 may be defined as an integer multiple of an RB. Figure 3 , the size of the subchannel (sizeSubchannel) can include five consecutive PRBs, but the present disclosure is not limited thereto, and the size of the subchannel can be configured differently. In addition, a subchannel generally includes consecutive PRBs, but does not necessarily include consecutive PRBs. Subchannel 310 can be the basic resource granularity of the PSSCH. In addition, the subchannel for the physical sidelink feedback channel (PSFCH) can be defined independently of the PSSCH.

[0072] refer to Figure 3, the starting position of subchannel 3-31 in the resource pool in the frequency domain can be represented by startRB-Subchannel (start RB-subchannel) 315. When resources are allocated on the frequency axis in units of subchannel 310, the resource pool configuration in the frequency domain can be performed via the RB index (startRB-Subchannel) 315 starting from the subchannel 310, information (sizeSubchannel) indicating how many RBs the subchannel 310 consists of, and configuration information of the total number of subchannels 310 (numSubchannel). According to various embodiments of the present disclosure, system information can be used to indicate the subchannels allocated to the resource pool in the frequency domain. For example, at least one of startRB-Subchannel, sizeSubchannel, and numSubchannel can be indicated as frequency resource pool configuration information in the SIB. When the subchannels of the PSFCH are defined independently of the PSSCH, the subchannel configuration information of the PSFCH and PSSCH can be indicated separately.

[0073] Figure 4 A signal flow for allocating sidelink transmission resources in a wireless communication system according to an embodiment of the present disclosure is shown. Figure 4 Signal exchanges between a transmitting terminal 401 , a receiving terminal 402 , and a base station 403 are shown.

[0074] As described below, the method by which a base station allocates transmission resources for sidelink communication can be referred to as Mode 1. Mode 1 is a resource allocation scheme based on base station scheduling. More specifically, in Mode 1 resource allocation, the base station can allocate resources for sidelink transmission to RRC-connected terminals based on a dedicated scheduling method. Because the base station can manage the resources for the sidelink, scheduled resource allocation facilitates interference management and resource pool management (e.g., dynamic allocation and / or semi-persistent transmission).

[0075] refer to Figure 4 , in operation 407, the transmitting terminal 401 residing (405) may receive a sidelink SIB from the base station 403. In operation 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 sent by the transmitting terminal 401. The sidelink SIB may be sent periodically or on demand. In addition, the sidelink SIB may include at least one of sidelink resource pool information for sidelink communication, parameter configuration information for sensing operation, information for configuring sidelink synchronization, or carrier information for sidelink communication operating at different frequencies. Although operations 407 and 409 have been described sequentially above, this is for ease of explanation, and operations 407 and 409 may be performed in parallel.

[0076] In operation 413, when data traffic for sidelink communication is generated in the transmitting terminal 401, the transmitting terminal 401 may be connected to the base station 403 via RRC. 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 transmitting terminal 401 generates data traffic. In addition, in the case of mode 1, in a state where the Uu-RRC connection is performed between the base station 403 and the receiving terminal 402, the transmitting terminal 401 may perform transmission to the receiving terminal 402 via the sidelink. In addition, in the case of mode 1, even when the Uu-RRC connection is not performed between the base station 403 and the receiving terminal 402, the transmitting terminal 401 may perform transmission to the receiving terminal 402 via the sidelink.

[0077] In operation 415, the transmitting terminal 401 may request the base station 403 to transmit resources for performing sidelink communication with the receiving terminal 402. In this case, the transmitting terminal 401 may request the base station 403 to transmit the resources for the sidelink using at least one of an uplink physical uplink control channel (PUCCH), an RRC message, or a media access controller (MAC) control element (CE). For example, when a MAC CE is used, the MAC CE may be a MAC CE with a buffer status report (BSR) in a new format, including at least one of an indicator indicating that it is a buffer status report for sidelink communication and information related to the size of data buffered for device-to-device (D2D) communication. In addition, when using the PUCCH, the transmitting terminal 401 may request sidelink resources by a one-bit scheduling request (SR) transmitted via the uplink physical control channel.

[0078] In operation 417, the base station 403 may transmit downlink control information (DCI) to the transmitting terminal 401 via the PDCCH. For example, the base station 403 may instruct the transmitting terminal 401 to complete scheduling of 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 scheme or a configured grant (CG) scheme.

[0079] In the case of a dynamic grant scheme, the base station 403 can allocate resources for the transmission of one transport block (TB) by sending a DCI to the transmitting terminal 401. The sidelink scheduling information included in the DCI may include parameters related to the initial transmission time and / or the transmission time of the retransmission, as well as parameters related to the frequency allocation location information field. The DCI for the dynamic grant scheme can be scrambled by a cyclic redundancy check (CRC) based on the sidelink V2X-radio network temporary identifier (SL-V-RNTI) to indicate that the transmission resource allocation scheme is a dynamic grant scheme.

[0080] In the case of a configured authorization scheme, resources for transmitting multiple TBs can be periodically allocated by configuring a semi-persistent scheduling (SPS) interval in the Uu-RRC. In this case, the base station 403 can allocate resources for multiple TBs by sending DCI to the transmitting terminal 401. The side chain scheduling information included in the DCI may include parameters related to the initial transmission time and / or the transmission time of retransmission and parameters related to the frequency allocation position information field. In the case of a configured authorization scheme, the initial transmission time (timing) and / or the transmission time and the frequency allocation position of retransmission can be determined according to the DCI sent, and the resource can be repeated at SPS intervals. The DCI of the configured authorization scheme can be scrambled based on the CRC of the SL-SPS-V-RNTI to indicate that the transmission resource allocation scheme is the configured authorization scheme. In addition, the configured authorization scheme can be divided into type 1CG and type 2CG. In the case of type 2CG, the base station 403 can activate and / or deactivate the resources configured by the configured authorization via DCI. Therefore, in the case of Mode 1, the base station 403 may transmit DCI via the PDCCH, thereby instructing the transmitting terminal 401 to finally schedule the sidelink communication with the receiving terminal 402 .

[0081] When broadcast transmission is performed between receiving terminals 401 and 402, in operation 419, transmitting terminal 401 may broadcast SCI to receiving terminal 402 via PSCCH without additional side chain RRC configuration (operation 411). In addition, in operation 421, transmitting terminal 401 may broadcast data to receiving terminal 402 via PSSCH.

[0082] When unicast or multicast transmission is performed between the receiving terminals 401 and 402, in operation 411, the transmitting terminal 401 may perform an RRC connection one-to-one with other terminals (e.g., the receiving terminal 402). In this case, in order to distinguish it from Uu-RRC, the RRC connection between the receiving terminals 401 and 402 may be referred to as PC5-RRC. In the case of a multicast transmission scheme, a PC5-RRC connection may be established separately between the terminals in the group and the terminals. Figure 4, the PC5-RRC connection (operation 411) is shown as an operation after the side chain SIB is sent (operations 407 and 409), but the PC5-RRC connection is performed before the side chain SIB is sent or before the SCI is broadcast (operation 419). If an RRC connection between terminals is required, the PC5-RRC connection of the side chain can be performed, and in operation 419, the transmitting terminal 401 can send SCI to the receiving terminal 402 via PSCCH in a unicast or multicast manner. At this time, the multicast transmission of SCI can be understood as group SCI. In addition, in operation 421, the transmitting terminal 401 can send data to the receiving terminal 402 via PSSCH in a unicast or multicast manner. In the case of mode 1, the transmitting terminal 401 can identify the side chain scheduling information contained in the DCI received from the base station 403 and perform side chain scheduling based on the side chain scheduling information. SCI may include the following scheduling information.

[0083] * Fields related to the transmission time and frequency allocation location information for initial transmission and retransmission

[0084] *New Data Indicator (NDI) field

[0085] * Redundancy Version (RV) field

[0086] *Information field indicating the reserved interval

[0087] In the information field indicating the reserved interval, when resources for multiple TBs (i.e., Multimedia Access Controller (MAC) Protocol Data Units (PDUs)) are selected, the interval between TBs is indicated by a fixed value, and when resources for one TB are selected, "0" can be indicated as the interval value between TBs.

[0088] Figure 5 The figure shows a signal flow for allocating transmission resources of a side link in a wireless communication system according to an embodiment of the present disclosure. Figure 5 The signal exchange between the transmitting terminal 501, the receiving terminal 502 and the base station 503 is shown.

[0089] As described below, the method in which the terminal directly allocates the transmission resources of the side link via sensing in the side link can be referred to as Mode 2. Mode 2 can be referred to as UE autonomous resource selection. Specifically, according to Mode 2, the base station 503 provides the side link transmit / receive resource pool of the side link to the terminal as system information or RRC message (e.g., RRC reconfiguration message, PC5 RRC message), and the transmitting terminal 501 selects the resource pool and resources according to a determined rule. Different from Mode 1 in which the base station directly participates in resource allocation, Figure 5 Mode 2 described in the specification can autonomously select resources and send data based on the resource pool previously received by the transmitting terminal 501 via system information.

[0090] refer to Figure 5 In operation 507, the transmitting terminal 501 residing in 505 may receive a sidelink SIB from the base station 503. In operation 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 sent by the transmitting terminal 501. The sidelink SIB may be sent periodically or on demand. In addition, the sidelink SIB information may include at least one of sidelink resource pool information for sidelink communication, parameter configuration information for sensing operation, information for configuring sidelink synchronization, or carrier information for sidelink communication operating at different frequencies. Although operations 507 and 509 have been described sequentially above, this is for ease of description, and operations 507 and 509 may be performed in parallel.

[0091] In the above Figure 4 In the case of , although the base station 503 and the transmitting terminal 501 operate in the RRC connected state, Figure 5 In operation 513, the base station 503 and the transmitting terminal 501 can operate regardless of whether the RRC between the base station 503 and the transmitting terminal is connected. For example, the base station 503 and the transmitting terminal 501 can even operate in idle mode 513 (where RRC is not connected). In addition, even when RRC is connected, the base station 503 can operate to autonomously select transmission resources by the transmitting terminal 501 without directly participating in resource allocation. In this case, the RRC connection between the transmitting terminal 501 and the base station 503 can be referred to as Uu-RRC.

[0092] In operation 515 , when data traffic for sidelink communication is generated in the transmitting terminal 501 , the transmitting terminal 501 may be configured with a resource pool through system information received from the base station 503 and directly select time domain and frequency domain resources by sensing in the configured resource pool.

[0093] When broadcast transmission is performed between the transmitting terminal 501 and the receiving terminal 502, in operation 520, the transmitting terminal 501 may broadcast SCI to the receiving terminal 502 via the PSCCH without additional side chain RRC configuration (operation 513). In addition, in operation 525, the transmitting terminal 501 may broadcast data to the receiving terminal 502 via the PSSCH.

[0094] When unicast and multicast transmission are performed between the transmitting terminal 501 and the receiving terminal 502, in operation 511, the transmitting terminal 501 may perform RRC connection one-to-one with other terminals (e.g., the receiving terminal 502). In this case, in order to distinguish it from Uu-RRC, the RRC connection between the transmitting terminal 501 and the receiving terminal 502 may be referred to as PC5-RRC. In the case of a multicast transmission scheme, PC5-RRC connections are established separately between the terminals in the group. Figure 5 Although the PC5-RRC connection (operation 511) is shown as an operation after the side chain SIB is sent (operation 507, operation 509), it can be performed before the side chain SIB is sent or before the SCI is sent (operation 520). If an RRC connection between terminals is required, the PC5-RRC connection of the side chain is performed, and in operation 520, the transmitting terminal 501 can send the SCI to the receiving terminal 502 via the PSCCH in a unicast or multicast manner. At this time, the multicast transmission of the SCI can be understood as a group SCI. In addition, in operation 525, the transmitting terminal 501 can send data to the receiving terminal 502 via the PSSCH in a unicast or multicast manner. In the case of mode 2, the transmitting terminal 501 can directly perform scheduling of the side chain by performing sensing and transmission resource selection operations. The SCI may include the following scheduling information.

[0095] * Initial transmission and retransmission transmission time and frequency allocation position information field

[0096] *New Data Indicator (NDI) field

[0097] * Redundancy Version (RV) field

[0098] *Information field indicating the reserved interval

[0099] In the information field indicating the reserved interval, when resources for multiple TBs (ie, multiple MAC PDUs) are selected, the interval between TBs is indicated by a fixed value, and when resources for one TB are selected, "0" can be indicated as the interval value between TBs.

[0100] Figure 6 The channel structure of a time slot for side link communication in a wireless communication system according to an embodiment of the present disclosure is shown. Figure 6 Shown are physical channels mapped to time slots used for sidelink communication.

[0101] refer to Figure 6 , before the start of the time slot 600, that is, after the previous time slot 605, the preamble 615 is mapped. Thereafter, from the beginning of the time slot 600, the PSCCH 620, the PSSCH 625, the gap 630, the PSFCH 635, the gap 640, and the preamble 645 are mapped.

[0102] Before transmitting a signal in the corresponding time slot 600, the transmitting terminal transmits a preamble 615 in one or more symbols. The preamble 615 can be used to allow the receiving terminal to correctly perform automatic gain control (AGC) when amplifying the power of the received signal to adjust the amplification strength. In addition, depending on whether the transmitting terminal has transmitted the previous time slot 605, the preamble 615 may or may not be transmitted. For example, when the transmitting terminal transmits a signal to the same terminal in the previous time slot (e.g., time slot 605) of the corresponding time slot (e.g., time slot 600), the transmission of the preamble 615 can be omitted. The preamble 615 can be referred to as a "synchronization signal," "sidelink synchronization signal," "sidelink reference signal," "mid-code," "initial signal," "wake-up signal," or other terms having equivalent technical meanings.

[0103] A PSCCH 620 including control information may be transmitted using symbols transmitted at the beginning of a slot, and a PSSCH 625 may be transmitted, which schedules control information for the PSCCH 620. The PSSCH 625 may be mapped to at least a portion of the SCI control information. Subsequently, a slot 630 exists, and a PSFCH 635, a physical channel for transmitting feedback information, may be mapped.

[0104] exist Figure 6 In the case of , PSFCH 635 is shown as being located at the end of the time slot. By ensuring gap 630, which is a predetermined idle time between PSSCH 625 and PSFCH 635, a terminal that has already transmitted or received PSSCH 625 can prepare to transmit or receive PSFCH 635 (e.g., switch transmission / reception). After PSFCH 635, gap 640, which is a predetermined idle time, exists.

[0105] The terminal can be pre-configured in the time slot position for transmitting PSFCH. The advance reception can be predetermined during the terminal manufacturing process, sent when connected to the sidelink related system, sent from the base station when connected to the base station, or received from other terminals.

[0106] exist Figure 6 In the embodiment described above, a preamble signal for performing AGC is separately performed in the physical channel structure in the sidelink time slot. However, according to another embodiment of the present disclosure, a separate preamble signal is not transmitted, and when receiving a physical channel for transmitting control information or data, the receiver of the receiving terminal can also use the control information or physical channel for data transmission to perform AGC.

[0107] Figure 7A A distribution 700 of feedback channels in a wireless communication system according to an embodiment of the present disclosure is shown. Figure 7AThe case where resources capable of transmitting and receiving the PSFCH are allocated in each time slot is shown.

[0108] refer to Figure 7A , the arrows indicate the time slots of the PSFCH in which the HARQ-ACK feedback information corresponding to the PSSCH is transmitted. Figure 7A , HARQ-ACK feedback information of PSSCH 711, 712, 713, 714, 715, 716, 717, and 718 transmitted in time slots 701, 702, 703, 704, 705, 706, 707, and 708 is transmitted in PSFCH 721, 722, 723, 724, 725, 726, 727, and 728 of the corresponding time slots. Since PSFCH is allocated to each time slot, PSFCH can correspond 1:1 with the time slot including PSSCH. For example, when Figure 7A When configuring the period of resources capable of transmitting and receiving PSFCHs through parameters such as periodicity_PSFCH_resource, periodicity_PSFCH_resource (PSFCH resource period) indicates one time slot. Alternatively, the period may be configured in milliseconds and indicated as a value allocated to each time slot according to the subcarrier spacing (SCS).

[0109] Figure 7B A distribution 750 of feedback channels in a wireless communication system according to an embodiment of the present disclosure is shown. Figure 7B It shows a case where resources are allocated for transmitting and receiving PSFCH every 4 time slots.

[0110] refer to Figure 7B , the arrows indicate the time slots of the PSFCH in which the HARQ-ACK feedback information corresponding to the PSSCH is transmitted. Figure 7B, only the last slot 754 of the four slots 751, 752, 753, and 754 includes a PSFCH 774. Similarly, only the last slot 758 of the next four slots 755, 756, 757, and 758 includes a PSFCH 778. Therefore, HARQ-ACK feedback information of PSSCH 761 in slot 751, PSSCH 762 in slot 752, PSSCH 763 in slot 753, and PSSCH 764 is transmitted from PSFCH 774 in slot 754. Similarly, HARQ-ACK feedback information of PSSCH 765 in slot 755, PSSCH 766 in slot 756, and PSSCH 767 in slot 757 is transmitted from PSFCH 778 in slot 758. Here, the index of the slot may be an index of a slot included in the resource pool. For example, the four time slots are not physically consecutive time slots, but may be time slots listed consecutively among the time slots included in the resource pool (or time slot pool) used for sidelink communication between terminals. The reason why the HARQ-ACK feedback information of the PSSCH sent in the fourth time slot is not sent on the PSFCH of the same time slot may be that the terminal completes the decoding of the PSSCH sent in the corresponding time slot and does not have enough time to send the PSFCH in the same time slot. For example, it may be because the minimum processing time required to process the PSSCH and prepare the PSFCH is not small enough.

[0111] Therefore, when resources capable of transmitting the PSFCH in time slot n+x are configured or provided, the terminal receiving the PSSCH in time slot n uses the smallest x among the integers greater than or equal to K to transmit the HARQ-ACK feedback information of the PSSCH using the PSFCH in time slot n+x. K can be a value pre-configured from the transmitting terminal or a value configured in the resource pool for transmitting the corresponding PSSCH or PSFCH. To configure K, each terminal can exchange its capability information with the transmitting terminal in advance. For example, K can be determined based on at least one of the subcarrier spacing, terminal capabilities, a configuration value with the transmitting terminal, or a resource pool configuration.

[0112] Figure 8 The following illustrates a signal flow for measuring and reporting sidelink channel status in a wireless communication system according to an embodiment of the present disclosure. Figure 8 An exchange of signals between a transmitting terminal 801 and a receiving terminal 802 is shown.

[0113] refer to Figure 8In operation 805, transmitting terminal 801 transmits a sidelink channel state information reference signal (CSI-RS) to receiving terminal 802. For example, transmitting terminal 801 transmits the sidelink CSI-RS to obtain channel information from receiving terminal 802, and receiving terminal 802 receives the sidelink CSI-RS. In addition, transmitting terminal 801 may request receiving terminal 802 to report sidelink channel state information (CSI). Sidelink CSI reporting may be enabled or disabled.

[0114] In operation 807 , the receiving terminal 802 measures a channel state of the side link between the transmitting terminal 801 and the receiving terminal 802 using the received side link CSI-RS.

[0115] In operation 809 , the receiving terminal 802 generates information about the sidelink CSI using the channel state measurement result. For example, 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 .

[0116] In operation 811, the receiving terminal 802 may send sidechain CSI to the transmitting terminal 801. In the present disclosure, when unicast transmission is performed between terminals in the side chain, sidechain CSI-RS transmission and sidechain CSI reporting are considered. For example, in the case of broadcast transmission, sidechain CSI-RS transmission and sidechain CSI reporting may not be supported. In addition, in the case of multicast transmission, the sidechain CSI-RS transmission and sidechain CSI reporting methods for multicast are not considered. Therefore, when the UE is not connected via PC5-RRC for unicast operation, the sidechain transmitting terminal cannot receive the SL CSI report from the receiving terminal. In addition, in the case of unicast transmission between terminals in the side chain, only non-periodic sidechain CSI reporting is considered.

[0117] The present disclosure is used to perform congestion control in a sidelink of V2X communication. The terminal's channel connection is determined based on whether the corresponding channel of the sidelink is congested. Congestion control is performed by limiting the configuration range of transmission parameters. For example, when the channel is congested, the terminal discards the transmission or controls channel access through scheduling adjustments. When the terminal accesses the channel, the terminal selects transmission parameters based on the channel congestion status, thereby improving the probability of successful transmission.

[0118] For congestion control, a terminal can measure the channel busy rate (CBR). The CBR is an indicator of how much of the channel is currently occupied by the terminal. It can be used to determine whether the corresponding channel on the sidelink is congested. The CBR measured in a specific time slot n can be defined as follows.

[0119] *CBR is defined as the ratio of subchannels in the resource pool whose sidelink received signal strength indicator (RSSI) measured by the terminal exceeds a (pre-)configured threshold. Here, CBR measurement can be performed in time slots [nX, n-1], where the time slot index is based on the physical time slot index.

[0120] **CBR measurements from a transmit perspective can be performed for the PSSCH region. Figure 6 , assuming 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 to which the PSCCH is transmitted overlap, the PSSCH region and the PSCCH region are interpreted as adjacent. If the PSSCH region and the PSCCH region are not located in adjacent resource regions, CBR measurement can be performed within the PSCCH region.

[0121] According to another embodiment of the present disclosure, from the perspective of transmission, CBR measurement can be performed on both the PSSCH region and the PSCCH region. Figure 6 , a PSSCH associated with a portion of the PSCCH is transmitted on a time resource overlapping with a non-overlapping frequency resource, but according to another embodiment of the present disclosure, there may be a situation where PSSCH and at least a portion of the PSCCH that are related to each other are transmitted in non-overlapping time resources. Here, the term "related" means that the PSCCH includes at least the information required to decode the PSSCH. When the PSCCH and the PSSCH are multiplexed as described above, assuming that the transmission power of the PSCCH area and the PSSCH area is constant and the RSSI can be measured accordingly in the PSCCH area and the PSSCH area, the CBR measurement can be performed simultaneously in each area without distinguishing between the PSSCH area and the PSCCH area. Specifically, in Figure 6 In the case of PSCCH and PSSCH, RSSI can be measured in symbols in the PSCCH region and PSSCH region. Figure 6 When multiplexing is performed as shown, it may be difficult for the terminal to distinguish between the PSCCH region and the PSSCH region when measuring the CBR. Therefore, CBR measurement can be performed on symbols of both the PSCCH region and the PSSCH region without distinguishing between the PSCCH region and the PSSCH region.

[0122] In addition, when Figure 6When the PSFCH region exists, it may be excluded from CBR measurement from a transmission perspective because it is a channel for transmitting feedback. For example, a terminal that transmits at least one of control information and data and measures CBR on at least one of the PSCCH and PSCCH may not perform CBR measurement on the PSFCH. Conversely, since the other terminal receiving data transmits feedback information via the PSFCH, CBR measurement can be performed on the PSFCH. For CBR measurement of the PSFCH region, refer to the following description.

[0123] **CBR measurement for feedback on transmission can be performed for PSFCH region. Figure 6 The above-mentioned measurement is described with reference to the PSFCH region shown in FIG7 .

[0124] *** In this case, it is assumed that ACK / NACK feedback for transmission is transmitted via PSFCH, and SL CSI feedback for transmission is transmitted via PSFCH. When SL CSI feedback is transmitted via PSSCH, CBR is measured in the PSSCH region as described above.

[0125] **X is the size of the window used to measure CBR. X can be a fixed value or a configurable value.

[0126] ***When X is a fixed value, X can be configured as 100 time slots. When X is a configurable value, the configuration value of X can be included in the resource pool configuration information. Before the terminal RRC is connected to the base station, the corresponding value in the terminal can be pre-configured, or configured from the base station via the SIB. After the terminal RRC is connected to the base station, X can be configured as a terminal-specific value. In addition, X can be configured via the PC5-RRC connection between the terminal and the terminal. For example, it can be configured via the resource pool configuration information through {100·2 μ , X is configured to one of 100} time slots. Here, μ is an index corresponding to a parameter set and is configured to the following values ​​according to a subcarrier spacing (SCS).

[0127] ****SCS=15kHz,μ=0

[0128] ****SCS=30kHz,μ=1

[0129] ****SCS=60kHz,μ=2

[0130] ****SCS=120kHz,μ=3

[0131] If X=100·2μ is configured in the above two configuration methods, if the CBR window is fixed at 100ms without considering the SCS and when X=100, the measurement time (ms) of the CBR window may vary depending on the SCS.

[0132] **Sidechain RSSI represents received signal strength. For example, the sidechain RSSI indicates the power received by the receiving terminal (unit: [W]) and is observed based on the effective OFDM symbol position of the corresponding channel in the sidechain time slot and the configured subchannel.

[0133] ***Here, the configured subchannel may refer to a subchannel allocated as a resource pool. In addition, the subchannel may be configured differently according to the corresponding channel. For example, the minimum configurable subchannel size of the PSSCH is 4RB and a maximum of 20 subchannels may be allocated. The minimum configurable subchannel size of the PSFCH is 2RB and a maximum of 40 subchannels may be allocated. The present disclosure is not limited thereto, and the size of the subchannel or the maximum number of subchannels may vary according to the SCS.

[0134] The congestion of the corresponding channel can be determined based on the CBR value measured by the definition of CBR. The terminal can 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 can be reported to the base station via Uu-RRC. In mode 1 of the sidelink resource allocation scheme, when the transmitting terminal requests the base station to send resources for performing sidelink communication with the receiving terminal, the base station can use the reported CBR information to allocate transmission resources. In addition, the base station can determine transmission parameter information (such as mode information of the PSSCH demodulation reference signal (DMRS), modulation and coding scheme (MCS), the number of transmission layers, etc.) and instruct the terminal to send the determined transmission parameter information. As described above, the base station can perform signaling of allocation information for transmission resources to the transmitting terminal via DCI. The base station can indicate transmission parameter information, such as mode information of the PSSCH DMRS, MCS configuration and the number of transmission layers, via the upper layer. For example, the base station can send transmission parameter information to the terminal via Uu RRC. However, the present disclosure does not exclude the use of DCI to signal transmission parameter information, such as PSSCH DMRS pattern information, MCS configuration, and the number of transmission layers. When sending a sidelink CSI report from a receiving terminal, it is necessary to dynamically change the transmission parameters based on the sidelink CSI. In this case, the transmitting terminal does not follow the transmission parameters (such as the PSSCH DMRS pattern information, MCS configuration, and the number of transmission layers signaled by the base station), but can determine the transmission parameters such as PSSCH DMRS pattern information, MCS configuration, and the number of transmission layers based on the direct sidelink CSI.

[0135] On the other hand, in Mode 2 of the sidelink resource allocation scheme, terminals not only perform resource allocation directly through sensing but also determine whether a channel is connected and transmission parameters by reflecting the CBR measured by the terminal. Therefore, in Mode 2, terminals can perform congestion control by measuring the channel occupancy rate (CR) and CBR measurements. In this case, packet priority can be reflected. When a transmitting terminal sends a packet, it can send a priority value indicating the corresponding packet to the receiving terminal via the SCI. CR is an indicator of how much a terminal occupies the channel, and the CR limit for the terminal's channel occupancy can be determined based on the CBR value. For example, when the channel is congested (i.e., when the measured CBR value is high), the CR limit is configured to be low, and the terminal should perform congestion control to ensure that the measured CR does not exceed the CR limit. To perform congestion control, the terminal should either discard transmissions or ensure that the CR measured through scheduling meets the CR limit. If the channel is not congested (i.e., when the measured CBR value is low), the CR limit is configured to be high, increasing the likelihood that the measured CR will not exceed the CR limit, thereby potentially increasing the terminal's channel occupancy and utilization.

[0136] Hereinafter, various embodiments of an operation of a terminal for performing congestion control in an NR sidelink are described.

[0137] First embodiment

[0138] According to the first embodiment of the present disclosure, the terminal may measure the CR for congestion control in mode 2. When the terminal selects resources via sensing in mode 2 among the sidelink resource allocation scheme, the terminal may reserve resources for transmitting one TB or reserve resources for transmitting multiple TBs. The configuration of whether the reserved resources are used to transmit one TB or multiple TBs may be determined from a higher level. In addition, in mode 2, the terminal may reserve resources for the retransmission of a TB and the initial transmission of a TB. When the terminal reserves transmission resources via sensing in mode 2, under the assumption that transmission occurs on the reserved resources, when the terminal measures the CR, the portion of the channel that is expected to be occupied and used in the future based on the current time point and the record of occupying and using the channel in the past may also be calculated. Therefore, the CR measured for PSSCH transmission in time slot n may be defined as follows.

[0139] Definition of CR measured for PSSCH transmission

[0140] *CR is defined as the total number of subchannels used for terminal transmission by occupying channels in the time slot [na, n-1] part and the subchannels authorized for use by occupying channels in the time slot [n, n+b] part divided by the total number of subchannels configured as the transmission resource pool in the time slot [na, n+b] part.

[0141] **Here, channel corresponds to PSSCH.

[0142] **Here, the slot index is based on the physical slot index.

[0143] **Here, a is a positive integer, and b is 0 or a positive integer. In addition, n+b cannot be configured to a value exceeding the last transmission opportunity granted via the transmission resource reservation.

[0144] ***M and N are values ​​defined as a+b+1=M and may be values ​​that satisfy the condition of a≥N determined by the terminal implementation. 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 RRC is connected to the base station, the corresponding values ​​may be pre-configured in the UE or configured from the base station via the SIB. After the terminal is RRC connected to the base station, M and N may be configured as terminal-specific values. For example, M is {1000·2 μ , 1000} the value of one of the time slots, N is {500·2 μ , 500} The value of one of the time slots, M and N can be configured via resource pool configuration information. Here, μ is an index corresponding to a parameter set (numerology) and is configured to the following values ​​according to the subcarrier spacing (SCS).

[0145] ****SCS=15kHz,μ=0

[0146] ****SCS=30kHz,μ=1

[0147] ****SCS=60kHz,μ=2

[0148] ****SCS=120kHz,μ=3

[0149] In the above two configuration schemes, if M = 1000·2 μ , N = 500·2 μ , is a scheme in which the CBR window is fixed at 100ms and is independent of the SCS. If M=1000, N=500 are configured, it is a scheme in which the measurement time (ms) of the CBR window may vary depending on the SCS.

[0150] **CR is measured for each (re)transmission.

[0151] **It is assumed that, when calculating the CR, the transmission parameters used in time slot n are reused even in transmissions that are authorized to occupy and use the channel in time slot [n, n+b].

[0152] ** As described by the third embodiment below, CR can be measured for priority.

[0153] **CR measurement schemes can vary depending on whether the aforementioned transmission types (such as broadcast, unicast, and multicast) can be configured simultaneously in a single resource pool or configured separately for each resource pool. According to the definition of CR, when different transmission types can be configured simultaneously in a single resource pool, CR for all transmission types can be measured simultaneously. When different transmission types are defined as being configured by partitioning the resource pools, CR can be measured separately for each transmission type. Here, broadcast can be referred to as the first transmission type, unicast can be referred to as the second transmission type, and multicast can be referred to as the third transmission type.

[0154] Based on the CR value measured based on the above definition, a terminal's channel occupancy level can be determined by reflecting how much the terminal has occupied the channel in the past and how much it will occupy in the future. Furthermore, the terminal should perform congestion control so that the measured CR value does not exceed the CR limit determined by the CBR. Therefore, accurate CR measurement is necessary. As described above, the CR definition assumes that when a terminal reserves transmission resources via sensing in Mode 2, transmission occurs within the reserved resources. However, this assumption may not always hold, depending on the retransmission scheme supported by the NR sidelink. Therefore, to address this issue, a method can be considered where the b value is always set to 0. Setting b to 0 indicates that CR calculation is not applied to the channel resources authorized to occupy and use the reserved transmission resources in time slot [n, n+b]. However, setting b to 0 does not consider channel occupancy fairness between terminals authorized to use a large amount of resources in time slot [n, n+b] and terminals that are not authorized. Therefore, the following describes a method for not transmitting to reserved transmission resources.

[0155] Specifically, the NR sidelink supports retransmission methods that include HARQ feedback-based retransmission (retransmission based on HARQ ACK / NACK feedback) and blind retransmission (retransmission without regard to HARQ ACK feedback information). With blind retransmission, retransmission must be performed regardless of whether the initial transmission and reception of the retransmission were successful. However, with HARQ feedback-based retransmission, retransmission can be determined based on the ACK / NACK feedback result. Furthermore, in Mode 2 of the NR sidelink, terminals can reserve transmission resources for both blind retransmission and HARQ feedback-based retransmission methods through sensing. Furthermore, with HARQ feedback-based retransmission methods, reserved transmission resources can be released based on HARQ ACK / NACK feedback. For example, when a transmitting terminal receives an ACK for a previous transmission, it can release the resources reserved for the next retransmission. For example, in the aforementioned definition of CR, when a terminal reserves transmission resources through sensing, the assumption that transmission must occur within the reserved resources is not met. Therefore, to accurately measure CR, it's necessary to consider the possibility of reserved resources being released. If this possibility is not considered, the greater the maximum number of retransmissions based on HARQ feedback and the greater the number of resources reserved for transmitting multiple TBs, the greater the inaccuracy of CR measurement. To address this issue, in the above definition of CR, when calculating the sum of the number of subchannels authorized to occupy and use the channel in time slot [n, n+b], the following calculation method can be used depending on the retransmission method.

[0156] Applying the weighted sum method when using HARQ feedback based retransmission

[0157] When using retransmission based on HARQ feedback in the sidelink, a weighted sum is applied to the number of subchannels of the channel authorized to occupy and use the channel for the i-th transmission of the TB at time slot [n, n+b]. Here, the weight is defined as W(i), where i=1 represents the initial transmission and i is a positive integer representing the i-th retransmission. The weight for the initial transmission is W(1)=1. The following method of applying the weight W(i) (i>1) to the retransmission can be considered.

[0158] **Method 1: The value of W(i) (i>1) can be determined by the terminal implementation.

[0159] **Method 2: The value of W(i) (i>1) can be configured. Information about the value of W(i) can be included in the resource pool configuration information. Before the terminal RRC is connected to the base station, the corresponding value can be pre-configured on the terminal, or it can be configured from the base station via the SIB. After the terminal RRC is connected to the base station, W(i) can be configured to a terminal-specific value. In addition, the information of W(i) can be configured via the PC5-RRC connection between the terminals.

[0160] **Method 3: W(i) = (0.1)i - 1. When the maximum number of retransmissions is 4, W(2) = 0.1, W(3) = 0.01, and W(4) = 0.001.

[0161] **Method 4: W(2)=0.1, W(i)=0 (i>2). The weighted sum is not applied after the third retransmission.

[0162] **Method 5: W(i)=0 (i>1). For example, weighted sum is not applied.

[0163] When the blind retransmission method is used in the side chain, since retransmission is performed regardless of whether initial transmission and reception of retransmission are successful, the above-mentioned weighted sum is not applied.

[0164] When the above definition of CR measured for PSSCH transmission and HARQ feedback-based retransmission is used, a measured value of CR to which a weighted sum is applied may be represented by Equation 1 below.

[0165]

[0166] In Equation 1, A, B(i), W(i), C, and NumMAXReTx may be defined as follows.

[0167] *A: The number of subchannels authorized to occupy and use the channel in time slot [na, n-1]

[0168] *B(i): The number of subchannels authorized to occupy and use the channel for the i-th transmission of TB in time slot [n, n+b]

[0169] *W(i): Weight applied to the number of subchannels authorized to occupy and use the channel for the i-th transmission of a TB at time slot [n, n+b]

[0170] *C: The total number of subchannels in the transmission resource pool when configured as time slot [na, n+b]

[0171] *NumMAXReTX: Maximum number of retransmissions supported for 1 TB

[0172] Equation 1 shows the CR calculation method proposed in the present disclosure when using retransmission based on HARQ feedback, and can be modified to other expressions with the same meaning. In addition, in Equation 1, when W(i)=1 is applied to all i, the weighted sum can also be applied to the blind retransmission method.

[0173] As described above, when b>0 is applied, when retransmission based on HARQ feedback is used, and when blind retransmission is used, how to reflect the number of subchannels authorized to occupy and use the channel during the CR window [n, n+b] has been studied. This can be described in Table 1 below.

[0174] Referring to Table 1 below, when SL HARQ is disabled, assuming blind retransmission, the subchannels authorized for use by occupying the channel during the CR window [n, n+b] can be reflected in the CR calculation without being discarded. On the other hand, when SL HARQ is disabled, assuming retransmission based on HARQ feedback, it can be assumed that the subchannels authorized for use by occupying the channel during the CR window [n, n+b] can be released based on HARQ feedback. In this case, the proposed weighted application method can be applied when performing accurate CR calculation using retransmission based on HARQ feedback.

[0175] Table 1

[0176]

[0177] Referring to Table 1, when evaluating the SL CR, if SL HARQ feedback is disabled, the terminal can assume that the transmission parameters in time slot n are reused according to the existing grant in time slot [n+1, n+b] without discarding packets. In addition, when evaluating the SL CR, the terminal can assume that the transmission parameters used in time slot n are reused according to the existing grant in time slot [n+1, n+b], and if SL HARQ feedback is enabled, the terminal can release the existing grant.

[0178] As described above, the NR sidechain considers both blind retransmission methods (retransmission based on HARQ feedback information) and HARQ feedback-based retransmission methods (retransmission based on HARQ ACK / NACK feedback). Both retransmission schemes can be used depending on the transmission type. In broadcast communications, since HARQ feedback is not supported, blind retransmission can be used. In unicast or multicast communications, since HARQ feedback is supported, at least one of the blind retransmission and HARQ feedback-based retransmission methods can be established and used.

[0179] In the above embodiments of the present disclosure, the case of configuring blind retransmission and the case of configuring retransmission based on HARQ feedback have been described separately. However, the present disclosure is not limited to this. In mode 2 of the NR side chain, blind retransmission and retransmission based on HARQ feedback can be configured and used at the same time. For example, when a maximum of 4 retransmissions are authorized, blind retransmission is used until 2 retransmissions, and whether to perform additional retransmissions can be determined based on HARQ feedback. For example, whether to perform additional retransmissions can be determined based on the HARQ feedback results. For example, blind retransmissions are performed until the first 2 retransmissions, and when NACKs are received continuously, additional retransmissions based on HARQ feedback can be performed or 2 blind retransmissions can be performed. In general, by considering the above method, when the number of blind retransmissions is configured as A and the number of retransmissions based on HARQ feedback is configured as B, a maximum of 4 retransmissions are authorized, and the following examples of configurations A and B can be considered.

[0180] *Example 1: A=0, B=4

[0181] *Example 2: A=1, B=1

[0182] *Example 3: A=1, B=2

[0183] *Example 4: A=2, B=0

[0184] A=0 means that blind retransmission is turned off, A=1 means 2 consecutive blind retransmissions, and A=2 means 4 consecutive blind retransmissions. In addition, B=0 means the case where retransmission based on HARQ feedback is turned off, and B=1 means the case where it can be determined based on HARQ feedback whether to perform 2 blind retransmissions after the first 2 blind retransmissions. In addition, B=2 means that the first 2 blind retransmissions occur and the 3rd and 4th 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, the proposed CR calculation method can be applied even when blind retransmission and retransmission based on HARQ feedback are configured at the same time (i.e., Example 2, Example 3). Specifically, when blind retransmission and retransmission based on HARQ feedback are supported at the same time, A and B described in Examples 1 to 4 above can be applied to the resources reserved for HARQ feedback retransmission at time slot [n, n+b].

[0185] Second embodiment

[0186] According to the second embodiment of the present disclosure, to control congestion in the V2X sidelink, a method for measuring CBR at a terminal and a method for exchanging CBR information between the transmitter and receiver are proposed. In the NR sidelink, CBR measurement for transmissions and feedback can be considered. In the LTE sidelink, HARQ ACK / NACK feedback or sidelink CSI feedback is not considered. However, in the NR sidelink, since HARQ ACK / NACK feedback and sidelink CSI feedback are considered, congestion control can consider the feedback of the receiving terminal in addition to the transmitting terminal's operations. Therefore, the transmitting terminal can measure CBR from the perspective of transmission, and the receiving terminal can measure CBR from the perspective of transmission feedback. CBR measurement by terminals in the sidelink can be defined as either a default feature or an optional feature. Furthermore, regardless of CBR measurement capability, it is possible to configure the CBR not to be used via higher layers. When CBR measurement is configured as optional, the CBR measurement capability can be categorized into four cases, as shown in Table 2 below, based on the CBR measurement capabilities of the transmitting and receiving terminals.

[0187] Table 2

[0188] CBR measurement capability of the sending terminal CBR measurement capability of the receiving terminal The first case X X Second case X O The third case O X The fourth case O O

[0189] Referring to Table 2, when the CBR measurement of the terminal is determined as a basic operation in the side chain, the CBR measurement capability of the terminal may correspond to the fourth case.

[0190] Figure 9 A signal flow for measuring and delivering a channel busy ratio (CBR) in a wireless communication system according to an embodiment of the present disclosure is shown. Figure 9 The signal exchange between the transmitting terminal 901 and the receiving terminal 902 is shown.

[0191] The transmitter can be understood as the subject that sends the signal, and the receiver can be understood as the subject that receives the signal. Therefore, in the V2X system, the transmitter can operate as a transmitting terminal and the receiver can operate as a receiving terminal. For example, in Figure 9 In the embodiment, CBR measurement is performed according to the CBR measurement capabilities of the transmitting terminal and the receiving terminal. If necessary, the operation of sending the measured CBR to the receiving terminal or sending the CBR measured by the receiving terminal to the transmitting terminal will be described.

[0192] refer to Figure 9, in operation 905, the transmitting terminal 901 and the receiving terminal 902 exchange information about CBR capabilities. As described above, when the transmitting terminal measures CBR from the perspective of transmission and the receiving terminal measures CBR from the perspective of feedback for transmission, the transmitting terminal and the receiving terminal may need information about each other's CBR capabilities. For example, when the transmitting terminal and the receiving terminal obtain information about each other's CBR capabilities, when the transmitting terminal requests the sidechain CSI, the transmitting terminal can instruct the receiving terminal to feedback the sidechain CSI by reflecting the CBR. For another example, if the receiving terminal has CBR capability, assuming that it is a basic operation for the receiving terminal to report the sidechain CSI, based on the CBR, the transmitting terminal can determine whether the CBR is reflected in the SL CSI reported by the receiving terminal. In addition, depending on the environment of the transmitting terminal and the receiving terminal, the difference between the CBR measured by the transmitting terminal and the CBR measured by the receiving terminal may increase. Therefore, when the transmitting terminal and the receiving terminal know each other's CBR capabilities, they can request each other's CBR information when necessary. The CBR capability information of the transmitting terminal and the receiving terminal can be exchanged during the PC5-RRC connection process. As Figure 4 and Figure 5 As described, in the case of sidelink unicast transmission, a PC5-RRC connection can be performed between terminals.

[0193] refer to Figure 9 , the CBR measurement can be performed by a transmitting terminal or a receiving terminal with CBR measurement capability (operations 907 and 909). In addition, depending on the situation of the side link, it may be possible that the transmitting terminal or the receiving terminal cannot measure the CBR despite the CBR measurement capability. In addition, depending on the environment of the transmitting terminal and the receiving terminal, the difference between the CBR measured by the transmitting terminal and the CBR measured by the receiving terminal may increase. In this case, in operation 911, the transmitting end may send the CBR measurement result to the receiving end, or in operation 913, the receiving end may send the CBR measurement result to the transmitting end. Reference Figure 9 , operations 911 and 913 are shown as being performed sequentially, but this is for ease of description, and operations 911 and 913 may be performed in any order.

[0194] For example, in the case where the transmitting terminal has a CBR measurement capability, the transmitting terminal may measure the CBR (operation 907) and transmit the measured CBR measurement result to the receiving terminal (operation 911).

[0195] Similarly, in the case where the receiving terminal has a CBR measurement capability, the receiving terminal may measure the CBR (operation 909) and transmit the measured CBR measurement result to the transmitting terminal (operation 913).

[0196] In addition, when both the transmitting terminal and the receiving terminal have CBR measurement capabilities, operations 911 to 913 may be performed.

[0197] However, the embodiments of the present disclosure are not limited thereto. Even if the transmitting terminal and the receiving terminal have CBR measurement capabilities, the operation of sending the CBR measurement results may be omitted. For example, a transmitting terminal with CBR measurement capabilities may not perform operation 911, and a receiving terminal with CBR measurement capabilities may not perform operation 913.

[0198] For example, the terminal may determine whether to send the measured CBR information according to the channel environment. Alternatively, whether to send the CBR measurement result may be predetermined or configured (for example, CBR transmission may be configured to be performed when the receiving terminal or the transmitting terminal has CBR measurement capability).

[0199] Alternatively, the CBR measurement result may be sent according to an indicator for instructing to send the CBR measurement result. For example, a transmitting terminal that has received the CBR measurement capability of a receiving terminal may send an indicator instructing the receiving terminal to send the CBR measurement result. Thus, the transmitting terminal may receive the CBR measurement result from the receiving terminal.

[0200] When the transmitter and receiver have each other's CBR information, the transmitter and receiver can determine channel congestion more accurately. Specifically, the CBR level can be determined using both the CBR level (RX) of the receiver and the CBR level (TX) of the transmitter. For example, the CBR level can be determined based on Max(CBR level (TX), CBR level (RX)), where Max is the maximum value of the CBR level of the transmitter and the CBR level of the receiver. In this case, the worst case of the CBR of the transmitter and receiver can be considered. Hereinafter, the CBR information of the transmitter and receiver described in Example 2 can be reflected to configure the CR limit reflecting the CBR and the transmission and feedback parameter range.

[0201] Third embodiment

[0202] According to the third embodiment of the present disclosure, congestion control can be performed so that the CR value measured based on the CR defined in the first embodiment does not exceed the CR limit value determined by the CBR. When the terminal receives the CR limit value using a high-layer parameter and the terminal transmits a PSSCH in time slot n, the value of the priority k should satisfy the condition of Equation 2.

[0203] ∑ i≥k CR(i)≤CR Limit (k) Equation 2

[0204] Here, CR(i) refers to the CR value for PSSCH transmission measured in time slot nY, where the priority of the priority field in the SCI is configured as i. Here, the value of Y is the processing time required to measure the CR and transmit the PSSCH in time slot n, which can be defined in units of time slots. The value of Y can be a fixed value or a configurable value.

[0205] Alternatively, differently from this, the value of Y may be determined according to the SCS as shown in Table 3. In the following Table 3, μ is a value corresponding to the SCS.

[0206] Table 3

[0207] μ (In time slot) 0 2 1 2 2 3 3 4

[0208] Table 3 shows the value of Y that varies with SCS based on the PSSCH preparation time in the NR system. Specifically, it is assumed that the PUSCH preparation time of the NR system is 10 symbols when μ = 0, 12 symbols when μ = 1, 23 symbols when μ = 2, and 36 symbols when μ = 3.

[0209] For example, if the value of Y is a fixed value, it can be Y=4. Further, when the value of Y can be configured, information indicating the value of Y can be included in the resource pool configuration information. Before the terminal is connected to the base station by RRC, the corresponding value in the terminal can be pre-configured and can also be configured from the base station via SIB. After the RRC connection is made with the base station, Y can be configured to a terminal-specific value. In addition, the value of Y can be configured via the PC5-RRC connection between the terminal and the terminal. In addition, CR Limit (k) is the CR limit value determined by the CR value measured in nY and the priority value k, and can be configured using higher parameters. Specifically, the CR limit value can be determined by the CBR value measured in the nY time slot. Figure 10 The terminal should discard the transmission of the PSSCH in time slot n or meet the CR limit of Equation 2 through terminal implementation. When the sidelink CSI is transmitted via the PSSCH, Equation 2 can be applied to the terminal that transmits the sidelink CSI. In the case where the terminal that transmits the sidelink CSI reports the sidelink CSI via the PSSCH, when the CR measured by the terminal does not meet the conditions of Equation 2, the operation of discarding the reporting of the sidelink CSI through the terminal or the terminal implementation to meet the CR limit of Equation 2 can be considered.

[0210] In the above equation 2, it has been described that the transmitting terminal performs congestion control via CR measurement on PSSCH. However, in the NR side chain, it can be considered that the receiving terminal performs congestion control via CR measurement on PSFCH. As described above, when the retransmission method based on HARQ feedback is used, HARQ feedback information can be sent to PSFCH, and as Figure 6 As shown in Figure 7, the CBR can be measured in the area where the PSFCH is transmitted. Therefore, congestion control can be performed so that the CR limit value determined by the CBR measured in the area where the PSFCH is transmitted is not exceeded. When the terminal is configured with a CR limit value via a higher parameter and the receiving terminal sends HARQ ACK / NACK feedback to the transmitting terminal via the PSFCH in time slot n, the priority value k should satisfy the following condition expressed by Equation 3.

[0211]

[0212] Here, CR FB (i) represents the CR value for the PSFCH measured in time slot nZ, where HARQ ACK / NACK feedback for the PSSCH transmission is transmitted in the SCI, and the priority of the field in the PSSCH transmission is configured as i. Here, the value of Z is the processing time required to measure the CR in time slot n and before transmitting the PSFCH, which can be defined in time slot units. The value of Z can be fixed or configurable.

[0213] Alternatively, in contrast to this, the value of Z may be determined based on the SCS as shown in Table 3 above. For example, when the value of Z is a fixed value, it may be Z=4. In addition, when the value of Z is configurable, information indicating the value of Z may be included in the resource pool configuration information. Before the terminal RRC is connected to the base station, the corresponding value in the terminal may be pre-configured or configured from the base station via the SIB. After the terminal RRC is connected to the base station, Z may be configured specifically for the terminal. In addition, the value of Y may be configured via a PC5-RRC connection between the terminal and the terminal. In addition, reference is made to the definition of the CR measured by the receiving terminal for PSFCH transmission. In addition, The CR limit value is determined by the value of the priority CR and the n value measured in nZ, which can be configured via upper layer parameters. Specifically, the CR limit value can be determined by the CBR value measured in time slot nZ. This will be described in the following Figure 11 The terminal shall satisfy the CR limit of Equation 3 by discarding the HARQ ACK / NACK transmission to the PSFCH in slot n or by the terminal implementation.

[0214] Different from the definition of CR for PSSCH transmission measured by the transmitting terminal, CR for PSFCH transmission measured by the receiving terminal in time slot n can be defined as follows.

[0215] Definition of CR measured for PSFCH transmission

[0216] *CR is defined as the value obtained by dividing the number of subchannels of a channel occupied and used by the terminal at time slot [na, n-1] by the total number of subchannels configured as PSCFH at time slot [na, n-1].

[0217] **Here, channel corresponds to PSFCH.

[0218] **Here, the slot index is based on the physical slot bit index.

[0219] **Here a is a positive integer, fixed to a predetermined value, or determined to be a configurable value.

[0220] ***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 by other values. Alternatively, when the value of a can be configured, information indicating the value of a may be included in the resource pool configuration information. Before the terminal RRC is connected to the base station, the corresponding value may be pre-configured in the UE and may be configured from the base station via the SIB. After the RRC connection is established with the base station, the value of a may be terminal-specific.

[0221] **CR is measured for each HARQ ACK / NACK transmission.

[0222] **As shown in Equation 3 and Figure 11 As described, CR can be measured for priority levels.

[0223] When a terminal performs HARQ ACK / NACK feedback via the PSFCH via Equation 3, congestion control using the CBR and CR has been described. The above embodiment is directed to an operation in which, when the conditions for congestion control in Equation 3 are not met, the receiving terminal does not provide HARQ ACK / NACK feedback to the transmitting terminal, even when HARQ ACK / NACK feedback is enabled and a retransmission method based on HARQ feedback is used. Alternatively, other congestion control methods may be considered for HARQ ACK / NACK feedback. For example, a CBR measurement value of the PSFCH channel may be used without using the CR measurement in Equation 3. In this case, the CBR measurement value of the PSFCH channel can be used by both the transmitting and receiving terminals. When HARQ ACK / NACK feedback is disabled and a retransmission method based on HARQ feedback is used, the transmitting terminal may measure the CBR of the PSFCH channel; when the measured value is greater than a configured threshold, the transmitting terminal may cancel the request for HARQ ACK / NACK feedback from the receiving terminal. Specifically, the transmitting terminal can indicate HARQ ACK / NACK feedback cancellation information by including 1 bit of information in the SCI. Alternatively, when HARQ ACK / NACK feedback is disabled and a retransmission method based on HARQ feedback is used, if the receiving terminal measures the CBR of the PSFCH channel and the measured value is greater than the configured threshold, a method of not performing HARQ ACK / NACK feedback to the receiving terminal can be used. Here, the threshold can be included in the resource pool configuration information. Before the terminal RRC is connected to the base station, the corresponding value can be pre-configured in the terminal and can be configured from the base station via the SIB. After the terminal RRC is connected to the base station, the threshold can be configured specifically for the terminal. In addition, the threshold can be configured via the PC5-RRC connection between the terminal and the terminal.

[0224] Fourth embodiment

[0225] Figure 10 The configuration of channel occupancy rate (CR) limit and transmission parameter range in a wireless communication system according to an embodiment of the present disclosure is shown.

[0226] According to the fourth embodiment of the present disclosure, congestion control can be performed by determining the configuration of the CR limit value according to the CBR and the range of the transmission parameters that can be configured according to the CBR. The CBR can be measured as a value between 0 and 100, but can be quantified according to the CBR range. For example, X CBR levels can be classified and used by mapping the CBR measurement results to the CBR levels corresponding to the corresponding CBR ranges. Therefore, in the side chain, the CR limit value and the range of configurable transmission parameters can be determined according to the CBR level and the priority of the packet to be sent. The terminal can perform congestion control via the CBR and the CR limit value mapped to the highest priority of the packet to be sent and the range of the transmission parameters. In the following, Figure 10 , an example of configuring the CR limit and transmission parameter range according to the CBR in the side chain and the priority of the packet is shown.

[0227] refer to Figure 10 , via the resource pool configuration 1010, the CR limit value 1060 corresponding to the CBR level 1030, the priority 1020 of the packet to be sent, and the range 1070 of the transmission parameters are configured. Here, before the terminal RRC is connected to the base station, the CBR level determined via the resource pool configuration and the CR limit value and the range of transmission parameters corresponding to the priority of the packet to be sent can be pre-configured at the terminal, and can be configured from the base station via the SIB. After the terminal RRC is connected to the base station, the terminal can receive the above-mentioned values ​​specific to the terminal. In addition, the CR limit value and the range of transmission parameters corresponding to the CBR level and the priority of the packet to be sent can be configured via the PC5-RRC connection between the terminal and the terminal. According to Figure 10 , the measured CBR can be used by mapping to the minimum and maximum values ​​of the CBR range 1040 configured according to the corresponding CBR level. Figure 10 , the CBR level can be divided into a maximum of X CBR levels. The details of the transmission parameter 1050 range tx-Parameters are described in Table 4 below.

[0228] As described above, congestion control can be performed by configuring the transmission parameter range. For example, when the channel is congested (when the CBR value is measured as high), interference between terminals in the congested situation can be minimized by reducing the size of the subchannel to which the PSSCH is allocated, lowering the maximum value of the transmission power, and reducing the number of retransmissions. At the same time, it is possible to adjust the transmitted signal to be successfully received by configuring the MCS to be low and reducing the number of transmission layers. Therefore, configuring the range of transmission parameters by reflecting the CBR is conducive to configuring parameters suitable for the channel conditions and is conducive to congestion control. The following table 4 is used as an example to illustrate the configuration method of the transmission parameter range. The transmission parameter set (SL-PSSCH-TxParameters) described in Table 4 may include a subchannel allocation range (minSubChannel-NumberPSSCH, maxSubchannel-NumberPSSCH), the number of retransmissions (allowedRetxNumberPSSCH), and the MCS configuration range (minMCS-PSSCH, maxMCS-PSSCH), PSSCH DMRS pattern information (additional-dmrsPSSCH), and the number of transmission layers (Txlayer-NumberPSSCH). In addition, assuming that CBR measurement is used, the transmission parameter set (SL-PSSCH-TxParameters) may include maximum transmission power information (maxTxPower). Some parameters included in the transmission parameter set (SL-PSSCH-TxParameters) described in Table 4 below may not be used, and other parameters may be considered separately.

[0229] Table 4

[0230]

[0231] In Table 4, minMCS-PSSCH and maxMCS-PSSCH can be used to indicate the MCS configuration range. Alternatively, a method of selecting MCS within a range smaller than maxMCS-PSSCH by configuring only maxMCS-PSSCH can be considered. In addition, in Table 4, Txlayer-NumberPSSCH indicates the number of transmission layers, n1 indicates 1-layer transmission, and n2 indicates 2-layer transmission. In addition, both mean that the terminal can independently configure the configuration of 1 / 2 layers. In Table 4, allowedRetxNumberPSSCH indicates the terminal retransmission number configuration, n0 indicates no retransmission, n1, n2, and n3 represent 2, 3, and 4 retransmissions, respectively, including initial transmission. In addition, all indicates that the terminal can autonomously configure the corresponding value. In Table 4, the subchannel allocation range can be indicated via minSubChannel-NumberPSSCH and maxSubchannel-NumberPSSCH. Here, the maximum number of subchannels (maxSubChannel) may vary depending on the channel bandwidth and SCS. In Table 4, maxTxPower indicates the maximum transmission power value limited for congestion control when using CBR. In Table 4, additional-dmrsPSSCH is the pattern information of PSSCH DMRS, indicating the number of additional DMRS symbols. When additional-dmrsPSSCH is configured to 0, it means that only front-loaded DMRS is sent, and when additional-dmrsPSSCH is configured to 3, it means that up to 4 DMRS symbols including front-loaded DMRS are sent. DMRS pattern information other than the number of additional DMRS symbols may be included. Here, via additional-dmrsPSSCH, the density of DMRS can be increased, and thereby the channel estimation performance can be improved in the low SNR area to improve the reception performance.

[0232] The transmission parameter set (SL-PSSCH-TxParameters) of Table 4 can be configured without considering the CBR. As described in the second embodiment of the present disclosure, operation without using CBR via a higher configuration can also be considered. When the transmission parameter set (SL-PSSCH-TxParameters) is configured without considering the CBR, it is 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 configured regardless of the CBR. If there is an SL CSI report, the transmitting terminal identifies the channel state via the SL CSI and selects the transmission parameters. In this case, whether there is an SL CSI report can be determined by one of the following conditions.

[0233] Determine whether there is a SL CSI report condition

[0234] *Condition 1: Depends on whether SL CSI reporting is enabled

[0235] *Condition 2: Depends on whether SL CSI reporting is triggered / activated

[0236] *Condition 3: Depends on whether the transmitting terminal receives the CSI report of the receiving terminal

[0237] Condition 1 is a method for determining the presence of an SL CSI report when the SL CSI report is disabled. Condition 2 is a method for determining the presence of an SL CSI report when the SL CSI report is disabled and the SL CSI report is activated. Depending on how the SL CSI report is triggered and / or activated, Condition 1 and Condition 2 may be the same or different. For example, when the SL CSI report is disabled, when the SL CSI report is triggered / activated, it corresponds to a case where Condition 1 and Condition 2 are the same. In addition, Condition 3 is a method for determining the presence of an SL CSI report when the actual transmitting terminal receives a CSI report from the receiving terminal. According to Condition 3, when there is no SL CSI report, the transmission parameter set (SL-PSSCH-TxParameters) can be configured without considering the CBR. If there is no SL CSI report, since the transmitting terminal cannot know the channel state between the terminals, it may be difficult to select the transmission parameters so that the receiving terminal can successfully receive the data sent by the transmitting terminal. Therefore, in this case, a transmission parameter set (SL-PSSCH-TxParameters) can be determined for each synchronization source of the terminal according to the absolute speed of the transmitting terminal. Here, the synchronization source can be at least one of a base station or a global navigation satellite system (GNSS). For a terminal that is not Uu-RRC connected to a base station, at least one of the GNSS or the terminal can be the synchronization source. By configuring a threshold value for the absolute speed of the terminal and comparing the absolute speed with a threshold value of the transmitting terminal, an optional transmission parameter set (SL-PSSCH-TRxParameters) can be determined based on whether the speed is greater than or less than the threshold value. At this time, the threshold value can be included in the resource pool configuration information. Before the terminal RRC is connected to the base station, the corresponding value can be pre-configured in the terminal and can be configured from the base station via the SIB. After the terminal RRC is connected to the base station, the corresponding value can be configured specifically for the terminal. In addition, the terminal can receive the threshold value via a PC5-RRC connection between the terminal and the terminal.

[0238] Therefore, the method for the transmitting terminal to select transmission parameters can be determined according to the following situations.

[0239] *Case 1: If there is no SL CSI report, and CBR is not considered and only the transmission parameter set (SL-PSSCH-TxParameters) is configured, the transmitting terminal can select the transmission parameters in the transmission parameter set.

[0240] **Case 1 corresponds to the case where CBR is not configured by upper layer configuration.

[0241] **Case 1 corresponds to the case of using transmission parameters set according to the absolute speed of the transmitting terminal.

[0242] **Case 1 may be limited to Mode 2. In Mode 1, the base station may indicate resource scheduling information via DCI, and send parameter information other than resource scheduling via Uu-RRC or DCI. At this time, the transmitting terminal follows the transmission parameters other than resource scheduling indicated by the base station. In the case where the transmission parameters are not indicated by Uu-RRC in Mode 1, Case 1 may be adopted, or the transmission parameters may be selected by the terminal implementation. Referring to Table 4, among the parameters included in SL-PSSCH-TxParameters, the subchannel allocation range (minSubChannel-NumberPSSCH, maxSubchannel-NumberPSSCH) and the number of retransmissions (allowedRetxNumberPSSCH) may be included in the resource scheduling information. In SL-PSSCH-TxParameters, parameters other than the above information may be included in the transmission parameter information (instead of resource scheduling).

[0243] *Case 2: If there is no SL CSI report, when a first transmission parameter set (SL-PSSCH-TxParameters) that does not consider CBR is configured and a second parameter set (SL-PSSCH-TxParameters) that reflects CBR is configured via higher layer configuration, the transmitting terminal selects transmission parameters within the range of parameters that overlap between the two transmission parameter sets. If there are no overlapping parameters, the transmission parameters are selected by the terminal implementation.

[0244] **Case 2 corresponds to the case where CBR is configured for use by upper layer configuration.

[0245] **Case 2 corresponds to a case where a set of transmission parameters according to the absolute speed of the transmitting terminal and a set of transmission parameters reflecting the CBR are used.

[0246] **For example, in the case of the MCS configuration range described in Table 4, since the MCS configuration range of the first transmission parameter set is 0 to 5 and the MCS configuration range of the second transmission parameter set is 3 to 9, the transmission parameters are selected from the overlapping MCS configuration ranges 3 to 5.

[0247] **Case 2 may be limited to Mode 2. In Mode 1, the base station may indicate resource scheduling information via DCI and transmission parameter information other than resource scheduling via Uu-RRC or DCI. At this time, the transmitting terminal follows the transmission parameters other than resource scheduling indicated by the base station. If in Mode 1, the indication of the transmission parameters is not indicated via Uu-RRC, Case 2 may be applied or the transmission parameters may be selected by the terminal implementation. Referring to Table 4, the subchannel allocation range (minSubChannel-NumberPSSCH, maxSubchannel-NumberPSSCH) and the number of retransmissions (allowedRetxNumberPSSCH) may be included in the resource scheduling information in the parameters included in SL-PSSCH-TxParameters. In SL-PSSCH-TxParameters, parameters excluding the above information may be included in the transmission parameter information other than resource scheduling.

[0248] *Case 3: When SL CSI reporting is present and CBR is configured not to be used by higher-level configurations, the parameters in the transmission parameter set (SL-PSSCH-TxParameters) are selected by the terminal implementation.

[0249] **Case 3 may be limited to mode 2. In mode 1, the base station may indicate resource scheduling information via DCI and transmission parameter information other than resource scheduling via Uu-RRC or DCI. At this time, the transmitting terminal follows the transmission parameters other than resource scheduling indicated by the base station. If in mode 1, the transmission parameters are not indicated via Uu-RRC, the transmission parameters may be selected by the terminal implementation, as in the above-mentioned case 3. Referring to Table 4, the subchannel allocation range (minSubChannel-NumberPSSCH, maxSubchannel-NumberPSSCH) and the number of retransmissions (allowedRetxNumberPSSCH) may be included in the resource scheduling information among the parameters included in SL-PSSCH-TxParameters. In SL-PSSCH-TxParameters, parameters excluding the above information may be included in the transmission parameter information other than resource scheduling.

[0250] *Case 4: When there is an SL CSI report and a transmission parameter set (SL-PSSCH-TxParameters) reflecting CBR is configured via a higher-level configuration, the transmitting terminal may select transmission parameters in the transmission parameter set.

[0251] **Case 4 corresponds to the case where CBR is configured to be used by a higher configuration.

[0252] **Case 4 may be limited to Mode 2. In Mode 1, the base station may indicate resource scheduling information via DCI and transmission parameter information other than resource scheduling via Uu-RRC or DCI. At this time, the transmitting terminal follows the transmission parameters other than resource scheduling indicated by the base station. If the transmission parameters are not indicated by Uu-RRC in Mode 1, the above-mentioned Case 4 may be applied or the transmission parameters may be selected by the terminal implementation. Referring to Table 4, the subchannel allocation range (minSubChannel-NumberPSSCH, maxSubchannel-NumberPSSCH) and the number of retransmissions (allowedRetxNumberPSSCH) may be included in the resource scheduling information among the parameters included in SL-PSSCH-TxParameters. In SL-PSSCH-TxParameters, parameters excluding the above information may be included in the transmission parameter information other than resource scheduling.

[0253] The following describes operations after the transmitting terminal selects transmission parameters from the transmission parameter set (SL-PSSCH-TxParameters) in Table 4.

[0254] *The transmitting terminal can transmit based on the selected MCS and deliver the information to the receiving terminal via the SCI.

[0255] *The transmitting terminal can transmit based on the number of selected transmission layers and send corresponding information to the receiving terminal via the SCI.

[0256] *In Mode 2, the transmitting terminal may perform resource selection using a sensing result based on the selected subchannel allocation length and the number of retransmissions, and may transmit the determined resource allocation information to the receiving terminal via the SCI.

[0257] *The transmitting terminal may perform transmission using the selected transmission power and transmit information about the reference transmission power to the receiving terminal.

[0258] **The reference transmission power can be the transmission power of at least one of a synchronization signal, DMRS transmitted via the physical sidelink broadcast channel (PSBCH), SL CSI-RS, or another reference signal. The reference transmission power can be referred to as the energy per resource element (EPRE), the synchronization signal, DMRS transmitted via the PSBCH, SL CSI-RS, or other sidelinks for the set of sidelinks within the system bandwidth (BW). It can be defined as the average power (in watts [W]) of the resource elements (REs) used to transmit the reference signal.

[0259] *The transmitting terminal may use the selected PSSCH DMRS pattern information for transmission and send the information to the receiving terminal via SCI or PC5-RRC.

[0260] Fifth embodiment

[0261] Figure 11 The configuration of the CR limit value and the feedback parameter range in the wireless communication system according to an embodiment of the present disclosure is shown.

[0262] According to the fifth embodiment of the present disclosure, a method for performing congestion control on transmission feedback based on CBR is proposed. As described above, since CSI feedback and HARQ ACK / NACK feedback are considered in the NR side chain, the operation of the receiving terminal for transmission feedback and the operation of the transmitting terminal for congestion control can be considered compared with the LTE side chain. CBR can be measured as a value between 0 and 100, but can be quantified according to the CBR range. For example, X CBR levels are classified, and the CBR measurement results can be mapped to the CBR level corresponding to the corresponding CBR range for use. Accordingly, in the side chain, the CR limit and the configurable feedback parameter range can be determined according to the CBR level and the priority of the packet to be sent. The terminal can perform congestion control via the CR limit and the range of feedback parameters mapped to the CBR and the priority of the received packet. Reference Figure 11 , illustrates an example of configuring the range of CR limits and feedback parameters based on the CBR and priority of the packet in the measurement.

[0263] See also Figure 11 , via the resource pool configuration 1110, the CR limit 1160 corresponding to the CBR level 1130 and the priority 1120 of the packet to be sent, and the range 1170 of the feedback parameter 1150 are configured. Here, before the terminal RRC is connected to the base station, the CBR level determined via the resource pool configuration and the CR limit and the range of the feedback parameter 1150 corresponding to the priority of the received packet can be pre-configured at the terminal, and the SIB can be configured via the base station. After the terminal is RRC connected to the base station, the terminal can be configured with the above-mentioned terminal-specific values. In addition, the CR limit and the range of the feedback parameter 1150 corresponding to the CBR level and the priority of the received packet can be configured via the PC5-RRC connection between the terminal and the terminal. According to Figure 11 , the measured CBR can be used by being mapped to the minimum and maximum values ​​of the CBR range 1140 set according to the corresponding CBR level. Figure 11 As shown, the CBR level can be divided into a maximum of X CBR levels. The details of the feedback parameter range (CSI parameter 1170) are described in Table 5 below.

[0264] In this embodiment of the present disclosure, a method for determining CSI feedback parameters based on CBR will be described. The method for performing congestion control for HARQ-ACK / NACK feedback based on CBR can be described with reference to the third embodiment. As described above, CBR refers to the value at which the terminal measures the congestion of the channel within a certain period of time, and the terminal can use the CBR value for congestion control. In addition, when the receiving terminal generates SL CSI information, it can select parameters suitable for the channel conditions based on the congestion situation, and when the selected parameters are fed back to the transmitting terminal, the parameters can be used as more effective information for the transmitting terminal to select transmission parameters. The following method can be considered for reporting SL CSI in the side link.

[0265] SL CSI transmission channel

[0266] * Method 1: SL CSI is carried and transmitted together with data via PSSCH (piggyback).

[0267] * Method 2: SL CSI is transmitted via PSSCH without data (SL CSI transmission only)

[0268] *Method 3: SL CSI is transmitted via PSFCH

[0269] In the case of method 1 and method 2, since the SL CSI is transmitted via PSSCH, the CBR measured for the above-mentioned PSSCH area can be used. In the case of method 3, since the SL CSI is transmitted via PSFCH, the CBR measured for the above-mentioned PSFCH area can be used. In the embodiment of the present disclosure, a case where the channel quality indicator (CQI) and the rank indicator (RI) are fed back as SL CSI information is considered. The configuration method of the feedback parameter range is explained below via Table 5. 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 also be additionally considered.

[0270] Table 5

[0271]

[0272] Referring to Table 5, the RI configuration range (allowedRI) can be determined within the range of the maximum number of transmission layers supported by the transmitting terminal. In Table 5, allowedRI indicates reportable RI, n1 indicates rank 1, and n2 indicates rank 2. Both indicate that the terminal can autonomously configure the configuration of rank 1 and rank 2. In addition, the CQI configuration range (minCQI, maxCQI) can be determined by the SL CQI table used. For example, when the SL CQI table reuses the CQI table used in NR Uu, the CQI configuration range (minCQI, maxCQI) can be determined from a maximum of 16 levels. On the other hand, when the SL CQI table is designed based on the MCS table used in NR Uu, the CQI configuration range (minCQI, maxCQI) can be determined from a maximum of 32 levels. As shown in Table 5, when CQI and RI are reported as SL CSI information, the receiving terminal can select feedback parameters within the CQI configuration range (minCQI, maxCQI) and RI configuration range (allowedRI) configured by the CBR level.

[0273] Figure 12 The configuration of a terminal in a wireless communication system according to an embodiment of the present disclosure is shown. Hereinafter, terms such as "... unit", "... part" and the like used below refer to a unit that processes at least one function or operation, which can be implemented by hardware or software or a combination of hardware and software.

[0274] refer to Figure 12 The terminal includes a communication unit 1210, a storage unit 1220 and a controller 1230.

[0275] The communication unit 1210 performs functions for transmitting and receiving signals via wireless channels. For example, the communication unit 1210 performs conversion functions between baseband signals and bit streams according to the system's physical layer standard. For example, during data transmission, the communication unit 1210 generates composite symbols by encoding and modulating the transmitted bit stream. Furthermore, during data reception, the communication unit 1210 recovers the received bit stream by demodulating and decoding the baseband signal. Furthermore, the communication unit 1210 up-converts the baseband signal to an RF band signal, transmits the signal via an antenna, and down-converts the RF band signal received via the antenna to a baseband signal. For example, the communication unit 1210 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, and the like.

[0276] In addition, the communication unit 1210 may include multiple transmit / receive paths. In addition, the communication unit 1210 may include at least one antenna array including multiple antenna elements. In terms of hardware, the communication unit 1210 may include digital circuits and analog circuits (e.g., radio frequency integrated circuits (RFICs)). Here, the digital circuits and analog circuits may be implemented in a single package. In addition, the communication unit 1210 may include multiple RF chains. In addition, the communication unit 1210 may perform beamforming.

[0277] The communication unit 1210 transmits and receives signals as described above. Therefore, all or part of the communication unit 1210 may be referred to as a "transmitter," a "receiver," or a "transceiver." In the following description, transmission and reception via a wireless channel are used in the sense of including the processing described above performed by the communication unit 1210.

[0278] The storage unit 1220 stores data such as basic programs, application programs, and configuration information for terminal operations. The storage unit 1220 may include volatile memory, non-volatile memory, or a combination of volatile and non-volatile memory. The storage unit 1220 then provides the stored data upon request from the controller 1230.

[0279] The controller 1230 controls the overall operation of the terminal. For example, the controller 1230 sends and receives signals through the communication unit 1210. In addition, the controller 1230 writes and reads data in the storage unit 1220. In addition, the controller 1230 can perform the functions of the protocol stack required by the communication standard. To this end, the controller 1230 may include at least one processor or microprocessor or may be part of a processor. In addition, the communication unit 1210 and a part of the controller 1230 may be referred to as a communication processor (CP).

[0280] According to various embodiments of the present disclosure, the controller 1230 may control the terminal to perform operations according to the above-described various embodiments.

[0281] Figure 13 The configuration of a base station in a wireless communication system according to an embodiment of the present disclosure is shown. Hereinafter, terms such as "... unit", "... part", etc. used below refer to a unit that processes at least one function or operation, and can be implemented by hardware, software, or a combination of hardware and software.

[0282] refer to Figure 13 The base station includes a communication unit 1310 , a backhaul communication unit 1320 , a storage unit 1330 and a controller 1340 .

[0283] Communication unit 1310 performs functions for transmitting and receiving signals via wireless channels. For example, communication unit 1310 converts baseband signals into bit streams according to the system's physical layer standard. For example, during data transmission, communication unit 1310 generates composite symbols by encoding and modulating the transmit bit stream. Furthermore, during data reception, communication unit 1310 recovers the received bit stream by demodulating and decoding the baseband signal.

[0284] Furthermore, the communication unit 1310 up-converts a baseband signal to a radio frequency (RF) band signal, transmits the signal via an antenna, and down-converts the RF band signal received via the antenna to a baseband signal. To this end, the communication unit 1310 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), and the like. Furthermore, the communication unit 1310 may include multiple transmit / receive paths. Furthermore, the communication unit 1310 may include at least one antenna array comprising multiple antenna elements.

[0285] In terms of hardware, the communication unit 1310 may include a digital unit and an analog unit, and the analog unit may include multiple subunits according to operating power, operating frequency, etc. The digital unit may be implemented with at least one processor (eg, a digital signal processor (DSP)).

[0286] The communication unit 1310 transmits and receives signals as described above. Therefore, all or part of the communication unit 1310 may be referred to as a "transmitter," a "receiver," or a "transceiver." In the following description, transmission and reception performed via a wireless channel are used in the sense of including the processing described above performed by the communication unit 1310.

[0287] The backhaul communication unit 1320 provides an interface for communicating with other nodes in the network. For example, the backhaul communication unit 1320 converts a bit stream sent from the base station to another node (e.g., another access node, another base station, an upper node, a core network) into a physical signal and converts a physical signal received from another node into a bit stream.

[0288] The storage unit 1330 stores data such as basic programs, applications, and configuration information for the operation of the base station. The storage unit 1330 may include volatile memory, non-volatile memory, or a combination of volatile and non-volatile memory. The storage unit 1330 then provides the stored data upon request from the controller 1340.

[0289] Controller 1340 controls the overall operation of the base station. For example, controller 1340 transmits and receives signals via communication unit 1310 or backhaul communication unit 1320. Furthermore, controller 1340 writes and reads data to and from storage unit 1330. Furthermore, controller 1340 may execute the functions of a protocol stack required by a communication standard. According to another exemplary embodiment, the protocol stack may be included in communication unit 1310. To this end, controller 1340 may include at least one processor.

[0290] According to various embodiments of the present disclosure, the controller 1340 may control the base station to perform operations according to the above-described various embodiments.

[0291] The methods disclosed in the claims and / or the methods according to various embodiments described in this disclosure may be implemented by hardware, software, or a combination of hardware and software.

[0292] When these methods are implemented by software, a computer-readable storage medium for storing one or more programs (software modules) may be provided. One or more programs stored in the computer-readable storage medium may be configured to be executed by one or more processors within an electronic device. At least one program may include instructions for causing an electronic device to perform methods according to various embodiments of the present disclosure as defined in the accompanying claims and / or disclosed herein.

[0293] The program (software module or software) may be stored in a non-volatile memory, which includes random access memory and flash memory, read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), magneto-optical disk storage devices, compact disc-ROM (CD-ROM), digital versatile disc (DVD) or other types of optical storage devices or magnetic tape. Alternatively, any combination of some or all of them may form the memory for storing the program. In addition, multiple such memories may be included in the electronic device.

[0294] In addition, the program can be stored in a storage device that can be connected to the electronic device through a communication network such as the Internet, an intranet, a local area network (LAN), a wide area network (WLAN), and a storage area network (SAN), or a combination thereof. Such a storage device can access the electronic device via an external port. In addition, a separate storage device on a communication network can access the portable electronic device.

[0295] In the above detailed embodiments of the present disclosure, the elements included in the present disclosure are expressed in the singular or plural, depending on the detailed embodiments presented. However, for the convenience of description, the singular form or plural form is appropriately selected according to the presented situation, and the present disclosure is not limited to elements expressed in the singular or plural. Therefore, an element expressed in the plural may also include a single element, or an element expressed in the singular may also include multiple elements.

[0296] While the present disclosure has been shown and described with reference to various embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents.

Claims

1. A method performed by a terminal in a wireless communication system, the method comprising: Identifying multiple authorized transmission resources for sidechain communication; performing transmission using a transmission resource from among the plurality of granted transmission resources; receiving an acknowledgment (ACK) of said sending; releasing one or more transmission resources among the plurality of granted transmission resources, which are resources used for retransmission corresponding to the ACK; measuring a channel occupancy rate (CR) at a time slot, wherein the CR is measured for resources excluding the released one or more transmission resources from among the plurality of granted transmission resources; and In case the measured CR does not exceed the CR limit used for congestion control, a physical sidelink shared channel (PSSCH) is transmitted.

2. The method according to claim 1, in, The CR is the total number of subchannels used for transmission in time slot [na,n-1] and subchannels authorized in time slot [n,n+b] divided by the total number of configured subchannels in the transmission pool of time slot [na,n+b], Wherein, a is a positive integer, b is 0 or a positive integer, and a+b+1=M, Among them, M is included in the resource pool configuration information, and Here, n, a, and b represent numbers associated with physical time slot indices.

3. The method according to claim 2, in, M is 1000 or 1000·2 μ time slots, and where μ is the index of the parameter set and is related to the subcarrier spacing (SCS).

4. The method of claim 1 , further comprising: The channel busy rate (CBR) is measured in time slot m, The CBR is the ratio of sub-channels in the resource pool whose sidelink received signal strength indicator (SL RSSI) exceeds a threshold. Wherein, the CBR is measured in the time window [mX, ml], Among them, X is included in the information of configuring resource pool. where m and X represent numbers associated with physical slot indices, and The CR limit is associated with the measured CBR.

5. The method according to claim 4, in, X is 1000 or 1000·2 μ time slots, and where μ is the index of the parameter set and is related to the subcarrier spacing (SCS).

6. The method according to claim 4, in, In case that a physical sidelink feedback channel (PSFCH) resource is configured, the PSFCH resource is excluded from the measurement of the CBR.

7. A terminal in a wireless communication system, the terminal comprising: transceiver; and A controller is coupled to the transceiver and is configured to: Identifying multiple authorized transmission resources for sidechain communication; performing transmission using a transmission resource from among the plurality of granted transmission resources; receiving an acknowledgment (ACK) of said sending; releasing one or more transmission resources among the plurality of granted transmission resources, which are resources used for retransmission corresponding to the ACK; measuring a channel occupancy rate (CR) at a time slot, wherein the CR is measured for resources excluding the released one or more transmission resources from among the plurality of granted transmission resources; and In case the measured CR does not exceed the CR limit used for congestion control, a physical sidelink shared channel (PSSCH) is transmitted.

8. The terminal according to claim 7, in, The CR is the total number of subchannels used for transmission in time slot [na,n-1] and subchannels authorized in time slot [n,n+b] divided by the total number of configured subchannels in the transmission pool in time slot [na,n+b], Wherein, a is a positive integer, b is 0 or a positive integer, and a+b+1=M, Among them, M is included in the resource pool configuration information, and Here, n, a, and b represent numbers associated with physical time slot indices.

9. The terminal according to claim 8, in, M is 1000 or 1000·2 μ time slots, and where μ is the index of the parameter set and is related to the subcarrier spacing (SCS).

10. The terminal according to claim 7, in, The controller is further configured to: The channel busy rate (CBR) is measured in time slot m, The CBR is the ratio of sub-channels in the resource pool whose sidelink received signal strength indicator (SL RSSI) exceeds a threshold. Wherein, the CBR is measured in the time window [mX, m-1], Among them, X is included in the information of configuring resource pool. where m and X represent numbers associated with physical slot indices, and The CR limit is associated with the measured CBR.

11. The terminal according to claim 10, in, X is 1000 or 1000·2 μ time slots, and where μ is the index of the parameter set and is related to the subcarrier spacing (SCS).

12. The terminal according to claim 10, in, In case that a physical sidelink feedback channel (PSFCH) resource is configured, the PSFCH resource is excluded from the measurement of the CBR.

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